Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
991 FXUS62 KKEY 111906 AFDKEY Area Forecast Discussion National Weather Service Key West FL 306 PM EDT Thu Jul 11 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 307 PM EDT Thu Jul 11 2024 It has been quite an active afternoon across the Florida Keys coastal waters. The remnants of the outflow boundary that sparked a lot of the convection seen over the past few hours is now moving through the Straits of Florida and across the far western Lower Keys. This outflow interacted with a cloud line that have developed over the Lower Keys, which quickly triggered storms that brought heavy rainfall to island communities between portions of Sugarloaf through Big Pine. Most of the activity has begun to deteriorate into stratiform rain aside from a few showers in the Straits and one across the western Lower Keys. Winds behind the outflow boundary remained elevated for a bit after it passed through, but have since come down in most locations. Temperatures have not reached their full potential thanks to the excess of cloud cover. Temperatures behind the outflow cooled off roughly 8 to 10 degrees, and the ASOS at Marathon is currently reporting a temperature of 79 degrees! The forecast over the next 24-48 hours is a little tricky, as there is still some drier air in place. Despite the drier layer sampled by the 12Z sounding this morning, showers and thunderstorms were able to develop and tap into the ample available CAPE. Boundary collisions and development along outflows will continue to be the main triggering mechanism for convection. A mid-level low will slowly dip southeastward closer to our area, which will continue to provide good upper divergence. This support aloft will help maintain these storms, however, some low level drier air could be entrained into these storms and cause them to fizzle earlier in their lifespan. As evidenced by today`s convective wind gusts across the forecast area, with some dry air still in place, it will be easier for stronger wind gusts to mix down to the surface in any storms tonight and tomorrow. Convection should wane this evening as the outflow boundary acts to stabilize the environment. Have maintained 20% PoPs for tonight. Tomorrow looks to possibly be a repeat of today, so have decided to increase rain chances to 40%. A weak wave will move from east to west across South Florida and the Keys starting tomorrow, which will begin to introduce deep tropical moisture back to the region and finally kick out any lingering Saharan air. Rain chances will remain elevated on Saturday as the best environment for convective development related to the wave will pass through at that time. After the wave exits to the west, deep ridging will build across the region. This expansive North Atlantic ridge will act as a conveyor belt to tropical moisture through at least the first part of next week. Have increased rain chances Sunday through Wednesday because confidence in the timing of this large swath of moisture has increased. Temperatures through next week will remain seasonable, with highs reaching the lower 90s each day and lows dropping only into the lower to mid 80s. The diurnal range of temperatures will only be 5 to 10 degrees, with the higher end of the range due to rain- cooled environments. Dew points will be in the upper 70s, so the humid Florida Keys summer is in full swing. && .MARINE... Issued at 307 PM EDT Thu Jul 11 2024 There are no watches, warnings, or advisories in effect for the Florida Keys coastal waters. From synopsis, light to gentle easterly breezes will prevail across the Florida Keys coastal waters through the rest of the work week, as high pressure remains in place from the Atlantic across the Florida peninsula and into the Gulf of Mexico. The high will strengthen over the western Atlantic this weekend, bringing moderate easterly breezes to the Keys waters Saturday through at least Sunday night. Breezes will begin to slack on Monday. && .AVIATION... (18Z TAFS) Issued at 307 PM EDT Thu Jul 11 2024 Shower and thunderstorm activity in the vicinity of both terminals will cause a fluctuation in VFR and MVFR conditions through this evening, but short term amendments may be necessary if stronger storms approach either terminal. The brunt of this activity diminishes later tonight, but lingering light showers may persist in its wake, and VCSH has been left in the TAFs until at least 02Z for this reason. Overall, north to northeast surface winds of 5 to 10 knots will slowly veer toward the east again overnight. && .CLIMATE... In Key West, July 11, 2015 was the last day of 28 consecutive days with low temperatures of 80 degrees or warmer, the longest such stretch on record. 2020 made a run for this record, but fell just short, ending a 27-day streak with lows of 80 degrees or warmer on July 14th. Temperature records in Key West date back to 1872. && .PRELIMINARY POINT TEMPS/POPS... Key West 82 90 83 91 / 20 30 20 40 Marathon 82 90 83 91 / 20 30 30 50 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...NB Aviation/Nowcasts....DP Data Acquisition.....DP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest