textproduct: Key West

KEY MESSAGES

- Confidence is increasing for an extended period of wet and windy conditions across the Florida Keys this weekend, and possibly into early next week.

- A Small Craft Advisory likely will be required by Sunday for portions or all of the Keys coastal waters. - Uncertainty remains very high regarding rain chances for next week.

SHORT TERM DISCUSSION

Issued at 940 PM EDT Thu Oct 15 2026 Generally uneventful weather conditions are still in place across the Florida Keys this evening as the bulk of the afternoon shower activity has tapered off. Radar derived rainfall amounts suggest the Middle Keys have only seen a few hundredths of an inch of rain over the past 6 hours, while the rest of the island chain has only see shower activity brush by. The heaviest showers just offshore of the Middle Keys may have produced up to nearly 2 inches, but the rest of the forecast area has only seen light to modestly moderate showers. Temperatures along the Keys are in the mid 80s, but there wont be much of an opportunity for some radiational cooling due to the moderate breezes (generally 10 to 15 mph) and some cloud cover advecting in from the east and the south. If winds were just a little bit lighter, we would be more optimistic regarding any cooling.

The lack of activity across the area may be attributed to the dominating deep area of high pressure off of the SE U.S. coastline. CIMSS vorticity analysis shows general subsidence over most of the southeast, including the Keys area. An upper level cell was noted around 200mb, but it is not reflected in the mid to lower levels. Shower activity in the distant Florida Straits has drifted into our waters, but the activity has fizzled out quick. The 00Z KKEY sounding did show a shallow layer of dry air near 850 mb, but the deeper dry air was above 500 mb. In fact, the sounding summary shows a calculated PWAT of 2.16, which is just above the 90th percentile of 2.06, so there is plenty of moisture available to support showers. Unidirectional wind flow up to 850 mb may help to prevent outflow boundaries from colliding, so while there isnt a significant source of lift available to trigger activity, we cant really rule out spotty showers during the overnight hours.

No changes or updates are proposed with this evening update.

DISCUSSION

Issued at 400 PM EDT Thu Oct 15 2026 The upcoming forecast will be dominated by the evolution of the next mid latitude trough currently amplifying across the heart of North America. Over the next couple of days the trough will amplify as it swings into eastern North America and link up with an upper level low over the Gulf of America. This will shove the deep layered ridge eastward into the Atlantic. Consequently, surface winds will trend downwards, becoming light through this period, possibly becoming variable Friday night. The already high deep layered moisture will remain elevated and may climb slightly. This along with continued instability and lack of inhibition will keep at least mid chance for precipitation despite the decelerating flow. Temperatures will remain near to slightly above normal with dew points holding in the mid to upper 70s.

The mid latitude trough will swing out into the Atlantic late this week, followed by deep layered ridging pushing eastward into the eastern United States. This will thrust a strong cold front southward across the Gulf of America, Florida, and the Atlantic Coast. Breezes are expected to freshen considerably beginning late Saturday, however guidance has been hinting at the front slowing to a crawl, possibly stalling within our forecast area. The combination of the frontal baroclinic zone, copious associated deep layered moisture, and fresh breezes will have a very high likelihood of considerable shower coverage with a chance for thunderstorms with the best chances occurring from late Saturday into early next week.

Unfortunately, improving weather and any post frontal cooling, drying and relaxing breezes will be completely dependent on when the front is finally flushed out of our area. The latest guidance drives the front southward into the northwestern Caribbean Sea in the Tuesday time frame. However, consistency has been poor. Stay tuned.

MARINE

Issued at 940 PM EDT Thu Oct 15 2026 There are no watches, warnings, or advisories in effect for the Florida Keys coastal waters. From synopsis, high pressure aligned across the southeastern United States and adjacent Atlantic will retreat eastward into the Atlantic over the next couple of days as a frontal system presses east and southeastward into the eastern United States. As a result, gentle to moderate breezes will relax, possibly becoming light and variable Friday night. The cold front is expected to drive southward into our Gulf waters Saturday night, resulting in northeasterly breezes freshening considerably, along with squally conditions. A Small Craft Advisory will likely be required for part or all of Keys waters by late weekend. These fresh northeasterly breezes are then expected to persist through the duration of the marine forecast.

AVIATION

(00Z TAFS) Issued at 940 PM EDT Thu Oct 15 2026 VFR conditions will prevail at both island terminals through the 00Z TAF period with FEW to occasionally SCT skies around FL025. High level clouds will brush across EYW, but these will be too high to impact flight categories. Chances for showers and thunderstorms will remain lower, around 30 percent, through most of the period, but these chances will increase near the very end of the period. Opting to keep the current TAFs dry due to low confidence regarding timing and potential impacts.

PRELIMINARY POINT TEMPS/POPS

Key West 81 89 79 87 / 30 30 60 60 Marathon 82 88 80 86 / 30 30 50 50

KEY WATCHES/WARNINGS/ADVISORIES

FL...None. GM...None.