{ "number": 733, "headline": "September 14, 2025 Sunday Evening Update", "standfirst": "NHC 70% high chance of developing tropical wave", "desk": "tropics", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-09-15", "published": "2025-09-15T01:16:19.688000Z", "updated": null, "access": "free", "body_html": "
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Good Evening! Hope everyone enjoyed the very warm late-summer weekend. While the calendar says autumn, we\u2019ll have well-above normal warmth across the Lower 48 into the end of the month.

Also, NHC will start up Invest 92L in the Main Development Region of the central Atlantic probably tomorrow. There is a 70% chance of development of a tropical wave forming into Gabrielle in the next several days. The disturbance has been generating convection for the last 48-hours and overcoming (slowly) the otherwise neutral environmental conditions e.g. dry air.

Invest 92L has a high chance of becoming Gabrielle \u2014 and models (conventional + A.I.) show a major hurricane in the central Atlantic in 7-days but most likely it will remain \u201cout to sea\u201d

Lower 48 Precipitable Water Forecast | Next 5-days

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Tropical Storm Mario (not Marco!) actually fell apart yesterday due to proximity to the coast of Mexico but has come back \u2014 may intensity a little to a 50-knot TS. Another system is likely on its heels \u2014 named Narda.

A cut-off low spins into the Carolinas this week and will actually dump quite a bit of rainfall (3\u201d-5\u201d) \u2014 this isn\u2019t a tropical system but it has some Atlantic moisture to work with. This trough is on the right side / downstream of a big Omega block in Canada that is keeping the central U.S. very hot

Lower 48 Satellite Image | Sandwich Composite

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Thunderstorms in the central and norther Plains.

Lower 48 Satellite Image | Mid-Level Water Vapor

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The trough over the Southeast is digging dry air into Florida and the Gulf of Mexico \u2014 actually comfortable tonight with dew points in the 60s in Orlando.

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Weather | Fronts this Evening

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RTMA Temperatures and Anomaly | 8:00 PM ET

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Lower 48 is above normal +1.1\u00b0F

Low Temperatures Monday Morning

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Chilly 20s and 30s showing up in the West including Oregon, Idaho, Wyoming and Colorado.

High Temperatures on Monday

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Still in the 90s along the Mississippi with 94 million at least 90\u00b0F

Rainfall Next 72-hours | NWS NDFD

3\u201d-5\u201d in North Carolina to Virginia from cut-off low pressure system

7-Day Precipitation from NOAA WPC

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North America Upper Level Height Anomaly | AIFS 18z | Next 10-days

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The ridge in Canada breaks down later in the week but then another block forms to the south over the Lower 48 = very warm weather into the following week!

NWS Blend of Models \u2014 5 day Average Temperature Anomaly (Days 1-5)

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NWS Blend of Models \u2014 5 day Average Temperature Anomaly (Days 6-10)

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ECMWF EPS 12z | 7-day Temperature Anomaly | Week 1 (Sept 14-20)

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ECMWF EPS 12z | 7-day Temperature Anomaly | Week 2 (Sept 21-27)

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Coast to coast warmth \u2026 and this ensemble mean will underestimate the potential warmth

Atlantic Hurricane Season

2025 Hurricane Season [Day 106]. My FORECAST for this year is (still) 14 named storms, 7 hurricanes, and 3 major hurricanes (near average)

2025 Season to Date: 6 named storms, 1 hurricanes, and 1 majors | ACE = 40 ACE of Erin: 32.2 (140-knots maximum wind)

ECMWF 12-Days Integrated Vapor Transport | 12z cycle

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The tropical waves behind Gabrielle do NOT develop in this cycle of ECMWF flagship model (12z)

Maximum intensity looks to be high end Category 4 in 9-days

The hurricane slows down well east of Florida \u2014 at 30\u00b0N \u2014 and then takes a right turn out-to-sea \u2014> \u201cfish mixer\u201d

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ECMWF 18z | Precipitable Water Next 6-days

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You can see the parade of tropical waves in the Precipitable Water field and then vorticity \u2026 we\u2019ll have to watch 2 more behind Gabrielle.

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NOAA GFS 18z | Vorticity 10-day Forecast

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Everyone is in agreement on developing a major hurricane.

Atlantic Basin Outlook | 8 PM ET Update

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70% chance of development with convection bubbling up again tonight

Atlantic Satellite Imagery | Infrared

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Water Vapor | Mid-level

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SST and SST Anomaly | ECMWF 12z analysis

Very warm water on the path of our next hurricane.

NOAA Tropical Surface Analysis | 18z

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Atlantic Tropical Waves = 3 with our 70% NHC

Eastern Atlantic and Africa Infrared Satellite

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ECMWF EPS 18z Ensemble | Active Cyclone Tracks Through 6-days

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Strong signal for Invest 92L \u2014> Gabrielle into likely a hurricane in 5-days.

ECMWF EPS 12z Ensemble | Active Cyclone Tracks Through 9-days

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\u2026 and a major hurricane in a week or so.

ECMWF EPS 12z Ensemble | Active Cyclone Tracks Through 12-days

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Some members have westward creepers \u2014 but they will all head out to sea \u2026

ECMWF EPS 12z Ensemble | Active Cyclone Tracks Through 15-days

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This is a STRONG signal for a major hurricane into the end of September. Bigger question is if another tropical wave can catch fire, or not.

AIFS-ENS Comparison at 12Z | Active Tracks at Day 8

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The A.I. trained ensembles have always been aggressive with tropical wave \u2026 no change to that thinking.

AIFS-ENS Comparison at 12Z | Active Tracks at Day 12

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AIFS-ENS Comparison at 12Z | Active Tracks at Day 15

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The outlier members near the U.S. are associated with other tropical waves that randomly pop up out of the Caribbean and Gulf. That\u2019s not a coherent signal at this time.

Eastern Pacific Tropical Update | Tropical Storm Mario

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40-knot tropical storm Mario

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Mario will reach cooler water and dry mid-level atmosphere by Tuesday and weaken probably quickly into a remnant low.

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", "body_key": null, "teaser_html": "

Also, NHC will start up Invest 92L in the Main Development Region of the central Atlantic probably tomorrow. There is a 70% chance of development of a tropical wave forming into Gabrielle in the next several days. The disturbance has been generating convection for the last 48-hours and overcoming (slowly) the otherwise neutral environmental conditions e.g. dry air.

Invest 92L has a high chance of becoming Gabrielle \u2014 and models (conventional + A.I.) show a major hurricane in the central Atlantic in 7-days but most likely it will remain \u201cout to sea\u201d

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