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Bob McDavitt's ideas for sailing weather around the South pacific

20 May 2018

Sam is going negative

WEATHERGRAM

YOTREPS

Compiled Sun 20 May 2018

 

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

Weather regimes – SAM

Humans love finding patterns in things. Our orbit around the sun is so repeatable and predictable that we have “seasons”. Watching weather maps long enough, one can see that sometimes the same weather system (or extreme) may repeat in clusters. Last week I blogged about ENSO showing how flip-flops of the sea surface temperatures near the Galapagos are used to help decide if the weather pattern for the next season or so can be slotted into an El Nino or a La Nina regime. There are other cyclic anomalies on different time scales that we can use to help forecast if a weather regime may occur over the next few months.

 

Tonight, I think I’ll blog about SAM, the southern annular mode. This is a measure of the strength of the westerly winds in the Polar vortex - the ring of westerly winds that circle the planet between 50S and the Antarctic circle (66 S). The value of SAM alters the north-south movement of this vortex. A high positive value of SAM occurs when the air pressure over Antarctica are lower than normal, so that the westerly winds in the polar vortex are stronger than normal (note, the actual isobars over Antarctica are always higher than those in the polar vortex, but SAM works with the anomaly values, not the actual values). So, in a high positive SAM the polar vortex is shifted southwards, and pressures over NZ are higher than normal, with weaker than normal westerly winds and settled weather.

 

This can be seen at blog.metservice.com/Southern-Annular-Mode

 

However, when SAM is negative, the westerly winds in the polar vortex are weaker. This allows the polar vortex to spread outwards and thus northwards, so that west to southwest winds over NZ are stronger than normal.

 

SAM tends to flip-flop from positive to negative, and then to hold a phase for several weeks. When SAM jumps from positive to negative, it usually means that the polar vortex weakens, and the blob of cold air that has been sitting over Antarctica and getting colder over a number of weeks is able to burst outwards like a dam break. In other words: “a polar outbreak”.

 

I can not find any real time. or forecast data for SAM (which refers to differences  in pressure anomalies in the zone south of 50S), however a proxy of SAM is available, namely the AAO or Antarctic Annular mode (average 700hPa Z wind component 20S to 90S) as at  www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/new.aao_index_ensm.html

 

And forecast issued today shows that the AAO is about to have a negative jump later this week. This indicates a good chance of a polar blast somewhere (not necessarily affecting NZ). Looking at EC data of the surface air temperature forecast on windy and comparing Sunday with the forecast for Friday, it seems that the main change may occur around south and southeast of South America.

 

TROPICS

It was an interesting week with a tropical cyclone making landfall from the Red Sea onto Ethiopia. There’s also a tropical low in the Arabian Sea and it is expected to make landfall onto Oman, the horn of Africa, this week. And the Indian Monsoon is poised to strike a few days earlier than normal.

See timesofindia.indiatimes.com/india/monsoon-to-arrive-on-southern-coast-on-may-29/articleshow/64221885.cms

Next week a tropical low is expected to form in Gulf of Mexico and then make landfall on Florida next weekend.

 

If we compare the past week’s rain map with the previous week 

as at trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

we can see the increase in activity across the Indian Ocean. There are also been a build up in activity in the NE Pacific Ocean. And the South Pacific Convergence zone has weakened and split into two.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

No tropical depressions or troughs this week. The SPCZ is expected to weaken and retreat to be just between Solomon Islands and Tuvalu, maybe as far east as Tokelau. This provides a good weather pattern for yachts seeking to go westward this week.

 

Subtropical ridge (STR)

The STR is weak in the South pacific this week, and that allows a LOW to form in a passing trough near 30S 170W on Monday UTC and to deepen and it travels off to the SE reaching a peak 995hpa near 38S 140W on Wednesday, then fade and go east. May affect traffic between NZ and Papeete, avoid.

Next HIGH is still quasi stationary around Aussie Bight this week, but expected to poke out a tongue of a ridge along 30S from Wednesday, and this should expand be a High east of NZ from Friday. No squash zones.

 

Around Tasman Sea, NZ/Aus to tropics

Disturbed SW flow. One front travelling east over NZ on Tuesday/Wednesday., with SW swells reaching 7+m in eastern Tasman Sea.

Next front travelling east across NZ on sat/Sun 26/27 May. There is a chance that a HIGH may bud off from Southern Ocean and move into Tasman Sea after this front. In which case there may be a good weather pattern for departing from NZ to the tropics around Monday 28 May. Still too far away to be sure.

The SW swells from South Tasman sea should reach New Caledonia south coast with a burst over 3m from Thursday 24 May until early next week.

 

New Zealand to French Polynesia

Avoid departing when a front s near NZ as on Tue/wed or Sat/sun, otherwise Ok to go.

 

Panama to Galapagos /Marquesas

Panama area is surrounded by active shower activity this week, and there are SW winds, so nothing favourable on offer this week. If you do motor off, go SSE to 4N 79W then SSW to 2N 80W and then west to 2N 86W.

From Galapagos area to Marquesas, departure can be any time this week. Best path for wind and current is to motor/sail to 4 South 95W, then sail to 6S 127W and then go direct.

 

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If you would like more detail for your voyage, then check metbob.com to see what I offer.

Or Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

bob@metbob.com or txt 6427 7762212

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

13 May 2018

Bob Blog 13 May 2018

WEATHERGRAM

YOTREPS

Compiled Sun 13 May 2018

 

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

The state of the ENSO =  neutral

 

The Atmosphere:

El Nino and La Nina are opposite ends of the swing of an identifiable tropical influence on our seasonal weather: the La Nina, caused by cooler than normal seas along the equatorial eastern pacific. shifts the subtropical ridge away from the equator, and the El Nino, with warmer than normal seas, draws the subtropical ridge closer to the equator. Their comings and goings can last several months, maybe over a year, and so their status can be used to help forecast the weather for the coming season.

ENSO = El Nino/Southern Oscillation. The main parameter we watch from the atmosphere is the Southern Oscillation Index SOI (30 day running mean) as it sums up the whole weather pattern over the South Pacific in one number. It is based on the standardized difference in the barometer readings between Tahiti and Darwin, in other words it counts the average number of isobars between them on the weather map. When the SOI is more than plus one (standard deviation from its mean) for more than a month we call it a LA NINA event, and when it stays more than minus one we call it an EL NINO event.

For the past year the SOI has been mostly around plus 0.5 to plus 1.0, consistent with a weak but rather persistent La Nina. The subtropical ridge line has been further from the equator than normal, and trade winds were stronger than normal, but are now close to normal.

However, over the past month, the SOI has settled into a near zero state, and has a NEUTRAL status.

Neutral conditions may be as seen at www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=soi&p=weekly

(Note that in this graph on the vertical axis 10 = 1 standard deviation)

 

The Ocean:

NINO3.4 is a region in the eastern equatorial Pacific Ocean that acts as a heat storage area during an El Nino or becomes cooler than normal during a La Nina. This plays with the heat budget of the atmosphere and thus with the weather patterns.

