Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
941 FXUS62 KKEY 120926 AFDKEY Area Forecast Discussion National Weather Service Key West FL 526 AM EDT Mon May 12 2025 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 412 AM EDT Mon May 12 2025 It has been a very busy overnight shift here at the office, and we aren`t done quite yet! GOES-19 Nighttime Microphysics shows the deep troughing draped over Mexico and the Gulf as well as low pressure centered over the Louisiana and Mississippi area. The "tail" of the low is dragging across much of the southeastern U.S. including most of Florida. Closer to home, our KBYX radar overlaid with lightning observations show plenty of showers with embedded thunderstorms across the forecast area. This activity is oriented along a south to north oriented band, and is lifting along the island chain and surrounding waters. Radar reflectivity has even picked up on the cyclonic rotation associated with a meso-low in the vicinity of Boca Grande, indicating there is ample shear aloft to get some of these stronger cells rotating. Between the onset of rain last night and 4 AM EDT this morning, the ASOS at Key West International Airport has reported a total of 1.18" of rain, and Marathon Airport has reported 0.16", a true testament to the slow west to east motion of these showers. For what it`s worth, radar estimated storm totals show areas that have seen up to 7 inches of rain so far, but these areas are located over the water, so only the sea creatures would be impacted. The environment looks favorable for this mess, for lack of a better word, to continue. NAEFS analysis has calculated this moisture plume to be approximately 4 to 5 standard deviations wetter than the climatological normal. Considering it is early May in a tropical climate, this is just a very wet atmosphere. Winds at the surface are out of the southeast, but forecast sounding data suggests persistent southwesterly flow from approximately 850 mb through 300 mb. This just means the conveyor belt of moisture runs deep, and we will probably see some training with these showers and thunderstorms. CAMs guidance coupled with water vapor imagery suggest a shallow wedge of relatively drier air will offer a break in activity during the morning and early afternoon, but this will give the atmosphere a chance to destabilize, and would lead to "spicy" weather again tonight. The good news is that guidance still shows the parent low lifting toward the northeastern U.S overnight tonight. As it tracks away, the line of showers and thunderstorms will lift out of our area. High pressure will be able to build in over the Gulf, and much drier air will bring our chances of showers back down to around 10% from the middle of the week onward. Breezes will slacken, becoming variable at times, before resuming an easterly direction. Temperatures will trend warmer, and our weather will feel more like summertime in the Florida Keys. && .MARINE... Issued at 412 AM EDT Mon May 12 2025 Very active weather continues across the Florida Keys waters today, and Special Marine Warnings will likely be needed. Winds and seas will be higher, and bay waters rough, in and near showers and thunderstorms. From synopsis, deep troughing over the Gulf is still in place with a plume of abundant moisture encompassing most of the forecast area. Moderate to occasionally fresh southeast to south breezes will veer southwesterly while the heart of the parent low meanders along the northern Gulf. Scattered to numerous showers with embedded isolated to scattered thunderstorms will continue through early Tuesday. As the low lifts toward the northeast during the middle of the week, higher pressure will be able to fill in behind it, encouraging drier weather and slackening breezes. && .AVIATION... (06Z TAFS) Issued at 412 AM EDT Mon May 12 2025 Latest radar imagery remains quite active across the Keys with a cluster of showers and embedded thunderstorms slowly migrating its way to the east northeast. This is expected to continue for the next few to several hours. As a result, periods of MVFR CIGs and VIS are likely with the potential for IFR conditions along with occasional cloud to ground lightning strikes and gusty winds. Activity is expected to wane from west to east with EYW ending around 12/09-10z and then MTH around 12/12-14z. However, the break is expected to be short-lived with another of showers and thunderstorms expected Monday night into Tuesday morning. && .CLIMATE... On this day in Keys Weather History, the daily record rainfall of 2.58 inches was recorded in Key West set back in 1898. Rainfall records for Key West date back to 1873. Also, the daily record rainfall of 0.94 inches was recorded in Marathon set back in 1987. Rainfall records for Marathon date back to 1951. && .PRELIMINARY POINT TEMPS/POPS... Key West 86 78 86 77 / 70 70 40 20 Marathon 85 78 85 77 / 70 70 50 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...DP Aviation/Nowcasts....MJV Data Acquisition.....MJV Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest