Translator

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

28 December 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 28 December 2014
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 Ocean: extra heat has been stored in the Pacific Ocean for a while now
and all the Oceanic indices have crossed the threshold into El Nino
territory.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
sums up the weather pattern over the South Pacific as one number. It is
based on the standardized difference in the barometer readings between
Tahiti and Darwin. It has been negative since July and dived below -10
(Australian units) for much of September, and again for a week in November,
then relaxed in early December, but last week started another negative dive.
The atmospheric El Nino is stuttering.
In an El Nino event the latitudes of the normal weather zones are drawn
closer to the equator, causing the South Pacific Convergence zone to shift
further north and east of its normal position.

TROPICAL TOPICS
The tropical low that formed last Wednesday between Samoa and
Rarotonga/Tahiti has travelled SE and faded.
Rain intensified in the South Pacific Convergence Zone last week. It also
reached deluging levels over Sri Lanka (with the arrival of a tropical Low)
and over Malaysia (as a monsoon---the most intense in decades).
Also at present there is a tropical depression situated east of Philippines,
travelling west, also TC KATE to SW of Cocos Island in the South Indian
Ocean.
And in the South Pacific another tropical low has formed today, just east of
Samoa. The latest thinking is that this South Pacific system may soon move
SSE with slight intensification getting close to Niue/Rarotonga by local
Monday.

Tropical Disturbance Summary For area Equator to 25S, 160E to 120W ISSUED
FROM RSMC NADI Dec 28/0126 UTC 2014 UTC.
TROPICAL DEPRESSION TD05F CENTER [1000HPA] ANALYSED NEAR 13.0S 169.0W AT
280000UTC. TD05F SLOW MOVING. POSITION POOR BASED ON MTSAT IR/VIS IMAGERY
AND PERIPHERAL OBSERVATIONS. SST AROUND 30 DEGREES CELSIUS.
CONVECTION REMAINS PERSISTENT IN THE PAST 06 HOURS. ORGANISATION REMAINS
POOR. THE SYSTEM LIES UNDER AN UPPER DIFFULENT REGION IN A MODERATE SHEARED
ENVIRONMENT. OUTFLOW GOOD TO THE SOUTHEAST. CYCLONIC CIRCULATION EXTENDS UP
TO 500HPA.
GLOBAL MODELS HAVE PICKED THE SYSTEM AND MOVE IT SOUTHEASTWARDS WITH SLIGHT
INTENSIFICATION.
POTENTIAL FOR TD05F TO DEVELOP INTO A TROPICAL CYCLONE IN THE NEXT 24 TO 48
HOURS IS LOW.
NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE AREA.
Fiji Met Service tropical disturbance discussion above is as at
http://www.met.gov.fj/aifs_prods/20036.txt
If you are in this area then please remain vigilant and keep up to date with
these latest TC bulletins.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is strong east of the dateline with strong NW winds on its northern
side, strong SE winds on its southern side and gale force squalls in-
between. A new branch is expected to form over Coral Sea from mid-week.

STR= Sub-tropical Ridge
A new High cell is crossing the South Island tonight and is expected to
merge with the quasi-stationary high near 40S 170W by mid-week, making a
larger High centered near 45S. This High should then travel east for the
remainder of the week along 45S.
The next High is expected to enter the central Tasman Sea on Wed/Thu and
fade on Friday. Another High is expected to cross Tasmania on Thursday and
then move east crossing central NZ over Sat 3/Sun 4 Jan. Good by then for
holiday weekenders.

Over NZ
Trough between Highs is expected to reach central Tasman by Tuesday and
cross NZ on Wednesday in time for local New Year s Eve. This should be
followed by a period of disturbed SW/S winds and fronts on Thursday and
Friday.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
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.
My website is at metbob.com Feedback to bob@metbob.com To unsubscribe:
send a reply email saying LEAVE.

23 December 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 24 December 2014
Bob McDavitts ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

I want to offer the best of greetings and good things to you and yours for
Christmas and the Yule-tide season.
This extra blog from me gives me the opportunity to update you with that
tropical low between Samoa and Tahiti as seen at
http://www.meteo.pf/observation.php?carte=pf
and at http://www.met.gov.fj/aifs_prods/0640.gif

The latest thinking about this feature is as follows:
>>>>
TROPICAL DISTURBANCE ADVISORY NUMBER A5 ISSUED FROM RSMC NADI Dec 23/1939
UTC 2014 UTC.
TROPICAL DEPRESSION 03F CENTER [999HPA] ANALYSED NEAR 13.8S 158.8W AT
231800UTC. DEPRESSION MOVING EAST AT ABOUT 06 KNOTS. MAXIMUM 10-MINUTE
AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 30 KNOTS.

OVERALL ORGANISATION HAS IMPROVED PAST 24 HOURS. DEEP CONVECTION HAS
INCREASED AND IS OVER THE EASTERN SEMI CIRCLE OF LLCC. SYSTEM LIES UNDER A
STRONG UPPER DIVERGENT REGION IN A LOW TO MODERATE SHEARED ENVIRONMENT.
OUTFLOW GOOD TO THE EAST AND NORTH BUT RESTRICTED ELSEWHERE. CYCLONIC
CIRCULATION EXTENDS UP TO 500HPA. SST AROUND 29 DEGREES CELCIUS. DVORAK
ANALYSIS BASED ON 0.4 WRAP GIVING DT=2.5, MET AND PT AGREE. FT BASED ON DT
THUS YEILDING T2.5/2.5/D0.5/24HRS.

GLOBAL MODELS AGREE ON A EASTERLY MOVEMENT THEN SOUTHEAST WITH FURTHER
INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE WITHIN THE NEXT
12 TO 24 HOURS IS MODERATE TO HIGH.

FORECASTS:
AT 12 HRS VALID 240600 UTC 14.2S 158.1W MOV ESE AT 04KT WITH 35 KNOTS CLOSE
TO CENTRE AT 24 HRS VALID 241800 UTC 15.2S 157.5W MOV SE AT 05KT WITH 40
KNOTS CLOSE TO CENTRE
OUTLOOK:
AT 36 HRS VALID 250600 UTC 16.4S 157.3W MOV SSE AT 06KT WITH 45 KNOTS CLOSE
TO CENTRE AT 48 HRS VALID 280600 UTC 17.6S 157.3W MOV S AT 06KT WITH 45
KNOTS CLOSE TO CENTRE

THE NEXT TROPICAL DISTURBANCE ADVISORY ON TD03F WILL BE ISSUED AT OR AROUND
240200UTC.
>>>>>>>>>>>>>
Updates on this Disturbance summary as seen at
http://www.met.gov.fj/aifs_prods/20032.txt
SO it is expected to go east then SE and may develop more and get named as a
tropical cyclone by Christmas Day.
If you are in the Tahiti/Southern Cooks area, then I recommend vigilance.

bob

Bob Blog

WEATHERGRAM
YOTREPS
Issued 24 December 2014
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.

I want to offer the best of greetings and good things to you and yours for
Christmas and the Yule-tide season.
This extra blog from me gives me the opportunity to update you with that
tropical low between Samoa and Tahiti as seen at
http://www.meteo.pf/observation.php?carte=pf
and at http://www.met.gov.fj/aifs_prods/0640.gif

The latest thinking about this feature is as follows:
>>>>
TROPICAL DISTURBANCE ADVISORY NUMBER A5 ISSUED FROM RSMC NADI Dec 23/1939
UTC 2014 UTC.

TROPICAL DEPRESSION 03F CENTER [999HPA] ANALYSED NEAR 13.8S 158.8W AT
231800UTC. DEPRESSION MOVING EAST AT ABOUT 06 KNOTS. MAXIMUM 10-MINUTE
AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 30 KNOTS.

