Translator

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

25 February 2018

Bob Blog 25 Feb 2018

WEATHERGRAM

YOTREPS

Compiled Sun 25 Feb 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.

 

Progress report from Greg Just in Vava’u and his program for Tongan weather stations:

“– the unit I had purchased has proven unreliable as It only lasted a year before having to replace the unit as all but one sensor died.”

“I have selected Davis Vantage Vue as a better model, based on an expat in Vava’u that has one that only broke when it fell from his windmill (rust in the mounts) after 10 years. The unit is roughly 50% more expensive. I am getting a unit up to trial in May on a yacht. This will be based in the bottom of the Vava’u group on an island resort so I can get feedback.”

“I am also waiting to trial 8 AIS units across Tonga with TCC (Tonga Commnications Corp), and can then host the weather stations / webcams at the same sites with UPS and Internet services provided free.”

“The local emergency assist project/NZ Police are also working with NZ Coastguard to mount sensors on Floating Buoys in Vava’u. Which will provide info on weather and Tsunami.”

“I was hoping to get the whole project funded by an Asian Development Bank Grant scheme. I am applying for another grant shortly through GCF as the project will be a lot easier if 100% funded all at once.”

  Greg went on to describe the Damage from GATI:

“No damage for Vava’u, a little damage in Ha’apai. Tongatapu/’Eua:  I’m guessing around 40% roof damage and 10% loss of buildings based on unofficial observations, huge crop and coconut damage. They have not had a high CAT cyclone for 60 years so had many flying objects especially.”

If you would like to make a donation to Tongan Weather stations go to

www.generosity.com/community-fundraising/weatherstations-webcams-for-tonga-and-pacific/x/7573544

 

The state of the ENSO = confused, La Nina ocean and neutral atmosphere.

The Atmosphere:

El Nino and La Nina are opposite ends of an identifiable tropical influence on our seasonal weather: either a La Nina, caused by cooler than normal seas along the equatorial eastern Pacific, which shifts the subtropical ridge away from the equator. Or an El Nino, with warmer than normal seas, which draws the subtropical ridge closer to the equator. Their comings and goings can last several months, maybe over a year,  and sometimes the state is in-between or neutral, and so their status may be used to forecast the weather for the coming season.

 

The main parameter we watch from the atmosphere is the Southern Oscillation Index SOI (30 day running mean) for 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 the placement of isobars 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.

 

After switching into a weak to moderate La Lina around last October, the SOI indicator turned negative last week, a sign that the La Nina may be  over and we are in neutral territory, as far as the atmosphere is concerned.

 

Neutral territory in the atmosphere as seen at 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 this cool period of a La Nina. In the ocean the coolness is continuing, reaching around -1C at times, showing no easing in this La Nina as far as the ocean is concerned

A continuing La Nina is seen at farmonlineweather.com.au/climate/indicator_enso.jsp?c=nino34&p=monthly

 

The International Research Institute of the Climate Prediction Centre compiles data from several ENSO prediction models. The mid-February probabilistic forecasts show this La ina is expected to revert to neutral territory by April/May. 

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

 

The sea surface temperature anomaly map shows a marked warmer-than-normal Gulf Stream of North America—so they may have an early spring, perhaps.   La Nina shows itself as several cooler eddies along the equator of a typical La Nina.  And there are several yellow/flecked with red zones of WARMER ocean, with one continuing around New Zealand.

New Zealand has just had its warmest summer on record thanks to this warm zone of sea temperatures.  We think it formed thanks to lighter winds and fewer clouds over the region last spring, but this is just a theory at this stage.

 

Sea surface temperatures across the Pacific are at www.ospo.noaa.gov/Products/ocean/sst/anomaly/index.html

 

TROPICS

The MJO has moved out of the Pacific and is now reforming in the Indian Ocean.  This means the risk of tropical cyclone formation in the South Pacific over the next few weeks is lower (but not negligible). 

There are no cyclones around this evening. We are having a welcome break.

The liquid remains of KELVIN have merged with the wet front crossing southern NZ tonight. Milford Sound have had over 300mm of rain so far today.

Looking at the weekly rain maps from last week and the week before, we can see an easing of the intensity of the rain in the South pacific.  There is an increase in activity around northeastern Australia. And in the ITCZ across the equatorial Atlantic.

See trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif for last week's rain

WEATHER ZONES

Weather Zones

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to be weaker than last week, and is spread rather thinly from Solomons to Vanuatu to Fiji/Tonga, and then as a narrow band across Samoa and Cook Islands, affecting parts of French Polynesia at times.

 

Subtropical ridge (STR)

HIGH is expected to travel east across the south Tasman Sea on Monday and then ‘squeeze’ around southern NZ on Tuesday and then travel NE to east of NZ and build as it travels east along 45S to east of NZ for the remainder of the week.

Next HIGH is expected to form east of New South Wales on Thursday and travel across southern NZ on Friday and weekend of Sat 3/Sun 4 March.

 

Around Tasman Sea

Front that was active over South Island today/Sunday is expected to fade over central NZ on Monday. A secondary low is expected to deepen on its western edge in the central Tasman Sea by Tuesday. This Low should deepen and approach South Island on Wednesday then weaken as it crosses southern NZ on Thursday.

From Thursday, a LOW may form between Fiji and New Zealand, with brisk easterly wind son its southern side.

 

Panama to Galapagos /Marquesas

If you are ready now to do this trip, then the next two weeks are looking OK with N to NE or East winds and a tail current as far as 3N.  After that there are light ESE winds to Galapagos, and a weak convergence zone near the equator.

As for going to Marquesas there seem to be moderate Southeast to East winds to west of 105W, and these should last until at least first or second week of March.

 

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

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 February 2018

When does a cyclone lose its name?

Incoming email this morning:

 

Bob hi

 

I hope you can help me out with this.

 

Marine insurers have, in the past, imposed extra conditions for damage or loss due to “named tropical storms”. This is the phrase they use rather than “tropical cyclone” or such and presumably covers the early stages of the storm before the eye develops and the later stages when they are often referred to as “ex tropical cyclone …”.

 

Recently there has been a move to exclude all damage or loss from named tropical storms. This is one of underwriters responses to the big losses they recently suffered in the Caribbean etc. This is a significant reduction in cover and I would like to understand it better.

 

The naming of tropical storms appears to be quite systematic worldwide so their birth is reasonably clear cut. However I can find nothing about their un-naming, about that point in time when they are no longer a “named tropical storm”. In an official metrological sense when do “named tropical storms” cease to be?

 

I hope you can shed some light on this for me.

 

Regards

 

+++++++++++++++++++++++

 

My reply

 

Hi there Bruce.

 

In summary, when the system is in the tropics and is expected to be able to produce gale winds it can hold a name as a tropical cyclone. .

 

As for the insurance term “named tropical storm”, the Insurance company is clearly reducing/limiting its coverage.  I suppose such a term only applies to marine insurance covering, in part, tropical areas. . It may be easier for you to dump that policy and get a “storm” policy which offers reasonable coverage for damage done by wind /rain/waves.

 

When a tropical cyclone leaves the tropics (latitude 23.5, as defined by the axial  tilt of the earth)   it is nominally  no longer a tropical cyclone.

 

Usually from that point it is called ex-tropical cyclone , or former tropical cyclone NAME  some also call it a cyclone/depression/low of tropical origin, or extra-tropical cyclone ( extra here has the meaning “out of”, as in extraordinary or extra-terrestrial) .

 

Usually the cyclone will be weakening by that stage and losing its tropical characteristics.  The main feature that distinguishes a tropical cyclone is the “eye wall” = a ring of intense wind and rain around the centre , with winds reaching at least gale force , averaging 33 knots  (gusting around 50 knots).   Another feature is to have spiral shaped convective bands . 

 

As the cyclone loses these characteristics , the TCWC (tropical cyclone warning centre) that monitors it reduces its Category , after dropping below Cat 1, it is deemed to be a depression or a low.   When less than Cat 1 is no longer has winds of gale force in its eyewall, and thus is unlikely to produce much damage.   Since this decision may require good evidence from a visible satellite imagery, it is usually made during daylight rather than overnight.

 

  Some lows of tropical origin take a while to unravel , and some manage to have a second life as a mid-latitude low. If these lows are still carrying damaging wind and rain then it helps the media to drop the word “tropical” and simply refer to the system as CYCLONE NAME.  I started doing this when on duty during Cyclone BOLA back in 1988.

 

Now, mid-latitude lows  do not have an eyewall  but may indeed have some areas with  gales. Most mid-latitude lows  are not given names.  (There has been some attempts by UK and USA to have a list of “winter named storms” recently , but that’s to help media coverage, not something that insurance companies have had a hand in).

 

There are two interesting cyclones in the  Australia/ NZ region as far as the relevance of the term  “named tropical storm” is concerned.

1.KELVIN has damaging winds and rain and was CAT2 when in made landfall in NW Australia last week .  It is now inland and has lost its tropical characteristics , but is still in a tropical latitude and bringing damaging rain.  The Bureau of Meteorology are keeping it as a named storm this morning , Cat 1 , and anticipating to drop its name (and treat it as an L) by this afternoon, as it leaves tropical latitude. The systems will still have a coherent Low centre and a zone of potentially destructive wind even when t loses it name.  It may well be called ex-KELVIN for a while (or maybe as a Low/depression of tropical origin).

see www.bom.gov.au/products/IDW60281.shtml , in AWST time

 

2.GITA is already south of the tropical border but still has a name and is described this morning to be Cat2.

 

Satellite imagery shows it has already lost its eyewall, and only has one spiral band of convection left at this stage.  Also it is beginning to encounter stronger NW winds aloft (part of a jetstream ahead of an approaching upper trough).  These winds are ripping off the upper clouds of GITA , leaving behind a rotating low. 

 

Satellite image source: www.meteo.nc/nouvelle-caledonie/observations/images-satellite

 

In New Caledonia time = UTC+11

 

MetService is the TCWC (tropical Cyclone warning Centre) for GITA and this morning have it as a “named tropical cyclone” of Cat 2  even tho’ it is near 30S, well out of the tropics.

 

The idea shown in the image above is that the system may continue to be a Cat2  this afternoon, but from then on will be a mid-latitude LOW, and no longer a “named tropical cyclone”.   The system has an estimated central pressure this morning of around  980 hPa and may deepen to 977hPa on Tuesday , thanks to the injection of cooler air on its southern side.  It will take a few days for this system to weaken, for its isobars to “unravel” and for the winds it brings to ease.

 

In a mid-latitude low the zones of strongest winds is usually alongside the “fronts” (leading edges of an invading airmass). As a mid-latitude low approaches New Zealand the zones of strongest winds become distorted by terrain effects due to the mountains, producing “rivers of wind “ and “puddles of calm” .  In the image above no attempt has been made to show  the likely boundary of gale winds for the likely future positions of this mid-latitude  low.    Instead, these are detailed at the Severe weather pages

 

www.metservice.com/warnings/severe-weather-warnings

www.metservice.com/warnings/severe-weather-watch

and www.metservice.com/warnings/severe-weather-outlook

 

 

So “Cyclone GITA”  has the potential to damage in New Zealand  over the next few days but will by then not be a “named tropical cyclone”.  There will be plenty of insurance claims , and they will be covered by “storm” damage --- but maybe not by the policy you seem to be referring to.  It may or may not help your case if the media continue to call this system “Cyclone GITA” while it has damaging wind and rain.

 

Bob McDavitt

 

Bob Blog 18 Feb 2018

WEATHERGRAM

YOTREPS

Compiled Sun 18 Feb 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.

 

My good wishes to the University students who are crewing on Training Tall Ship SSV ROBERT C SEAMANS.

The vessel visited Auckland last week and sailed to Opua late in the week ( see www.sea.edu/sea_currents/all_robert_c_seamans/category/robert_c._seamans).

Captain, and Professor in Nautical Science, Elliot Rappaport invited me on deck.

I especially like that the students manage a full-time marine lab and also are one of the VOS (Voluntary Observing Ships) that send in regular weather reports using properly calibrated instruments. These observations, around the planet, are part of what helps the global weather models in touch with the real world. See www.wmo.int/pages/prog/amp/mmop/JCOMM/OPA/SOT/vos.html

In a month or so they will be going to Lyttelton then Chathams then French Polynesia, I hope they get to enjoy NZ and then have a Bon Voyage to FP.

 

TROPICS

We have been having an MJO in the Pacific, a period of extra convection. The passage of this pulse around the world can be tracked with a phase diagram. This diagram shows that the current MJO is fading away. It is expected to continue to fade this week and to revert to the Indian Ocean. A n MJO is often associated with triggering tropical cyclones, and this one helped FEHI and GITA to form. Now that the MJO is moving off we may be able to have a few settled weeks, but there is still the risk of another tropical cyclone forming. The next MJO, around mid to late March, should exacerbate that risk.

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

 

GITA brought destructive wind and rain to Tongatapu and surrounding Islands, and got larger and more intense over southern Lau, affecting Ono-i-lau and Vatoa (Cat 4). Since then it has been keeping away from land. It is now weakening as it heads SW across the tropical border and likely to become ex-tropical on Monday, giving wind gusts to around 35 knots to Lord Howe Island.

 

Then it is expected to curve to S then SE and cross central NZ on Tuesday night and then be south of Chathams by Thursday. May have gusts over 60 knots and swell to over 8 significant metres in its dangerous quadrant as it approaches land, which will then be on its NE side, affecting Taranaki to Kapiti/Nelson. By then the system should be unravelling and its heaviest rain may be in the southern semicircle rather than the NE quadrant, which means Westland/uller /Nelson/Marlborough/ Kaikoura Ranges may well get drenched.

Ensemble runs from the Canadian model, may be seen at www.tropicaltidbits.com.

 

In the past week TC KELVIN (up to CAT 2) formed off NW Australia and made landfall over ‘the’ Kimberley. It is now a rain depression fading as it travels south into the Australian interior.

Satellite imagery of both cyclones may be seen at www.metservice.com/maps-radar/satellite/australia-infrared.

 

There is a small Tropical Low over the COOK Islands vaguely east of Palmerston island and north of Rarotonga. It is expected to travel off to the south over next few days without developing any further, but it does contain squally showers.

 

Looking at the weekly rain maps from last week and the week before, we can see that the most intense rain around the world is in the South Pacific Convergence zone. It has spread east and is now lapping on western parts of French Polynesia. Further west, it has thinned and shifted north to be over Solomon Islands to Tuvalu/Tokelau.

The track of GITA stands out, but KELVIN’s track is less obvious.  See trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active across the whole region mainly from Solomons to Tuvalu to Tokelau/Samoa to the Cook Islands and western parts of French Polynesia.

 

Subtropical ridge (STR)

HIGH to east of NZ at around 160W is quasi-stationary and is expected to travel northeast and end the week near 25S 140W.

The next HIGH is currently in the Australian Bight and is expected to travel across Southern Ocean late this week and across northern NZ next weekend 24/25 Feb with light winds.

 

Around Tasman Sea

A week to avoid the Tasman Sea, because of ex-GITA.   On Monday  the upper trough moving onto NZ from the southern ocean will encounter this system from the tropics.  The strengthening NW winds aloft will likely capture ex GITA and shear it apart, venting its top half quickly downstream. However, the models are indicating there should still be sufficient rotation  in the surface low to bring wind/swell/rain and storm surge to NZ shores.  Also the injection of cooler air into the system helps it deepen as a mid-latitude low.

 

Panama to Galapagos

If you are ready now to do this strip, then the next two weeks are looking OK with N to NE winds as far as 5N. After that there are light ESE winds to Galapagos, and a weak convergence zone from 5N to 2N.

 

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

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.

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

 

11 February 2018

Bob Blog 11 feb 2018

Bob Blog 11 Feb 2018

Posted on February 11, 2018

 

WEATHERGRAM

YOTREPS

Compiled Sun 11 Feb 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

This MJO period of expected extra convection which has been visiting the South pacific over last few weeks is now reaching its peak.

Over Samoa on Saturday UTC, after a week of heavy convective rain, Topical Cyclone GITA brought even more intense rain along with some damaging winds. GITA is still developing in intensity and size and is now heading for southern Tonga, then southern Lau group in Fiji.

GITA is disrupting the South Pacific Convergence zone and may take some of its energy off to the south. Later this week it is expected to  turn south into the Tasman Sea and weaken, and  its remnants may reach New Zealand some stage after Friday…progress may be much slower than the models are showing at present—they are not to be trusted this far out ( see www.tropicstidbits.com for latest track map).

 

There is a Tropical Low 997hPa this evening located to south of French Polynesia and moving off to the southeast, Associated convergence zone is likely to bring squally showers to Tahiti until mid-week, with strong northerly winds especially on Tuesday UTC.

 

There is another minor tropical depression located in the SPCZ at present to NW of GITA, and this system is expected to fade in a few days.

 

Tropical Storm 02W or TWO has developed in the NW Pacific and is heading west and expected to visit the Philippine Islands in a few days. And there is a tropical low in the south Indian Ocean.

 

Looking at the weekly rain maps from last week and the week before, as at trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif , we can see that the South Pacific Convergence zone has been the site of the most intense train on the planet for the past week, especially in a zone form Samoa to western parts of French Polynesia.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active across the whole region mainly from Solomons to Tuvalu to Samoa to parts if the Southern Cooks and parts of French Polynesia. TC GITA is likely to take some of the energy of the SPCZ off to the west then SW/S/SE around that quasi-stationary HIGH located NE of NZ.

Tropical Cyclones act as safety values and remove extra heat from the sea. disturbing that energy as wind and rain over a wide area. Let’s hope GITA does this job without doing much more damage.

 

Subtropical ridge (STR)

HIGH to east of NZ at around 160W is supported by conditions aloft to be quasi-stationary. It is expected to start the week near 40S and to track to 35S then a new cell should bring its centre of pressure back to 40S. It is a major factor in moulding the track of GITA.

A weak High is expected to travel east across mainly southern NZ on Wednesday, making that and Thursday the driest days of the week for NZ.

 

Around Tasman Sea

A week to avoid the Tasman Sea or travelling to NZ, because of GITA.

 

Panama to Galapagos

I’ll be adding this zone to my weekly outlooks for the next few months.

If you are ready now to do this strip, then the next two weeks are looking OK with N to NE winds as far as 5N and a weak convergence zone the light winds to Galapagos.

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

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.

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

04 February 2018

Bob Blog 4 Feb 2018

WEATHERGRAM

YOTREPS

Compiled Sun 4 Feb 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 may be seen at ww.ospo.noaa.gov/data/sst/anomaly/2018/anomnight.2.1.2018.gif

The SST anomaly image still shows cooler than normal seas along the equatorial east pacific, but these are less than last month. Maybe indicating this La Niña period has peaked as far as the ocean is concerned.

The Tasman sea warm zone has been there since November and is affecting the local weather, supporting warmer than normal air temperature, and feeding moist air to the low-pressure systems crossing the Tasman Sea.

 

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

 

There was a strong three-wave pattern in the northern hemisphere last month with lows preferring to form near Japan, eastern North America and western Europe— this is no longer the case with a four or five wave pattern, things are more changeable.  In the southern Hemisphere only the zone from Indian Ocean, cross Australia, to the Tasman Sea area has been favourable for low development.

 

The subtropical ridge over the South Pacific is still in place but weaker than last month.  The 1015hP (blue) isobar has shifted to east of New Zealand, so that the prevailing winds over the North Island are from the north. As long as this continues, air temperatures over New Zealand are likely to remain above normal.

 

The last 30 days of rainfall, and its anomaly, as seen at TRMM at trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html, shows that, in the Pacific, both the ITCZ and the SPCZ have an average position last month further AWAY FROM the equator than normal. This is typical of La NINA. Interestingly in the Atlantic, the ITCZ is closer to the equator than normal—this shows that there is more happening than can be explained by just examining LA NINA.

 

TROPICS

TC FEHI travelled across the Tasman sea and its remains reached NZ area last Thursday on 1st February bringing wind and rain to many areas. It arrived during the spring tide after a near-perigean full moon, the second full moon in January (thus a ‘blue’ moon) and, coincidently, the day after a lunar eclipse (‘blood’ moon). The inverse barometric effect from the lower that normal pressures, and the storm surge from strong northerly winds can be seen at the NIWA tide gauge at Porirua (around 12 n miles NW of Wellington) at www.niwa.co.nz/our-services/online-services/sea-levels

This storm surge brought some damage to Nelson wharf area, especially the Boat Shed Café, see www.stuff.co.nz/nelson-mail/101096861/storm-surge-forces-closure-of-nelsons-historic-waterfront-venues

 

The central part of FEHI took a while to unravel. It was still intact when it visited Auckland on Friday bringing a few hours of squally downpours. This can be seem on Himawari satellite imagery at youtu.be/o-vkKKok9w8 or MetService radar imagery at youtu.be/c_lFzIhR9MY .

 

There is an MJO period of expected extra convection traveling across the Pacific Ocean this week and maybe next week, raising the potential for Tropical Low development to HIGH.  There is also in place a zone of near equatorial westerly winds and four incipient lows, any of these may develop into a tropical cyclone over the next few days. Once formed, these systems will likely travel south. Near-equatorial westerly winds can be seen on windy.com , and this is another herald for cyclones.

 

In the India Ocean TC CEBILE is still traveling off to the south and fading.

 

Looking at the weekly rain maps from last week and the week before, we can see that the main convective rain over the past week has shifted from the equatorial Indian Ocean to the northern Australia and Coral Sea region. See trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active across the whole region mainly from Solomons to Northern Vanuatu to Fiji to Samoa to Cooks and to parts of French Polynesia.  Any of the tropical lows currently on the SPCZ may develop to a cyclone this week. The models seem to prefer the low near Fiji.

 

Subtropical ridge (STR)

HIGH travelling east of Tasmania on Monday is expected to travel east across the south Tasman Sea on Tuesday and Wednesday, across southern NZ on Thursday and then further east to east of NZ along around 35 to 40S.

 

Around Tasman Sea

East to SE winds at first this week north of 30S, but a trough may approach from the north after Wednesday turning winds E then NE near New Zealand.

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

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.

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

Blog Archive