textproduct: Key West

KEY MESSAGES

- Conditions will be marginally favorable for island cloud line formation near portions of the Florida Keys Thursday. Cloud line development will carry the risk of waterspouts.

- A chance of showers with a slight chance of thunderstorms will persist through tonight.

- Light to gentle east to southeasterly breezes will occasionally become variable through Thursday afternoon.

MARINE

Issued at 300 PM EDT Wed Jul 1 2026

Isolated showers and thunderstorms for the most part have fizzled out. Residual cloud line across the Lower and Middle Keys with on occasion develop showers and possibly a brief thunderstorm that could drift out over the surrounding nearshore waters. Otherwise, watching convection developing across the southern mainland, which has the potential to advect south and southwest across our waters. Outside of any convection, expect light, variable breezes to generally freshen to light to gentle breezes. We will continue to see at least one more day of overnight peaks followed by lulls during the late morning and afternoon. Starting late Thursday, a high pressure across the region will gradually build, allowing for breezes to freshen slightly further.

AVIATION

(18Z TAFS) Issued at 300 PM EDT Wed Jul 1 2026

VFR conditions expected outside of any cloud line convection this afternoon. Watching for convection to move off the mainland this evening and overnight that may pass close to either MTH or EYW terminals. General winds will be light and variable to start and gradually clock around from the east to southeast.

PREV DISCUSSION

Issued at 600 AM EDT Wed Jul 1 2026

Weather conditions during the overnight shift have remained mostly unremarkable outside of a few isolated showers and thunderstorms, mainly across the Florida Straits. Only a handful of lightning strikes were detected by the GOES-19 satellite, especially before midnight. Along the island chain, temperatures have sat in the lower to mid 80s with dew points in the mid to upper 70s. The exception, similar to yesterday morning, is on Big Pine Key where radiational cooling brought temperatures down to the upper 70s.

Amplified ridging across the eastern U.S., centered somewhere around western Virginia, will continue to keep sensible weather mostly benign. Forecasting when, and where, showers and thunderstorms will pop up feels almost impossible, because we have two different mechanisms we are depending on the trigger activity. The light and variable wind field opens the door for possible cloud line development either over, or adjacent to, portions of the island chain during the afternoon. This would result in very localized pockets of showers and thunderstorms, as well as a possibility for waterspouts. The second trigger for activity comes from the afternoon thunderstorms over the mainland that stem from sea breeze convergence. This activity can either drift into our forecast area, or outflow boundaries can collide and trigger new activity, which is essentially what we saw yesterday. All of this is to say that the ingredients for some showers and thunderstorms are there as is pretty typical for July in Florida. The question is simply where and when does this activity pop up.

After today, the ridging will nudge toward the Atlantic coastline. While this happens, a pulse or two of vorticity will undercut the ridge and clip the area, which will nurture an environment conducive to an increase in showers and thunderstorms. This isn't a pattern evolution that would favor a widespread washout over the holiday weekend, but both deterministic and ensemble guidance show some deeper moisture and better instability that would translate to an increase in the amount of activity somewhere within the boundary of our CWA. Probabilistic guidance favors activity during the day on Independence Day, and if we can work over the environment, that may give us a window of drier conditions for anyone celebrating outdoors. However, that hyperlocal scale is unrealistic to try and forecast for three days out, so the pattern will continue to be monitored.

PRELIMINARY POINT TEMPS/POPS

Key West 83 92 83 92 / 30 10 20 10 Marathon 82 89 83 90 / 30 20 20 10

KEY WATCHES/WARNINGS/ADVISORIES

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