Bobgram 21 Sep

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 21 September
There is a solar eclipse over NZ on Monday morning
And then the equinox is expected on Tuesday morning New Zealand time.
This year's Ozone hole

https://www.facebook.com/ECMWFcopernicus/videos/this-year-the-ozone-hole-pre
sented-an-early-development-reaching-a-larger-than-a/767656056069254/
Europe's Copernicus Atmosphere Monitoring Service says the ozone hole over
Antarctica formed earlier this year than in 2024, covering about 8 million
square miles during the first half of September. The service says the hole
grew larger than the long term average but did not reach anywhere near the
record size of 11.4 million square miles in 2006. The U.N. weather agency
says the layer of stratospheric ozone should recover to 1980 levels by
around 2066 over Antarctica, 2045 over the Arctic and 2040 for the rest of
the world.

The 'blob' is back - except this time it stretches across the entire North
Pacific
Based on the CNN write up at
https://edition.cnn.com/2025/09/19/climate/pacific-ocean-blob-hot-water-glob
al-warming


A record-breaking and astonishingly expansive marine heat wave is underway
in the Pacific Ocean, stretching about 5,000 miles from the water around
Japan to the West Coast of the United States. The abnormally warm "blob" of
ocean water, which is getting a significant boost from human-caused global
warming, is affecting the weather on land and could have ripple effects on
marine life.
The North Pacific warmed at the fastest rate of any ocean basin on Earth
during the past decade, according to Michael McPhaden, a senior scientist at
the National Oceanic and Atmospheric Administration.
And the entire North Pacific Ocean Basin is involved in the current marine
heat wave, standing out starkly on weather maps. This event is unique for
its intensity and extraordinary geographic reach, and for its potential to
eventually alter large-scale weather patterns if it continues.
In parts of the North Pacific, from the Gulf of Alaska south to the coast of
California, this heat wave is known as a "blob" of unusually hot water. It
is part of a pattern of marine heat waves in this area following a severe
heating event in 2013 that lasted until 2016. That heat wave remains the
most severe on record. It's warm waters extended deep into the upper layers
of the ocean, which allowed it to persist through the stormy winter months.
This one, however, is more likely to prove fleeting in the northeastern
Pacific since it is more surface-based. Winter storms should be about to
stir up cooler water and end this blob. Even so, it ranks as the
fourth-largest Northeast Pacific blob yet observed.
The cause of the ongoing marine heat wave is a "persistent anomalous wind
conditions" associated with stagnant high-and low-pressure areas. This
stagnation affects the discourage the normal upwelling pattern.
This increase in marine heat waves and accelerated warming in the North
Pacific Ocean is attributed to global warming pollution from burning fossil
fuels. The fingerprint of climate change is clearly evident in what is
transpiring now in the North Pacific.
TROPICS
The latest cyclone activity report is at zoom.earth and tropic.ssec.wisc.edu
and Tropical Cyclone Potential is from
https://www.ospo.noaa.gov/products/ocean/tropical/tcfp/

In the north Atlantic: Tropical Storm Mario passed off Mexico's Pacific
coast, while Gabrielle spun up in the mid-Atlantic Ocean after weeks of
unusual calm during the normal peak of the Atlantic hurricane season.
In the western Pacific: RAGASSA is crossing the Philippines and NEOGURI is
moving off to the Northeast.
Weather Zones
Mid-week GFS model showing isobars, winds, waves (purple), rain (red), MT
(Monsoonal trough), STR (Subtropical Ridge), SPCZ (South Pacific Convergence
Zone) CZ (Convergence Zone)

Rain accumulation this week from Windy.com below is very similar to last
week. It shows well defined SPCZ between Solomon Islands and Funafuti and
again east of Samoa. It may shift south onto Samoa late in the week.
The fronts crossing NZ are expected to drop another week of intense rain
over the Southern alps, topping up the hydro lakes. Australia is looking to
have a dry week.

Wind accumulation from windy.com below shows disturbed westerlies south of
30S, typical of spring. Some wind in the Coral Sea but no squash zone s in
the tropics. Maybe a lull around Suwarrow Island.

LOWS and HIGHS
There is a steady easterly migration with Low 1 going SE and High 1 slowly
following.
As for NZ area, a series of fronts are expected there from Monday to
Wednesday, followed by a westerly flow on Thursday and then another front on
Friday.

As for Australia HIGH H2 is expected to start the week in Aussie bight then
travel northeast across the continent reaching Queensland on Thursday then
weakening as it travels across the Tasman Sea and then goes east along 30S
north of NZ this weekend.
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Contact is bob@metbob.com or text 64277762212.
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