At the farmonline web site we can see the trend in the sea surface temperature in the NINO3.4 area. The diagram shows the weekly temperature anomalies since Jan 2015, with the El Nino of 2015 looking like a hump on a camel. Since then there has been a cool period late 2016/early2017, then a warm period until July 2017, and then a cool period. That cool period seems to be coming to an end now, and the sea surface temperature are near normal.

Near normal as seen at www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=nino34&p=monthly

Waters beneath the surface are slightly warmer than normal

 

The International Research Institute of the Climate Prediction Centre compiles data from several ENSO prediction models. The model predictions for the Nino 3.4 SST anomaly is that the seas ae likely to gradually WARM during the rest of this year, but the mean of the predications has only warming to 0.5 above normal--- not enough to be called an El NINO event (but closer to it that we have been for a while).

See CPC/IRI predictions at iri.columbia.edu/our-expertise/climate/forecasts/enso/current/

 

Latest SST anomaly map shows the remains of a large blue pool of cooler water across the central equatorial Pacific. Also, there are warmer yellow waters appearing around the Galapagos.

See the Sea surface temperatures across the Pacific on 10May at www.ospo.noaa.gov/Products/ocean/sst/anomaly/index.html

 

TROPICS

 

There are a few tropical depressions in the north Pacific, but they seem to be weak this week.

The rain map for the past week shows peak rainfall occurring around Indonesia and Micronesia – see rmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

No tropical depressions or troughs this week. The SPCZ is expected to remain strong over Solomon Islands and then weak across Tuvalu and Tokelau, then strong from around Niue to Southern Cooks.

 

Subtropical ridge (STR)

HIGH to east of NZ is expected to remain quasi-stationary near 30S shifting from 160W on Monday to 140W by end of the week.

Next HIGH is expected to remain quasi stationary around Aussie Bight this week and may poke out a tongue of high pressure across the north Tasman sea late in the week. There should be a squash zone of strong SE winds forming in the northern coral sea from Tues 15 Nay, in response to this HIGH, and this squash zone may extend to New Caledonia/ southern Vanuatu next week.

 

Around Tasman Sea

Low 1 in mid Tasman Sea on Monday is expected to travel onto central NZ on Wednesday.

Low 2 should form southeast of Lord Howe on Wednesday and then travel onto northern NZ on late Thursday. After that there may be a trough passing over NZ on Sunday, and then, with luck, a swing to SW winds.

 

New Zealand to Tropics

There may be a gap between passing troughs lows with a departure from Northland on Tuesday, or late Friday, otherwise may need to wait until SW winds arrive next week.

 

New Zealand to French Polynesia

Northwest to westerly winds or an offer for a good start this week.

OK for sailing east, but don’t depart in the passing troughs on late Thursday.

 

Panama to Galapagos /Marquesas

For sailing from Panama, the upcoming week looks to have head winds from SW /S around 15 knots. May be better to stay put and hope for better next week.

From Galapagos area to Marquesas, departure can be any time this week. Best path for wind and current is to motor/sail to 4 South 95W, then sail to 7S 130W and then go direct

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

06 May 2018

Bob Blog 6 May 2018

WEATHERGRAM

YOTREPS

Compiled Sun 06 May 2018

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

ONE addition to last week’s Blog:

In French Polynesia: the PolyMagNet (Polynesian Magellan net) takes reports from vessels under way and is a good source for information exchange about anchorages, weather, services, events and activities. Twice daily on 8173 kHz at 18:00 and 4:00 UTC. Most of the 7 net controllers have been around French Polynesia for many years and have plenty of info to share with new arrivals.

 

Weather trend over the last month.

Sea Surface temperature anomalies as at end of April may be seen at www.ospo.noaa.gov/data/sst/anomaly/2018/anomnight.4.30.2018.gif

The SST anomaly image is now noticeably different from what it was at end of March.  With sea temperature sin the south Tasman Sea near normal, and the cool anomalies near the equatorial East Pacific much weaker than what they were.  In fact, some warm anomalies are starting to show near the Galapagos

The Gulf Stream off the east coast of North America continues to stand out as being much warmer than normal; this extra heat continues to energize storms over the northeast of North America into their spring.  Warm anomalies continue over much of the North Pacific, and that may be an indicator to a busy cyclone season there later this year.

During April there really was only one cyclone KENI which started near Vanuatu and peaked near Kadavu in southern Fiji. There was intense monsoonal rain over Fiji during the fortnight ahead of KENI, and the cyclone managed to take those clouds away. A full time-map of the season’s cyclones can be seen on wikipedia at en.wikipedia.org/wiki/2017%E2%80%9318_South_Pacific_cyclone_season

To see how the annual weather cycle and the seasons are working out, take a  look at the average isobar maps and their anomalies at www.esrl.noaa.gov/psd/map/images/fnl/slp_30b.fnl.html

The averaged-isobar map shows that subtropical ridges are looking good in both hemispheres.  The anomalies show that the HIGHS which were affecting NZ have been replaced by lows. The 1015hP (between blue and white) isobar has retreated during the last month to a smaller area over the NZ region, and can be seen shifting northwards over Australia.

The last 30 days of rainfall, and its anomaly, may be seen at TRMM at trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html

This rain map shows the “extra convergence zone” stretching from just south of Galapagos westwards to NW of Marquesas, but weaker than normal.  It also shows very dry conditions for the past month over northern Australia, and dry in Brazil.

 

 

TROPICS

The MJO oscillation is traveling across northern Australia this week, but is weak and not expected to do much.There is a weak tropical depression between Philippines and Micronesia and it is expected to shift off to the north this week.

 

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to remain close to where it was last week, with  its activity focused on a line stretching from Solomon Islands to Rotuma to Samoa to Southern Cooks.

Convection between Galapagos and Marquesas is expected to continue to weaken.   

Accumulated rainfall for next week from windyty.com.

 

Subtropical ridge (STR)

HIGH in the central Tasman Sea on Monday is expected to slowly travel is expected to slowly travel across northern NZ on Wed and Thursday, and then off to the northeast of NZ from Friday.  There is likely to be a squash zone of enhanced trade winds on the north side of this HIGH from Southern Cooks to Tonga early next week.

Around Tasman Sea

Deep Low from the Southern Ocean is expected to whip past southern NZ on Monday /Tuesday /Wednesday with strong westerly winds and large swells.

Another Low is expected to visit Tasmania on Thursday and then travel northeast into the central Tasman sea on Sunday and Monday. Avoid.

This Low should bring a S/SW wind change to the Southport to Noumea route on Sunday/Monday 13/14 May. The SE winds should return to the Noumea area by end of Tuesday 15 May, but it may be a few weeks before this pattern repeats, so this opportunity may be best on offer for a while for sailing from Southport to Noumea.

 

New Zealand to Tropics

Looks Ok for departures until Tuesday. After that, voyages going north  are likely to encounter northerly winds ahead of the next incoming trough by Friday.

New Zealand to French Polynesia

Light winds over northern NZ until Wednesday, and then northerly winds, which may be somewhat wet, but ok for sailing east.

 

Panama to Galapagos /Marquesas

For sailing from Panama, the upcoming week looks to be just light winds as far as 5North and then  SSW to SE winds.  Difficult.

From Galapagos area to Marquesas, departure can be any time this week. Best path for wind and current is to motor/sail to 4 South 95W, then sail to 7S 130W and then go direct

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

29 April 2018

Bob Blog 29 April

WEATHERGRAM

YOTREPS

Compiled Sun 29 April 2018

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

FIVE Amendments/additions to last week’s blog.

1.For those depending on Shortwave radio, remember that ZLM / Taupo Maritime Radio offer a continuous 7/24 Trip reporting service see www.maritimenz.govt.nz/about/what-we-do/safety-and-response/maritime-radio.asp

2.Northland Radio ZMH292 is owned and operated by Peter Mott and provides free of charge check in service on multiple maritime frequencies.  Note that Peter is NO LONGER a coordinator for PACSEANET.  Northland Radio tracks vessels and has a formal policy for dealing with a missed check in.   To use Northland Radio, operator requires Maritime Restricted Radio Operators Certificate (MRROC).  In the maritime radio service, the callsign is assigned to the vessel, and in New Zealand it starts with ZM. See northlandradio.nz/faq/

3.PACSEANET is a ham (amateur radio) network providing a free of charge check in service on amateur frequency 14300KHz USB in the 20 metre band (at 0300UTC).  To participate, operator needs to hold an Amateur Radio Operators Certificate (General class or above).  In the amateur radio service, the callsign is assigned to the licensed operator, so this is a different callsign from using a maritime callsign.  In New Zealand amateur callsigns start with ZL.   See pacseanet.com

4.EMAIL: To get a one-off weathergram via email:

Send an email to query@saildocs.com, no subject needed with message SEND nz.wgrm

Or Send an email  to yotreps@oceantracking.com, no subject needed with message WEATHERGRAM

 

To subscribe/unsubscribe to Weathergram

Via saildocs, send an email to query@saildocs.com, no subject needed with message SUB nz.wgrm   (or SUBSCRIBE nz.wgrm)

To cancel use CANCEL nz.wgrm or UNSUB nz.wgrm or UNSUBSCRIBE nz.wrrm

 

Via oceantracking, send an email to totreps@oceantacking.com, no subject needed with message JOIN WEATHERGRAM

To cancel use LEAVE WEATHERGRAM

5.And exciting NEW information

In association with www.cruisersat.net  we have set up two new ways to subscribe to WEATHERGRAM

long – (this has all the text), ideal for those using sat phone or HF SSB with sailmail/winlink and

short - for those using satellite messengers such as Garmin inReach—reducing the weathergram to 4 text messages.

To subscribe, email the message (no subject needed) "subscribe boatname" to weathergram@cruisersat.net for long version or to weathergram_short@cruisersat.net for short version. Boatname has to be unique and less than 20 characters long.

Once subscribed you will receive weekly weathergram in short format optimised for satellite messenger. You also will be able to send message to weathergram_short@cruisersat.net to ask Bob a question. The Boatname that you used when subscribing will be used to sign your message.

 

TROPICS

There is expected to be a weak MJO burst of extra energy travelling across Northern Australia to Coral Sea during the next two weeks.  This increases the risk of tropical cyclone formation.

One has formed in the Indian Ocean near 12S 88E between Cocos and Chagos Islands.

see www.metoc.navy.mil/jtwc/products/sh2118.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ has been reasonably quiet for past few weeks and is expected to gradually become more active over the next few weeks.  This week its activity should be focused on a line stretching from Solomon Islands to northern Vanuatu to southern Fiji.

The “extra convergence zone” around 5 to 7S from SW of Galapagos around 95W to 110Wis still there but fading. 

Accumulated rainfall for next week is seen at windyty.com.

 

Subtropical ridge (STR)

HIGH is expected to travel east this week, into central Tasman Sea south of Lord Howe island on Monday and Tuesday, then onto central NZ by Thursday and Chatham Islands by Friday, then off to the east.

Around Tasman Sea

Low is expected to cross northern NZ on Monday and then should move off to the east from Tuesday.   There is likely to be a SQUASH ZONE of strong SE winds just NE of NZ on Thursday between the new HIGH and the old Low.  This zone at its peak may have swell over 5 metres from the southeast so is worth avoiding.

Should be Ok to depart from northern NZ for the tropics after that squash zone, maybe on Thursday- such a voyage may encounter NE winds near 26S on Sun/Mon 5/6 may,  but these can be accommodated with waypoints.

 

New Zealand to French Polynesia

That Low travelling east asway from NZ with a squash zone on Thursday  is likely to delay a comfortable start from NZ until Thursday (but perhaps a start  from Auckland southwards may be done late Wednesday).  Those who departed last week should make their way to around 28S to get on the right side of this system.

 

Panama to Galapagos /Marquesas

For sailing from Panama, there is expected to be some moderate northerly winds early n the week and the best-looking day for departure is YUESDAY (local). Will need to work in with SW/S/SE winds from 5N onwards.

From Galapagos area to Marquesas, departure can be any time this week. Best path for wind and current is to motor/sail to 5or 6S 95W then go west to 125W and then go direct

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom.

Or, if email wasn’t from WordPress then send a reply email saying LEAVE or QUIT

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

22 April 2018

Bob blog 22 April , where to get weather info

WEATHERGRAM

YOTREPS

Compiled Sun 22 April 2018

 

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

Now that cruising sailors are on their final preparations for departing New Zealand / Australia for the warmth of the tropical Islands, ‘t’is is a good time to review the ways to obtain weather forecasts and/or ways to give position reports when at sea.

 

This may look like advertising, oh well, I only do it once a year. I advise those who are planning to depart to do their homework NOW, check these web sites and at least know what’s available. If I’ve forgotten something, please sting me with feedback. I have not canvassed any of the services listed below for promotion, so what you read now is purely my opinion, hopefully unbiased, except when I mention MetBob.

 

1. For those depending on Shortwave radio, all the Oceanic the HIGH SEAS forecast for the area SUBTROPIC from MetService is read out in English via ZLM at 0303hr, 0903hr, 1503hr and 2103hr NZST on 6224 and 12356KHz and at 0333hr, 1003hr, 1533hr and 2203hr NZST on 8297 and 16531 KHz.

 

The SUBTROPICS boundary changed on 13 December 2017 and the map  shows the new boundaries, see http://www.metservice.com/marine-surf/high-seas/pacific

 

2. With SSB there is access to the well-known PacSeaNet, offering a free-of-charge daily check-in service.

 

Your SSB license allows you to participate. Listen in at 0300UTC on 14300KHz in the 20 metre band.

 

Position reports are received and reported in the well-know YOTREPS format and displayed online. People onshore can listen in to the radio feed from the Pacseanet.com website. This net includes 17 listening station dotted between Australia and Alabama. They pride themselves in being able to listen to all yachts across the Pacific, reception conditions allowing.

