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

Storm · Forecast to formNorth Pacific

A new low might form south of Petropavlovsk-Kamchatsky on Friday night

Petropavlovsk-Kamchatsky, Russia — Could pass near Petropavlovsk-Kamchatsky Sat morning; 1 in 10 forecasts bring it within 160 km.

Updated Tues., Sept. 29, 11:37 a.m. GMT+12 · 52 forecast tracks from NOAA, ECMWF and Environment Canada: low

This storm is no longer in our active list. This is its last forecast, from the Mon 28 Sep 12Z–18Z runs.

Petropavlovsk-Kamchatsky, Russia — Could pass near Petropavlovsk-Kamchatsky Sat morning; 1 in 10 forecasts bring it within 160 km.

Quick answers

As of the Mon 28 Sep 12Z–18Z model runs · updated Tues., Sept. 29, 11:37 a.m. GMT+12

Where will the North Pacific low off Kamchatka form?
Forecasts that develop it have the centre forming about 290 kilometres south of Petropavlovsk-Kamchatsky on Friday night. The most likely path takes it about 450 kilometres northwest of Unalaska by Monday night, Oct. 5.
When will the North Pacific low off Kamchatka be closest to Petropavlovsk-Kamchatsky?
Most likely Saturday, Oct. 3, around 9 a.m. GMT+12. Across the forecasts the comes between Sat 3 a.m. and Sat 4 p.m. GMT+12. Most forecasts pass the centre 80–1,000 kilometres southeast of Petropavlovsk-Kamchatsky.
What is the chance it passes within 160 kilometres of Petropavlovsk-Kamchatsky?
11%: 1 in 10 forecasts bring the storm’s centre within 160 kilometres of Petropavlovsk-Kamchatsky. Rain, wind and coastal flooding can reach well beyond 160 kilometres from the centre.
How much rain could Petropavlovsk-Kamchatsky get while the North Pacific low off Kamchatka passes?
From Tue noon (when the forecast’s rain totals start) to Sat 6 p.m. GMT+12, the end of the window when its centre is closest to Petropavlovsk-Kamchatsky, the middle of NOAA’s 31 GEFS forecasts brings 84 mm of rain and melted snow to Petropavlovsk-Kamchatsky; nearly all bring 13 mm or more and nearly all bring 25 mm or more; nearly all bring 51 mm or more. By Sat midnight, when that window opens, the middle forecast already has 57 mm. That is all the rain in that time, not only the North Pacific low off Kamchatka’s, from one model (GEFS) on a coarse grid; local official forecasts can differ. Petropavlovsk-Kamchatsky: rain and wind this week →
How sure is the forecast?
Path certainty: low. 52 of 185 show the storm, and they closely on its path.
Do the AI and physics models agree?
Largely, yes. Chance within 160 kilometres of Petropavlovsk-Kamchatsky: AI ensembles (AIFS ENS, AIGEFS) 9%, physics ensembles (GEFS, ECMWF ENS, GEPS) 13%. By model: GEFS 10%, ECMWF ENS 14%, AIFS ENS 6%, AIGEFS 13%, GEPS 14%. By Sunday night, Oct. 4 the AI ensembles’ middle track is about 100 kilometres east of the physics ensembles’. At its deepest, the AI ensembles take it to about 977 and the physics ensembles to about 970 mb.
Will the North Pacific low off Kamchatka become a bomb cyclone?
29% of forecasts (3 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 about 290 kilometres south of Petropavlovsk-Kamchatsky on Friday night, at about 985 .

How sure. 52 of 185 show the storm, and they closely on its path.1

How strong. It is still strengthening: forecasts deepen it to about 973 by Saturday night. Three in 10 forecasts make it a , deepening about 24 millibars or more in a day.

What’s uncertain

Whether it forms. 52 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 Petropavlovsk-Kamchatsky, most forecasts put the between 80 and 1,000 kilometres away, most likely Saturday 9 a.m.

Later on. The forecasts fan out after Saturday. By Tuesday night, Oct. 6, the is about 1,600 kilometres 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 160 kilometres. Shaded columns are night; times are in your time zone.

Rain and wind this week in Petropavlovsk-Kamchatsky and Unalaska.

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

ModelTracks
NOAA
7 of 3118Z
arrived 2 h 12 min ago
ECMWF
16 of 5112Z
arrived 4 h 47 min ago
ECMWF
12 of 5112Z
arrived 6 h 50 min ago
NOAA
12 of 3112Z
arrived 6 h 29 min ago
Environment Canada
5 of 2112Z
arrived 8 h 17 min ago

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 near 922 mb now, in the Southern Hemisphere; 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 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-2026-0259.

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 52 tracks…

Stormlines Tracks: NOAA, ECMWF, Environment Canada

Full forecast
Through Wed midnight GMT+12