Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
813 FXUS62 KKEY 081917 AFDKEY Area Forecast Discussion National Weather Service Key West FL 317 PM EDT Tue Jul 8 2025 ...New AVIATION... .AVIATION... (18Z TAFS) Issued at 306 PM EDT Tue Jul 8 2025 VFR conditions are expected to prevail at both EYW and MTH for the rest of today and into tonight. While a few cloudlines have attempted to form in the vicinity of the island chain, none have developed in such a way that impacts either terminal yet. Meanwhile, a cluster of thunderstorms moving southwest off of South Florida poses somewhat of a threat to the Lower Keys if it holds together over the next few hours, but low confidence in it surviving the trip will keep mention out of the TAFs for now. Short term amendments will cover any unexpected developments relating to reigniting cloud lines and the previously mentioned thunderstorm cluster. Near surface winds will be out of the northeast at 5 to 10 knots, with occasional higher gusts near 15 knots at EYW early. && .PREVIOUS DISCUSSION... Issued at 1120 AM EDT Tue Jul 8 2025 Another summer day is underway across the Florida Keys. KBYX radar detects a few showers with a thunderstorm here and there bubbling along old outflow boundaries in the Straits of Florida and in the Gulf waters west of the Lower Keys. Meanwhile, GOES-19 visible imagery notes cumulus cloud streamers propagating southwest off of the Middle Keys with not much else over the island chain. This has allowed for a warm start to today with temperatures on land already reading in the mid to upper 80s. Moderate northeast to east winds prevail along the Reef and up into South Florida with a mainland shadow keeping skies clear in our Gulf waters just off of Florida`s west coast. Overall, breezes are slightly higher than yesterday while shower coverage has shifted more to our southern waters. The short term forecast finds us in a bit of a lull regarding rain chances. Normally, a typical summer day with gentle to moderate northeast breezes and average moisture content would point us towards cloudlines forming along the island chain. While this isn`t entirely out of the question, there are a few factors working against it today. While this morning`s KKEY sounding did observe a near normal PW value (~1.8 inches), CIMSS MIMIC TPW depicts a swath of relatively dry air (PW of ~1.6 inches) over the keys between a slug of tropical moisture in the Gulf and moisture associated with the incoming inverted trough churning through the east end of The Bahamas. Furthermore, dry air observed just above the inversion at 900 mb may also be entraining into pockets of developing convection making any deep development short lived at best. Finally, breezes are a touch higher than the usual nearly stationary cloudline likes to live in. Despite all of these factors working against rainfall, we still are opting to sit on the higher side of guidance with slight rain chances just below normal for this time of year. As the previously mentioned inverted trough continues to shift west, rain chances will gradually increase through tonight and into tomorrow. && .FORECAST... Issued at 452 AM EDT Tue Jul 8 2025 CIMSS analysis products have been very helpful when it has come to trying to sort this pattern out. MIMIC Layer PWAT shows that comparatively drier air will prevail for at least today, but an area of enhanced moisture exists over the Bahamas and eastern Cuba. Vorticity analysis shows an elongated area of relative vorticity at the 200 mb level overhead, but this feature is lost as we progress downward through the atmosphere, and is likely playing a role in our quieter radar. However, at the 500mb and 700mb levels, we can see two areas of interest over the Bahamas, and to the south of Cuba. With the deep layer steering flow looking a little kinky, it is hard to say which once of these areas is going to possibly result in some active weather. Global deterministic and ensemble guidance are still indicating that one of these areas of cyclonic flow will push across the area Wednesday night and Thursday, bringing an uptick in moisture and an increase in PoPs. For now, we will continue to advertise PoPs between 30 and 40 percent from Wednesday onward, with a peak of 50 percent PoPs on Thursday. The uncertainty mainly stems from guidance struggling to reflect this wave at the surface, but there are some hints of an inverted trough in the lower levels of the atmosphere. && .MARINE... Issued at 1120 AM EDT Tue Jul 8 2025 No watches, warnings, or advisories are currently in effect for the coastal waters of the Florida Key. From synopsis, a building Atlantic High will sustain gentle to moderate breezes for the next few days. Chances for showers and thunderstorms will be close to normal through Wednesday, but an easterly wave and veering winds may generate elevated shower coverage from Wednesday evening through the end of the week. && .CLIMATE... On this day in 2023, the daily record high temperature of 97F was recorded at Marathon. Temperature records for Marathon date back to 1950. && .PRELIMINARY POINT TEMPS/POPS... Key West 81 91 81 91 / 20 30 40 50 Marathon 81 89 81 89 / 20 30 40 50 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...JAM 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