{ "number": 770, "headline": "October 21, 2025 Tropical Storm Melissa Watch", "standfirst": "NHC 100% chance of Tropical Storm Melissa developing Tuesday", "desk": "tropics", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-10-21", "published": "2025-10-21T13:09:42.055000Z", "updated": null, "access": "free", "body_html": "
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Good Morning! This is post 768 in this newsletter\u2019s 2-year history from Dr. Ryan Maue.

Waiting on formation of Tropical Storm Melissa later today (100% chance) with initial cone and forecast likely at 11 AM ET. Until then, we\u2019ll quickly update the maps/models to figure out where Melissa is headed, and how slowly it will get there!

There is an increasing potential for a Category 5 hurricane in the Western Caribbean.

The vast majority of reliable model solutions keep Melissa over the deep warm ocean heat content through 7-days.

ECMWF 06z Precipitable Water | Next 6-days

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From the ECMWF 06z flagship model, Tropical Storm Melissa will track south of Hispaniola near Jamaica in the coming days, and steadily intensifies to low-970s mb pressure in 4-days settling between Jamaica and Haiti. The slow movement and extreme ocean heat content = rainfall amounts measurable in the feet (> 4 feet)

Into this weekend, we see that ECMWF does NOT take Melissa across Hispaniola (as GFS continues to insist), but instead does a slow loop \u2014 nearly stationary next to Jamaica into early next week.

ECMWF Cyclonic Vorticity Next 6-days

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ECMWF Wind Gusts Next 6-days

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The small inner-core or vortex of Melissa = potential for extremely rapid intensification especially if the wind shear decreases enough.

We don\u2019t typically use the global models for intensity forecasts due to their lower spatial resolution (grid spacing) but ECMWF at 9 km resolves ~970 mb with a tiny vortex. To me, that favors potential for Category 5 with the ocean heat content and 29\u00b0 to 30\u00b0C SSTs.

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

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The flagship 00z solution extends here into Day 12 \u2014 and shows a monster Hurricane Melissa spinning over the very warm western Caribbean before sprinting across eastern Cuba into the Atlantic. Still not worrying about the East Coast \u2014 that would be 10 days down the road \u2014 and would require an extremely rare alignment or weather pattern to repeat a Sandy-like trough capture.

Weather Trader is a reader-supported newsletter with 1x to 2x daily weather updates. To receive new posts and support my work, consider becoming a free or paid subscriber, and sharing!

Atlantic Basin Outlook | 8 AM ET Update

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Invest 98L \u2014> 100% \u2014> Tropical Storm Melissa.

2025 Hurricane Season [Day 143]. My FORECAST for this year is 14 named storms, 7 hurricanes, and 3 major hurricanes (near average)

2025 Season to Date: 12 Named Storms, 4 Hurricanes, and 3 Majors | ACE = 100

ATCF Spaghetti | Invest 98L

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Caribbean IR Satellite Loop

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Very healthy blob of convection with Invest 98L \u2014> Melissa.

NOAA Tropical Surface Analysis | 06z

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Atlantic Tropical Waves = 3 \u2014> Invest 98L has 100% chance of development in the Caribbean

Google Deep Mind Forecast Tracks | Invest 98L

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50-members from this A.I. trained system \u2014 which has performed very well after storm formation \u2014 shows 2 camps: westward/more intense vs. into Hispaniola.

There are members at 894 mb, and many others at Category 5 pressure \u2014 assuming Melissa heads westward w/o as much northward component of motion like the ECMWF 06z.

ECMWF 00z EPS Internal Tracker | Invest 98L

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Similar story from the EPS 00z (internal tracking routine provided by ECMWF) \u2014 the red tracks = major or even Category 5 hurricanes that linger longer SW of Jamaica before accelerating out-to-sea. The animated \u201cactive tracks\u201d show the 2 potential outcomes very nicely, but the majority of solutions now drift WSW away from Jamaica and Haiti.

Active Tracks Animation | ECMWF EPS 00z through 12-days

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If we sort the members that do have hurricanes, then the expected track out of the western Caribbean is near/east of Florida and then into the Western Atlantic.

NOAA GEFS 00z & 06z (31-members) | Through 7-days

GEFS Ensemble Tracks favor a more northward solution but there are a minority that match ECMWF EPS + Google Deep Mind.

GFS 06z is due north to Hispaniola in 3-days as a major hurricane (not favored solution)

Eastern Pacific Tropical Weather Outlook | 8 AM ET

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70% chance of formation of another tropical cyclone (next name is Sonia) in the next several days. However, the convection is not well organized and any development would be slow.

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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Waiting on formation of Tropical Storm Melissa later today (100% chance) with initial cone and forecast likely at 11 AM ET. Until then, we\u2019ll quickly update the maps/models to figure out where Melissa is headed, and how slowly it will get there!

There is an increasing potential for a Category 5 hurricane in the Western Caribbean.

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