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

30 December 2018

Bob Blog 30 Dec 2019

WEATHERGRAM

YOTREPS

Compiled Sun 30 Dec 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.

 

Here’s one of the original verses from Robby Burns “Auld Lang Syne”

 

We twa hae paidl'd i' the burn

Frae mornin' sun till dine.

But seas between us braid hae roar'd

Sin auld lang syne.

 

Or in modern English:

We two have paddled in the stream,

From morning sun till dine;

But seas between us broad have roared

Since long ago

 

So, here’s my wish to you for 2019: May there be more fun paddling in the stream.

 

THE TROPICS

Latest cyclone activity and TCFP tropical Cyclone Formation Potential may be seen at www.ssd.noaa.gov/PS/TROP/TCFP/index.html or tropic.ssec.wisc.edu

 

With the MJO of increased activity making its way across northern Australia eastwards to the western Pacific, tropical depressions are starting to develop and the next few weeks are looking to be busy.

 

Tropical Depression USMAN has been very slow-moving over Philippines, and associated heavy rain has a death toll of 16 people so far.  Track map from www.rappler.com/nation/special-coverage/weather-alert/219814-tropical-depression-usman-pagasa-forecast-december-28-2018-2pm

 

In the South Pacific,  there are 5 depressions at present.

94P and 98P are likely to deepen and travel SE. 94P/TD03F is likely to visit Fiji on 31 Dec/ 1 Jan and southern Tonga on Wed 2 Jan. Followed by 98P over Fiji on Friday 6 Jan and central Tonga on Sat/Sun 5/6 Jan.

 

95P is expected to deepen in Gulf of Carpentaria over next few days and then go east and deepen over Coral Sea, possibly making landfall near Bowen on Sunday 6 Jan.

 

96S and 97P are not expected to deepen.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is at peak activity this week and there is a good chance that tropical depressions may deepen into cyclones. Today a depression has formed to SE of Tonga , on the southeast end of the SPCZ, and this is expected to travel southeastwards, laying a trail of lower pressures so that moisture from the SPCZ can fine its way into the more southern latitudes.

 

Subtropical ridge (STR)

HIGH near 40S to east of NZ is expected to be slow-moving until Wednesday and then move off to the southeast.

HIGH in Tasman Sea near 35S is expected to remain slow-moving until Thursday and then be joined by another HIGH from Tasmania and the combo should move over NZ on sat/sun 5/6 Jan.

There is likely to be a squash zone of enhanced SE winds on the north side of these HIGHS. .

 

Troughs around Tasman/New Zealand

Fronts should visit the South Island this week and finally be followed by a southerly change reaching the North Island on Friday.

 

Between Tropics and Australia.

With a high in the Tasman Sea and low pressures in the Coral Sea, expect fresh to strong easterly or ESE winds between New Caledonia and Queensland.

 

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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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23 December 2018

Bob Blog 23 Dec

WEATHERGRAM

YOTREPS

Compiled Sun 23 Dec 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.

 

Today’ weathergram includes a link to a recent video from Mainsail that looks at marine meteorologists around the world—from dingy sailing to America’s Cup/Volvo/Vendee Glob races to forecasting for solo around the world sailors.  This video requires a good Internet connection, but should give you some “holiday” viewing that may share some of what motivates us meteorologists.

See

edition.cnn.com/2018/10/15/sport/mainsail-october-weather-americas-cup-spt-intl/index.html

 

At Christmas time we start thinking of the prospects for the Sydney Hobart Race starting on Boxing Day:

 

See sailing.org/news/88257.php

In an early forecast prediction, the Bureau of Meteorology's Simon Louis told a selection of navigators at a Rolex Sydney Hobart Yacht Race press conference at the Cruising Yacht Club of Australia today to expect a little of everything in the early stages of the 628 nautical mile race.

Louis said, "The long-range weather models show relatively light winds as the yachts leave Sydney Harbour, but with a 15-20 knot (and gusts to 35 knots) north to north-easterly winds which should continue during Boxing Day night and into the next day, with the breeze expected to go around to the west later." This scenario will leave some dead spots in between.  The model is also showing a weak trough over the far NSW coast throughout this period, with lighter and more variable winds off the far south coast and into Bass Strait.

 

 

THE TROPICS

Latest cyclone activity and TCFP tropical Cyclone Formation Potential as seen at www.ssd.noaa.gov/PS/TROP/TCFP/index.html or tropic.ssec.wisc.edu

 

CILIDA is travelling off to the southeast in the South Indian Ocean.  NE of this is a tropical depression named  KENUNGA  (from last week) near 18S 77E travelling southwest.

There is a near 20% probability of development in the next few days around Micronesia and up to 6% probability of a tropical cyclone forming around the northern part of Australia or in the Coral Sea.   This probability increases with time into the New Year, so if interested in sailing in that area, “you’d better watch out”.

This footprint of increased probability is consistent with an MJO oscillation of increased convection travelling eastwards from the Indian Ocean to the Pacific Ocean over the next few weeks.  When an MJO does this in December we usually have a period of near-equatorial westerly wind appear—and sure enough one of these is forming now around Papua New Guinea and likely to extend to almost 180 longitude  by the end of this week (as may be seen at windy.com).