 

3. Another SSB service is offered by Yachts in Transit or YiT. Patricia and David from Gulf Harbour Radio use the web site http://www.yit.co.nz \to keep track of boats that listen to their rollcall/weather service. FIRST register on this web site with your boat and crew details and then you simply email or radio in your position and conditions in preferably each day (send@yit.co.nz or via SSB). These reports are plotted on a webpage for you and your friends. The website offers a link to hear the radio online, and also to view all the South Pacific AIS data.

 

David is on air, daily except Sunday NZ date at 1915UTC/0715am NZST on ZMH286 on 8752Khz or 8779KHz or 8297KHz. Other frequencies have been allocated for far away yachts. He first takes in reports and then, at 1930UTC/0730am NZST does a round-up of the weather in each island group, including passage weather,  from east to west across the South Pacific,

 

4. Those who have access to email have several options:

 

Saildocs may be used to relay the text details of a webpage even if you only have email and no access to the Internet. They are able to send you the latest edition of MetService warnings by sending an email, no subject necessary, to query@saildocs.com with message

 

SEND http://m.metservice.com/warnings/marine

 

For subtropics use SEND http://tgftp.nws.noaa.gov/data/raw/fq/fqps43.nzkl..txt

 

For Fiji MetService High Sea use SEND http://www.met.gov.fj/aifs_prods/10140.txt

 

This system also works for Northland coastal sailors using a smart phone with email.

 

The formula to get a copy of the latest coastal area BRETT via email is to send an email to query@saildocs.nz with message SEND http://m.metservice.com/marine/coastal/brett

 

5. YOTREPS was originally setup to allow yachts with email access to file their position reports and receive weather data. It started back in 1997/1998 thanks to the inspiration of Mike Harris of SV PANGOLIN. He has retired from this now and it is being maintained by www.oceantracking.com You can still use it to file your YOTREPS by email to Reports@oceantracking.com and receive by email the Fleet code or my weathergram. I have had problems uploading my weathergram to them over last few weeks,but should be able to get that sorted.

 

6. Some satellite phones now provide wifi/bluetooth that allows nearby smart phones to connect to the Internet via an ap.  One of the smart phone aps that make good use of this feature is www.predictwind.com which supplies forecast model data, Observations, and, at the Professional Account level, tools for routing and comparing departure dates. It also has a position tracking tool.

 

And, I think, Windy.com also has a position tracking option via an ap.

 

7. Some satellite phones now allow text messages, even if they don’t allow emails. Text messages are all that is needed by some web-based position-tracking sites such as YellowBrick or Garman InReach or Bluewater Tracks.

 

Of course, the AIS system allows tracking via Satellite (without  “phone”), but the display online of that data is restricted by subscription to sites such as marinetraffic.com.

 

8.  A new provider is cruisersat.net— using sophisticated filters to reduce the text of  a weather forecast /warning to a pithy TEXTABLE alternative, free of charge to the average user of text on any satphone. They also have a forecasting option based on NOAA weather models. They have asked me if I would like to make my Weathergram available via their system. If you’d like this, please provide me with some feedback, and I’ll decide accordingly.

 

9. MetBob. Ahhh yes—— I am available to help with emails or texts covering weather to help with departure date planning, waypoints for the voyage and updates along the way.

 

Here is a copy of my terms and services for your consideration:

 

There are three ways I, as retired MetService weather ambassador, may further help you with weather information:

 

Weathergrams (free), MetPack (a book), and voyage forecasts (charges apply).

 

a: Weathergrams: This is a Weathergram. I occasionally (usually on a Sunday) email out my evaluation of weather patterns around the South Pacific, aiming on what weather is worthwhile to AVOID. These are great for helping to pick windows of opportunity for good sailing weather.

 

Internet site is weathergram.blogspot.com .

 

Illustrated edition is at metbob.wordpress.com/

 

b: Mariners MetPack for Southwest Pacific: This book is available from www.boatbooks.co.nz/weather.html#23104.

 

It is also online free of charge at about.metservice.com/our-company/learning-centre/mariners-met-pack/

 

Pass that around,  as this link, in  itself, is worth a free drink anywhere, so I’m told.

 

c: Voyage Forecasts: When available I can compile and email weather forecasts for your voyage on the high seas in the South Pacific. Charge is $10NZ per 5 minutes with NO Goods or Sales tax component. Anything taking less than 5 minutes is called a quickie and sent without charge.

 

Preparation – Takes me 5 to 10 minutes (usually less than 5 so no charge), to do a weather outlook picking departure day that avoids rough weather.

 

Departure – Takes me 30 to 40 minutes to do a full voyage forecast, see http://www.metbob.com for an example.

 

Updates – Takes me around 10 to 20 minutes. When underway, to get an update email or TXT me a position report and ask for an update.

 

I tab together the charges during the voyage and email you an Invoice via PayPal AFTER the voyage.

 

This may be settled via cheque or securely online by credit card on PayPal –

 

My PayPal name is bob@metbob.com.

 

Forecast limitations: Weather is a mix of pattern and chaos. A forecast is just an idea from isobar/computer patterns, and chaos comes from the real world to unravel the pattern.

 

I combine together the data from a combination of several wind/wave/current models/patterns and use a routing program www.expeditionmarine.com/about.htm to come up with what I think is the most comfortable looking voyage, reducing it to a series of simple waypoints for you to follow.

 

My ideas should only be used as a supplement to official sources, not a replacement. My liability is limited to the value of my invoice. Under the Law of the Sea (UNCLOS) and GMDSS regulations: the skipper is responsible for navigation of the vessel..

 

End of where-to-get-weather  review==============================================

 

TROPICS

 

We are having a quiet period at present. The MJO phase diagram can be used to detect further activity, if you know how to read it. Basically, it says the next dose of activity in the western parts of the South Pacific may be in the Northern Coral Sea in early May, but does not look to be marked enough to do much. We shall see.

 

MJO Phase diagram is seen at www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is going thru a quiet period at present, and should be weaker this week than last week.

Even so, at the southeast end of the SPCZ a LOW is expected to form around 30S 155-160E around 26/27 April at the end of this week. This affects yachts sailing from NZ to French Polynesia but may help them follow the rhumb line rather than do the “east then left: triangular route.

There is still an “extra convergence zone” around 5 to 7S from SW of Galapagos around 95W all the way to west of 180. It’s not extreme but is worth avoiding. It shouldn’t really be there in late April, but c’est la vie: maybe it marks the dying part of the recent La Nina.

 

Accumulated rainfall for next week may be seen at windyty.com.

 

Subtropical ridge (STR)

It’s the second and final week of the school holidays in NZ, and all parents are watching the weather map for a STR to cross New Zealand, Yes, there is one. And it looks like it should travel east across the North Island on Wednesday and Thursday—something only possible in Autumn. Wednesday is ANZAC day, a day to remember war victims/heroism—and a new Peace Memorial (rather than a war memorial) is opening in Porirua, Wellington.

So, parents, you have been given your window, don’t muck it up.

