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

23 February 2014

BOB's BLOG issued 23 Feb 2014

WEATHERGRAM
YOTREPS
Issued 23 February 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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

In the past few weeks the northern winter has been brutal in eastern US and
over UK. The jet streams have had more latitude coverage than normal, and
have maybe been held in position by a blocking pattern. Also the stronger
than normal upper winds may have been extended higher upwards in the
atmosphere by a westerly phase of the Quasi Biannual Oscillation  a weather
driver in the stratosphere.
The QBO can be seen at the NCEP website.

SOI The Southern Oscillation Index SOI 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.
SOI (30 day running mean) continues on its roller coaster ride for 2014.
It peaked on late January/early February and is now sliding down. On 23
February the 30-day running mean was 0.13.

TROPICAL TOPICS
Weekly accumulated rain maps show a buildup of rain around Papua New Guinea
in the past week, due to enhanced equatorial westerlies.
There are no active tropical storms at present. The risk of tropical cyclone
formation in the South Pacific rises to MODERATE this week, with the most
likely areas being between Vanuatu and Fiji. Most models are picking this
development to likely occur around Wednesday with the disturbance then
moving S and then SE, and the associated trough crossing
Tonga and Niue on Sat/Sun 2/3 March. Avoid.

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The South Pacific Convergence zone is expected to remain active between
Papua New Guinea and Tonga/Niue. Another, weaker, zone is expected to hover
between Tokelau and French Polynesia.
There has been a burst of near equatorial westerly winds across the Timor
Sea last week and this is currently travelling from north of the Solomons
towards Tuvalu. It is likely to help aid the formation of a Low near Fiji by
Wednesday.

Sub-tropical Ridge STR
That Cicada High mentioned in last weeks Weathergram managed to bring
warm temperatures to NZ. It has travelled off to the east and that trough
which crossed NZ last weekend is followed by a few days of cooler southerly.
The HIGH now in the Tasman Sea is expected to cross central NZ and move off
to the east by Thursdaynot as long and not as warm as last weeks HIGH.

New Zealand area
A cold front is expected to lick the southern areas on Monday.
Then a combo of fronts is likely to spread a trough and then southerly
change across the whole of NZ during Thursday 27 to Sat 1 March.
Then another slow-moving HIGH is likely for the following week.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe. Weathergram text only (and translator) is at
weathergram.blogspot.co.nz My website is at metbob.com - To unsubscribe send
an email to bob@metbob.
com saying unsubscribe. Feedback to bob@metbob.com

16 February 2014

BOBGRAM issued 16 Feb 2014

WEATHERGRAM
YOTREPS
Issued 16 February 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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI The Southern Oscillation Index
SOI 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.
SOI (30 day running mean) has relaxed from its recent high. Its 30-day
running mean was over plus 1 for late Jan/early Feb and then dropped. it
was 0.58 on 15 February.

German Scientists Josef Ludescher et al have published a paper in the past
week which claims that El Nino episodes can now be detected as much as a
year ahead and that there is a 75% chance of one starting late in 2014. The
abstract of their paper is at www.pnas.org/content/111/6/2064.
abstract

The Ocean:
The warmer the sea the quicker it evaporates, tossing water vapour into the
air, where is rises and cools into cloud. The equatorial Pacific region
hosts the widest and warmest sea on the planet. Thus its sea surface
temperatures SST may be thought of as a factor in the running of planetary
weather engine. When SST in the target zone (equatorial Pacific between
dateline and Galapagos) are notably cooler than normal, this is called a La
Nina episode.
The SST in the target zone as measured via satellite is in the blue (cooler
than normal) at present, but not by much. The cool blue hue covers much of
the SE Pacific with a broad brush at present as seen in the latest NOAA
satellite data. There is also blue stuff in the Tasman Sea and around NZ -
this indicates an early start to autumnal conditions here, and also may
demotivate any tropical systems that may move onto NZ during the next few
weeks,

TROPICAL TOPICS
Weekly rain accumulated images show that the most intense rain last week was
about and south of southern French Polynesia- even more intense than the
reported trouble spots :eastern USA or southern UK.
There are No tropical storms at present The risk of tropical cyclone
formation in the South Pacific is expected to remain low this coming week.
The Monsoonal trough in Australia is starting to vent its energy across New
South Wales and is expected to breed some lows that may deepen as they cross
the South Tasman Sea/ South Island area on 17-18 February and again on 20-22
February.

