textproduct: Key West

KEY MESSAGES

- Conditions remain somewhat favorable for an island cloud line and associated waterspouts this afternoon.

- Rain and thunder chances will gradually return to near normal by early to middle of next week.

- Highs near 90 and dewpoints in the mid to upper 70s suggest afternoon heat indices will peak at 105 to 108 degrees.

DISCUSSION

Issued at 431 AM EDT Sat Aug 22 2026

At the surface, a weak region of high pressure is extending from the Bahamas, across the Keys, and through the Gulf associated with both a deep-layer Atlantic ridge and persistent, broad ridging centered over the Desert Southwest. Longwave troughing extends from an upper-level low over Quebec to as far south as the northeastern Gulf where a localized lower height region and subtle surface trough continues to support isolated to scattered shower/thunderstorm activity in the waters west of Tampa. A weak frontal boundary will stall along the Gulf Coast region today. It appears that deeper moisture content will remain focused just to our north/northwest closer to the convergent axis while latest forecast soundings and short term guidance suggests our PWATs will remain near the 10th to 25th percentiles for today, ranging from 1.4-1.6". This localized pocket of drier air is currently viewable on the GOES-E Split Window product and will likely be the primary limiting factor for our rain chances today. Our winds will remain on the weaker side with a general southeasterly component due to being within influence of the western periphery of the North Atlantic ridge, but winds may become variable at times this afternoon in which case conditions could become somewhat conducive for waterspouts if cloud line formation is able to occur. Otherwise, there is a slight chance of thunderstorms across the Upper Keys due to weak low-level speed convergence over the Bahamas which may support isolated thunderstorm develop west of Andros Island this afternoon. Any development that occurs may drift into the eastern Straits of Florida and towards the Upper Keys.

This setup will remain largely unchanged through Sunday and into next week due to the stagnant upper-level pattern. With mostly sunny skies and rain chances below-normal, afternoon heat indices along the island chain should easily reach the 105-108 degree range with highs in the lower 90s and dewpoints in the mid to upper 70s. Moisture advection early next week should bring the return of near- normal, to perhaps above-normal, rain chances, particularly as southeasterly flow becomes better established and the forecast area becomes better aligned with the zone of weak low-level speed convergence.

MARINE

Issued at 431 AM EDT Sat Aug 22 2026

No watches, warnings, or advisories are currently in effect for the Florida Keys coastal waters.

From synopsis, a split ridge pattern remains in place across the Florida Keys coastal waters. This will promote generally light to gentle southeast to south breezes through Sunday, becoming variable at times during the afternoon hours. While North Atlantic ridging builds westward, southeasterly to easterly breezes will become more established for Sunday night through the middle of next week, becoming gentle and at times moderate during the overnight hours.

AVIATION

(06Z TAFS) Issued at 431 AM EDT Sat Aug 22 2026

VFR conditions are forecast to continue at both terminals through this TAF period. Weak surface ridging will promote generally light, SE winds, occasionally VRB during the afternoon, and dry low to mid- level air should limit our overall rain chances today. Will monitor for cloud line formation this afternoon in which case a vicinity shower or storm may develop, but confidence is too low to mention in the TAF at this time.

PRELIMINARY POINT TEMPS/POPS

Key West 92 82 92 83 / 10 10 10 10 Marathon 90 82 90 82 / 10 20 20 20

KEY WATCHES/WARNINGS/ADVISORIES

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