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Storm · Forecasts split · Forecast to formNorth Pacific

A new low is likely to form over the Northwest Territories on Thursday morning

Northwest Territories — Forecast to form Thu morning, about 400 mi NW of Yellowknife; 9 in 10 forecasts show it.

Updated Wed., Nov. 11, 9:41 p.m. UTC · 172 forecast tracks from NOAA, ECMWF and Environment Canada: medium

Northwest Territories — Forecast to form Thu morning, about 400 mi NW of Yellowknife; 9 in 10 forecasts show it.

Quick answers

As of the Wed 11 Nov 12Z model run · updated Wed., Nov. 11, 9:41 p.m. UTC

Where will the low over the Northwest Territories form?
Forecasts that develop it have the centre forming about 400 miles northwest of Yellowknife on Thursday morning. The forecasts split: 7 in 10 move faster, while 3 in 10 move more slowly.
How sure is the forecast?
Path certainty: medium. 172 of 185 show the storm, and they on where it goes. The forecasts shifted about 60 miles southeast since the previous run.
Do the AI and physics models agree?
Broadly, with some differences. 6 in 10 AI- (AIFS ENS, AIGEFS) move faster, against 8 in 10 physics-ensemble forecasts (GEFS, ECMWF ENS, GEPS). By Saturday morning the AI ensembles’ middle track is about 40 miles west of the physics ensembles’. Both take it to about 987 at its deepest.
Will the low over the Northwest Territories 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 forms. The forecasts that show it have the centre taking shape about 400 miles northwest of Yellowknife on Thursday morning, at about 988 .

How sure. 172 of 185 show the storm, and they on where it goes. The forecasts shifted about 60 miles southeast since the previous run.1

How strong. Forecasts have it filling steadily, to about 992 by Saturday. None of them turn it into a rapidly deepening .

What’s uncertain

Whether it forms. 172 of 185 develop it; the rest do not. Storms that exist only in the forecast can change a lot from run to run.

Which way it turns. Seven in 10 forecasts move faster; the other three in 10 move more slowly. By Saturday evening the two paths are about 30 miles apart.

Later on. The forecasts fan out after Thursday. By Sunday morning, the is about 700 miles across.2

When it arrives

No town we track is within reach of this storm; it stays about 400 miles northwest of Yellowknife.

What the forecasts said vs what happened

Collecting: so far at most 1 run of any one model made 2 days 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
21 of 3112Z
arrived 4 h 18 min ago
Latest run
ECMWF
51 of 5112Z
arrived 25 min ago
Latest run
ECMWF
50 of 5112Z
arrived 3 h 7 min ago
Latest run
NOAA
31 of 3112Z
arrived 1 h 33 min ago
Latest run
Environment Canada
19 of 2112Z
arrived 4 h 35 min ago
Latest run

Also tracking

  1. North Pacific low west of British ColumbiaLikely to pass 10–130 mi S of Anchorage Wed night; 7 in 10 forecasts bring it within 100 mi
  2. North Atlantic lowLikely to pass 10–80 mi from A Coruña Fri night; 9 in 10 forecasts bring it within 100 mi
  3. Southern Ocean lowVery deep low bottoming out near 950 mb Wed night, in the Southern Hemisphere; all 185 forecasts show it
  4. Southern Ocean lowVery deep low bottoming out near 954 mb Wed night, in the Southern Hemisphere; all 185 forecasts show it
  5. South Atlantic lowVery deep low in the Southern Hemisphere, near 958 mb now and filling; all 185 forecasts show it
  6. See all 24 storms →

Notes

  1. Forecast tracks from the 12Z 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 100 miles of a spot at any time in the next 10 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-2026-2395.

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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