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Nerd mode: every forecast, readouts, filters and range & bearing for weather enthusiasts

Storm · Forecasts splitSouthern Ocean

The Amundsen Sea low could move more slowly — or move faster

Bellingshausen Sea — Very deep low bottoming out near 958 mb Wed morning, about 1,450 km S of South Georgia; all 185 ensemble forecasts show it.

Updated Tues., Sept. 29, 2 a.m. UTC · 185 forecast tracks from NOAA, ECMWF and Environment Canada: high

Bellingshausen Sea — Very deep low bottoming out near 958 mb Wed morning, about 1,450 km S of South Georgia; all 185 ensemble forecasts show it.

Quick answers

As of the Mon 28 Sep 12Z–18Z model runs · updated Tues., Sept. 29, 2 a.m. UTC

Where is the Amundsen Sea low going?
The centre is over the Bellingshausen Sea, moving east at about 90 km/h. The forecasts split: 6 in 10 move more slowly, while 4 in 10 move faster.
How sure is the forecast?
Path certainty: high. All 185 show the storm, and they broadly on its early path. Little has changed since the previous run.
Do the AI and physics models agree?
Broadly, with some differences. 7 in 10 AI- (AIFS ENS, AIGEFS) move more slowly, against 5 in 10 physics-ensemble forecasts (GEFS, ECMWF ENS, GEPS). By Wednesday afternoon the AI ensembles’ middle track is about 80 kilometres northwest of the physics ensembles’. Both take it to about 957 at its deepest.
Will the Amundsen Sea low become a bomb cyclone?
Unlikely. None of the 185 deepen it fast enough to count as a (a pressure fall of roughly 24 in 24 hours, adjusted for latitude).

New to these maps? Read how to read a spaghetti map, or see the week’s rain and wind around the world on the globe.

What we know

Where it is. At 2 a.m. Tuesday, the centre was over the Bellingshausen Sea, with a central pressure near 963 .

How sure. All 185 show the storm, and they broadly on its early path. Little has changed since the previous run.1

How strong. It is still strengthening: forecasts deepen it to about 958 by Wednesday morning. None of them turn it into a rapidly deepening .

What’s uncertain

Which way it turns. Six in 10 forecasts move more slowly; the other four in 10 move faster. By Wednesday afternoon the two paths are about 60 kilometres apart.

Later on. The forecasts fan out after Tuesday. By Wednesday afternoon, the is about 350 kilometres across.2

When it arrives

No town we track is within reach of this storm; it stays over the Bellingshausen Sea.

DetailsStrength, sources and the fine print

How strong it gets

Central pressure over time. The line is the middle forecast; the band holds 8 in 10 of them.

(lower is stronger)

Times are shown in

Where the forecasts come from

ModelTracksStatus
NOAA
31 of 3118Z
arrived 2 h 36 min ago
Latest run
ECMWF
51 of 5118Z
arrived 13 min ago
Latest run
ECMWF
51 of 5118Z
arrived 1 h 26 min ago
Latest run
NOAA
31 of 3118Z
arrived 38 min ago
Latest run
Environment Canada
21 of 2112Z
arrived 8 h 41 min ago
Latest run

Also tracking

  1. Southern Ocean low south of New ZealandVery deep low near 921 mb now, in the Southern Hemisphere; all 185 forecasts show it
  2. Southern Ocean lowVery deep low in the Southern Hemisphere, near 936 mb now and filling; all 185 forecasts show it
  3. Southern Ocean lowVery deep low bottoming out near 953 mb Thu morning, in the Southern Hemisphere; all 185 forecasts show it
  4. Hurricane PoloCould pass near San Diego Wed morning; 1 in 10 forecasts bring it within 160 km
  5. Southern Ocean low south of New ZealandVery deep low in the Southern Hemisphere, near 939 mb now and filling; 9 in 10 forecasts show it
  6. See all 30 storms →

Notes

  1. Forecast tracks from the 18Z model run: GEFS (31), ECMWF ENS (51), AIFS ENS (51), AIGEFS (31), GEPS (21). A single run is one high-resolution forecast; ensemble forecasts are the same model run many times with small changes.
  2. The cone encloses where the centre is expected to be about two times in three at each hour, from the spread of the forecasts, widened by 20 percent; not yet calibrated against past storms. It shows uncertainty in the track, not the size of the storm.
  3. Shading shows the share of forecasts that bring the centre within 160 kilometres of a spot at any time in the next 6 days. Rain, wind and surge can reach much farther.
  4. Times are in your time zone. Arrival windows run from the earliest to the latest closest approach across forecasts that bring the centre within about 300 miles (500 km).
  5. NOAA/NCEP.
  6. Data Source: Environment and Climate Change Canada.
  7. This service is based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF). Source: www.ecmwf.int. Licence: CC BY 4.0.
  8. Cyclone tracks computed by Stormlines from the model fields.
  9. Reading these maps: , or the illustrated guide to spaghetti models. The week’s rain, wind and temperature everywhere: the Stormlines globe.
  10. How often these forecasts turn out right: the season’s forecast check, AI vs physics.
  11. Stormlines storm ID: L-2026-0127.

Stormlines draws every storm the world’s ensemble forecasts can see: tracks from NOAA (GEFS and the AI ensemble AIGEFS), ECMWF (ENS and the AI ensemble AIFS) and Environment Canada (GEPS), updated as each model run lands. Coastlines and place names from Natural Earth; sea areas from IHO Sea Areas, version 3 (Flanders Marine Institute, marineregions.org, CC BY 4.0; modified: simplified, some islands removed, names edited).

Not an official forecast. For warnings and decisions, follow your national weather service.

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