textproduct: Key West

KEY MESSAGES

- Tropical Storm Bertha is located across the north-central Gulf, and the National Hurricane Center continues to issue advisories. This system poses no threat to the Florida Keys.

- Heat indices may approach 105 to 110 degrees each afternoon for some Florida Keys island communities, especially in the Upper Keys.

- Moisture will be gradually increasing starting Thursday in association with an easterly wave moving in from the Atlantic. This will allow for decent chances of accumulating rainfall for the end of the week.

DISCUSSION

Issued at 331 AM EDT Wed Jul 22 2026

A relatively benign overnight for the Florida Keys. Some moisture rounding the base of a ridge out across the Atlantic is pivoting through our far eastern areas this morning. This has allowed for some isolated showers to develop and occasionally pass over the Upper Keys. Most of these showers have been shallow with tops around 15 thousand feet, which has placed them below below the -20 degree celsius, which we look for as an indicator for lightning initiation. In face, surprisingly most of these showers are even below the freezing level. Otherwise, as the aforementioned ridge continues to nose back in to the west, this is maintaining an east to southeast across the area.

Elsewhere, the National Hurricane Center continues to issue advisories on Tropical Storm Bertha. At 2 am, TS Bertha was located about 75 miles east of the Mississippi River Delta and continues a westward movement. Bertha does not pose a risk for the Florida Keys.

As the ridge continues to move westward from the Atlantic, we will continue to be suppressed in the sense of vertical upward motion and rain chances will continue to be limited today through Thursday. Thereafter, moisture in association with an easterly wave will slowly filter into the region starting Thursday evening. Models disagree on which side will be the wettest and thereby the best chances for wetting rains. For now have trended PoPs up for both Thursday night and Friday to account for this discrepancies until models get into better alignment.

Beyond the end of the week, the forecast remains rather chaotic with models at odds with each other. Once this easterly wave passes through it will become a matter of whether troughing truly builds as equatorward as some models think. The ECMWF has a trough that parks itself across the eastern U.S. including Florida and the Florida Keys for days. This would result in southwest to west winds and even brief periods of west to northwest winds. On the other hand, the GFS has the trough held up further north across Central and Panhandle Florida, which would result in our winds returning east to southeast. A nearly polar opposite result. Unfortunately, given such outcomes, have tried a middle of the road approach for now with the understanding that this will likely change as we get closer to next week.

MARINE

Issued at 331 AM EDT Wed Jul 22 2026

A ridge across the Atlantic is nosing westward across the Florida Keys coastal waters this morning. In addition, moisture along the periphery of said ridge is pivoting across the far eastern waters. This has resulted in isolated showers that are passing through the Straits of Florida, northwest across the Hawk Channel waters, and in to the Florida Bay. Moisture will on occasion pivot through resulting in periodic showers and isolated thunderstorms. Otherwise, winds will remain east to southeast over the coming days. As an easterly wave moves in from the Atlantic, expect an increase in rain and thunder chances. Winds will briefly go northeast to east Thursday night into Friday as the feature moves through. Thereafter, low confidence in wind direction and speeds due to large spread in model solutions behind the easterly wave.

AVIATION

(06Z TAFS) Issued at 331 AM EDT Wed Jul 22 2026

VFR conditions are expected. Moisture will slowly filter in from the east, resulting in isolated showers. Highest chances for showers will be east of the MTH terminal. Brief MVFR conditions are possible from passing showers. Near surface winds will hold out of the east to southeast around 10 knots.

PRELIMINARY POINT TEMPS/POPS

Key West 90 82 90 81 / 10 10 20 50 Marathon 90 83 91 82 / 20 10 20 50

KEY WATCHES/WARNINGS/ADVISORIES

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