{ "number": 738, "headline": "September 18, 2025 Thursday Hurricane Season", "standfirst": "Tropical Storm Gabrielle nearly gave up but is back in business", "desk": "tropics", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-09-19", "published": "2025-09-19T00:22:30.052000Z", "updated": null, "access": "free", "body_html": "
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Good Evening!

Tropical Storm Gabrielle was a naked swirl of low-level clouds all day but has since erupted with convection down shear \u2014 on the eastward side of the center of circulation. Once the shear relaxes and the effects of the mid-level trough (TUTT) subside, then Gabrielle can resume intensifying as an upright, fully functional tropical system.

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Temperature Analysis | 6:45 PM ET

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HOT in the Mississippi River valley with mid to upper 90s today

Temperature Anomaly | 6:45 PM ET

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The heat wave is 15\u00b0F to 20\u00b0F above normal \u2026 and warmth extends from Memphis into the Northeast. Lower 48 is 3.4\u00b0F above normal

HRRR Simulated Radar Next 48-hours

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North America Precipitable Water | Next 6-days

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  1. Next tropical storm in the Eastern Pacific \u2014> (maybe) Narda \u2014 will push moisture into Southern California again by this weekend, with another tropical system following as the EPAC blows through the alphabet with weak, short-lived storms.

  2. Tropical Storm Gabrielle passes east of Bermuda but uncertainty about intensity: TS to major hurricane \u2026 remains. NHC is at 85-knots (Category 2) maximum

  3. Atmospheric rivers plow into Western Canada and then Pacific Northwest U.S. into next week \u2014 autumn like pattern

NWS NDFD Precipitation Next 48-hours

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Quite the rainfall for the Sierra and deserts \u2014 including Death Valley, Las Vegas, and Phoenix.

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NOAA WPC Precipitation + Anomaly | Next 7-days

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Little if any rain from the Northeast through Mid-Atlantic into North Florida = brown & red = much below normal through next 7-days.

Tropical moisture into California = huge bonus for the tail end of monsoon season.

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Atlantic Basin Outlook | 5 PM ET Update

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1 more area on the Atlantic Outlook but low chance from a tropical wave that just emerged off African coast.

2025 Hurricane Season [Day 110]. My FORECAST for this year is (still) 14 named storms, 7 hurricanes, and 3 major hurricanes (near average)

2025 Season to Date: 7 named storms, 1 hurricanes, and 1 majors | ACE = 41 ACE of Erin: 32.2 (140-knots maximum wind)

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Gabrielle should become a hurricane in 4-days by Sunday, but there is uncertainty as the center reformed/jumped northward to almost 20\u00b0N \u2026 I think previous forecasts of Category 4+ were contingent on a much further south center (15\u00b0N) but we may be seeing a reversion to the mean \u2026 and NHC going with Category 2.

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Tropical Storm Gabrielle (07L) ATCF Spaghetti

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ECMWF Ensembles 12z | Gabrielle

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Some variety in the maximum intensity but near majority show Category 3 pressure < 960s mb but probably not until it reaches higher latitude \u2014 and possibly as a post-tropical cyclone

ECMWF 12-Days Integrated Vapor Transport | 12z cycle

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Flagship model ECMWF 12z did not have another wave developing behind Gabrielle

ECMWF 18z | +4 Days MSLP | UV850 | PWAT

Can\u2019t say ECMWF Control (18z) is too terribly interested in Gabrielle with maybe minimal hurricane intensity

HAFS A and HAFS B mesoscale models (18z) with disorganized, minimum TS intensity at Day 5.

The uncertainty with intensity is not unusual with a system in its formative stages \u2026 and we have plenty of time to watch Gabrielle as it battles back against dry air and wind shear

Atlantic Satellite Imagery | Infrared

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Mid-Level Water Vapor

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Tropical Upper Tropospheric Trough (TUTT) undercutting Gabrielle with westerly wind shear and mid-level dry air, but that should subside

SST and SST Anomaly | ECMWF 12:00 UTC Forecast

Warm pool 28\u00b0 to 29\u00b0C plenty sufficient for any category of hurricane along the entire track of Gabrielle (07L)

NOAA Tropical Surface Analysis | 18z

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Atlantic Tropical Waves = 3 with the most recent coming off Africa (20%)

Eastern Atlantic and Africa Visible Satellite

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The healthy tropical wave that came off Africa today has mostly poofed

Long Loop of IVT from Day 2 to 15

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Cool to watch this African easterly wave born in Ethiopia and then take 8-9 days to cross Africa \u2026 emerge into the Atlantic at about 15\u00b0N \u2014 and weaken immediately.

ECMWF EPS 12z Ensemble | All Cyclone Tracks Through 10-days

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

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Gabrielle might be the ONLY show in town for the next 2-weeks from the full-physics EPS 15-day model

AIFS-ENS Comparison at 12z | Active Tracks at Day 10

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

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A.I. trained ensembles are MUCH busier with plenty of tropical cyclones all over the place \u2014 but I suspect these are FALSE ALARMS as the AIFS-ENS has been way too eager to develop every tropical wave \u2014 likely a bias/problem with the lower resolution (0.25\u00b0) model

Eastern Pacific Tropical Update | Invest 96E

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Next system would be named Narda but it is running out of time to organize before reaching cooler waters.

Western Pacific Typhoon Season Update | 24W and 25W

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3 concurrent tropical storms \u2014 and Ragasa and Neoguri should both become powerful Typhoons.

Tropical Storm Ragasa (24W)

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The potential intensity of Ragasa is easily Category 5 and could approach T 7.5 (155-knots) in short order heading just north of Luzon, Philippines over some of the deepest and warmest \u201cpool\u201d of tropical SSTs for some of history\u2019s most intense Typhoons.

HAFS-A 12z dips to about 906 hPa

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The size of Ragasa will be LARGE but it apparently will fit just between Luzon and Taiwan meaning it will largely head westward into China without disruption. This is not good!

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Threat to Hong Kong | ECMWF 18z location on Wednesday

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Tropical Storm Neoguri (25W)

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HAFS-A with 963 mb central pressure with Neoguri

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The parent domain of Neoguri shows a hyper intense Ragasa with 208 knot winds at 850 hPa and a surface pressure of 899 mb \u2026 okay then!

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EPS 12z Ensemble Spaghetti \u2014 Stall and loop in 5-days

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ECMWF 18z | 4-days Snapshot | UV850 | PWAT | MSLP

A big Super Typhoon + a little Super Typhoon = 2 maybe!

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Tropical Storm Gabrielle was a naked swirl of low-level clouds all day but has since erupted with convection down shear \u2014 on the eastward side of the center of circulation. Once the shear relaxes and the effects of the mid-level trough (TUTT) subside, then Gabrielle can resume intensifying as an upright, fully functional tropical system.

HOT in the Mississippi River valley with mid to upper 90s today

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