 

As for cruising sailors, anyone attempting an early departure from northern NZ is likely to be thwarted by onshore NE wind after that mid-week High and should wait until around 1 May when the southerly wind son the backside of the following low decrease. That gels with the nominal 1st of May.

 

Around Tasman Sea

Problems. A low is expected to form in a trough of New South Wales, south of Lord Howe Island. This is expected to travel across North island don Friday /Saturday, mucking up last weekend of school holidays.

Opportunities: That low should kill the trade winds between New Caledonia and Australia and offer OK conditions, at least for motoring, from Australia to New Caledonia.

 

Panama to Galapagos /Marquesas

For sailing from Panama, there is expected to be some moderate northerly winds on Monday. After that the winds are likely to switch to light southwesterly. So, if you are waiting to go, go Monday.

As from getting from Galapagos to Marquesas this week, first motor sail to around 5S 95W (may also find a tail current), then can sail direct, but that “extra” convergence zone continues to straddle 5 to 6S from about 90W to beyond 120W. Something to avoid.

 

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom. Or, to unsubscribe, send a reply email saying LEAVE.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

15 April 2018

Bob Blog for 15 April

WEATHERGRAM

YOTREPS

Compiled Sun 15 April 2018

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

TROPICS

IRIS: There were still convective squalls in the remains of IRIS in the Coral sea until last Thursday, about four weeks after it started.  

KENI: Tropical cyclone KENI travelled over Kadavu on Tuesday 10 April, and then went southeast out of the tropics.  As it left the tropics, KENI was captured by the jetstream belonging to an approaching upper trough.  This ripped the upper part of the tropical feature to bits, but the surface low wasn’t affected much, as evidenced by (modelled) isobars around the centre.  This is shown in an animation I took using Windy, looking at the EC model. 

 To see this, visit youtu.be/6c4EP-NcrcI, entitled KENI and the Jets.

This animation also shows the squally trough that crossed North Island on Tuesday 10 April and how clouds in this feature were able to bring twisting winds and tornadoes to New Plymouth, and, a few hours later, were able to bring jetstream like-winds downwards as damaging downbursts that fanned Auckland on Tuesday evening. The peak gust at the airport was over 80 knots and the gale lasted around 14 hours. My email server was knocked offline for a day.  Anyone who sent me an email last Wednesday was sent a bounce message that may have said things like “domain doesn’t exist” or even “has been blacklisted”. Charming, I don’t think.

Tropical Outlook for remainder of the month:

The next MJO (or pulse of enhanced convection) is still building in the Indian Ocean and now looks like it will reach Western Pacific towards the end of April.   By then the nominal cyclone season will be ending. And until then it looks as if the South Pacific should be in a period of quieter convection. So, the signs are now pointing to an end of this cyclone season in the South Pacific (but North Australia may get one more opportunity towards end of the month). 

Now that cruising sailors are preparing for their voyages to the tropics, if you wish to join an organised rally, well the Down Under crowd are in full swing arranging the GO EAST Cruisers rally from the Gold Coast (starting around 14 May) to New Caledonia.  For more info see www.downunderrally.com/about-go-east/ The Island Cruising New Zealand are organising a rally from Opua to Tonga, but registration for this is now full. If you’d like to join the waiting list then see www.islandcruising.co.nz/?page_id=3896

 

WEATHER ZONES

SPCZ

The SPCZ is weaker and thinner than last week, and is expected to stretch from eastern Solomon Islands, to Wallis/Futuna and between Samoa and Tonga to Austral islands.

There is still an “extra convergence zone” around 5 to 8S from SW of Galapagos around 100W to northeast  of the Marquesas around 120W.

Subtropical ridge (STR)

HIGH between Fiji and NZ tonight is travelling away to east along 30S and should fade away by Wednesday.

Next HIGH is expected to form in central Tasman Sea on Tuesday and Wednesday and then travel northeast across northern North Island by the 21/22 weekend.  This system should flatten the large swells that are in the Tasman Sea at the start of the week, so that there may be a reasonable opportunity for some trans-Tasman sailing.

And, now that these Highs are travelling east along 30 to 35S, this offers a reasonable opportunity for vessels seeking an opportunity to sail from NZ to French Polynesia.

 

Around Tasman Sea

Some deep lows are expected to be travelling east along 50S in the Southern Ocean, so there should be an enhanced westerly flow across central and southern NZ this week.  The Southern Alps are consequently expected to get more rain than the SPCZ.

Panama to Galapagos/Marquesas

For sailing from Panama,  there is expected to be some moderate northerly winds on Tuesday/Wednesday/Thursday.   After that the winds are likely to switch to light southwesterly.  So, if you are waiting to go, take this opportunity.

As from getting from Galapagos to Marquesas this week, first motor sail to around 5S 94W (may also find a tail current), then can sail direct, but that “extra” convergence zone continues to straddle 5 to 6S from about 100W to 120W. Something to avoid.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com

To unsubscribe, send a reply email saying LEAVE.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

08 April 2018

Bob Blog 8 April

 

WEATHERGRAM

YOTREPS

Compiled Sun 8 April 2018

 

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

One of my blog followers, who uses saildocs to receive this weathergram, informed me last week that he received a spam email using my email address bob@metbob.com. Has anyone else received anything?

 

Fifty years ago, on Tuesday 10 April, a storm from the tropics met with a cold front just off Wellington and re-intensified. As a result, the Inter-island ferry WAHINE sunk and 51 lives were lost that day. Our house lost its chimney. The storm was terrifying and tragic but also awesome and awful. It inspired me to study weather as a career.

See nzhistory.govt.nz/culture/wahine-disaster

 

For those of you who are now planning to depart Australia or NZ for the tropical Islands (after the cyclone season) and would like as assisted passage: here is some good news:

 

Island Cruising New Zealand are organising a rally from Opua to Tonga. Sadly the registration for this is now full, but if you’d like to join the waiting list then see www.islandcruising.co.nz/?page_id=3896

 

And the Down Under crowd are in full swing arranging the GO EAST Cruisers rally from the Gold Coast starting around 14 May  (well after the Commonwealth Games)  to New Caledonia. For more info see www.downunderrally.com/about-go-east/

 

So, when will this cyclone season finish?

 

During the last week of March and first few days of April an MJO event travelled across the South Pacific. An MJO event is the passing of a burst of tropical convection, called a Madden Julian Oscillation or MJO. This has now gone, but there is still some “left over” tropical cyclone activity sorting itself out (see below). The interesting thing is that some computer models are forecasting the MJO oscillation to travel more quickly that normal around the world so that the next one may reach South Pacific in late April, perhaps triggering another cyclone. There does seem to be a lot of variation in the MJO models— and if the next MJO is weak or arrives after late April, then that increases the chances that this is the last week of cyclone activity for the season.

 

MJO phase may be seen at www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml

 

TROPICS

After three weeks, IRIS is now fading away in the Coral sea. It still has a low-level circulation of wind, but that’s about all. Associated onshore winds on the south of IRIS have been bringing showers to the Gold Coast for the Commonwealth Games. That’s normal weather for them.

