textproduct: Key West

KEY MESSAGES

- Conditions will be favorable for island cloud line formation near portions of the Florida Keys today. 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 this evening.

DISCUSSION

Issued at 1031 AM EDT Wed Jul 1 2026

A fairly benign start to the day, however, there is an interesting feature that has taken shape across the extreme Southeast Gulf Waters. Winds overnight came off the mainland, resulting in a northeast to east wind. Then after midnight, the weak synoptic flow around the ridge came back in from the east to southeast. This directional change resulted in mass and momemtum converging across the Gulf and we now have a weak, broad mesovort. This shows up very well on visible satellite and over the last hour convection is bubbling along the periphery of the mesovort.

While this feature will continue to pop off convection across the SE Gulf waters, we will have to keep an eye on it's effect later this morning and afternoon. Conditions are still conducive for a cloud line to develop and this mesovort could help lend some organization if it should develop. The wind profile from the surface up through an about 700 mb would also support at least marginal conditions for a waterspout or two to form within any cloud line.

Given the uncertainty of how mesoscale features will fully interact with one another, opted to leave rain/thunder chances at slight for now.

MARINE

Issued at 1031 AM EDT Wed Jul 1 2026

Light and variable breezes have settled in across the coastal waters surrounding the Florida Keys and will maintain through the afternoon and evening. Should convection develop over the mainland and eject south to southwestward across the Keys and surrounding waters, we could see a quick uptick in northeast breezes. Otherwise, as was the case last night, the weak synoptic flow from the high should induce an east to southeast wind overnight. High pressure sprawled across the Atlantic and just to our south will gradually build, allowing for a very slow freshening to occur.

AVIATION

(15Z TAFS) Issued at 1031 AM EDT Wed Jul 1 2026

VFR conditions will prevail outside of any potential cloud line development later this morning and afternoon. A few showers and possibly a thunderstorm could develop within this line as we saw yesterday. Mentions of VCSH/TS will be added as conditions present themselves. Otherwise, light and variable winds expected through the period, outside of convection.

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 92 83 92 83 / 20 30 20 10 Marathon 89 82 89 83 / 20 20 20 10

KEY WATCHES/WARNINGS/ADVISORIES

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