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

28 February 2016

BOB BLOG 28 Feb 2016

WEATHERGRAM

YOTREPS

Issued 28 February 2016

 

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.

 

Tropical cyclone WINSTON

I repeat that I am willing to help ANY yacht with FREE weather information if they agree to fill up with medical supplies on their way to FIJI/TONGA as part of SEA MERCY to supply relief after this cyclone season. This way I sponsor humanity.

See http://www.seamercy.org/

or

https://www.facebook.com/metbobnz/posts/1731717857039648

 

WINSTON is slowly petering away (apologies for this pun, based on a Kiwi politician, at least he himself, MP of our Northland, is above such a rub).

Its central circulation is still spinning as a tropical depression on the Coral Sea

There's a chance (rather low) that it may redevelop. It has warm sea surface temperatures in favour, but has lost its top clouds, so this is an unlikely chance.

Its higher clouds have been entrained into a trough that is crossing northern New Zealand.

as seen at http://www.tropicaltidbits.com/storminfo/11P_gefs_latest.png

 

TC YALO was briefly alive between Southern Cooks and French Polynesia but has now faded.

 

 

Rainfall in the tropics over the past week

as seen at

http://trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

shows the weakening of convection around Australia and an activation of convection between Cooks and French Polynesia, this is also now weakening.

 

Panama to Galapagos:

As for departing this week--- OK to go, but light winds at times. Good surface currants are expected.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

SPCZ stretches from Solomons to in-between Cook Islands and French Polynesia this week and is expected to slowly weaken.

 

STR= Sub-tropical Ridge

HIGH travelling east across southern Tasman next few days and central NZ during mid-week then to east of, and about, central NZ for the remainder of the week. This should hold troughs away AFTER mid-week.

 

For NZ and Tasman Sea

Troughs are expected to cross northern NZ on Monday and early Tuesday local, associated with the entrainment of tropical air from the top half of WINSTON.

 

>>>>>>

See my yotpak at boatbooks.co.nz/weather.html for terms used.

See my website www.metbob.com for information on tailor-made voyage

forecasts- Feedback to bob@metbob.com. Tell anyone you like that to subscribe they should email me.

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

Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom right to subscribe.

To unsubscribe send a reply email saying LEAVE.

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

bobmcdavitt@hotmail.com

 

 

 

Bob Blog 28 Feb 2016: WINSTON Peters

WEATHERGRAM

YOTREPS

Issued 28 February 2016

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.

 

Tropical cyclone WINSTON

I repeat that I am willing to help ANY yacht with FREE weather information if they agree to fill up with medical supplies on their way to FIJI/TONGA as part of SEA MERCY to supply relief after this cyclone season. This way I sponsor humanity.

See http://www.seamercy.org/

or

https://www.facebook.com/metbobnz/posts/1731717857039648

 

WINSTON is slowly petering away (apologies for this pun, based on a Kiwi politician, at least he himself, MP of our Northland, is above such a rub).

Its central circulation is still spinning as a tropical depression on the Coral Sea

There’s a chance (rather low) that it may redevelop. It has warm sea surface temperatures in favour, but has lost its top clouds, so this is an unlikely chance.

Its higher clouds have been entrained into a trough that is crossing northern New Zealand.

as seen at

http://www.tropicaltidbits.com/storminfo/11P_gefs_latest.png

 

TC YALO was briefly alive between Southern Cooks and French Polynesia but has now faded.

 

Rainfall in the tropics over the past week

as seen at

http://trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

shows the weakening of convection around Australia and an activation of convection between Cooks and French Polynesia, this is also now weakening.

 

Panama to Galapagos:

As for departing this week--- OK to go, but light winds at times. Good surface currants are expected.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

SPCZ stretches from Solomons to in-between Cook Islands and French Polynesia this week and is expected to slowly weaken.

 

STR= Sub-tropical Ridge

HIGH travelling east across southern Tasman next few days and central NZ during mid-week then to east of, and about, central NZ for the remainder of the week. This should hold troughs away AFTER mid-week.

 

For NZ and Tasman Sea

Troughs are expected to cross northern NZ on Monday and early Tuesday local, associated with the entrainment of tropical air from the top half of WINSTON.

>>>>>> 

See my yotpak at boatbooks.co.nz/weather.html for terms used.

See my website www.metbob.com for information on tailor-made voyage forecasts– Feedback to bob@metbob.com. Tell anyone you like that to subscribe they should email me.

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

Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom right to subscribe.

To unsubscribe send a reply email saying LEAVE.

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

 

21 February 2016

Bob Blog

WEATHERGRAM

YOTREPS

Issued 21 February 2016

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.