 

Near 17S 170E, around 100 miles ENE of Port Vila is tropical depression TD13F (Fiji Met) or 17P (Guam) continues to be a worry. Its central pressure is 998hPa, and nearest barometer at Port Vila is this evening rising rather than falling.

However, the system has persistent convection and is well placed for development and may well get named soon. It is currently doing a loop and is expected to travel southeast, skirting Fiji on Tuesday.

 

Fiji has been experiencing monsoonal rain during the past week with flooding in Labasa and Western division, and two dead, one missing. If this depression does visit Fiji over next few days it will be most unwelcome- and bring some wind as well as further rain— a week or so after JOSIE’s Easter visit.

See www.radionz.co.nz/international/pacific-news/354442/two-dead-one-missing-in-fiji-as-bad-weather-continues

 

A comparison of the weekly rain map trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

from last week with the previous week shows IRIS in the Coral Sea and the monsoonal rain over Fiji. There has also been a river of moisture extending from west of Hawaii to the USA west coast, a “pineapple express”. The “equinoctial convergence zone” between south-of-Galapagos and north-of-Marquesas is still there.

 

What is a Pineapple express? see denver.cbslocal.com/2018/04/07/pineapple-express-northern-california/

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is still intense and is expected to persist over Fiji to Samoa to Southern Cooks/French Polynesia his week. Avoid

 

Subtropical ridge (STR)

HIGH forming to NE of NZ on Monday is expected to travel off to the east along 35 to 40S this week.

Next HIGH is different, because it has budded off the ice shelf and the southerly winds on its leading edge are expected to shovel cold air onto New Zealand on Tuesday and Wednesday, dropping air temperatures to lowest so far this year. This HIGH should travel north across the Tasman sea on Wednesday and then east along 30S to north of NZ on Thursday and Friday.

Third HIGH this week is expected to form in south Tasman sea on Thursday and travel onto northern NZ by Saturday.

 

Around Tasman Sea

By mid -week the isobars are likely to be southerly from 60S to Fiji/17S. This cold outbreak is likely to be accompanied by large southerly swells from the Southern Ocean, well over 5 metres in places, but with a long period. It may trigger three smaller lows.

Another intense front is expected to cross southern NZ on Thursday and deepen into a LOW east of NZ on Friday 13th.

It isn’t really a good week from departing NZ, but those Highs in the Tasman Sea may allow a reasonable voyage between Australia and NZ.

 

Panama to Galapagos /Marquesas

Only light variable winds are forecast between Panama and Marquesas this week (and next week). The “equinoctial” convergence zone continues to straddle 5S from about 95W to 120W. Something to avoid.

For those trying to get from Galapagos to Marquesas, motor sail to 5S 95W and then go direct, may need to drop to 6S at times to avoid convection.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com,

To unsubscribe, send a reply email saying LEAVE.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

01 April 2018

Bob Blog 1 April

WEATHERGRAM

YOTREPS

Compiled Sun 1 April 2018

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

Weather trend over the last month.

Sea Surface temperature anomalies as at end of March may be seen at www.ospo.noaa.gov/data/sst/anomaly/2018/anomnight.3.29.2018.gif

The SST anomaly image is much the same as t beginning of March, it still shows cooler than normal seas along the equatorial East Pacific, but somewhat weaker.

The Tasman sea warm zone, which has been there since November and which has been breaking records, is still there.  Looks like it may prolong autumn over NZ.

And the Gulf Stream off the east coast of North America continues to stand out as being much warmer than normal; this extra heat has energized storms over the northeast of North America, bringing regular winter snow and floods to Boston. Looks like there are more to come.    

South Pacific Cyclones during March have started near Vanuatu area. HOLA wen t SE, LINDA went south, IRIS went SW and bounced off the jetstream and is now in the coral Sea. And the most recent, JOSIE, has brought killing rains to western Fiji and is expected to go SE then SSE.

 

The cyclones we have so far this season my be seen on  time line at  en.wikipedia.org/wiki/2017%E2%80%9318_South_Pacific_cyclone_season .

 

To see how the annual weather cycle and the seasons are working out, take a look at the average isobar maps from www.esrl.noaa.gov/psd/map/images/fnl/slp_30b.fnl.html

The low pressures over Europe has encourages cold easterly winds, and the above maps show that this anomaly stretches from Siberia to Boston.  Ouch.

The anomaly map shows that lows are likely to form in the Micronesia to Hawaii area.

The subtropical ridge over the South Pacific has stayed in much the same place and intensified, typical or early autumn.  The 1015hP (between blue and white) isobar now covers all of South Australia and Tasman Sea.   Isobars southwest of NZ are closer together, an indication that the westerly winds of the roaring 40s are intensifying.

 

The last 30 days of rainfall, and its anomaly, as seen at TRMM, are at trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html

In the Pacific, the drier than normal zone along the equator is typical of a La Nina episode.

 

TROPICS

IRIS lost its upper clouds in a jetstream last week, but its lower circulation was able to hold together and was diverted northwards over warm Coral Sea.  It has rejuvenated, and the label IRIS is good enough to refer to this entity as it may re-intensify. It is expected to meander SW then NW this week but not expected to make landfall. It contains squally rain.

 

JOSIE has been bringing heavy rain to Fiji in the days leading into Easter and was named on Easter Saturday.  Its rain has brought a death toll of at least 2, and 3 missing in Fiji so far:fijitimes.com/story.aspx?id=440188

It is expected to travel SE and fade well to east of New Zealand.

 

JELAWAT formed over Micronesia during last week and is traveling NE into the North Pacific.

A comparison of the weekly rain map from last week with the previous week shows the path of the cyclones and some heavy rain north of Hawaii.  The “equinoctial convergence zone” between south-of-Galapagos and north-of-Marquesas is still there.  See trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is reforming on the back end of JOSIE, covering southern coral sea and northern Vanuatu /Fiji. with an arm extending to Southern Cooks.

Another tropical Low is likely to form over Vanuatu on Thursday/ Friday and follow JOSIE to south of Fiji during weekend of 7 and 8 April.

 

Subtropical ridge (STR)

HIGH over northern NZ today Sunday is expected to travel off to the east between 35 and 40S.  

New HIGH is expected to travel across southern New South Wales on Wednesday and stall in the central Tasman Sea for the remainder of the week.  This High should steer JOSIE clear of NZ.

 

Around Tasman Sea

Between those two Highs, a FRONT is expected to travel over South Island on Monday and fade over North Island on Tuesday.  A more intense front is expected to travel over NZ early next week around 9 and 10 April.

 

Panama to Galapagos /Marquesas

Today’s data is showing that the recent period of good winds for departing Panama is now expected to be replaced by light winds from around mid-week.   The coming period of light winds may last for a while, at least until end of next week.

The “equinoctial” convergence zone continues to straddle 5S from about 90W to 120W. Something to avoid.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom.

Or, if email wasn’t from WordPress then send a reply email saying LEAVE.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

25 March 2018

Bob Blog for 25 March 2018

WEATHERGRAM

YOTREPS

 

Compiled Sun 25 March 2018

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

=======================

 

TROPICS

Cyclone MARCUS, after hitting Darwin as a CAT 2 system last week, intensified to a CAT 5 cyclone, but is now weakening.

See mashable.com/2018/03/21/cyclone-marcus-strongest-storm-2018/#GOM9uShzdiqQ

 

NORA has moved onshore from the Gulf of Carpentaria onto northern Australia and is now weakening.

 

IRIS formed over Vanuatu is the past few days and is now travelling south across the Coral Sea. It is likely to encounter a jetstream on the northeast side of an upper trough by mid-week. This may well rip IRIS apart, but some models are indicating that the surface part of this system may then travel west or east for a few more days.

 

And a cyclone is now starting to form in Micronesia and is expected to travel north then northeast this week

 

A comparison of the weekly rain map from last week with the previous week shows the path of the cyclones and some heavy rain around Hawaii. Notice that the “equinoctial convergence zone” between south of Galapagos and Marquesas is still there.

 

See trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

 

The SPCZ is at the south-end of its range this week, covering New Caledonia, Fiji and Southern Tonga/Niue.

 

A LOW is expected to form on the SPCZ near 25S to south of Southern Cooks by mid-week, and then to travel off to the southeast.

 

Subtropical ridge (STR)

Large HIGH to east of NZ that dominated proceedings last week is expected to finally shift off to east along 45S.  There is likely to be a squash zone between this HIGH and the Low forming south of Southern Cooks.

New HIGH is expected to form in central Tasman Sea on Monday and Tuesday, then travel across central NZ on Holy Thursday and Good Friday. Then it is likely to fade east of NZ on Holy Saturday.

 

Around Tasman Sea

Low crossing south of Tasmania on Monday is likely to bring a gale to Bass Strait. As a consequence, the start of the Melbourne to Osaka yacht race has been delayed. Associated front is expected to cross South Island on Tuesday, and as a weak front over North island on Wednesday.

Another front is expected to travel onto South Island on Holy Saturday.

 

Panama to Galapagos /Marquesas

Today’s data the weather pattern is looking good for a departure from Panama any day this week.

Between the south of Galapagos and Marquesas there is the “equinoctial” convergence zone, mainly along 5 to 6S between 90W and 115W. Something to avoid.

 

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212

I’m on Facebook at /www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom.

Or, if email wasn’t from WordPress then send a reply email saying LEAVE.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

18 March 2018

Bob Blog 18 March 2018

WEATHERGRAM

YOTREPS

Compiled Sun 18 March 2018

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

=======================

A couple of weeks ago I mentioned Jimmy Cornell’s “Ocean Atlas”.

There is also an online site at www.pitufa.at/oceanwinds/  which gives the monthly averaged wins from scatterometer (satellite-derived) wind data.   The data only covers 5-10 years, so is of low quality but is well presented, so you can pan and zoom around the world’s oceans.  Left click on a spot to get a wind rose, and adjust the month at top right to quickly compare one month with another.  This offers a quick way for you to absorb the big picture.

 

EQUINOX

The Latitude of the overhead sun changes throughout the year. The sun is directly over the equator at Tuesday 20 March 1615 UTC (Wednesday morning 5:15am NZDT), and that’s the equinox.  Australia, New Zealand and Samoa switch from Daylight or Summer time to standard time on 1 April.

World Met Day

Another day worth noting this week is World Met day on 23 March. This marks the anniversary of the opening of the World Meteorological Organization as part of the UN in 1950.  This year’s theme is WEATHER READY, CLIMATE SMART, WATER WISE

See  public.wmo.int/en/resources/world-meteorological-day/wmd-2018

TROPICS

HOLA was briefly followed by LINDA in the Coral Sea, but LINDA was blown apart by strong upper winds.

Cyclone MARCUS hit Darwin as a CAT 2 system yesterday.

See www.theguardian.com/australia-news/2018/mar/18/cyclone-marcus-leaves-tens-of-thousands-in-darwin-without-power-or-drinkable-water

It’s been a while since Darwin has had strong winds, so the trees were easily damaged.

Possible future track for MARCUS may be seen at www.tropicaltidbits.com

In the South Indian Ocean ELIAKIM is moving southeast away for Madagascar.

 

A comparison of the weekly rain map from last week with the previous week, as seen at trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif, shows the path of cyclones HOLA and MARCUS, and a build-up of activity near Micronesia.  There is also a continuation of the “equinoctial convergence zone” between Galapagos and Marquesas.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to remain strong this week and extend all the way across the South Pacific from Solomon Islands to French Polynesia, but with small gaps.

A subtropical low is expected to form near 30S in the trough south of Southern Cooks by mid-week and then travel southeast.  This may become a recurring pattern over the next few weeks, affecting the route between NZ and Tahiti. So, anyone planning this route in next few months should watch how this low behaves.

 

A tropical low is expected to form in the Coral Sea late in the week, and probably travel to the southeast.

 

Subtropical ridge (STR)

Large HIGH east of NZ at start of the week should keep a ridge of settled weather over northern NZ until end of Tuesday. 

New HIGH is expected to travel east across Tasmania from Wednesday and to south of South Island on Friday/Saturday and the northeast to the east of NZ by early next week.

 

Around Tasman Sea

Trough from the SOUTHERN OCEAN is expected to move onto South Island on Tuesday and then stall near central and northern NZ with cold southerly winds from Wednesday to Friday.

 

Panama to Galapagos /Marquesas

Today’s data suggest a departure from Panama before 21 March may be better than  21 March onwards, because the winds near 6N are expected to fade away from 24 March.

Between Galapagos and Marquesas there is the “equinoctial” convergence zone, mainly along 4S between 90W and 105W.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

If you would like more detail for your voyage, then check metbob.com to see what I offer.

Feedback to bob@metbob.com or txt 6427 7762212 or www.facebook.com/metbobnz/

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom. Or send a reply email saying LEAVE.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

11 March 2018

Bob Blog for 11 March 2018

WEATHERGRAM

YOTREPS

Compiled Sun 11 March 2018

 

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

=======================

Just a brief blog this week, for I’m on holiday, touring the South Island.

 

TROPICS

We are waiting for the remains of HOLA to skirt past northern NZ on Monday/tomorrow. The dangerous quadrant of a southern hemisphere cyclone is the one that is FRONT LEFT of the travelling centre, where the speed of movement adds to the spinning winds. The faster the speed of movement, the greater the danger. It looks like the dangerous quadrant of HOLA may miss NZ

See www.msn.com/en-nz/news/national/cyclone-hola-may-not-make-nz-landfall/ar-BBK5vGt?li=BBqdk7Q&ocid=iehp

 

Around northern Australia, the monsoonal rain is continuing, and a Low is expected to form in the Coral Sea this week and drift somewhat to the south. Another Low is expected to form in the Gulf of Carpentaria, and travel west, maybe towards Darwin.

 

The rain map for last week, at trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif,  shows the track of HOLA.  It also shows the formation of a convergence zone along 5South between Galapagos and the equator. This convergence zone tends to form around this time of the year because this is when the sun is directly overhead these latitudes. Now that it has formed, it may last for several weeks, and so I’ve nicknamed it the Equinoctial Convergence Zone.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to remain strong this week and help produce a Low in Coral Sea.

 

Subtropical ridge (STR)

HIGH is expected to form in central Tasman Sea on Tuesday/Wednesday and travel across northern NZ on Thursday.

Next HIGH is expected to form in Tasman Sea on Friday and move travel across central NZ on Sat/Sunday.

 

Around Tasman Sea

Remains of HOLA should skirt around the NE of NZ on Monday, followed by a Southwest flow on Tuesday.

After a cold front over South Island on Thursday and North Island on Friday, there may be a strong easterly flow over northern NZ on the south side of a Low.

 

Panama to Galapagos /Marquesas

A departure before Thursday may encounter a longer than normal period of light winds from 80W to 110W.

A departure after Thursday 15 March may have slightly better winds as far as 82W, maybe 85W.

 

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04 March 2018

Bob Blog 4 March

WEATHERGRAM
YOTREPS
Compiled Sun 04 March 2018
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

For those who like to plan their voyages across the ocean well in advance, and decide to the nearest month when to reach where, according to the averaged weather, I recommend the NEW edition of Jimmy Cornell's "Ocean Atlas". JC has updated his popular atlas and sent me a demo copy as he asked me to review the South Pacific part. See cornellsailing.com/
I particularly liked the detail that has gone into the pilot charts, and the text on various matters such as weather and currents... and an interesting chapter about the various names for the winds around the world. The passage maps make this a valuable primary resource for all cruising sailors.
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Weather trend over the last month.
Sea Surface temperature anomalies as at 1st March may be seen at www.ospo.noaa.gov/data/sst/anomaly/2018/anomnight.3.1.2018.gif

The SST anomaly image still shows cooler than normal seas along the equatorial east pacific, but these are less than last month. So this La Nina is started to fade away in the Ocean.
The Tasman sea warm zone has been there since November and gave us our warmest ever measured summer. It too is starting to weaken. Cyclones during February have stirring the surface layer of the sea and mixed it with cooler temperature from underneath. This zone is still flecked with red spots as is much of the 40S latitude in the southern hemisphere. Interesting.
And the Gulf Stream off the east coast of North America is standing out as being much warmer than normal, this extra heat should energize storms over the northeast of North America.
To see how the annual weather cycle and the seasons are working out, check the average isobars for past 30 days and their anomaly isobar maps from www.esrl.noaa.gov/psd/map/images/fnl/slp_30b.fnl.html

FEBRUARY
The "beast from the east" has only been active for the past week and doesn't stand oy=ut in these 30-day averages.
The subtropical ridge over the South Pacific is still in place much as it was in January. The 1010hP (between light and dark blue) isobar has shifted north onto southern NZ, indicating that the northward seasonal shift of the subtropical ridge is already happening, and NZ should see the return of South/Southwest winds penetrating further north during March.
The last 30 days of rainfall, and its anomaly, is seen at TRMM at trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html

In the Pacific, both the ITCZ has an average position last month further AWAY FROM the equator than normal. This is typical of La NINA. Interestingly, the South Pacific convergence zone is somewhat north of normal (except where GITA visited Tonga, and tropical lows drenched southern parts of French Polynesia). In the Atlantic, the ITCZ is closer to the equator than normal.
TROPICS
TC DUMAZILE has formed in the Indian Ocean, indicating that a new pulse of MJO energy is forming there. It is off the east cat of Madagascar and expected to go southeast into the mid-latitudes and its remnants may reach 50S/Port-aux-Francais.

There is a tropical low between Fiji and Vanuatu. Some models have it deepening when it travels southwest towards Erromango/Tanna in southern Vanuatu on Wednesday/Thursday, and then recurving and travelling quickly southeastwards to east of NZ by late Saturday/Sunday 10/11 March.
To keep an eye on this feature follow Fiji Met Service at www.met.gov.fj/aifs_prods/20036.txt
Looking at the weekly rain maps from last week as at trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif and the week before, we can see an increase in the intensity of the rain around Fiji to Niue, and in the ITCZ across the Pacific.
Around northern Australia, the monsoonal rain is continuing.

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This week is the thirtieth anniversary of Cyclone BOLA affecting New Zealand in March 1988. It hovered off to the north of NZ for three days when the moist eastly winds on its south side hammered our Gisborne coast. It was held there by a large HIGH east of NZ. It seemed to hold onto a Cyclone category according to the Saffir-Simpson scale until it got south to around 42S (As seen at Wiki Project TC tracks at en.wikipedia.org/wiki/Cyclone_Bola) ---- but really, as soon as it left the tropics it transited into a mid-latitude depression - We dropped the word "tropical" and kept referring to it as "Cyclone Bola" to help the broadcasting media deliver the severity of the weather forecast to those at the receiving end.
As seen at blog.metservice.com/Cyclone-Bola
I was one of the lead forecasters on duty at the time. I can remember that we allowed TV reporters to do live interviews from our forecast room, maybe for the first time?.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is expected to strengthen this week and a pulse of convection is likely to travel southwards with that tropical low as it moves to Vanuatu and then Southeast to east of NZ.
However, the rain accumulation map at windy.com suggests that this pulse of convection may weaken a lot as it leaves the tropics.

Subtropical ridge (STR)
HIGH to east of NZ was unbudging last week but is moving is expected to move off to the east this week. It would have been interesting if that low from Vanuatu had formed last week--- its trip to the southeast would've been blocked and it may have taken a path like Bola. However, Bola had more moisture to start with.
Next HIGH is expected to form east of Tasmania on Tuesday and travel across southern NZ on Saturday and then weaken over the North Island on Sunday, helping to direct the low from the tropics harmlessly off to east of North Island.

Around Tasman Sea
Trough over the North Island on Monday. Front reaching the South Island on Monday is expected to be drawn to the northeast on Tuesday and deepen into a secondary Low northeast of North Island on Thursday and Friday. There may be strong winds around the south and west sides of that secondary low.

Panama to Galapagos /Marquesas
Looks Ok to depart Panama from Monday to Thursday this week, after that the voyage may encounter a longer than normal period of light winds from 80W to 110W, and it may be better to wait until mid-next-week.

Britian
The cold air that reached Britain last week had been dislodged from the Arctic circle by an freak heat wave in the Arctic circle. See www.thetimes.co.uk/article/beast-from-the-east-caused-by-freak-arctic-heatwave-h3krhw8r5
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If you would like more detail for your voyage, then check metbob.com to see what I offer.
Feedback to bob@metbob.com or txt 6427 7762212
I'm on Facebook at /www.facebook.com/metbobnz/
Weathergram text only (and translator) is at weathergram.blogspot.co.nz.
Weathergram with graphics is at metbob.wordpress.com, Subscribe/unsubscribe at the bottom.
Or, if email wasn't from WordPress then send a reply email saying LEAVE.
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