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active between Papua New Guinea/central and northern Vanuatu/ Samoa at first this week and is expected to drift south so that it may reach New Caledonia /Fiji/Tonga by the end of the week.  A tropical Low is likely to develop in the Coral Sea by early next week.

 

Subtropical ridge (STR)

 HIGH forming over Chatham Islands on Monday is expected to travel eastwards along 40S this week.

HIGH forming in western Tasman Sea on Monday is expected to travel eastwards and widen so that it spreads onto NZ on Sat/Sun 29/30 Dec, after affecting the Sydney-Hobart race. 

There is likely to be a squash zone of enhanced SE winds on the north side of these travelling Highs.

 

Troughs around Tasman/New Zealand

LOW is deepening to NW of NZ on Monday and expected to travel southeastwards across North Island on Tuesday/ Christmas Day, and then clear off to the southeast across Chatham islands on Wednesday/Boxing day, followed by a cool southerly flow for a few days over NZ, – with peak southerly swells along East Coast on Thursday/Friday.

  

Between Tropics and Australia.

With a high in the Tasman Sea and low pressures in the Coral Sea, expect strong easterly winds between New Caledonia and Queensland.

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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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16 December 2018

Bobblog 16 Dec

WEATHERGRAM

YOTREPS

Compiled Sun 16 Dec 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.

 

LISA BLAIR is expected to reach Sydney on Monday, after departing from there on 14 October, and should then complete her adventure to be the first woman to do a solo unassisted non-stop sailing circumnavigation of Australia, to raise awareness of the need for Climate Action Now.

Her tracker site is gis.ee/lb/ Shows that she was hove-to in a gale last night but is now making sail for Sydney in easing conditions.

Her vessel is named S/V CAN standing for Climate Action Now.

MetBob has proudly been sending her daily weather comments. It is an honour for me to be involved in a campaign that raises awareness of the need for Climate action.

It is fitting for Lisa that the COP24 UN Climate conference in Poland has finally today been adopted. OK, it’s really only a starting point, and some are still grumbling it isn’t ambitious enough, but it’s the start of a rule book.

We need to heed what our kids are saying about the need for action. See a 15yo Swedish schoolgirl talk to COP24 at tinyurl.com/yaryncz6 (this comes courtesy of Bernie Sanders’ Democracy Now Facebook site).

“It is the sufferings of the many which pay for the luxuries of the few.”

 

If you agree that we should slow down our use of fossil fuel, for the benefit of the future weather, and for our children’s sake, and have been thrilled by the adventurous spirit of LISA and CAN in their circumnavigation of Australia, then please visit her website and read her blogs at lisablairsailstheworld.com/. Yes, a book is coming, covering her circumnavigation of Antarctica.

 

THE TROPICS

Latest cyclone activity and TCFP tropical Cyclone Formation Potential as seen at www.ssd.noaa.gov/PS/TROP/TCFP/index.html or use tropic.ssec.wisc.edu

There is a twin of cyclones in north and South Indian Ocean, with TC PHETHAI moving north onto east coast of India in next few days, and TC KENANGA moving southwest over open sea in South Indian Ocean.

 

TC OWEN did redevelop in gulf of Carpentaria and has now returned southeast back to east of the Australian coast, but has lost its support supporting structure and is now unravelling. Its energy managed to activate and deepen the heat low over interior of Victoria/New South Wales last few days, producing enhanced NE winds offshore for Lisa Blair on SV CAN, and also drenching rain to places such as Melbourne on Friday, and golf ball-sized hail to Sydney on Saturday. I suppose one pro is that its rain has helped dampen the bush in northern Queensland after recent bushfires,

 

An MJO episode of enhanced convection is travelling eastwards this week across Indonesia and north Australia, and likely to move into Pacific Ocean later this month, increasing the risk of tropical cyclone formation, as can be seen in the formation Potential map.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active between Papua New Guinea/central and northern Vanuatu/ Fiji and occasionally Tonga /Samoa. From early in the week a low of tropical origin is expected to drift off to the southeast of Tonga and deepen in the mid latitudes.

 

Subtropical ridge (STR)

HIGH over NZ tonight is expected to move off to the east next few days along 35S.

Part of this high is expected to reform near 25S to NE of NZ by mid-week and then slide to Southeast so that by weekend of 22/23Dec there may be a squash zone of near strong SE winds between Tahiti and Tonga.

 

Troughs around Tasman/New Zealand

Trough with a cold southerly wind change expected to reach southern NZ on Monday and then go northeast and reach North island as a low on Thursday.

Low over interior Victoria/New South Wales is expected to deepen off Bass Strait on Thursday, then travel east and cross the South Island on Saturday with wind and rain affecting all NZ.

 

Between Tropics and Australia.

With the remains of TC OWEN hovering off the northern Queensland coast and an STR near or south of 25/30South we can expect moderate SE winds between New Caledonia and Brisbane for most of this week.

 

From Tahiti to Tonga

Trough over Tonga /Niue early in the week, then OK, but enhanced SE winds on weekend of 22/23 Dec

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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

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

09 December 2018

Bob Blog 9 dec

WEATHERGRAM

YOTREPS

Compiled Sun 09 Dec 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 TROPICS

Latest cyclone activity and TCFP tropical Cyclone Formation Potential as seen at www.ssd.noaa.gov/PS/TROP/TCFP/index.html or tropic.ssec.wisc.edu

There are no Tropical cyclones around at present, although there are some potential regions for development near Sri Lanka and to east of Majuro. 

Tropical depression 05P/97P was named OWEN last Sunday, and then lost its tropical cyclone credentials (no more a ring of gale winds) on Tuesday, however it has continued has a tropical depression and is still spinning.  It seems likely to cross Northern Queensland over next day or so and may deepen again in Gulf of Carpentaria mid-week.

Plots of the main global models for the likely track of OWEN may be seen at tropicaltidbits.com

 

There is another tropical Low between 05P and New Caledonia—and this is being watched closely and has been labeled 98P (1000hPa).

The latest isobar map drawn by Fiji Met (www.met.gov.fj/weather_maps.php) also shows another low 997hPa at 23S165W and SE of Niue, and Fiji Met are watching this as a possible tropical disturbance in their TC 3 day outlook at www.met.gov.fj/tc_outlook.pdf

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active between Samoa and Southern Cooks.  Part of it may move south and visit Fiji to Tonga on Thursday and Friday. 

 

Subtropical ridge (STR)

 HIGH in the Tasman Sea tonight is expected to travel NE and fade near 175E by end of Tuesday.

 Another HIGH is expected to form over southern NZ on Wednesday and to travel northeast along eastern NZ to be east of Northland by Sunday, extending a ridge back onto Northern NZ early next week.

 

Troughs around Tasman New Zealand

Trough is expected to deepen off Tasmania on Monday and weaken over Northern NZ on Thursday/Friday.

Another Low is expected to deepen off New South Wales on Thursday/ Friday and cross the Tasman Sea over the weekend and visit central NZ mid next-week.

Arrange to arrive in NZ between the troughs.

From Tahiti to Tonga

Active convergence zone this week.  May as well stay put.

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

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

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

02 December 2018

Bob Blog 2 Dec

WEATHERGRAM

YOTREPS

Compiled Sun 02 Dec 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.

 

Review of November weather:

Sea Surface temperature anomalies as at end of November may be seen www.ospo.noaa.gov/Products/ocean/sst/anomaly/index.html

The eastern equatorial Pacific around Galapagos is the focal region for ENSO and is now getting warm enough to almost be called an El Nino event.  There is currently a patch of warm water around NZ, but this may change during the next month or so, affecting the NZ summer.  There is also warmer than normal conditions between Solomon Islands and French Polynesia, and this may add oomph to the South pacific Convergence zone. 

The Gulf Stream off the east coast of North America and the Kuroshio current off Japan still stand out, which is unusual so late in the year.

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

The subtropical ridge in the southern hemisphere has weakened and gone north in November.

Zooming into the NZ area, there has been a radical drop in pressure north of 45S, the 1015hP isobar has retreated  well to west and east of the Tasman sea, and the tropics have dropped to below 1010.  Sure enough the weather features in the Tasman Sea were decided troughy (after a month marked by blocking highs).  I suppose December will either continue with a troughy Tasman or continue the rhythm and have some blocking highs. Wish we could tell in advance, but weather is a mix of pattern and chaos.

 

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

The rain map shows extra convergence around  and to the north of the Solomon Islands, and also that the Intertropical convergence zone and the South Pacific Convergence zone seem to be shifting toward the equator--- an El Nino trait.

 

THE TROPICS

Latest cyclone activity and TCFP tropical Cyclone Formation Potential as seen at www.ssd.noaa.gov/PS/TROP/TCFP/index.html or tropic.ssec.wisc.edu

Tropical depression 05P /97P has deepened to 993hpa in the Coral sea and is expected to continue to deepen over next 24 hours and go south and then go west, but may fade before it gets to northern Queensland.   It is quiet elsewhere for a change.

 WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active and moving south. it is likely to visit Fiji by mid-week, maybe the Loyalty Group to Minerva on Thursday, and maybe Tonga by local Friday.

Subtropical ridge (STR)

A new HIGH is expected to travel eastwards into the South Tasman sea by Wednesday and then go NE into central Tasman sea by the weekend.  It is a slow-moving system and may fade around Wed 12 Dec and the be replaced by another High reaching northern NZ around sat/sun 15/16 Dec.

 

Tropics to New Zealand

Trough is expected to bring a W/SW change to North island during Tuesday and then that High in the Tasman sea should maintain a southerly flow over northern NZ until end of next week.  Departures from the tropics before Thursday will encounter weak headwinds near NZ.

Between Tropics and Australia.

The High moving into Tasman Sea from mid-week means easterly winds from New Caledonia to Australia, good for sailing to Australia.  If wanting to go the other way, then depart before mid-week or go well south to avoid the easterly winds.

 

From Tahiti to Tonga

Trough related to the SPCZ is likely to reach Tonga by local Friday and then travel east.

 

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

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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