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OFF SOUTH-WEST MEXICO — A 40-MPH TROPICAL STORM WITH A FORECAST CATEGORY-4 CEILING, AND A SECOND STORM BEHIND IT

On the board · September 21, 2026 →
BUILDING · September 21, 2026 · NO. 0921
THE STORM

Both weekend genesis areas delivered. The nearer storm sits about 270 miles south of Manzanillo at 40 mph, moving east-north-east at 5, and the advisory forecasts rapid intensification to a Category-4 major hurricane by about 72 hours, with interests along the south-west coast of Mexico told to monitor its progress. The second, far offshore at about 50 mph and 1002 mb, becomes a hurricane later this week over open water with no land threat. Behind them a new area south-west of the Gulf of Tehuantepec carries 30 percent over seven days, and the disturbance east-south-east of Hawaii has risen to about 70 percent over seven days, with a depression likely south or south-east of the islands mid-to-late week and heavy rain possible over east Hawaii. A cross-agency board sizes about 0.827 million people inside tropical-storm-force winds today, which is a snapshot of the present wind field and not of the forecast one.

THE RECORD

30 turning points on record since Aug 16 — the 8 most recent shown.

Sep 21↑ intensified sharply
Sep 20↑ moved up the board
Sep 19↑ moved up the board
Sep 18▽ slipped down the board
Sep 17easing → building
Sep 15→ held
Sep 15▽ slipped down the board
Sep 15▽ designation Tropical Storm→Tropical Depression
WHO IT TOUCHES
Public safetyfive warning systems live at once, and the distance between the warning and the water is different in every one
Aviationat least 275 flights already cancelled on a holiday weekend, with three more boards to buffer
Maritimea fishing fleet with a 72-hour window, an island ferry network inside a transitioning typhoon, and a coastal wind pulse firming to about 80 km/h
Supply chainsrail suspended through a holiday weekend, a Rhine at 16.0 cm, and a coast that may lose its ports inside three days
CONNECTED

The planet's tropical energy has left one ocean and concentrated in the other — and both halves of that sentence sit next to a record.

The named storm gets the coverage and the unnamed cyclone gets the people.

WHAT THEY'RE SAYING

Forecasters already project the tropical storm off southwest Mexico will reach major hurricane strength. Communicators have emphasized the likelihood of rapid strengthening and have called attention to possible effects on Socorro Island and nearby coasts. They have also noted that the system recently developed from an area that was being watched for development, consistent with the official outlook for continued intensification.

HU@hurricane_chaseSep 20Tropical storm south of Mexico is forecast to rapidly intensify into a major hurricane with possible impacts to Socorro Island and nearby coasts.
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WX@WxAtomSep 20Former invest area has become a tropical depression expected to strengthen into a major hurricane off Mexico by midweek.
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