Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
429 FXUS62 KKEY 190713 AFDKEY Area Forecast Discussion National Weather Service Key West FL 313 AM EDT Wed Aug 19 2026 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... - A swath of Saharan dust will remain across the Keys today, maintaining rain-free conditions. - Rain chances will slowly increase later this week as dust concentrations decrease. - Warm and muggy conditions will continue throughout the work week, with light and often variable breezes. && .DISCUSSION... Issued at 306 AM EDT Wed Aug 19 2026 It is yet another morning with clear skies across the Florida Keys and surrounding coastal waters as the expansive SAL that has brought a remarkable stretch of record low atmospheric moisture values continues. Most recently, the 00Z KEY RAOB sampled a PWAT value of 0.97 inches, which is well below the daily minimum for the 19th of August, low/mid RH values of 40% and 26% respectively, and an inversion marking the base of the SAL around 950 mb. While this inversion still provides evidence that the presence of the SAL is still in full control, it should also be noted that the inversion is not nearly as pronounced as what it has been the past several days and this is likely a sign that dust concentrations are finally starting to slowly decrease. That said, environmental conditions across the Florida Keys today will still closely resemble suppressive characteristics as another rain-free day is forecast once again, but today will be a transitional period as a gradual moistening trend commences and persists into the coming days. This isn`t to say that rain chances will abruptly ramp up by any means, but an introduction of slight PoPs generally returns to the forecast through the remainder of the work week. Regarding the synoptic picture, surface analysis shows high pressure across the Gulf with its axis bisecting the Florida straits and this will yield a low-level NW flow across the Florida Keys today. Meanwhile, weak cyclonic flow aloft will gradually become established in the northeastern Gulf as a weak upper level low slowly develops throughout the day. While the KEY CWA should be far enough removed from the upper low to take advantage of any forcing for ascent, enhanced moisture associated with this feature will cause a sharp moisture gradient across the mainland with PWATs in excess of 2 inches across much of north/central FL compared to the exceptionally dry values across the Keys. However, the proximity of the upper low coupled with the low-level northerly flow will finally start to moisten atmospheric conditions across the Keys, which could favor some shower activity developing by this evening depending on the evolution of outflow boundaries originating from seabreeze convection across SEFL later today. Highest rain chances this evening will generally be north of the Island Chain and across the Bay/Gulf side waters where slight PoPs are in place. A slight decrease in boundary layer flow on Thursday could then introduce cloud line development as a possibility and with much less dust to contend with, there are some signals for precip activity but PWATs will still be quite below the daily mean values for this time of the year. The aforementioned upper low in the northeastern Gulf will weaken late week and into the weekend as longwave troughing gradually amplifies across the eastern US. This trough will push a frontal boundary into the northern Gulf Coast and Southeast US late weekend and into early next week. As this occurs, a more familiar pattern develops locally as Atlantic high pressure at the surface brings a more southeasterly flow regime back to the Florida Keys by late weekend and into next week. Should this pattern materialize, it is possible that daily PoPs may finally return to normal climatological levels, though this may take until next week to fully develop as another wave of Saharan Dust could push through the region this weekend but dust concentrations shouldn`t be quite as extreme as what has been recently observed. Either way, an eventual end to this incredible mid August dry stretch is within sight but there remains no signals for any substantial rains at this time. && .MARINE... Issued at 306 AM EDT Wed Aug 19 2026 A ridge axis draped across the Florida Keys will maintain a mostly variable wind pattern through the remainder of the week with wind speeds mainly less than 10 knots. However, brief surges in wind speeds are possible in the evening hours with breezes occasionally approaching 15 to 20 knots near the Upper Keys. Exercise cautionary conditions may be periodically required for waters adjacent to the Upper Keys. A broad swath of Saharan air blanketing the area will maintain rain-free conditions today, but rain chances will slowly increase into late week as moisture slowly recovers. By the weekend, a light and variable flow pattern should persist on Saturday before winds gradually increase and become more southeasterly by late weekend and into next week. && .AVIATION... (06Z TAFS) Issued at 306 AM EDT Wed Aug 19 2026 VFR conditions will prevail at both Island Chain terminals throughout the TAF period. Surface winds today will be out of the NW at 5-10 kts before gradually becoming more light/VRB overnight into Thursday morning. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...RG Aviation/Nowcasts....RG Data Acquisition.....RG Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest