{ "number": 746, "headline": "September 25, 2025 Thursday Morning Hurricane Season", "standfirst": "Imelda expected to form in next 48-hours increasing potential to threaten Southeast U.S.", "desk": "tropics", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-09-25", "published": "2025-09-25T13:20:24.825000Z", "updated": null, "access": "free", "body_html": "
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2025 Hurricane Season [Day 117]. My FORECAST for this year is (still) 14 named storms, 7 hurricanes, and 3 major hurricanes (near average)

2025 Season to Date: 8 Named Storms, 2 Hurricanes, and 2 Majors | ACE = 59

Good Morning! This is post 746 in this newsletter\u2019s brief history (~2 years)

I really enjoy collecting the maps and typing up these posts \u2014 keeps me updated and engaged every day on the ongoing weather in the tropics and around the world.

Morning IR Satellite Loop

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Both Invest 94L [90%] and Tropical Storm Humberto are firing off vigorous convection \u2026 especially Humberto in an optimal environment for rapid intensification.

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SSTs are very warm along the path of both systems > 28.5\u00b0C

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NHC Track for Tropical Storm Humberto

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Track of Humberto is more typical \u2014 like Gabrielle before \u2014 but west of Bermuda. The hurricane will be LARGE and likely a major within 3-4 days, but probably sooner as NHC intensity forecasts are typically quite conservative.

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Humberto ATCF Spaghetti

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Current thinking: Humberto will intensity into a large, major hurricane by 4 days (Monday) and will control the twin cyclone system \u2014 with a PUSH of Imelda away toward the Southeast coast \u2014 and then perhaps a DRAG out to sea.

Most ECMWF Ensembles at 00z were Category 3-4 central pressure \u2014 very soon, too suggesting imminent rapid intensification

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HAFS-A [Nest] +3 days | Central Pressure 957 mb \u2014 Category 4

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Invest 94L \u2014> Imelda | ATCF Track Spaghetti

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Both HAFS-A and HAFS-B Mesoscale Hurricane Models

Similar track & intensity (Category 1-2) into South Carolina / Georgia border by late Monday

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HAFS-B Parent

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Key to the track of Imelda \u2014 intensity and size of Humberto and its ability to PUSH Imelda into the coast

Note, the systems gain latitude TOGETHER and are side by side here with HAFS-B (and HAFS-A, not shown). However, that\u2019s uncertain with global modeling e.g. ECMWF 06z

Atlantic Basin Outlook | 8 AM ET Update

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NHC has Invest 94L at 90% development \u2014 likely in next 48-hours

Medium and Extended Range

Steering Currents: bit of a blocking ridge to north of Imelda and Humberto force each to head westward until a sprawling trough digs into the Northeast and allows Humberto first to race out to sea \u2026

However, Imelda may get left behind while sitting off the U.S. East Coast into early October.

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ECMWF Next 12-Days Integrated Vapor Transport | 00z cycle

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Wild flagship model solution at 00z through 12-days showed both Humberto and Imelda (94L) becoming hurricanes \u2026 with the two hurricane system eventually turning/looping in tandem

Humberto leaves to the ENE out to sea but Imelda is left behind to spin off the East Coast and expand in size over the Gulf Stream

ECMWF 06z Relative Cyclonic Vorticity | Next 6-days

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Imelda is FASTER than Humberto with a track into South Carolina in 5 days (Mon-Tues)

ECMWF 06z Precipitable Water | Next 6-days

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Most recent 06z cycle of the ECMWF (flagship) model has Imelda gaining latitude faster than Humberto, which is very intense (Cat 4+)

HIGH uncertainty \u2014 but interests along the U.S. East Coast should monitor BOTH systems which will interact

ECMWF 06z | 850 hPa Wind Speed | Next 6-days

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Atlantic Satellite Imagery | IR and Mid-Level Water Vapor

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NOAA Tropical Surface Analysis | 18z

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Atlantic Tropical Waves = 2 including Invest 94L being watched with HIGH chance of development (90%)

ECMWF EPS 06z Ensemble | All Cyclone Tracks Through 6-days

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Continuing to trend toward Hurricane Imelda being a threat to land \u2014 with the forward motion being the main differentiator in terms of intensity at landfall in the Southeast.

00z Ensembles through 10-days

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Hurricane Gabrielle another 24-36 hours before transitioning to post-tropical

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Category 1 Hurricane Gabrielle (85-mph | 970 mb) racing ENE at 32 mph to the Azores as a Hurricane into Friday

Post-tropical hurricane-force later on Friday \u2014 may landfall Portugal this weekend but much weaker as equivalent of minimal TS or TD (35 knot winds)

Eastern Pacific Tropical Update | Hurricane Narda

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Hurricane Narda | Category 1 | 90 mph Winds

Narda will remain well away from land \u2026 and perhaps intensify to near major hurricane strength in the coming days

Maps sourced from weathermodels.com designed and innovated by yours truly! Please subscribe there for real-time access to the newest maps, charts from all of the weather models including ECMWF.

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I really enjoy collecting the maps and typing up these posts \u2014 keeps me updated and engaged every day on the ongoing weather in the tropics and around the world.

Both Invest 94L [90%] and Tropical Storm Humberto are firing off vigorous convection \u2026 especially Humberto in an optimal environment for rapid intensification.

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