textproduct: Key West

KEY MESSAGES

- Gentle to modestly moderate southeasterlies will prevail during the overnight hours, and into Thursday morning.

- Bouts of elevated rain and thunder chances will continue through the end of the work week.

- Rain chances will return to near normal by the weekend, and will continue through early next week.

DISCUSSION

Issued at 939 PM EDT Wed Aug 5 2026 Well, we guess we had to pay for our calmer conditions during our evening shift yesterday. We just didn't expect to have to pay for it so soon. Our KBYX radar has been a busy team player as it has continued to detect showers and thunderstorms across the forecast area throughout this shift. MRMS QPF estimates suggest the island chain did not see much of the rain from the widely spread activity, and rainfall totals of up to a tenth of an inch were seen across most of the Keys. A few spots along the northern portions of Key West and Stock Island may have see up to a quarter of an inch, but rainfall totals higher than this were over our marine zones. The heftier thunderstorms that brushed the Lower Keys around 8PM also brought gusts of near 25 knots, or 29 mph. We could also hear the thunder quite clearly from inside the office!

The environment was unsurprisingly primed for this. Our 00Z KKEY sounding showed a fairly deep, moist profile through most of the vertical column. There was a pool of relatively drier air in the mid levels, but it didn't seem dry enough to impact the towering convection. The calculated PWAT was 2.15", and the ML CAPE was an impressive 3000 J/kg with almost no inhibition to stop the atmosphere from utilizing this energy. Current radar imagery shows the activity over the western portions of our forecast area is gradually weakening, indicating that the available energy may have been mostly used up. However, the isolated pockets of thunderstorms entering our Florida Straits from Andros still have some energy to play with, so we aren't quite out of the woods with respect to some nighttime activity. It also looks like there may be some rogue ghost boundaries across the Straits just waiting to have a run in with an outflow boundary. All of this is to say that the inherited forecast package advertising a chance of showers and thunderstorms (around 40%) seems appropriate for the overnight period. Temperatures shouldn't have much of an opportunity to rebound with the mix of partly and mostly cloudy skies, so the current temperatures in the lower to mid 80s should hold through the night.

No changes to the forecast package are needed with this evening update.

MARINE

Issued at 939 PM EDT Wed Aug 5 2026 On and off showers and thunderstorms during the overnight hours may warrant Short Term Forecasts (NOWcasts) and Marine Weather Statements due to marine hazards associated with this activity such as gusty and erratic winds, higher and rougher seas, and lightning strikes. As activity tapers off, a gentle to moderate southeasterly wind field will resume through the nighttime and into Thursday. Any lull in our active pattern shouldn't last too long, and an uptick in activity may occur again Thursday afternoon.

AVIATION

(00Z TAFS) Issued at 939 PM EDT Wed Aug 5 2026 Opportunities for VCTS near KEYW will persist through ~04Z with a general lull in activity expected near both terminals through the remaining overnight hours. The active pattern continues tomorrow, but due to low predictability in how convection will evolve, I opted to include a mention of VCSH by 12Z followed by a persistence forecast with PROB30s for TSRA in the 21-00Z time frame. Breezy southeasterly sfc winds will increase to 10-12 kts by tomorrow afternoon with occasional gusts up to 18-20 kts.

PRELIMINARY POINT TEMPS/POPS

Key West 83 92 83 92 / 40 40 60 40 Marathon 83 90 83 90 / 40 40 60 40

KEY WATCHES/WARNINGS/ADVISORIES

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