Bobgram

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 24 August 2025

NASA Extends PREFIRE Mission to 2026

NASA's PREFIRE (Polar Radiant Energy in the Far-InfraRed Experiment)
mission uses two CubeSats spectrophotometers, each no larger than a

The satellites are in what's called an asynchronous near-polar orbit,
traveling near the poles with each pass but hours apart from one
another. This provides two snapshots of the same area over time,
enabling the mission to capture phenomena that occur on short
timescales, such as cloud cover's temporary effects on the temperature
of the area beneath it.

While the tropics take in the greatest share of the Sun's energy,
winds, storms, and ocean currents carry much of that heat toward the
colder polar regions, which receive far less sunlight. Ice, snow, and
clouds in these regions then release some of the heat into space,
primarily as far-infrared radiation. The difference between the heat
absorbed in the tropics and the heat radiated out at the poles
strongly influences global temperatures and helps drive Earth's
climate and weather systems.

The global energy budget is interesting….

Note there is incoming of 341.3 W/m2 and outgoing of
101.9+238.5W/m2=340.4 .

The data collected gives new details about the changing glow found in
processes such as the melting and freezing of surface ice, seasonal
snow changes, and variations in cloud cover.

"The PREFIRE satellites show that at these longer wavelengths, the
amount of radiation going into space can differ from one type of ice
to another by as much as 5%," said Brian Drouin, PREFIRE's project
scientist at JPL. "Measurements that look at the same areas but with
shorter wavelengths do not show this difference."

"We have the capacity to collect data for the whole world, not just
the poles. What we'll be able to do is look at the size of ice
particles in clouds that affect energy exchange between Earth and
space," said PREFIRE's principal investigator, Tristan L'Ecuyer of the
University of Wisconsin–Madison. "We'll be able to incorporate the
data into weather prediction models to improve forecasts and improve
our understanding of how moisture circulates, which affects where
storms form and how precipitation moves around the world."

TROPICS

The latest cyclone activity report is at zoom.earth and
tropic.ssec.wisc.edu and Tropical Cyclone Potential is
from www.ospo.noaa.gov/products/ocean/tropical/tcfp/

• Hurricane ERIN underwent one of the most rapid intensifications of
any Atlantic basin storm in history, exploding in force from a
tropical storm to a Category5 hurricane in just 25 hours.

• Tropical Storm Lingling drenched southern Japan's Kyushu Island and
nearby smaller islands.

WEATHER ZONES

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 shows well defined
SPCZ between Solomon Islands and Fiji and a passing trough south of
Fiji and another south of French Polynesia.   Also, a large dry zone
over Australia.

Wind accumulation from windy.com below shows generally OK ailing winds
in the tropics. And the roaring forties extending  north almost to
Noumea at times .

LOWS and HIGHS

HIGH H1 centred east of NZ tonight is now moving off to the east or
northeast leaving a ridge over central NZ and a squash zone of East to
NE winds between Northland and New Caledonia.

Low L1 is tonight between Lord Howe and Noumea, and by Wednesday is
expected to be north of Northland with Front crossing Fiji.  Front
reaching Tonga area on Thursday.  Avoid.

Later in the week it should travel off to the southeast of NZ,
followed by a westerly flow.

Then L2 from the Aussie Bight is expected to cross Tasmania by Friday
and NZ on Friday /Saturday

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