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The South Pacific Convergence zone is expected to become active over
Solomons and Vanuatu and Fiji, and drift south of Fiji by Friday, allowing a
sub-tropical low to form between Fiji and NZ on Sat 22 February. This low is
expected to the drift SW towards Norfolk Island by wed 26 February.
A second branch of the SPCZ is likely to harass islands from Samoa to
central French Polynesia.
And southern Islands of French Polynesia (Tuamotu/Gambier) are likely to
have a cold front (associated with a low in the southern ocean) move across
them on Wed to Friday 19/21 UTC.

Sub-tropical Ridge STR
The 'Cicada' High that was introduced to NZ in last week's Weathergram is
likely to move to east of NZ on Monday/Tuesday and then hover near 170W
until Friday 21 Feb and then roll off to the east-so this week it is
expected to maintain a ridge 'back' onto part of NZ , helping the cicada
chirp by day.
The next high is expected to travel quickly across the Australian Bight
during the week, cross Tasmanian on Sat 22 Feb and then the South Tasman Sea
on Sunday and central NZ on Monday 24 Feb

New Zealand area
Intense front is expected to cross South Island on Mon/Tue 17/18Feb Weak
ridge from the 'Cicada' High should return on Wed/Thu 19/20 Feb Then a more
intense front and associated low from the Tasman Sea should cross southern
(and affect central) NZ on Fri/Sat 21/22 Feb followed by a cool and windy
S/SE flow (over all NZ) on Sun 23 Feb.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe. Weathergram text only (and translator) is at
weathergram.blogspot.co.nz My website is at metbob.com - To unsubscribe from
this email reply with an email saying UNSUBSCRIBE.
Feedback to bob@metbob.com

09 February 2014

BOBGRAM

WEATHERGRAM
YOTREPS
Issued 09 February 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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI The Southern Oscillation Index SOI 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.
SOI (30 day running mean) has jumped into possible La Nina territory over
the past few weeks. Its 30-day running mean has remained over plus 1.30 from
1 to 9 Feb if this continues for a few more weeks then we will be diving
onto a new La Nina episode.

The Ocean: The warmer the sea the quicker it evaporates, tossing water
vapour into the air, where is rises and cools into cloud. The equatorial
Pacific region hosts the widest and warmest sea on the planet. Thus its sea
surface temperatures SST may be thought of as a factor in the running of
planetary weather engine. When SST in the target zone (equatorial Pacific
between dateline and Galapagos) are notably cooler than normal , this is
called a La Nina episode.
The SST in the target zone is measured by the NINO3.4 index and this has
taken a notable drive during the past few weeks. This means that both
atmospheric and oceanic parameters in the tropical Pacific are now trending
towards a La Nina event.

Interesting websites
A few weeks ago I mentioned the great imagery available at http://earth.
nullschool.net/
Well, they have now added latest imagery from the OSCAR satellite and these
are worth checking out- (click on earth then Mode>Ocean). A quick link
covering the Tasman Sea is at bit.ly/1aFdDNm and sort of explains why the
larger snapper are offshore from Auckland at present (thanks to John Neal of
MAHINA TIARE III for this update).

For those seeking weather satellite imagery covering a whole year for
educational purposes check out www.youtube.com/watch?v=m2Gy8V0Dv78
(EUMETSAT).

TROPICAL TOPICS
The risk of tropical cyclone formation in the South Pacific is expected to
be LESS than normal over the next few weeks.
Cyclones made brief appearances over western New Caledonia (EDNA) and in
Gulf of Carpentaria (FLETCHER) last week. At present TC FOBANE is in the
south Indian Ocean.

The Australia Monsoonal trough is still in peak heat and wet the wet zone is
draping northern Australia and the hot zone is covering central and southern
Australia. The Monsoonal Low currently over NW Australia is expected to soon
start travelling south and the southeast across central Australia this week
spawning a series of smaller lows all going southeast and moving into the
South Tasman Sea by the weekend 15/16 Feb and then across southern NZ early
next week. These lows are likely to have very strong wind changes with them
and the Monsoonal trough is bringing a culmination of heat-wave conditions
to central and then SE Australia over the next few days. Peak days may be
Tue /Thu 11/13 Feb
see www.bom.gov.au/australia/heatwave/

WEATHER ZONES
South Pacific Convergence Zone SPCZ
EDNA took the main part of the convection that was in the Coral Sea away
into the mid-latitudes. What remains behind may need/take few weeks to
rebuild.
There is a second branch of the SPCZ between Samoa and French Polynesia,
with random and moderate activity. There is a tropical low between Southern
Cooks and Papeete tonight with gale force squalls and lots of lightning. It
is expected to go south and then fade mid-week near 25S.

Sub-tropical Ridge STR
A HIGH is expected to get pushed out of the way by the advancing Australian
monsoonal trough on Tuesday/Wednesday and then travel NE across the Tasman
Sea on Thursday and across the North Island on Friday/Saturday/Sunday-
cicada weather.

New Zealand area
NZ starts the week with a ridge over the south and a trough to the NE. A
passing small but intense Southern Ocean Low is expected to cross the South
Island on Tuesday and Wednesday followed by a cool SW flow covering all NZ
by Thursday 13th.
Then that high should cross NZ late in the week followed by hot northerly/NW
winds for the South island on Sat/Sun 15/16 Feb.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe. Weathergram text only (and translator) is at
weathergram.blogspot.co.nz My website is at metbob.com - To unsubscribe send
an email to bob@metbob.com saying unsubscribe. Feedback to bob@metbob.com

02 February 2014

BOBGRAM issued 2 Feb 2014

WEATHERGRAM
YOTREPS
Issued 02 February 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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI 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.
SOI has jumped into possible La Nina territory over the past few weeks.
Its 30-day running mean was plus 1.30 on 1 Feb.

TROPICAL TOPICS
The combination of a new moon and a perigean moon is bringing King Tides
around the worldand this is causing damage in the UK where it has been
combined with strong onshore winds. The high water of a King tide of Feb
CE2014 is an initial indicator of what rising sea levels may add to the
average tide by CE2100. There need to be local corrections applied due to
rising and falling landmasses and maybe a shift of the sea-level surface
around the planet by then, but sceptics who ignore these signs do so at the
risk of their grandchildrens welfare. Its up to international politicians
to respond on our behalf; the IPCC can only point out to all the signs of
where we are going.

Islands such as those in Tuvalu and Kiribati are especially vulnerable at
the time of the King tide. Luckily there was nothing much extra from the
weather this time round.

Why was TC JUNE followed by TC DYLAN????.. well we have TWO warning centres
in this part of the world. Fiji looks after 160E and eastwards and is the
South Pacific Basin (and named TC JUNE), Australia looks after 160E and
westwards, the Australian Basin (and their names are up to DYLAN).

Cyclone DYLAN was too large in size and unable to develop to it full
possible potential before it went inland across the Townsville area last
Thursday. It did bring some minor wind and storm-surge damage and some
much-needed rain, but didn't break the central Queensland drought. Would
have been more damaging if it stayed offshore and deepened a few days then
went onshore with the peak of the King Tides, but no one in their right mind
would want to see that!. Phew, it missed.

The Australia Monsoonal trough is in its peak at present, and expected to
drift south this week. A Low is likely to form inland over northern
Australia by Monday and then drift west  It is likely to develop into a
tropical cyclone when it drifts onto the sea over NW Australia early next
week around 10 or 11 Feb. Avoid.

The next tropical feature in the South Pacific is already forming in the
Coral Sea just west of Vanuatu. This is expected to deepen into a possible
cyclone by Tuesday and track southwards to west of New Caledonia on
Wednesday and then unravel in the central Tasman Sea. However it is expected
to inject moisture and lower-density air into the eastern side of a low from
the Southern Ocean  the one that is expected to cross Tasmania on sat/Sun
8/9 Feb. This difference in density between the west and east side of this
Low is likely to aid further deepening of this feature as it crosses the
South Tasman Sea and sideswipes southern NZ next week. Avoid.


WEATHER ZONES

South Pacific Convergence Zone SPCZ
This is very active in the Coral Sea at present and expected to form a Low
by Tuesday that tracks south to west of New Caledonia on Wednesday and then
unravels in the Tasman Sea.

Sub-tropical Ridge STR
The HIGH in the Tasman Sea is expected to make a rare crossing of central NZ
on Monday (=height of summer conditions) and then wander off to the NE of
the North Island on Tuesday and then to east of NZ along 35S for the rest of
the week.

New Zealand area
Ridgey and summery. A trough is likely to cross NZ on Tue 4/wed 5 Feb and
then a HIGH crossing Tasmania on Tue 4 Feb is expected to cross central and
Southern NZ on Thu 6 Feb (Waitangi Day, a public holiday in NZ) to Sun 9
Feb. So most of NZ gets a ridgey week at last and enjoys summer- However
Northland gets a lot of easterly wind and swell  surf up East coast.
This is the week that air temperatures normally reach their maximum of the
year in NZ, and indeed this seems to be the case for 2014. Next week the
downward drift starts all the way to the depths of winter.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe. Weathergram text only (and translator) is at
weathergram.blogspot.co.nz My Website is at metbob.com - To unsubscribe send
an email to bobmcdavitt@hotmail.com saying unsubscribe. Feedback to
bob@metbob.com

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