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

31 January 2016

Bob Blog 31 Jan 2016

Bob Blog 31 Jan 2016
WEATHERGRAM
YOTREPS
Issued 31 January 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.

During summer there are cycles of increased convection every 4 to 6 weeks or
so that can trigger tropical cyclones. These are called Madden Julian
Oscillations and the phase diagram of the MJO can be seen at
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml
This phase diagram shows that the next cycle of increased convection for the
South Pacific is likely to be around mid-February, but that it is also
likely to be weaker than the MJO cycle we had at the turn of the year.

The meteorologists at Meteo France in New Caledonia are constructed a model
that converts the behavior of MJO into a probability map for the formation
of tropical cyclones, and it is no great surprise this model also is
picking mid-February and the most likely timing for the net cyclone.
To see this goto
http://www.meteo.nc/modules/mod_cyclone_experts/assets/popup/850_bis_cycl.ph
p?dossier=L3Byb2QvY3ljbG9uZXMvZXhwZXJ0cw==


Tropical Cyclones
TC STAN formed during the past week over the seas to northwest of Australia
and is now moving inland.
Weekly rain maps for the tropics (from
http://trmm.gsfc.nasa.gov/rmm_rain/Events/big_global_accumlation.gif) over
the past two weeks show a gradual strengthening of the South Pacific
Convergence Zone, especially in the Coral Sea and along the Queensland
coast.

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.

STR= Sub-tropical Ridge
HIGH east of NZ on Monday is expected to move off to the east later this
week.
New HIGH over Tasmanian at end of the week is expected to travel into mid
Tasman early next week.

For NZ and Tasman Sea
Trough that is crossing New South Wales on Monday is expected to deepen into
a low over mid Tasman sea by late Wednesday and then deepen further an it
travels across northern NZ during long weekend of 6 to 8 Feb (Waitangi day
public holiday has been Mondayised).

>>>>>>
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 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.
Send replay email saying LEAVE to drop off this list

24 January 2016

Bob Blog

WEATHERGRAM

YOTREPS

Issued 24 January 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.

 

This El Nino cycle seems to now be relaxing. The monthly NINO 3.4 index which measure the amount of heat stored in the eastern equatorial Pacific Ocean reached a maximum of +3.0 in December--- slighter more than the previous strong El Nino in 1997/98, and is now relaxing. Maybe this heat is being released into the atmosphere activating  weather systems around the world.

NINO 3.4 index may be  seen at http://www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=nino34&p=weekly

 

In spite of the easing of NINO3.4, the weekly SOI index has become more intense over the past two weeks:

SOI index may be seen at  http://www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=soi&p=weekly

 

Tropical Cyclones

TC VICTOR moved under the Jetstream and lost its top and has be downgraded to a tropical low. Soon it will leave the tropics and may unwind a little more at it travels south to the  east of North Island.

When it encounters colder and denser air near 40S on Thursday it may deepen again for a day or so.

 

Tropical Storm CORENTIN is the only tropical cyclone around this evening and is in the Indian Ocean.

 

Weekly rain maps for the tropics, as seen at http://trmm.gsfc.nasa.gov/rmm_rain/Events/big_global_accumlation.gif ,

over the past two weeks show a weakening of the South Pacific Convergence Zone, and a build-up of activity in the Indian Ocean.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

Most of the old SPCZ has been taken south by VICTOR, but a new one is reforming mainly between equator and 10S. The equatorial westerly winds

that were around last week have all gone now.

 

STR= Sub-tropical Ridge

STR is strong near 40S to east of NZ, with a quasi-stationary High near 160W. The remains of VICTOR are being directed southwards around the

western side of this High.

The next HIGH is expected to travel along 50Sacrosss the South Tasman Sea on Tuesday and around the south end of the South Island on Wednesday and

Thursday, delaying the southward progress of the remains of VICTOR.

 

For NZ and Tasman Sea

Unsettled. On Monday a low is expected to cross the South Island, and a lingering trough should move onto the North Island on Tuesday. On

Wednesday and Thursday the low that was once VICTOR may regenerate as it travels south off the east coast of North Island and central NZ  And from

Friday an E/NE flow is likely over the country as the new HIGH builds east of the South Island.

>>>>>> 

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.

 

 

22 January 2016

TC VICTOR starting it unwind as it dances around Nuku'alofa

The gales of VICTOR are tonight unwinding  as the cyclone slowly unravels  and dances around Nuku'alofa. 

