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

Sections

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

StormNorth America

The low over California could pass near San Diego on Tuesday evening

San Diego — Could pass near San Diego Tue evening; 3 in 10 forecasts bring it within 100 mi.

Updated Mon., Sept. 28, 7 p.m. PDT · 139 forecast tracks from NOAA, ECMWF and Environment Canada: medium

San Diego — Could pass near San Diego Tue evening; 3 in 10 forecasts bring it within 100 mi.

Quick answers

As of the Mon 28 Sep 12Z–18Z model runs · updated Mon., Sept. 28, 7 p.m. PDT

Where is the low over California going?
The centre is about 110 miles east of San Diego, moving south at about 40 mph. The most likely path takes it about 180 miles northeast of Los Angeles by Wednesday night.
When will the low over California be closest to San Diego?
Most likely Tuesday, Sept. 29, around 5 p.m. PDT. Across the forecasts the comes between Mon 5 p.m. and Thu 9 p.m. PDT. Most forecasts pass the centre 60–240 miles northeast of San Diego.
What is the chance it passes within 100 miles of San Diego?
31%: 3 in 10 forecasts bring the storm’s centre within 100 miles of San Diego. Elsewhere: Los Angeles 24%, Sacramento 21%, San Francisco 20%. Rain, wind and coastal flooding can reach well beyond 100 miles from the centre.
How much rain could San Diego get while the low over California passes?
From Mon 5 p.m. to Thu 11 p.m. PDT, the end of the window when its centre is closest to San Diego, the middle of NOAA’s 31 GEFS forecasts brings almost no rain or melted snow to San Diego; fewer than 1 in 10 bring 0.5 in. That is all the rain in that time, not only the low over California’s, from one model (GEFS) on a coarse grid; local official forecasts can differ. San Diego: rain and wind this week →
How sure is the forecast?
Path certainty: medium. 139 of 185 show the storm, and they on where it goes. The forecasts shifted about 50 miles south since the previous run.
Do the AI and physics models agree?
Broadly, with some differences. Chance within 100 miles of San Diego: AI ensembles (AIFS ENS, AIGEFS) 32%, physics ensembles (GEFS, ECMWF ENS, GEPS) 30%. By model: GEFS 3%, ECMWF ENS 47%, AIFS ENS 22%, AIGEFS 48%, GEPS 29%. By Wednesday evening the AI ensembles’ middle track is about 150 miles west of the physics ensembles’. Both take it to about 1,001 at its deepest.
Will the low over California 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 7 p.m. Monday, the centre was about 110 miles east of San Diego, with a central pressure near 1,003 .

How sure. 139 of 185 show the storm, and they on where it goes. The forecasts shifted about 50 miles south since the previous run.1

How strong. Forecasts keep its central pressure near 1,005 through Wednesday. None of them turn it into a rapidly deepening .

What’s uncertain

How close it comes. For San Diego, most forecasts put the between 60 and 240 miles away, most likely Tuesday 5 p.m.

Later on. The forecasts fan out after Monday. By Wednesday night, the is about 600 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 San Diego, Los Angeles, Sacramento and San Francisco.

What the forecasts said vs what happened

Collecting: so far at most 1 run 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
4 of 3118Z
arrived 2 h 44 min ago
Latest run
ECMWF
46 of 5118Z
arrived 21 min ago
Latest run
ECMWF
47 of 5118Z
arrived 1 h 34 min ago
Latest run
NOAA
27 of 3118Z
arrived 47 min ago
Latest run
Environment Canada
15 of 2112Z
arrived 8 h 50 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. Amundsen Sea lowVery deep low bottoming out near 957 mb Tue night, in the Southern Hemisphere; all 185 forecasts show it
  5. Hurricane PoloCould pass near San Diego Wed morning; 1 in 10 forecasts bring it within 100 mi
  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 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-2026-0103.

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.

Loading 139 tracks…

Stormlines Tracks: NOAA, ECMWF, Environment Canada

Full forecast
Through Wed 11 p.m. PDT