Tropical cyclone WINSTON

During Saturday (local) the eye of Cat 5 TC WINSTON made a direct hit over Vanua Balavu and Koro,

and last night it skirted across the north coast of Viti Levu.

Death toll is at present 7, and contact is still to be restored with several Islands.

It has today been travelling west, still Cat 5 and is expected to turn south on Monday local.

Computer models come up with different possibilities for WINSTON later this week

– most likely it will weaken as it encounters cooler seas and turn west around the south of New Caledonia.

On my illustrated site i show the lots of barometer and winds from Nadi last night from

from http://www.aviador.es/Weather/Meteogram (only aviators know about Density Altitude).

These show Gusts to 70 knots = 130 kph

Fiji Met service Radar shows that the southern half of WINSTON was weakened as the system encounter the mountains of Viti Levu:

See https://youtu.be/DZUiBDvPSGM for the animation

And WINSTON delivered over 800mm of rain in a day to several parts of Fiji.

Estimated gust intensities in TC WINSTON from JTWC of 160 knots makes WINSTON the most intense Southern hemi TC.

So says the media, but this will need to wait until the post-storm data verification analysis before becoming official

– RSMC already is coming in with lower numbers (mind you, WINSTON seems to be intensifying again tonight).

Seen on TWITTER

TC URIAH in the Indian Ocean is weakening at 26S as it leaves the tropics.

At present there are no other cyclone around, but the South Pacific Convergence Zone SPCZ has a long stretch of near equatorial westerly/northwesterly winds along its northern side. There are some interesting tropical depressions along the South Pacific Convergence Zone, one in the Coral Sea and another near Tahiti. Also a third tropical depression may form near American Samoa during their local Monday—they are near the middle of the confluence between the near equatorial westerly winds to the north and the SE trade winds to the south.

Rainfall in the tropics (seen at http://trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif)

over the past week shows the weakening over convection to NW of Australia and the activating of convective rain

along the South Pacific Convergence zone.

Panama to Galapagos:

As for departing this week--- Not as good as last week. Some convective showers are likely near 5N on local Wednesday and Thursday

followed by a burst of strong NE winds from Panama to Isla del Malpelo from local Friday to local Sunday.

Either get south of 5N by end of Wednesday r wait for a better pattern.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is now very active, and indeed may be reaching its seasonal maximum in intensity this week.

It is capable of producing another one, may be two tropical cyclones before it weakens.

There may be one of the e cyclones forming near American Samoa by mid-week. Hard to tell for sure,

so plan for the worst and hope for the best.

 

STR= Sub-tropical Ridge

HIGH travelling east across NZ this week is very strong and supported well aloft.

It should easily be able to deflect WINSTON to the west. There is a chance that WINSTON’s moisture

may be captured and entrained into the next trough that follows this HIGH.

 

For NZ and Tasman Sea

Trough is expected to visit Tasmania and south Tasman Sea on Wednesday local and cross South Island

and central Tasman by Friday and maybe stall over North Island on Sat/Sun 27/28 Feb.

Its rain depends on how much it entrains from the tropics.

 

>>>>>>

See my yotpak at boatbooks.co.nz/weather.html for terms used.

See my website http://www.metbob.com for information on tailor-made voyage forecasts

– Feedback to bob@metbob.com. Tell anyone you like that to subscribe they should email me.

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

Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom right to subscribe.

 

 

 

 

14 February 2016

Bob Blog 14 feb 2016

WEATHERGRAM

YOTREPS

Issued 14 February 2016

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.

 

Panama to Galapagos:

The best time of the year to do his trip is during the next month.

Looking at the monthly averaged scatterometer maps from the SCOW website at

http://numbat.coas.oregonstate.edu/scow/wind_speed_dir.html

for February, March and April shows that over much of the Pacific nothing seems to change during these months,

BUT the finer details shows a significant change in the averaged winds between Panama and Galapagos.

During February and early March there are regular period of NE winds over the Panama end of this trip,

with light SE winds around Galapagos.

 

Well, after the equinox (21 March) the likelihood of those useful NE bursts of wind around Panama dropdown significantly,

so that they are replaced by just light winds in the April average map.

Also across most of the route to the equator there are head winds from the south or southwest. Not so good.

 

Note that these averaged out maps are a OK guide for date-planning purposes,

but treat them as not being from the real world- the daily weather patterns are much more variable.

 

As for the influence of the current El Nino: This episode seems to have reached its peak,

and models are expecting the parameters we use to measure it to return to normal levels by May or June.

The extra heat that has been stored in the sea seems now to be going into the atmosphere,

and so is available for stronger weather events around the planet during the next 6 weeks or so,

but it is unlikely that anything severe will appear in the Panama to Galapagos region.

 

As for departing this week--- Looks mostly good, with convection showers between 2 and 6N mostly keeping well away

to west of 87W or along Colombian coast. However the forecast is for some strong (and thus uncomfortable) NE winds near 8N to 6N

on Monday or Friday UTC.

 

Tropical Cyclones

TC URIAH is in the Indian Ocean:as seen at http://www.bom.gov.au/products/IDW60281.shtml

 

TC TATIANA was in the Coral Sea travelling south but has been disrupted by strong winds aloft and is now downgraded to a tropical low.

 

TC WINSTON started in the middle of last week between Vanuatu and Fiji and has been drifting south and then sliding east. It was managed to miss out from being decapitated by the jetstream and now seems likely to be deflected to the northeast so that it might visit Tonga later this week. The more reliable EC model has it visiting Fiji. Worth watching and avoiding.

see http://www.met.gov.fj/aifs_prods/65648.html

Looking at the upper winds WINSTON is embedded in a SW flow and keeping away from the jetstream-

see http://squall.sfsu.edu/gif/jetstream_sohem_00.gif

 

Rainfall in the tropics over the past week has been most active in central Indian Ocean, in the Coral Sea and between Vanuatu and Fiji.

All these areas are now places where tropical cyclones are active.

Rain for the past week may be seen at http://trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ now stretches all the way across the south pacific and is intense. At the beginning of the week it extends from Solomons across Vanuatu to WINSTON, and then arcs from WINSTON across Tonga and Niue to Southern Cooks. As WINSTON travels to northeast the SPCZ will travel with it.

There is a possibility that another tropical depression may form near Southern Cooks by Tuesday UTC/local Monday, and then travel off to the southeast.

 

STR= Sub-tropical Ridge

HIGH east of NZ on Monday is expected to remain quasi-stationary at around 45S.

Next HIGH is expected to cross Tasmania around Friday and then move northeast across the Tasman and reach central NZ around Tue 23 Feb.

 

For NZ and Tasman Sea

Trough in the central Tasman Sea by Tuesday is expected to cross NZ on Wednesday and Thursday.

May be wetter than last week’s trough, as it may entrain some tropical moisture from the remains of TATIANA.

This trough is likely to be followed by a cooler southerly flow on Friday to Sunday.

>>>>>> 

See my yotpak at boatbooks.co.nz/weather.html for terms used.

See my website www.metbob.com for information on tailor-made voyage forecasts– Feedback to bob@metbob.com.

Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom right to subscribe.

 

07 February 2016

MetBob Blog 7 Feb

WEATHERGRAM
YOTREPS
Issued 7 February 2016
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.

Over the past month the isobar patterns have been remarkable in the northern hemisphere, with the Siberian winter HIGH and the North Pacific lows both more intense than normal.
See http://metbob.us12.list-manage.com/track/click?u=297f1d13c59cf6261733851cb&id=c41d223b89&e=78b77fda36

Also the HIGHS have been higher than normal around Australia and New Zealand, and there have been lower than normal pressure near Tahiti.
As seen at http://metbob.us12.list-manage1.com/track/click?u=297f1d13c59cf6261733851cb&id=8e363b8d63&e=78b77fda36

In spite of these anomalous HIGHS, there has been good rainfall over Australia and NZ during the past month, and the drier than normal areas in the past month have actually been over Vanuatu/Fuji/Tonga; as seen at http://metbob.us12.list-manage.com/track/click?u=297f1d13c59cf6261733851cb&id=b2af754e2b&e=78b77fda36

Tropical Cyclones
There are none around at present but there are possible topical lows forming near 14S 58E, 5S 87E, 15S 158E, and 9S 175E. That last one is expected to deepen further and may turn into a cyclone SW of Tuvalu later this week, travelling to SW of Fiji around 11 to 13 February.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is reforming mainly between equator and 10S, with tongues of convection onto northern Vanuatu and towards Samoa and Fiji. Tropical LOW is expected to deepen over Tuvalu on Wednesday local and then travelling south to be SW of Fiji on Thursday 11 to Saturday 13 February.

STR= Sub-tropical Ridge
HIGH east of NZ on Monday is expected to move off to the east along 45S.
HIGH over central Tasman Sea on 10 Feb NZ is slow-moving and expected to get east of NZ on 13 Feb then start travelling off to the east.

For NZ and Tasman Sea
Trough in the central Tasman Sea is expected to cross NZ on Tuesday and Wednesday then fade off to the east. Next trough is expected to skirt around southern NZ on Saturday 13th, followed by another on 16th Feb.

>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts– Feedback to bob@metbob.com.

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