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StormNorth Pacific

The North Pacific low west of British Columbia is likely to pass near Anchorage on Wednesday night

Anchorage, Alaska — Likely to pass 15–160 mi S of Anchorage Wed night; 6 in 10 forecasts bring it within 100 mi.

Updated Tues., Nov. 10, 9:46 a.m. AKST · 181 forecast tracks from NOAA, ECMWF and Environment CanadaOne of the 5 forecast models is running late; its previous run is used.: low

Anchorage, Alaska — Likely to pass 15–160 mi S of Anchorage Wed night; 6 in 10 forecasts bring it within 100 mi.

Quick answers

As of the Mon 9 Nov 18Z – Tue 10 Nov 12Z model runs · updated Tues., Nov. 10, 9:46 a.m. AKST

Where is the North Pacific low west of British Columbia going?
The centre is about 240 miles southwest of Juneau, moving north at about 25 mph. The most likely path takes it about 25 miles south of Anchorage by Thursday morning.
When will the North Pacific low west of British Columbia be closest to Anchorage?
Most likely Wednesday, Nov. 11, around 9 p.m. AKST. Across the forecasts the comes between Wed 10 a.m. and Thu 11 a.m. AKST. Most forecasts pass the centre 15–160 miles south of Anchorage.
What is the chance it passes within 100 miles of Anchorage?
60%: 6 in 10 forecasts bring the storm’s centre within 100 miles of Anchorage. Elsewhere: Kodiak 17%. Rain, wind and coastal flooding can reach well beyond 100 miles from the centre.
How much rain could Anchorage get while the North Pacific low west of British Columbia passes?
From Tue 9 a.m. (when the forecast’s rain totals start) to Thu 3 p.m. AKST, the end of the window when its centre is closest to Anchorage, the middle of NOAA’s 31 GEFS forecasts brings 0.15 in of rain and melted snow to Anchorage; fewer than 1 in 10 bring 0.5 in. By Wed 9 a.m., when that window opens, the middle forecast already has 0.09 in. That is all the rain in that time, not only the North Pacific low west of British Columbia’s, from one model (GEFS) on a coarse grid; local official forecasts can differ. Anchorage: rain and wind this week →
How sure is the forecast?
Path certainty: low. 181 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?
Not yet: they differ. Chance within 100 miles of Anchorage: AI ensembles (AIFS ENS, AIGEFS) 71%, physics ensembles (GEFS, ECMWF ENS, GEPS) 50%. By model: GEFS 35%, ECMWF ENS 49%, AIFS ENS 76%, AIGEFS 61%, GEPS 76%. By Thursday morning the AI ensembles’ middle track is about 260 miles north of the physics ensembles’. Both take it to about 969 at its deepest.
Will the North Pacific low west of British Columbia 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 10 a.m. Tuesday, the centre was about 240 miles southwest of Juneau, with a central pressure near 971 .

How sure. 181 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 989 by Thursday. None of them turn it into a rapidly deepening .

What’s uncertain

How close it comes. For Anchorage, most forecasts put the between 15 and 160 miles away, most likely Wednesday 9 p.m.

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

When it arrives

When the centre passes closest to each place, earliest to latest across the forecasts. Places are ordered by the most likely time.

Window of Most likely timeNight
is the share of forecasts that bring the centre within 100 miles. Shaded columns are night; times are in your time zone.

Rain and wind this week in Kodiak and Anchorage.

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 3112Z
arrived 1 h 13 min ago
Latest run
ECMWF
48 of 5118Z
arrived 17 h 10 min ago
Older run (newer ones delayed)
ECMWF
51 of 5112Z
arrived 24 min ago
Latest run
NOAA
30 of 3106Z
arrived 4 h 15 min ago
Latest run
Environment Canada
21 of 2112Z
arrived 1 h 23 min ago
Latest run

Also tracking

  1. North Atlantic lowLikely to pass 20–140 mi SW of A Coruña Fri afternoon; 7 in 10 forecasts bring it within 100 mi
  2. Southern Ocean lowVery deep low in the Southern Hemisphere, near 946 mb now and filling; all 185 forecasts show it
  3. Southern Ocean lowVery deep low in the Southern Hemisphere, near 951 mb now and filling; all 185 forecasts show it
  4. Ross Sea lowVery deep low bottoming out near 957 mb Wed afternoon, in the Southern Hemisphere; nearly all forecasts show it
  5. South Atlantic lowVery deep low bottoming out near 958 mb Wed afternoon, in the Southern Hemisphere; nearly all forecasts show it
  6. See all 26 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 8 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-2026-2668.

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 Thu 9 a.m. AKST