Bob Blog 24 April

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.
Compiled Sunday 24 April 2022
The 2021-2022 Cyclone Season
The time-map at my blog at metbob.com, from
en.wikipedia.org/wiki/2021-22_South_Pacific_cyclone_season, shows all the
tropical depressions and named cyclones that affected the South Pacific
region during the cyclone season that started on 1 November 2020 and ended
on 30 April 2021
Five named storms is below average. 2 directly affected NZ and that's above
average.

Tropical Cyclone Ruby
Peak 110 kph 975hPa
On December 13, Tropical Cyclone Ruby came from Australian waters and moved
southeast across the Tasman Sea. On 14-15 December its remanets brought
heavy rain to parts of NZ

Severe Tropical Cyclone Cody
Peak 95-130 kph 971hpa
From January 5, as a depression, this system brought heavy rain to Fiji.
4,000 people had to be evacuated. On January 10, a man drowned in Fiji
while attempting to cross a flooding river. On the same day, the system was
upgraded to a Category 1 tropical cyclone Cody.

Severe Tropical Cyclone Dovi
Peak 175 kph 940 hPa
From February 6, a Tropical Low formed west of Vanuatu. By February 9 it was
named as cyclone DOVI. On February 10 Dovi made landfall onto the Isle of
Pines in New Caledonia, where it became slow-moving and intensified,
bringing widespread flooding to parts of Vanuatu and New Caledonia.
On February 13 Dovi made landfall as an extratropical storm in the Waitomo
District in New Zealand's North Island. Severe weather was felt across much
of the island, with heavy rain causing flooding and slips, and closing
Auckland harbour bridge. A preliminary figure for damage done by Dovi in New
Zealand is $44.4million

Tropical Cyclone Eva
Peak 65kph 995hPa
On February 27 EVA was named near New Caledonia. It faded in the north
Tasman Sea in early March.

Tropical Cyclone Fili
Peak 110kph 977 hPa
On April 3, a tropical depression started developing well northwest of Vila.
On April 5 it was named northwest of New Caledonia and passed by close to
their south coast on 6-7 April. Then on 12-13 April it passed close to the
northeast of North Island, hitting East Coast and Gisborne areas hard.

A time-latitude diagram for the Tasman Sea area has been constructed using
psl.noaa.gov/map/time_plot/. At my blog at metbob.com, it shows the isobaric
pressure for each day from Dec to Easter, with Highs appearing as
yellow/orange areas and Lows as blue/white. The orange line shows that the
latitude used by passing highs shifted south until end of February and is
now shifting north. The cyclones timings are labelled along with the
tropical intrusion on March 21st.

It is interesting to compare these cyclones with the passing MJO (Madden
Julian Oscillation) pulses, shown at my blog at metbob.com is a
time-longitude plot from NOAA in USA as blue shading in the OLR (outgoing
longwave radiation) anomolies, This diagram shows two MJO events, one in
December triggering RUBY and CODY and another in April triggering FILI.
Interestingly, DOVI and EVA did not occur during an MJO.

TROPICS
There are no cyclones around now and even the areas of potential development
are shrinking.
It is safe to say that the South Pacific Cyclone season is now over.

WEATHER ZONES
SPCZ=South Pacific ConvL1ergence zone.
The SPCZ is south of normal, across Coral Sea Vanuatu Fiji Tonga and then
southeast into a low L1.
A convergence zone /trough over Austral and Gambier Island sis expected to
fade.

HIGHS and LOWS
Low L1 is expected to form in convergence zone south of Niue by mid week and
then deepen as it travels SE.
Low L2 is expected to travel east along 50S.
A High H1 south of Tasmania is expected to travel ENE form 50S to 40S
reaching central NZ by end of week.
Because of H1, northern Tasman and Coral seas have easterly winds this week,
strong in places.
Travel from Tahiti to Tonga should check to avoid L1 and dodge SPCZ.
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If you would like more detail for your voyage, then check metbob.com to see
what I offer.
Or Facebook at /www.facebook.com/metbobnz/
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 64277762212
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