FXUS62 KKEY 270838 AFDKEY

Area Forecast Discussion National Weather Service Key West FL 438 AM EDT Sat Jul 27 2024

New DISCUSSION, MARINE, AVIATION

DISCUSSION
Issued at 430 AM EDT Sat Jul 27 2024 KBYX radar has shown isolated shower and thunderstorm activity mainly in two different regions. Those regions are across the offshore Gulf waters and across the Cay Sal Bank just outside the Florida Keys coastal waters. This activity has remained in the same areas for much of the night with the Island Chain remaining virtually dry with the exception of the Upper Keys near Carysfort Reef Light and Ocean Reef where earlier shower activity sent an outflow boundary through resulting in wind gusts to near 20 knots.
Temperatures along the Island Chain are in the lower 80s with some isolated locations in the mid 80s and dew points in the mid 70s.
The humidity combined with the air temperature is making it feel like it is between 89 to 95 degrees out there.

Deep mean layer ridging remains the dominant feature across the Atlantic, especially in the low to mid levels with a TUTT cell present in the mid to upper levels over the Bahamas, Cuba, and the northeastern Caribbean Sea. CIMSS Vorticity also shows the TUTT cell remaining mostly an upper level feature, but there is some reflection down to 700 mb. As a result, marine platforms are observing east to southeast winds near 5 knots with the Island Chain communities observing near 5 mph.

FORECAST
Deep mean layer ridging across the Atlantic is expected to continue to dominate the sensible weather across the Keys through the remainder of the weekend into early next week. The TUTT cell that has been talked about for the last few days continues to remain in place over the Bahamas southward through Cuba and into the northeast Caribbean Sea. The Keys remain on the western side of this TUTT which is typically the drier side compared to the east side. CIMSS Vorticity shows the TUTT cell still mostly in the upper levels with some reflection seen at 700 mb but this remains mostly an upper level feature. In the low to mid levels, the expansive ridge in place across the Atlantic continues to remain in control with the western periphery extending westward through the Keys. In addition, a plume of Saharan dust is working its way northwestward around the southwestern periphery of the aforementioned ridge. Therefore, PoP chances were lowered for today through Sunday night from 20% to 10%. Also, winds are expected to be very light, especially for Sunday, and therefore, there is the potential for a Heat Advisory but we will re-evaluate tonight.

Monday and Monday night, the deep mean layer ridge remains in control with slightly more increased moisture rounding the southwestern periphery of the ridge as the previous Saharan dust starts to vacate the region. Therefore 20% PoPs remain.

Mid to late week, moisture increases a little bit more resulting in PoPs returning to near normal for this time of the year which is near 30%. Therefore, no change to the extended period this forecast package. Overall, continue to expect daytime highs in the lower 90s and overnight lows in the lower to mid 80s.
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