Bob Blog 19 Jan 2020

WEATHERGRAM

YOTREPS

Compiled Sun 19 Jan 2020

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.

Sea Surface temp Anomalies shows a recent marine heat wave off to east of NZ.

Coastal upwelling and a persistent SW airflow over New Zealand have led to Sea Surface Temperatures (SST) approximately 2 degrees Celsius lower than usual for this time of year around New Zealand’s West Coast (based on long term averages).

A large SST anomaly (with SST of +5°C above the average) to the east of New Zealand has begun to weaken as it slowly moves eastwards.

The SST anomaly data were obtained from NOAA satellites, and represents the difference between the daily SST and the long-term average.

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The resulting animation (at http://www.metocean.co.nz/news) covers the period from 13th December 2019 to 10th January 2020, and depicts a large blob of surface water +5°C above average persisting for about 16 days (13-28 December) before slowly dissipating as it tracks eastward.

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The Tropics

. The latest cyclone activity report is at tropic.ssec.wisc.edu and TCFP tropical Cyclone Formation Potential at http://www.ssd.noaa.gov/PS/TROP/TCFP/index.html

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Cyclone TINO visited Fiji and Tonga this weekend and is now going southeast. It may do a loop near 35S and then continue as a mid-latitude cyclone southeast to 45S. .

The cyclone potential remains high north and northwest of Fiji, but the forecast is for no cyclones forming this week. TINO has taken a lot of the oomph out of the South Pacific Convergence zone.

WATHER ZONES

Weather Zones (see text) as expected Wednesday 00UTC showing isobars, winds, waves(magenta) STR, and SPCZ. Pink area = lightning likely (high CAPE)

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SPCZ=South Pacific Convergence zone.

The SPCZ is quieter this week after TC TINO has taken most of its oomph. It is also north and east of its normal position, from east of PNG to Tuvalu to Samoa to Aitutaki area.

N to NW winds on its northern side and southeast wind s on its southern side.

Big swells and a storm surge which may lead to coastal flooding around the southern Cooks and some moderate easterly swell to eastern Northland.

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Accumulated rainfall for next week from windyty.com (isobars are for Sunday night).

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Swell on Wednesday

Subtropical ridge (STR)

HIGH is expected to stall around /west of northern NZ for the coming week

Another High is expected to skirt around southern NZ and then, when it is east of the South Island, travel off to the northeast, .

Tasman Sea /NZ/Aus

A trough is expected to stall in the western Tasman sea over the South Island slowly going south rather than east.

As for Noumea to Australia: Mainly SE winds so OK.

As for Sydney to NZ: should wait until the trough moves on, after 23 jan

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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 with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

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

Contact is bob@metbob.com or txt 6427 7762212

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