textproduct: Key West

KEY MESSAGES

- A Coastal Flood Statement is in effect for the Middle and Lower Keys, with minor saltwater flooding possible around the time of high tide again late Thursday morning and afternoon.

- Rain and thunder chances through Thursday will generally be limited to any island cloud line formation or storms pushing off the South Florida Mainland in the afternoon and evening hours.

- Previously expected elevated rain chances for Friday night through Saturday night now appear a bit less likely, with Saharan dust inhibiting more widespread shower activity.

AVIATION

(18Z TAFS) Issued at 125 PM EDT Wed Aug 12 2026 VFR conditions are expected to persist at both EYW and MTH terminals through the TAF period. However, a cloud line, particularly effecting the Lower Keys may result in some brief periods of MVFR CIGs. Near surface winds will remain east to southeast through the period with the exception of this evening where winds may briefly become northeast to east. Also, convection over the South Florida mainland may drift southwestward this evening after 13/00z which may bring a shower to the terminals. However, due to low confidence in timing and placement, VCSH was not included.

PREV DISCUSSION

Issued at 400 AM EDT Wed Aug 12 2026 The 00z evening sounding at KEY sampled a relatively moist boundary layer up to around 825 mb, capped by a weak 2C inversion, along with substantial dry air aloft. Satellite-derived dust products indicate the Florida Keys remain on the southern periphery of a plume of Saharan dust extending from the southern Gulf eastward all the way to western Africa. Synoptic low-level wind and pressure analysis places a weak area of high pressure centered in the central North Atlantic, with a series of climatologically-favored easterly waves traversing the Atlantic to the south. With the lack of shower activity across the entire CWA, land-based surface observations indicate temperatures generally in the mid 80s across the Island Chain at this early evening hour.

For today through Thursday, the aforementioned high pressure system will weaken, supporting a slackening overall low- level surface wind pattern. This wind pattern, coupled with northeasterly steering flow, will support possible cloud line development in the afternoon hours. In addition, outflow from any developing shower and thunderstorm activity over the South Florida Mainland may propagate southwestward, supporting isolated showers and thunderstorms in the evening hours. Coinciding these scenarios being depicted, there will continue to be substantial dry air above the boundary layer. In what would normally be a dry short- term forecast, will advertise low- end slight rain and thunder chances to account for these scenarios.

Beyond Thursday, global numerical weather prediction models suggest the surface high will somewhat strengthen and rebuild westward in the North Atlantic. With the axis of the associated ridge positioned just north of South Florida, this will support general freshening east to southeast breezes. Forecast vorticity fields indicate a weak tropical wave currently in the vicinity of Hispaniola will push through the Straits of Florida just to the south of the Keys Friday afternoon through Saturday. Combined with the somewhat speed convergent flow for this period, this would seem to suggest a bit elevated rain and thunder chances for that period. However, forecast soundings suggest a continued poor thermodynamic profile owed to the continued overlay of Saharan dust. We will monitor moisture profile trends, as any modest undulation in deeper tropospheric moisture will win out over the dust, especially with low-level cyclonic support for ascent.

As the wave departs, high pressure is expected to dominate the forecast beyond through at least the middle of next week. NASA dust aerosol forecast products suggest an even drier, dusty tropospheric profile will be possible, suggesting possible rare near-nil rain chances for late in the weekend through early next week.

In terms of the tropics, although the National Hurricane Center is monitoring three possible areas in the North Atlantic for tropical cyclone development in the next seven days, all three systems will remain weak, with no expected impacts to the Keys.

MARINE

Issued at 127 PM EDT Wed Aug 12 2026 A Coastal Flood Statement is now in effect for the Middle Keys and remains in effect for the Lower Keys, with minor saltwater flooding possible around the times of high tide again late Thursday morning and afternoon. Boaters can expect less clearance under fixed bridges, especially around the time of high tide. From synopsis, a high pressure system centered in the central North Atlantic will shift eastward and weaken through Thursday. Gentle east to southeast breezes will slacken, becoming light and variable at times in the afternoon hours. As the high restrengthens and builds westward, breezes will somewhat freshen for late in the work week through the weekend.

KEY WATCHES/WARNINGS/ADVISORIES

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