OVERALL ORGANISATION HAS IMPROVED PAST 24 HOURS. DEEP CONVECTION HAS
INCREASED AND IS OVER THE EASTERN SEMI CIRCLE OF LLCC. SYSTEM LIES UNDER A
STRONG UPPER DIVERGENT REGION IN A LOW TO MODERATE SHEARED ENVIRONMENT.
OUTFLOW GOOD TO THE EAST AND NORTH BUT RESTRICTED ELSEWHERE. CYCLONIC
CIRCULATION EXTENDS UP TO 500HPA. SST AROUND 29 DEGREES CELCIUS. DVORAK
ANALYSIS BASED ON 0.4 WRAP GIVING DT=2.5, MET AND PT AGREE. FT BASED ON DT
THUS YEILDING T2.5/2.5/D0.5/24HRS.

GLOBAL MODELS AGREE ON A EASTERLY MOVEMENT THEN SOUTHEAST WITH FURTHER
INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE WITHIN THE NEXT
12 TO 24 HOURS IS MODERATE TO HIGH.

FORECASTS:
AT 12 HRS VALID 240600 UTC 14.2S 158.1W MOV ESE AT 04KT WITH 35 KNOTS CLOSE
TO CENTRE AT 24 HRS VALID 241800 UTC 15.2S 157.5W MOV SE AT 05KT WITH 40
KNOTS CLOSE TO CENTRE

OUTLOOK:
AT 36 HRS VALID 250600 UTC 16.4S 157.3W MOV SSE AT 06KT WITH 45 KNOTS CLOSE
TO CENTRE AT 48 HRS VALID 280600 UTC 17.6S 157.3W MOV S AT 06KT WITH 45
KNOTS CLOSE TO CENTRE


THE NEXT TROPICAL DISTURBANCE ADVISORY ON TD03F WILL BE ISSUED AT OR AROUND
240200UTC.
>>>>>>>>>>>>>
Updates on this Disturbance summary as seen at
http://www.met.gov.fj/aifs_prods/20032.txt
SO it is expected to go east then SE and may develop more and get named as a
tropical cyclone by local Christmas Day.
If you are in the Tahiti/Southern Cooks area, then I recommend vigilance.

bob

21 December 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 21 December 2014
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 Ocean: extra heat has been stored in the Pacific Ocean for a while now
and all the Oceanic indices have crossed the threshold into El Nino
territory.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
sums up the weather pattern over the South Pacific as one number. It is
based on the standardized difference in the barometer readings between
Tahiti and Darwin. It has been negative since July and dived below -10
(Australian units) for much of September, and again for a week in November,
but has since been relaxing again--- the atmospheric El Nino is stuttering

In an El Nino event the latitudes of the normal weather zones are drawn
closer to the equator, causing the South Pacific Convergence zone to shift
further north and east of its normal position.

TROPICAL TOPICS
Weekly rain maps over the past fortnight show an increase in convection over
the past week east of 180 and another increase to NE of Madagascar in the
western South Indian Ocean.
A MJO (Madden Julian Oscillation of enhanced convection) is now fading near
and just east of 180 after it made its way eastwards across the Coral Sea
last week.
This has allowed a zone of near equatorial westerly winds to extend along
5 to 15S as far east as Samoa. These near equatorial westerly wind tend to
upset the wets facing harbours in Tuvalu and Tokelau.
These west or NW winds also accentuate the convection in the South Pacific
Convergence zone, and help tropical depressions to form.
One is forming now east of Samoa and north of Niue:
It has strong NW winds on its NE side and strong SE winds on its SW side The
latest thinking is that this system may soon move SE to the area between
Rarotonga and Tahiti by Christmas Day:

Tropical Disturbance Summary For area Equator to 25S, 160E to 120W ISSUED
FROM RSMC NADI Dec 20/2347 UTC 2014 UTC.
TROPICAL DISTURBANCE 03F CENTER {[1004HPA]} ANALYSED NEAR 13.2S 170.0W AT
202100UTC. TD03F SLOW MOVING. POSITION POOR BASED ON MTSAT VIS/IR IMAGERY
AND PERIPHERAL OBSERVATIONS. SST AROUND 30 DEGRESS CELCIUS.
ORGANISATION IS POOR. CONVECTION IS PERSISTANT IN THE NORTHERN SEMICIRCLE
AND DETACHED FROM SUPPOSED LLCC IN THE PAST 06 HOURS. THE SYSTEM LIES IN A
DIFFULENT REGION, EAST OF A SHORTWAVE UPPER TROUGH IN A LOW SHEARED
ENVIRONMENT. CYCLONIC CIRCULATION EXTENDS UPTO 500HPA.
GLOBAL MODELS HAVE PICKED THE SYSTEM AND MOVE IT EAST-SOUTHEASTWARD WITH
LITTLE INTENSIFICATION.
POTENTION FOR TD03F TO DEVELOP INTO A TROPICAL CYCLONE IN THE NEXT 24 TO 48
HOURS IS LOW.
NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE AREA.
Fiji Met Service tropical disturbance discussion above is as at
http://www.met.gov.fj/aifs_prods/20036.txt
If you are in this area then please remain vigilant and keep up to date with
these latest TC bulletins.

MJO cycles are usually paced about 6 weeks apart and are known to increase
the risk of tropical cyclone formation as they pass. This MJO is this week
bothering places east of 180. My take on this is that for the next few weeks
the Southwest pacific will be between MJO events and the risk of enhanced
convection/tropical disturbances will drop to LESS THAN NORMAL by New Year
and stay that way for a few weeks. Thats good news.

WEATHER ZONES
Note that there are expected to be STRONG NE winds near and north of the
equator, making a E swell there over 2.5 significant metres.

SPCZ=South Pacific Convergence zone.
SPCZ is strong east of the dateline with strong NW winds on its northern
side, strong SE winds on its southern side and gale force squalls in-
between. Avoid.

STR= Sub-tropical Ridge
Finally, after several weeks, a High is expected to get east of central NZ
on Monday. This HIGH should expand to over 1030 hPa and move slowly NE
across Chatham Islands on Tuesday and NE to 35S 165W by Sun 28 Dec.

Over NZ
Next main trough is expected to reach SW of South Island on Boxing Day and
spread NE (and weaken) to northern NZ by Sat/Sun 3/4 January.
Nice Holiday weather over northern NZ (albeit NE winds from 23 to 30 Dec),
but try and avoid sailing during the weekend of 3 and 4 Jan.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
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.
My website is at metbob.com  Feedback to bob@metbob.com To unsubscribe from
WordPress: click the "unsubscribe" link on the bottom of the email.
Or, if email wasn't from WordPress then send a reply email saying LEAVE.

14 December 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 14 December 2014
Bob McDavitts ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

The Ocean: extra has been stored in the Pacific Ocean for a while now and
all the Oceanic indices have crossed the threshold into El Nino territory.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
sums up the weather pattern over the South Pacific as one number. It is
based on the standardized difference in the barometer readings between
Tahiti and Darwin.
It has been negative since July and dived below -10 (Australian units) for
much of September, and again for a week in November, but has since been
relaxing again the atmospheric El Nino is stuttering In an El Nino event
the latitudes of the normal weather zones are drawn closer to the equator,
causing the South Pacific Convergence zone to shift further north and east
of its normal position.

TROPICAL TOPICS
A MJO (Madden Julian Oscillation of enhanced convection) is making its way
now eastwards across the South Pacific Ocean this week, and this has formed
near-equatorial west/NW winds over northern Australia and in the northern
Coral Sea. These may reach 180 in the next week or so, making for
challenging conditions for fishing and diving in Tuvalu and Kiribati.
MJO cycles are usually paced about 6 weeks apart and are known to increase
the risk of tropical cyclone formation as they pass. This MJO has triggered
a small Tropical Cyclone over the open sea to SW of Indonesia called BAKUNG
near 9S 87E. However this MJO is early in the season and is NOT expected to
form a TC in the Pacific.

Weekly rain maps over the past fortnight show an increase in convection over
the past week spreading eastwards across Northern Australia. Also the rain
that was over Philippines with HAGIPUT about a week ago has gone now.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is now split into several distinct convergence zones, and this makes
the next week more volatile than normal. The MJO does this, but I think this
MJO might not trigger a TC in our region. That just raises the ante for the
next MJO, which is likely in January. I suppose thats good news for
Christmas /New Year travellers.
The MJO has triggered a series of sub-tropical troughs in the northern
Tasman SeaOne is passing by northern NZ tonight and gave wind and rain here
for past 24 hours, upsetting our Christmas in the Park in Auckland last
night and cancelling at least one local youth group picnic today.
Yuck. But it is a sign of summer, I suppose.
After this week there should be two Convergence Zones: One visiting New
Caledonia and Fiji for Christmas and another, likely to be intense, between
Samoa and Southern Cooks/ French Polynesia. Disturbing Christmas weather
here.

STR= Sub-tropical Ridge
The troughs forming in the northern Tasman Sea have dislodged the STR to
southern NZ (first time in weeks, a nice change for them). One High is
expected to move off to NE of NZ over next few days as another Low crosses
the Tasman Sea from Thursday to Sunday 21st (over South Island).
This should set things up so that next HIGH crosses central Tasman Sea 40S
from Sunday to Wednesday (fading over North Island) and the following HIGH
travels along 45S from Wed crossing central NZ on Friday/Saturday.
Happy settled weather for Christmas to NZ.

Over northern NZ
Strong East/NE/NW winds on Monday/Tuesday/Wednesday from passing trough,
then quieter northerly winds until a weak trough is expected on Sun/Mon
21/22 Dec, and then SE winds.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
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.
My website is at metbob.com  Feedback to bob@metbob.com To unsubscribe
send a reply email saying LEAVE.

07 December 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 07 December 2014

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 Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
sums up the weather pattern over the South Pacific as one number. It is
based on the standardized difference in the barometer readings between
Tahiti and Darwin.
It has been negative since July and dived below -10 (Australian units) for
much of September, relaxed for a while in October, and dived below -
10 early in early November, and is now hovering near -10.

We know that in an El Nino event the latitudes of the normal weather zones
are drawn closer to the equator, causing the South Pacific Convergence zone
to shift further north and east of its normal position.

TROPICAL TOPICS
Typhoon HAGUPIT is tonight moving NW across northern Philippines. Just over
a year and a month after HAIYAN.
Usually December is a quiet month for cyclones in the NW Pacific, however
another tropical system is expected to form near 5N 140E by Tuesday and
deepen as it passes near Yap on Wednesday/Thursday and then deepen further
until it is expected to visit northern Philippines next Sunday, one week
after HAGIPUT. However if this system takes a track similar to HAGIPUT then
it may encounter cooler conditions in the recently stirred surface waters
and thus not intensify as much. We hope.

Weekly rain maps over the past fortnight show an increase in convection over
the past week spreading eastwards from Indonesia to Micronesia. This
increase in convection is associated with what is called an MJO or Madden
Julian Oscillation, and has helped trigger and fire up HAGIPUT and may
trigger a few more tropical lows in the Micronesian area during the next two
weeks.
This increase in convection may well gradually make its way into the Pacific
Ocean over the next few weeks. By mid-December this is expected to increases
the risk of a tropical cyclone generating in the area north of Vanuatu.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is expected to take a week off over PNG and Solomon Islands and be
strong from northern Vanuatu to Wallis/Futuna to Samoa to Southern Cooks.
>From the end of this week there is likely to be an increase in activity
around Australia and in the area about and north of Vanuatu.

STR= Sub-tropical Ridge
The STR has split into a strong zone well to the south from Aussie Bight
to south Tasman Sea, and a northern zone lingering at 30S between NZ and
Niue.
The northern High is expected to slowly travel east to southeast between
30S and 35S as a low deepens between the Highs in the Tasman Sea by
Thursday local.

Over northern NZ
Brief ridge is expected to cross northern NZ on Monday with light winds,
followed by a N/NW flow on Tuesday to Friday (as low develops in Tasman
Sea) and then an associated front on Saturday, followed by a brief cool
southwest flow on Sunday 14 Dec, and then light winds in a ridge on
Monday 15 Dec.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
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.
My website is at metbob.com  Feedback to bob@metbob.com
To unsubscribe send a reply email saying LEAVE.

Blog Archive