Storm · Forecast to formNorth Pacific
A new low is likely to form over the open North Pacific on Saturday night
San Francisco — Could pass near San Francisco Thu evening; 1 in 10 forecasts bring it within 100 mi.
Updated Wed., Nov. 11, 1:41 p.m. PST · 150 forecast tracks from NOAA, ECMWF and Environment Canada: medium
San Francisco — Could pass near San Francisco Thu evening; 1 in 10 forecasts bring it within 100 mi.
Quick answers
As of the Wed 11 Nov 12Z model run · updated Wed., Nov. 11, 1:41 p.m. PST
- Where will the North Pacific low form?
- Forecasts that develop it have the centre forming over the open North Pacific on Saturday night. The most likely path takes it about 500 miles west of Astoria by Tuesday night, Nov. 17.
- When will the North Pacific low be closest to San Francisco?
- Most likely Thursday, Nov. 19, around 7 p.m. PST. Across the forecasts the comes between Thu 4 a.m. and Fri 1 p.m. PST. Most forecasts pass the centre 90–1,450 miles northwest of San Francisco.
- What is the chance it passes within 100 miles of San Francisco?
- 11%: 1 in 10 forecasts bring the storm’s centre within 100 miles of San Francisco. Elsewhere: Eureka 12%. Rain, wind and coastal flooding can reach well beyond 100 miles from the centre.
- How sure is the forecast?
- Path certainty: medium. 150 of 185 show the storm, and they on where it goes. The forecasts shifted about 110 miles southwest since the previous run.
- Do the AI and physics models agree?
- Broadly, with some differences. Chance within 100 miles of San Francisco: AI ensembles (AIFS ENS, AIGEFS) 15%, physics ensembles (GEFS, ECMWF ENS, GEPS) 8%. By model: GEFS 3%, ECMWF ENS 4%, AIFS ENS 16%, AIGEFS 13%, GEPS 24%. By Monday night, Nov. 16 the AI ensembles’ middle track is about 90 miles north of the physics ensembles’. At its deepest, the AI ensembles take it to about 971 and the physics ensembles to about 975 mb.
- Will the North Pacific low become a bomb cyclone?
- 58% of forecasts (6 in 10) 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 over the open North Pacific on Saturday night, at about 1,007 .
How sure. 150 of 185 show the storm, and they on where it goes. The forecasts shifted about 110 miles southwest since the previous run.1
How strong. It is still strengthening: forecasts deepen it to about 970 by Monday night, Nov. 16. Six in 10 forecasts make it a , deepening about 24 millibars or more in a day.
What’s uncertain
Whether it forms. 150 of 185 develop it; the rest do not. Storms that exist only in the forecast can change a lot from run to run.
How close it comes. For San Francisco, most forecasts put the between 90 and 1,450 miles away, most likely Thursday 7 p.m.
Later on. The forecasts fan out after Sunday. By Thursday afternoon, Nov. 19, the is about 1,050 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.
Rain and wind this week in Astoria, Portland, Eureka, San Francisco and Sacramento.
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)
Where the forecasts come from
| Model | Tracks | Status | |
|---|---|---|---|
NOAA | 22 of 31 | 12Z arrived 4 h 18 min ago | Latest run |
ECMWF | 41 of 51 | 12Z arrived 25 min ago | Latest run |
ECMWF | 46 of 51 | 12Z arrived 3 h 7 min ago | Latest run |
NOAA | 24 of 31 | 12Z arrived 1 h 33 min ago | Latest run |
Environment Canada | 17 of 21 | 12Z arrived 4 h 35 min ago | Latest run |