textproduct: Key West

KEY MESSAGES

- Small Craft Advisory conditions expected for all Keys waters by Saturday morning, persisting through at least early next week. Near- gale breezes will be possible at times Sunday evening through Monday evening.

- Gusty winds in frequent fast-moving showers will likely push through the Keys sometime between Friday night and Monday. Confidence in timing is very low at this time.

- Moderate coastal flooding in the Upper Keys will expand to the Lower and Middle Keys Sunday evening through early next week, with major coastal flooding possible in the Upper Keys.

DISCUSSION

Issued at 250 PM EDT Thu Oct 22 2026 A very complicated, chaotic synoptic pattern extending across the CONUS eastward into the North Atlantic. An amplified upper-level ridge extends across the Midwest all the way up into south- central Canada, with its surface reflection being a surface high pressure system centered just north of the Great Lakes region. To its east, a quasi- stationary positively tilted trough extends from the Florida Peninsula northeastward to Subtropical Storm Josephine off New England. Finally, a low-level cyclonic feature is currently straddled between South America and the Dominican Republic. This feature will be become an area of increasing interest over the next several days. Closure to home, the aforementioned trough over the Eastern Seaboard has started to have an increasing influence on the Florida Keys over the past 12 hours, including falling heights at all levels based on the 12z morning sounding at KEY. Skies are mostly sunny across the Keys, with the exception of portions of the Upper Keys, which are occasionally getting grazed by a few isolated showers with origins over the South Florida Mainland.

For tonight, the low-levels below 850 mb should gradually continue to moisten. This should support speed convergence-driven light showers, mainly in the Upper Keys, but certainly cannot be ruled out in the Lower and Middle Keys. The surface high pressure system will dive southeastward towards New England over the next couple of days and amplify, while the weak trough in the eastern Caribbean lifts northeastward. The interaction of these features will support fresh to strong breezes developing late Friday night into early Saturday, with winds likely peaking Sunday night through Monday.

In terms of rainfall, the weekend forecast is highly dependent on the ultimate strength and placement of the lifting Caribbean pressure perturbation. Should the system wrap up into a closed low, this may support an in-situ frontal boundary to push through the Keys, quickly drying the islands sometime on Saturday. Conversely, should the system remain largely disorganized and sloppy, the moisture may continue to extend quite further west through at least Sunday. Although most numerical weather prediction guidance has trended to the former outcome, we feel it is prudent to acknowledge both scenarios are about equally as likely at this time. Will maintain mid-level rain chances through early next week, while emphasizing a very low confidence rainfall forecast. A second high pressure system will finally slide all of the troughing features eastward by the middle of next week, supporting a more confident dry, yet continued breezy forecast.

Despite the low confidence rainfall forecast for the next several days, there remains high confidence in a pretty impactful coastal flooding event through early next week. We are approaching our peak annual King Tides coincident with the prolonged northeasterlies. Coupling this with existing backup of the Gulf Stream off the East Coast caused by Josephine as well as any potential rainfall bouts, the Lower and Middle Keys will likely be at moderate flooding levels by Sunday evening, with the Upper Keys possibly approaching major flooding. Coastal Flood Advisories will likely be extended to the Lower and Middle Keys, with Coastal Flood Warnings possible for the Upper Keys.

MARINE

Issued at 250 PM EDT Thu Oct 22 2026 As breezes freshen overnight, Small Craft Exercise Caution headlines are included for all of the Keys marine zones. Small Craft Advisories will likely be required for all Keys coastal waters by Friday evening or Saturday morning. Tides will remain elevated for the next several days, peaking Sunday night through Tuesday. Boaters can expect less clearance under fixed bridges.

From synopsis, high pressure centered near the Great Lakes region will continue to slide eastward and strengthen over the next several days. The high will interact with a developing disturbance in the eastern Caribbean, supporting freshening northeasterly breezes over the next several days. Breezes will peak Sunday night through Monday night, when strong to near gale breezes will be possible. The freshening breezes and a surge of moisture will also support possible elevated rain and isolated strong thunderstorm chances Friday night through Monday.

AVIATION

(18Z TAFS) Issued at 250 PM EDT Thu Oct 22 2026 VFR conditions will prevail at both island terminals through 18z Friday afternoon. Also a few passing showers cannot be ruled out overnight, lack of coverage and expected minimal impacts to ceilings and visibilities warrants leaving any mention out of the TAFs at this time. Near-surface winds will lull briefly in the evening ours, with increasing frequency of gusts 18 to 20 knots in the early morning hours.

KEY WATCHES/WARNINGS/ADVISORIES

FL...Coastal Flood Advisory until 5 AM EDT Friday for FLZ076.

GM...None.