textproduct: Key West

KEY MESSAGES

- Island cloud line formation will be possible in the late morning or afternoon hours through the weekend.

- Waterspouts will be possible with any developing island cloud line.

- Conditions will remain seasonably warm and muggy, with heat indices approaching near 100F each afternoon through early next week.

DISCUSSION

Issued at 1045 PM EDT Thu Jun 11 2026 A muggy, seasonable night is unfolding across the Florida Keys. Just before dinner time, an expansive, but very thin, cloud line developed from Cudjoe Key and extended to the west past the Marquesas Keys. Cloudlines have a habit of seeing waterspout formation, but we did not receive, nor see any evidence of, waterspouts with this specific cloudline. Eventually, showers tapered off, and we are now left with an echo-free KBYX radar. GOES-19 Nighttime imagery is picking up on some low to mid level clouds across the area. Our 00Z KKEY sounding from this evening shows a fairly moist column of air aloft outside of some dry air intrusion between 800mb and 650mb (give or take a few mb). Light, backing winds haven't favored additional shower development, and these shower-free conditions will likely carry over into the overnight hours as the synoptic pattern remains fairly benign. Of note, the aforementioned sounding calculated a PWAT value of 2.16" which is just a touch above the 90th percentile. With this much moisture, any amount of shower activity cannot be ruled out, but a lack of any sort of lift means that we can maintain the inherited slight chance for tonight, and into tomorrow morning. Current surface observations shows seasonable, but still warm and muggy, conditions with temperatures in the lower 80s and dew points in the mid 70s. This gives us heat index values near 90F, but the light winds and mostly clear skies should encourage some radiational cooling.

No changes are needed to the current forecast package at this time.

MARINE

Issued at 1045 PM EDT Thu Jun 11 2026 There are no watches, warnings, or advisories in effect for the Florida Keys waters. From synopsis, a weak high pressure system in the west- central North Atlantic will slide eastward over the next several days, merging with another high pressure system in the eastern North Atlantic. This will support light to gentle east to southeast breezes gradually veering to the southeast to south through the weekend and into early next week.

AVIATION

(00Z TAFS) Issued at 1045 PM EDT Thu Jun 11 2026 VFR conditions will prevail at both island terminals with easterly winds near 10 knots. Opting to keep TAFs dry for now, but afternoon showers associated with cloudline development will be possible during the afternoon. Will introduce at least VCSH if deemed appropriate in a future package.

CLIMATE

On this day in 1999, the daily record rainfall of 2.50" was recorded in Key West. A local climate report says the rain fell in less than three hours, and the associated thunderstorms produced wind gusts estimated to be between 50 and 60 mph, and resulted in minor damage on Stock Island. Rainfall records for Key West date back to 1871.

PRELIMINARY POINT TEMPS/POPS

Key West 81 89 81 90 / 10 20 10 10 Marathon 81 89 80 89 / 20 20 10 10

KEY WATCHES/WARNINGS/ADVISORIES

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