Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
790 FXUS62 KKEY 181847 AFDKEY Area Forecast Discussion National Weather Service Key West FL 247 PM EDT Tue Jun 18 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 247 PM EDT Tue Jun 18 2024 Surface analysis shows two features driving our winds; an expansive high in the western North Atlantic and a large Central American Gyre (CAG) over the Yucatan Peninsula. Marine observation platforms are measuring winds of 15 to 22 knots along the Reef, with the higher sustained winds in the western waters. Showers in our southwestern waters that were previously riding along in the fast easterly flow have waned for the most part, and GOES Visible Satellite is depicting mostly clear skies across the Florida Keys forecast area. This abundant sunshine has allowed temperature to climb into the upper 80s. The high in the western North Atlantic will slowly seep southward over the next few days, Meanwhile, the CAG will meander around the Yucatan while simultaneously spitting out possibly a few disturbances. The locations of these features will keep a tightened gradient across the region, and a prolonged period of elevated easterly winds is expected. The Florida Keys will find themselves in an area of weak confluence between the aforementioned low and high pressures. The confluence plus the moist easterly breezes will allow for above normal rain chances (30-40%) for the next few days. Thereafter, there is a decent amount of uncertainty regarding the forecast and there is a lot of run-to-run inconsistencies with the global models. The first question mark is the inverted trough moving along in the easterlies that models have been attempting to develop into a closed surface low the past few days before shoving it somewhere along the Southeast coast. The strength of this trough and if it can actually develop into a closed low will be the deciding factors of if our winds will decrease for a brief time later this week. The stronger the potential system is, the more interruption in the ridge which could lead to a brief decrease in winds later this week. Models have backed off on the development of this trough, so winds will most likely remain elevated through at least the start of the weekend. The second question mark is the extent and timing of moisture streaming into our area. The exact details are blurry on that, so have decided to broad-brush 40% through most of the extended forecast. As we head into next week, winds will have come down, which will act to bring rain chances down a touch for the time being. && .MARINE... Issued at 247 PM EDT Tue Jun 18 2024 A Small Craft Advisory is in effect for all Florida Keys coastal waters. From synopsis, strong surface high pressure centered off the New England coast working in tandem with falling pressures over the Yucatan Peninsula and the Bay of Campeche is expected to result in moderate to fresh breezes tonight through late week. An area of low pressure may develop mid week a few hundred miles north of the central Bahamas towards mid week and move towards the Southeast coast. This may result in a slackening of breezes, but confidence is decreasing in the development of this system. && .AVIATION... (18Z TAFS) Issued at 247 PM EDT Tue Jun 18 2024 VFR conditions will prevail at both EYW and MTH for the rest of today and into tonight. While shower activity has dwindled from this afternoon, there still remains a chance of showers through the overnight hours. VCSH has been discontinued at both terminals due to lack of activity but may be required again once showers develop later this evening. Timing and exact coverage of developing convection is too uncertain to include VCSH at this time. Near surface winds will be out of the east to southeast at near 15 knots with gusts up to near 25 knots. && .CLIMATE... In 1972, during the early morning hours, Tropical Storm Agnes passed northward through the Yucatan channel. The outer rainbands of Tropical Storm Agnes spawned at least three, to as many as six tornadoes in the Florida Keys, including a F2 tornado in Big Coppitt Key, a F2 tornado in Key West, and a F1 tornado in Conch Key. Total damage was estimated at just over $500,000 (1972 USD). About 40 people were injured in Big Coppitt Key, making the Big Coppitt Key tornado the worst in the history of the Florida Keys in terms of total number of injuries. && .PRELIMINARY POINT TEMPS/POPS... Key West 82 89 82 89 / 30 40 40 50 Marathon 82 89 82 89 / 30 40 40 40 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...Small Craft Advisory for GMZ031>035- 042>044-052>055-072>075. && $$ Public/Marine/Fire...NB Aviation/Nowcasts....JAM Data Acquisition.....DR Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest