Bob Blog 26 April

WEATHERGRAM

YOTREPS

Compiled Sun 26 April 2020

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.

 

Noonsite offers a website with latest info on which ports are open/closed due to Covid 19 see

www.noonsite.com/news/novel-coronavirus-2019-ncov-special-procedures-being-introduced-in-ports-of-entry-worldwide/

….scroll down and look for South Pacific region

America Samoa has a 14-day quarantine and all other port in South Pacific remain closed.

MAY be able to enter Tahiti with prearranged authorization, however this is now discouraged.

See www.noonsite.com/news/french-polynesia-if-you-have-an-alternative-dont-come/

SEAMERCY is planning (and has permission) to arrange yachts to help deliver supplies to relieve Vanuatu/Fiji/Tonga from damage from TC HAROLD.

SEAMERCY’s Fleet director and Coordinator Jonathan Robinson tells me that: “Disaster Response without boots on the ground or vessels in the water is proving to be quite challenging!”

SO, if you would like to help….

See www.noonsite.com/news/vanuatu-sea-mercy-lands-first-container-of-disaster-relief-supplies-post-cyclone-harold-amidst-covid-travel-restrictions/

 

While on the Internet check out www.youtube.com/watch?v=XYtPVso2w0c

This is from earth.nullschool.net, and shows an animation of water vapor in the atmosphere. Water vapor turns into cloud when its temperature reaches its dew point.

The animation shows that the tropics are the source of most of the water vapor in the atmosphere, and goes mainly from east to west,

that there is a drop off in the subtropics,

and that the mid-latitudes have west-going troughs each laden with moisture ( but usually less that the tropics)., separated by dry zones also travelling westwards.

Enjoy watching the change of the seasons.

 

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are no cyclones around at present. But there is a Tropical depression in the NE Pacific Ocean, going west-northwest then west.

Extended weather models no longer show a Tropical Depression near coastal Queensland in early May (as was mentioned last week).

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to stretch from Coral Sea / Solomon Islands across Northern Vanuatu /Fiji and south Tonga then fading further to the SE.

Passing trough over Tahiti area mid-week, associated with a Low near 30-35S.

Passing trough expected over Fiji/Tonga on Thu/Fri.

  

Subtropical ridge (STR)

HIGH moving into Tasman sea on Monday is expected to cross central NZ 1032hPa on Wednesday and then move off to the east along 30 to 40S. associated small squash zone near 25S between NZ and Fiji on Tue/Wed.

Next High is expected in Tasman early next week.

 

Tasman Sea /NZ/Aus

Passing trough over South Island on Monday, followed by a SW flow on Tuesday

Increasing NW winds over Tasman Sea /NZ by Friday.

Passing trough over NZ this weekend around sat 2/ Sun 3 May with strong winds.

 

From Panama:

Northerly winds to 8N this week, Light winds and ITCZ from 6N to 3N then light SW winds to 2N NW of Galapagos then gradual swing to SE trade winds.

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

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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Bob's Blog 19 April

WEATHERGRAM

YOTREPS

Compiled Sun 19 April 2020

 

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.

 

Review of the 2019-2020 Cyclone Season, from Bob McDavitt of MetBob

The tropics are quiet at present and the normal cyclone season ends on 1 May, so the cyclone season is hopefully over. The extended weather models are picking there may ne a Tropical depression around 4 May near Queensland , but the details are likely to change , and, fingers crossed,it may be just a depression.

 

For a  review of  the  cyclone   season  see en.wikipedia.org/wiki/2019%E2%80%9320_South_Pacific_cyclone_season

 

The season began with the arrival of Tropical Depression 01F on November 22, near the Solomon Islands, which would later become Tropical Cyclone Rita. Rita would then peak as a Category 3 on the Australian scale. Tropical Disturbance 02F was designated sometime later, but didn't last long after that. Sarai formed on December 23, lasting into the new year before finally ceasing to exist on January 2. Not too long after that, Tino formed and affected eastern Fiji and the surrounding area before dissipating. On January 24, a depression formed and dissipated the next day without been named. In early February, another low originally in the Australian region crossed the 160th meridian east and emerged in the South Pacific. It strengthened into severe tropical cyclone Uesi and affected New Caledonia and New Zealand. In mid-February four disturbances formed, 07F, 08F, 09F and 10F. 07F & 08F dissipated before becoming tropical depressions but the other 2 strengthened into tropical cyclones Vicky and Wasi. In mid-March, Gretel entered the basin. It dissipated shortly afterwards. In early April, Harold also entered the basin from the Australian region. It rapidly intensified into a Category 5 Severe tropical cyclone as it impacted Vanuatu, Fiji, and Tonga.

 

So far TINO was the most expensive (at present) and HAROLD the deadliest cyclone (27) for the season.

 

The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are no cyclones around at present. The MJO quiet cycle is expected over the South Pacific for the next few weeks and then the nominal cyclone season ends at end of the month.

Extended weather models are starting to show a Tropical Depression near coastal Queensland by 4 My, but details are likely to change.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to be quieter than normal this week, stretching from Coral Sea to Vanuatu toa passing trough between New Caledonia and south of Fiji (Wed-Fri) to Samoa to Southern Cooks/Tahiti area.

 

Subtropical ridge (STR)

HIGH that has been northeast of NZ last few days is now moving off to the east along 30-35S. Associated ridge is likely over NZ Monday night/Tuesday

Next HIGH is expected to move into Tasman Sea along 30-35S on Thursday then go east to reach northern NZ early next week north to 30S by Thursday and the east along 25-30S passing by north of NZ on Friday.

 

Tasman Sea /NZ/Aus

Passing trough over Northland tonight. Then Ok for departure this week

W/SW flow over remainder of NZ on Monday.

Light wind to NW winds on Tuesday, passing trough on Wed, Low and a trough on Thursday followed by disturbed westerlies

 

From Panama:

Light winds for departure this week, but there may be some northerly winds to 5N next week ITCZ mainly from 4N to 2N,

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

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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Bob Blog 12 April

WEATHERGRAM

YOTREPS

Compiled Sun 12 April 2020

 

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.

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Volcanic eruptions:

Krakatoa in Indonesia has erupted spewing ash to 47.000ft. If there is enough ash in the stratosphere then this may reduce sunlight and drop the surface air temperature for next few days/weeks/maybe months. A Volcano in Iceland is threatening to blow, and any resulting ash cloud may affect air transport (which is already affected by Covid 190.

 

The state of the ENSO = neutral

It has been months since we have looked at ENSO, so here goes.

 

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.

 

The Atmosphere:

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.

 

Since a brief El Nino in late September the ENSO has been neutral, but in the last week there is a trend that may bring another El Nino episode. The subtropical ridge line has recently shifted north over New Zealand, opening the door over the South Island to episodes of cold SW wind.

 

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 a CPC 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 May 2019. Temperature have been slightly above normal (global warming?) except for a cool period last September.

They are now reasonably steady, and below the El Nino threshold of  over  +1  degrees.

 

Neutral oceanic conditions are seen at

www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

Waters just beneath the surface are slightly warmer than normal.

See Data for 30 March as at www.bom.gov.au/climate/enso/#tabs=Sea-sub%E2%80%93surface

 

The International Research Institute of the Climate Prediction Centre compiles data from several ENSO prediction models.

The model percentage predictions based on Nino 3.4 SST anomaly is that the neutral conditions are most likely (over 50%) until August and hen the seas are likely to gradually COOL later in the year, with a La Nina becoming 35% likely by the end of the year (neutral also 35, and El Nino only 20%).

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

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

Latest SST anomaly map shows a patch of cooler than normal sea near central Pacific, surrounded by slightly warmer than normal sea.

 

The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are no cyclones around at present.

 

Cyclone HAROLD was Cat 5 over Vanuatu, Cat 4 for southern Fiji, and Cat 5 when it went slightly south of Tonga, It has produced lots of damage along or near its path, the most damaging cyclone of the season.

However, the MJO quiet cycle is expected over the South Pacific for the next few weeks and then the nominal cyclone season ends at end of the month.

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

After HAROLD the SPCZ is expected to be quieter than normal this week, stretching from Solomon island s to northern Vanuatu to between Fiji and Samoa to Tahiti area.

 

Subtropical ridge (STR)

HIGH that has been east of NZ last few days is now moving off to the east along 25S but may stall and fade near 170W for a few days.

Next HIGH is expected to move into Tasman Sea along 35S on Tuesday then go north to 30S by Thursday and the east along 25-30S passing by north of NZ on Friday.

 

Tasman Sea /NZ/Aus

Front travelling over NZ tonight followed by strong west to SW flow.

Deep Low down to 960hPa near 52S 175E on Monday night is expected to travel NE to east of Chatham Islands by Wednesday and then ease and go east. The following strong to gale SW flow should bring swells to over 6m to west coast by Tuesday and maybe to around 15m to Chatham Islands by early Wednesday. A brief ridge on Thursday, then another front and strong westerly change on Friday.

 

From Panama to Galapagos/Marquesas:

Mirror convergence zone is still there near5S from 110W to 150W, slowly shifting north.

ITCZ is mainly near 4N, and southerly winds are likely along 2N from 80W to 92w with a good tail current.

 

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

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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Bob Blog 5 April

WEATHERGRAM

YOTREPS

Compiled Sun 05 April 2020

 

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.

 

Voyaging in a COVIDI9 world:

I’ve decided to continue my weekly blog, issuing BASIC weather details to be aware of in the South Pacific. After my weathergram last week, I got a backlash of emails asking for suggesting I may stop, and we now have TC HAROLD anyway. If you are voyaging or plan to then let me know at bob@metbob.com

 

End of DST, Time zone changes:

Australia, New Zealand and (Western) Samoa reverted to STANDARD TIME earlier today.

For Lord Howe this is a change of only 30 minutes from UTC +11 to UTC+10.30.

Fiji is already at UTC+12 (finished Daylight saving on 12 Jan)

Vanuatu, New Caledonia, Tonga, Niue, Cooks and French Polynesia are not observing daylight time this year.

American Samoa doesn’t observe DST.

 

Note that Good Friday and Easter Sunday are wide-spread public holidays this wee.

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

This MJO has peaked over South Pacific in the last week, helping TC HAROLD to form NW of Vanuatu. HAROLD is now category 4 and may reach top Category 5 as it crosses Vanuatu next few days. It is then expected to travel East-southeast and brush southern Fiji on Wednesday.

 

There is another cyclone over the open sea of the Indian ocean: IRONDRO

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to follow TC HAROLD and extends to Niue.

 

Subtropical ridge (STR)

HIGH SE of NZ has been giving golden weather to parts of NZ for last few days and is now expected to move off to the east along 50S next few days.

Next HIGH should cross Tasmania on Wednesday and then travel north and fade away along Aus coast by Good Friday.

 

Tasman Sea /NZ/Aus

Trough crossing South Island on Monday followed by cool SW flow on Tuesday, another trough on Wednesday then strong westerlies on Thursday/Friday (gentler further north) and another trough for all NZ on Saturday.

 

From Panama to Galapagos/Marquesas:

Mirror convergence zone is still there along 5S from 110W to 150W.

ITCZ is spreading into Panama region bringing more showers, and northerly wind s in Panama may turn southerly from 8 to 15 April. This marks the beginning of the end of OK weather patterns for going SW.

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

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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