 

VICTOR has been giving low pressures (below 1000hPa)  and strong and gusty winds to NIUE all week, with wind slowly swinging from a southerly to a northerly as VICTOR travelled slowly south.

 

NIUE weather data for past week  may be seen at Weather Underground at http://www.wunderground.com/history/airport/NFTF/2016/1/22/WeeklyHistory.html?req_city=Fuaamotu&req_statename=Tonga&reqdb.zip=00000&reqdb.magic=2&reqdb.wmo=91879&MR=1

 

Then VICTOR started to move to the southwest, getting closer to the equator-ward entrance region of the Jetstream—a  place favorable for further formation and surface pressure fall.

  However tonight VICTOR has gone too far to the southwest and is now encountering the increasing shear of the Jetstream, so will “have its top knocked off”.

 

 

Here is the latest text report about VICTOR from the Fiji Met Service at http://www.met.gov.fj/aifs_prods/20032.txt

 

TROPICAL DISTURBANCE ADVISORY NUMBER A36 ISSUED FROM RSMC NADI Jan 220746 UTC.

 

TROPICAL CYCLONE VICTOR CENTRE 995HPA CATEGORY 1 WAS LOCATED NEAR 22.0S 174.4W AT 220600 UTC. POSITION GOOD BASED ON HR GOES IR IMAGERY AND SURFACE OBSERVATIONS. CYCLONE MOVING WEST 09 KTS. MAXIMUM 10 MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 35 KNOTS.

 

And this evening’s threat  map from Fiji Met Service may be seen at http://www.met.gov.fj/aifs_prods/65648.html

 

VICTOR has managed to dissipate a lot of energy from the ocean/atmosphere  as wind and rain (and swell , and mostly this has been done over the open sea,  and thus not been too been too damaging.

 

Bob McDavitt

 

 

17 January 2016

Bob Blog

WEATHERGRAM

YOTREPS

Issued 17 January 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.

 

The current Madden Julian Oscillation has managed to circle the planet in the past six weeks (since early Dec).  The MJO Phase may be seen at

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml.

The CA Model shows that the MJO may soon embark on another circumnavigation—If so it is likely to reach the western Pacific again from early February, and we can expect the next cluster of tropical cyclones in our area around mid-February.

Currently the MJO is in the Indian Ocean and indeed there is a tropical Low forming east of Madagascar with two more on its eastern side.

  This also shows up in the Meteo France at New Caledonia’s Cyclone probability diagram seen at

http://www.meteo.nc/modules/mod_cyclone_experts/assets/popup/850_bis_cycl.php?type=occ&dossier=L3Byb2QvY3ljbG9uZXMvZXhwZXJ0cw==#1

 

Tropical Cyclones

TC PALI moved SW towards the equator and faded away at 2N.

TC ALEX in the mid north-Atlantic ocean popped up as a strange surprise.

Tropical cyclone ULA finally faded to north of NZ over past few days.

TC VICTOR was named on Friday evening (Fiji date) and is now approaching CAT 4 between Niue and the Southern Cooks.

For the latest update check http://www.met.gov.fj/aifs_prods/65648.html

Or http://www.met.gov.fj/aifs_prods/65661.html

To see how TC VICTOR modifies (or is modified by) the near-by jetstream, see my video blog at https://youtu.be/rWmTchT38SQ

 

The weekly rain maps for the tropics over the past two weeks show a transfer of heaviest rain from the PALI area to the VICTOR area.

These can be seen at http://trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

 

WEATHER ZONES

 

SPCZ=South Pacific Convergence zone.

Most of the old SPCZ has been taken south by VICTOR, but a new one is reforming mainly between equator and 10S, on the south end of the fading zone of equatorial westerly winds.

A tropical LOW is expected to form near Tahiti by mid-week and travel to the SE – may bring some squally showers.

 

STR= Sub-tropical Ridge

STR is strong along 30 to 40S across the South Pacific this week, HIGH near 40S 160W is quasi–stationary and will likely slow the progress of VICTOR and knock it to the SW along its NW shoulder.

 

For NZ and Tasman Sea

A wet trough is expected to cross the country on Monday and Tuesday.

Then a disturbed west/northwest flow is expected to cover central and southern parts, with a ridge of high pressure over the northern third.

>>>>>> 

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.

 

 

10 January 2016

Bob Blog 10 Jan 2016

WEATHERGRAM

YOTREPS

Issued 10 January 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.

 

During the past month of strong El Nino conditions the averaged weather map had lower than normal pressures along eastern Pacific and western/central North America, also over north Atlantic/UK, the Ukraine, and parts of the Southern ocean.  Other areas , including the South Tasman  Sea,  have been having higher than normal pressures.

See the 30 day MSL Anomalies at http://www.esrl.noaa.gov/psd/map/images/fnl/slp_30a.fnl.anim.html

 

Tropical Cyclones

Tropical cyclone ULA is still going, and tonight affects the SE parts of Vanuatu.  During Monday it is expected to travel south past east- of-New Caledonia, and later this week should travel SE taking it to the NE of NZ.

For an update on this track see http://www.met.gov.fj/aifs_prods/65648.html

Or http://www.met.gov.fj/aifs_prods/65661.html

 

The feature that was near the equator 180 earlier this year has finally worked its way to 7N and earned the name TC PALI. 

It can be seen at http://www.prh.noaa.gov/cphc/tc_graphics/2016/graphics/CP012016W.gif

 

Weekly rain maps for the tropics over the past two weeks show a build-up of rain intensity to around Northern Cooks and near Eq 180 (TC PALI).

These 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 is expected to remain active in the zone between the trade winds and the equatorial westerlies, around Northern Cooks.

  This is expected to deepen into a new tropical Low by mid-week and maybe further by the weekend as it travels south across Southern Cooks.   By then yet another

tropical low may form NW of Tahiti and travel southeastwards.

 

STR= Sub-tropical Ridge

HIGH crossing central NZ on Monday should travel off to eat by Tuesday.

Next HIGH is expected to cross south Tasman Sea on Wednesday and then linger over NZ until Saturday.

 

For NZ and Tasman Sea

A mixed bag this week. Fresh SW winds for Northland are expected on Wed and Saturday, otherwise moderate variable winds.

>>>>>> 

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.

 

 

03 January 2016

Bob Blog

WEATHERGRAM

YOTREPS

Issued 03 January 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.

 

This El Nino may be starting to relax now.  The weekly value of the SOI index has relaxed over the last few weeks as seen at

http://www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=soi&p=weekly

The heat stored in the eastern equatorial Pacific Ocean is measured by the NINO3.4 parameter and this has reached a monthly value of 3.0 in December 2015, exceeding the monthly values recorded in the previous extreme El Nino of 1997/1998 . As seen at

http://www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=nino34&p=monthly

 

Tropical Cyclones

Tropical cyclone ULA brought storm force winds to Vava’u but these were from the east and the Vava’u group is reasonably well sheltered from that direction, and its hilly terrain sort of knocked ULA a bit. Some minor damage was shown on SBS News on twitter.

ULA is now slowing down and although it may weaken on Monday, it still has the possibility of developing later this week  Fiji Met service are tracking this Cat3 system as it travels across southern Lau group tonight.

So far there have been three fatalities reported and several people are missing.

The latest track map has it possibly turning NW again by Wednesday and that may allow the system to redevelop.

For an update on this track see http://www.met.gov.fj/aifs_prods/65648.html

Or http://www.met.gov.fj/aifs_prods/65661.html

 

Weekly rain maps for the tropics over the past two weeks show a build-up of rain intensity to the NW of Fiji. 

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

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to remain active to north of 5S with the near- equatorial westerlies and also between Samoa and Tahiti.  There is a good chance that a tropical Low may develop near 15S 153W by Wednesday UTC (local Tuesday) and then deepen and move towards between Tahiti and

Southern Cooks by this weekend.   Keep checking, as we are approaching a summit of activity for this cyclone season according to the MJO. 

 

STR= Sub-tropical Ridge

Next HIGH to travel across the Tasman Sea and central NZ is likely on Tuesday and Wednesday.

Another slower moving HIGH is likely from Friday to Sunday.

 

For NZ and Tasman Sea

On Friday to Sunday NZ got some rain from the subtropics.  Very welcome for the farmers with parched pastures but off-putting to the holiday-seekers.

Next trough is likely to be a LOW deepening off northern New South Wales on Wednesday and crossing NZ on Friday /Saturday.

>>>>>> 

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 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.

 

 

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