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StormSouthern Ocean

The Southern Ocean low south of New Zealand will slowly weaken as it heads southeast

Southern Ocean — Very deep low near 920 mb now, in the South Pacific and filling; nearly all forecasts show it.

Updated Tues., Sept. 29, 1:35 a.m. UTC · 179 forecast tracks from NOAA, ECMWF and Environment Canada: low

Southern Ocean — Very deep low near 920 mb now, in the South Pacific and filling; nearly all forecasts show it.

Quick answers

As of the Mon 28 Sep 12Z–18Z model runs · updated Tues., Sept. 29, 1:35 a.m. UTC

Where is the Southern Ocean low south of New Zealand going?
The centre is in the South Pacific, moving southeast at about 50 km/h. The most likely path takes it about 800 kilometres southeast of McMurdo Station by Wednesday morning.
How sure is the forecast?
Path certainty: low. 179 of 185 show the storm, and they on where it goes. Little has changed since the previous run.
Do the AI and physics models agree?
Largely, yes. By Wednesday morning the AI ensembles’ middle track is about 80 kilometres east of the physics ensembles’. Both take it to about 920 at its deepest.
Will the Southern Ocean low south of New Zealand 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 in the South Pacific, with a central pressure near 920 .

How sure. 179 of 185 show the storm, and they on where it goes. Little has changed since the previous run.1

How strong. Forecasts have it filling steadily, to about 942 by Wednesday. None of them turn it into a rapidly deepening .

What’s uncertain

Later on. The forecasts fan out after Wednesday. By Wednesday morning, the is about 800 kilometres across.2

When it arrives

No town we track is within reach of this storm; it stays in the South Pacific.

What the forecasts said vs what happened

Collecting: so far at most 2 runs of any one model made 1 day ahead can be checked. We show how the forecasts did once a model has 4. How good are the forecasts this season?

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 12 min ago
Latest run
ECMWF
45 of 5112Z
arrived 4 h 47 min ago
Latest run
ECMWF
51 of 5118Z
arrived 1 h ago
Latest run
NOAA
31 of 3118Z
arrived 14 min ago
Latest run
Environment Canada
21 of 2112Z
arrived 8 h 17 min ago
Latest run

Also tracking

  1. Hurricane PoloCould pass near San Diego Wed morning; 2 in 10 forecasts bring it within 160 km
  2. Southern Ocean lowVery deep low in the Southern Hemisphere, near 936 mb now and filling; all 185 forecasts show it
  3. Amundsen Sea lowVery deep low bottoming out near 956 mb Tue night, in the Southern Hemisphere; all 185 forecasts show it
  4. Southern Ocean lowVery deep low bottoming out near 953 mb Thu morning, in the Southern Hemisphere; nearly all forecasts show it
  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 27 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-2026-0055.

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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Stormlines Tracks: NOAA, ECMWF, Environment Canada

Full forecast
Through Wed 6 a.m. UTC