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Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
007 FXUS62 KKEY 140848 AFDKEY Area Forecast Discussion National Weather Service Key West FL 448 AM EDT Wed Aug 14 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 448 AM EDT Wed Aug 14 2024 Despite the early hour, heat indices remain around 100 degrees across the island chain. Temperatures have struggled to drop any further than the mid 80s and dew points have held steady in the upper 70s to near 80 degrees. A few island communities have experienced a brief cooldown with some of the shower activity passing through, but the bulk of the convection has remained south of the island chain. CIMSS MIMIC TPW places the Keys in a swath of robust moisture, with drier air on its heels near Andros Island. A ridge axis remains across South Florida and is maintaining gentle breezes this morning. With the aforementioned drier air encroaching on our eastern waters this morning, we may see a decrease in shower activity later this evening. The drier air does not appear to be moving fast enough at this time to hamper shower activity through at least late morning into early afternoon, so have bumped PoPs to 30% for today. Tropical Storm Ernesto is just north of Puerto Rico and is moving to the northwest. An upper-level trough across the Eastern Seaboard will start to drive Ernesto to the north to northeast as it becomes the main steering mechanism over the next day or so. In terms of the weather back home, the same upper trough will cause the Atlantic rigde to recede to the east. This will allow our wind field to collapse by this afternoon, when winds are forecast to become light and variable. With light winds, mesoscale processes such as boundary collisions, cloud lines, and mainland convection drifting south will be the main drivers of convection through most of the extended forecast. Looking ahead to the end of the week, a backdoor boundary will sag southward down the Florida peninsula before washing out across Central/South Florida. Deep tropical moisture ahead of it will bring increased rain chances Friday through Saturday. This washed out boundary will slide across the Keys on Saturday night, which will bring dew points down a degree or two and hopefully put us just out of Heat Advisory criteria. Ahead of this boundary, oppressive dew points will remain in place, and temperatures will peak in the lower to mid 90s each day. Some communities experienced heat index values in the 113-115 degree range yesterday, and with similar conditions in place today, an Excessive Heat Warning is not out of the question. Have held off for now and stuck with a Heat Advisory for today. We will continue to monitor near term temperature and dew point trends closely. && .MARINE... Issued at 448 AM EDT Wed Aug 14 2024 There are no watches, warnings, or advisories in effect for the Florida Keys coastal waters. An Atlantic ridge axis stretching west across South Florida will support light to gentle easterly breezes through this afternoon before becoming variable. Breezes will shift to the northwest by Thursday night as a trough dips south along the Eastern Seaboard. As the ridge axis fractures over the Florida Peninsula, breezes will become more chaotic for Friday through Sunday. Strengthening Tropical Storm Ernesto near the Leeward Islands will slowly turn northward, likely impacting the island of Bermuda as a hurricane Friday night through Saturday. && .AVIATION... (06Z TAFS) Issued at 448 AM EDT Wed Aug 14 2024 VFR conditions are expected to prevail at both EYW and MTH today. A broken line of nocturnal showers will cross the island chain this morning resulting in a VCSH mention in the TAFs. Afterwards, while a shower cannot be ruled out, exact location and timing is too uncertain to include mention. Near surface winds will be generally out of the east at 4 to 9 knots early, becoming light and variable. && .CLIMATE... On this day in 2021, the remnants of Tropical Storm Fred moved southwest of Key West on August 14th. Fred produced maximum sustained winds of 32 mph (maximum wind gusts of 45 mph), while Smith Shoal Light, Sand Key Light, and Sombrero Key measured maximum sustained winds of 34 knots (maximum wind gusts of 50 knots, 40 knots, and 40 knots, respectively). Maximum rainfall for this event was measured in the Upper Keys with Key Largo measuring 2.48 inches of rain, Florida Keys Marathon International Airport measuring 0.99 inches, and Key West International Airport measuring 0.73 inches. No significant damage was reported with only minor street flooding and isolated power outages being the biggest impacts. && .PRELIMINARY POINT TEMPS/POPS... Key West 93 83 92 83 / 30 30 30 30 Marathon 93 83 92 83 / 30 30 30 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory from 10 AM this morning to 7 PM EDT this evening for FLZ076>078. GM...None. && $$ Public/Marine/Fire...NB Aviation/Nowcasts....JAM Data Acquisition.....JAM Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest