Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
777 FXUS62 KKEY 190906 AFDKEY Area Forecast Discussion National Weather Service Key West FL 506 AM EDT Thu Sep 19 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 505 AM EDT Thu Sep 19 2024 Its a bit of a slower start to convective action this morning across the Florida Keys. By this time in the previous two mornings, a large cluster of showers with embedded thunderstorms was ongoing near the island chain. That is not the case today as shower coverage currently only spans the deep Gulf waters and just off the Atlantic coast of the Upper Keys. This deficit isn`t due to a lack of boundaries as a few can be observed meandering through our area. The major hinderance to precipitation development this morning is likely a combination of drier air aloft (as observed in yesterday evening`s sounding) and the boundaries not providing consistent lift as they outrun convection. Due to the lack of convection over land, temperatures across the island chain stand in the lower 80s. More inland portions of larger islands (like Big Pine Key) have taken advantage of our light winds and is reporting temperatures approaching the dewpoint values in the upper 70s. Despite the slower start, today is forecast to be quite similar to yesterday. Troughing aloft from the deep layer low over the Carolinas and decent instability are still in place. Model soundings suggest the mid to upper levels of the atmosphere will moisten up a touch thus removing some of the inhibiting dry layers. All things considered, we should be juiced up for a round of scattered convection and isolated thunderstorms once again even if it initiates later than previous days. If all else fails, light breezes combined with island heating effects could help spark cloud lines along the island chain. After a round of storms, expect a good lull in activity as the atmosphere recovers before the next round. Have elected to go with high end chance PoPs today and into tonight as timing for the next round or so of convection is up in the air. This regime of weather will persist until this weekend when the troughing in the southeast CONUS drifts out into the Atlantic. From then, easterly breezes will gradually return with our usual ridging pattern. Rain chances, however, will remain above average as deep tropical moisture will stick around. A question mark still remains towards the end of the forecast period as guidance struggles to make light of a disturbance in the northwest Caribbean that simply doesn`t exist yet. Stay tuned to forecast changes in the coming days as we wait to see if something forms and where it progresses. && .MARINE... Issued at 505 AM EDT Thu Sep 19 2024 From synopsis, light and often variable breezes will continue through the remainder of the week due to persistent troughing near the Atlantic Coast. Expect higher winds and seas in and around thunderstorms. The troughing will meander southeast to southward this weekend and into early next week and deepen while ridging builds in across the southeast. Confidence in the extended forecast is very low due to uncertainties with this evolution, as well as expected formation of a low in the northwestern Caribbean Sea. A Coastal Flood Advisory remains in effect for the Upper Keys, and a Coastal Flood Statement remains in effect for the Middle and Lower Keys. Boaters can expect less clearance under fixed bridges. && .AVIATION... (06Z TAFS) Issued at 505 AM EDT Thu Sep 19 2024 Scattered shower and isolated thunderstorm coverage near the island chain thus far this early morning has been less than anticipated. However, numerous lurking boundaries should fire development around sunrise, warranting inclusion of VCSH for several hours at both terminals. Thereafter, following an expected lull in activity, scattered showers and isolated thunderstorms should once again fire in the vicinity of the terminals. Uncertainty in timing of convective initiation prevents mention of any impacts to visibilities and ceilings at this time. && .CLIMATE... On this day in Keys weather history in 1954, the daily record low temperature of 67F was recorded in Marathon. Temperatures records for Marathon date back to 1950. && .PRELIMINARY POINT TEMPS/POPS... Key West 90 80 90 81 / 50 50 40 40 Marathon 90 81 90 80 / 50 50 40 40 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 PM EDT this afternoon for FLZ076. GM...None. && $$ Public/Marine/Fire...JAM Aviation/Nowcasts....BT Data Acquisition.....BT Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest