textproduct: Key West

KEY MESSAGES

- Island cloud line formation will be possible in the late morning or afternoon hours through the weekend.

- Waterspouts will be possible with any developing island cloud line.

- Conditions will remain seasonably warm and muggy, with heat indices approaching near 100F each afternoon through early next week.

AVIATION

(18Z TAFS) Issued at 125 PM EDT Thu Jun 11 2026 Despite a thick cirrus deck based at around FL150, VFR conditions will prevail at both island terminals through 18z Saturday afternoon. The best chances for an isolated shower or thunderstorm will be associated with possible island cloud line formation in the late morning or early afternoon hours Saturday. Near- surface winds will light, generally out of the east to southeast, occasionally backing to the northeast to east.

DISCUSSION

Issued at 421 AM EDT Fri Jun 12 2026 What large scale features are playing a role in the current weather pattern? The aforementioned tropical wave was absorbed into a Central American Gyre over southern Mexico and Central America. Its role for Florida Keys weather is that it will weaken nearby high pressure systems, leading to our light breezes, and send waves of high altitude ice clouds across the eastern Gulf. Meanwhile, the Atlantic High has moved far to the East of Bermuda. A stronger high pressure system over the eastern United States could build winds across the Keys, but a series of lows unleashed multiple rounds of severe convection across the Midwest which also weakened the southeastern US high. The result is a relatively stagnant pattern across the Florida Keys. Breezes are light to gentle, divergence in the upper atmosphere is elsewhere, suggesting the weather for the upcoming weekend will be defined by diurnal heating cycles. There is one more caveat, a dry layer identified by last night's 00Z sounding between 800 and 650 mb. NASA forecast models that focus on aerosols highlighted a region of higher than normal optical thickness over South Florida and the Keys. It's possible that one of the reasons shower coverage has been so sparse the past few days was a lingering layer of Saharan dust.

What does this mean for the upcoming weekend and next week? Models suggest a drier pattern is setting up across the Keys. The Central American Gyre will divert the most moisture-laden air west of the Keys. Model ensembles show a pronounced trough forming over the eastern United States, which would prevent the southeast US high from redeveloping and freshening breezes across the Keys. In this environment, the main concerns become cloud line showers, potential waterspouts, and heat risk. Heat indices near 100 F are possible, and we are not even in the hottest month of the year. Stay hydrated, watch clouds over the water, and stay cool when possible!

MARINE

Issued at 1107 AM EDT Fri Jun 12 2026 No watches, warnings, or advisories are in effect for the Florida Keys coastal waters. From synopsis, elongated high pressure extending from the Southeast eastward to the western North Atlantic will support light to gentle east to southeast breezes today through Saturday, gradually veering to the southeast to south for Sunday through early next week. Shower coverage across the Florida Keys coastal waters will remain low while a layer of dry air lingers in the lower atmosphere.

KEY WATCHES/WARNINGS/ADVISORIES

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