BobBlog

WEATHERGRAM

YOTREPS

Compiled Sun 31 March 2019

 

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 MARCH

Sea Surface temperature anomalies as at end of March may be seen at

www.weatherzone.com.au/climate/indicator_sst.jsp?lt=global&lc=global&c=ssta

 

The main pattern changes are a cooler South Indian Ocean and a warmer Coral Sea. It may be that fresh melt water from the recent Antarctic summer has gone north into the South Indian Ocean.

Elsewhere the changes are more subtle—even in the target area for El Nino, the eastern equatorial Pacific,

 

To see how the annual weather cycle and the seasons are working out, check the average isobars for past 30 days and their anomaly from www.esrl.noaa.gov/psd/map/images/fnl/slp_30.fnl.htmlclip_image005

There is a strong “WAVE 3” pattern in the southern hemisphere with HIGHS lingering over Southern Indian Ocean, east of NZ, and west of the Andes. Troughs and southerly outbreaks have been encouraged into the Aussie Bight.

The low-pressure anomalies around the Arctic and northern Europe are related to the Polar vortex. And there is still a large anomalous HIGH around the Antarctic.

 

Zooming into the NZ area, and comparing monthly anomalies for end of Feb with end of March, shows that the main difference is the expanding of the HIGH east of NZ with a 1020 isobar pushing the 1015 from 45S to 55S. Further north, the 1010hP (between light blue and dark blue) isobar is in much the same place, but the 1005 that was around Vanuatu and New Caledonia has faded.

 

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

And this shows that even in this monthly averaged image the rain track of TC IDAI into eastern Africa stands out. The ITCZ has been wetter than normal across the central Pacific, and below normal across the eastern Pacific. The “mirror Convergence Zone” along 5degrees south in the Eastern Pacific has blossomed in March. There are dry patches appearing in the South Pacific during the “wet” season.

 

THE TROPICS

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

TC JOANINHA continues on its voyge southwards across the Indian Ocean, and has now left the tropics. The probability for cyclone formation is high around the Marshall islands, the Timor Sea , and. Less so, around Solomon Islands.

For rain in the past week, see trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

Rainwas strongest near JOANINHA and between Nauru and Fiji. There was also a drenching day over NZ Southern Alps, with one raingauge measuring over 1000mm of rain but TRMM doesn’t seem to resolve that finely. This rai took out a bridge, see www.facebook.com/watch/?v=342974573228755

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active over Papua New Guinea and parts of the Coral Sea. A LOW is forming southeast of Niue and expected to deepen as it travels southeast out of the tropics, bringing a few days of vigorous SW winds and swell to Niue and NW winds and rain to Southern Cooks.

 

Subtropical ridge (STR)

HIGH expected to spread across Tasmania on Monday and Tuesday and then to fade in central Tasman sea/ central NZ on Wed and Thurs.

Next HIGH is expected to travel east to south of Tasmania on Thursday, south of NZ on Fri, then to east of NZ along 45S from Sat.

 

Australia/Tasman Sea / New Zealand

Active front expected to cross NZ on Monday followed by a cooler south/SW flow on Tuesday, and then another cold front from the south on Thursday and Friday, dropping temperatures.

 

Panama to Marquesas

SW swells are starting to arrive in the Gulf of Panama. Good northerly winds for departure from Panama until local Wednesday, then light winds and a motoring start.

There is a reasonable tail current to north end of Galapagos, then go to 6S 100W, to avoid the “mirror convergence zone” along around 5 South,

 

Port Vallarta to Marquesas

Light winds for starters over next few days, best winds for departure this week are likely to be after Friday.

Weak ITCZ likely between 6N and 2N, and then a “mirror CZ” near 3 to 5S

 

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If you would like more detail for your voyage, then check metbob.com to see what I offer.

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Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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