Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
883 FXUS62 KKEY 250820 AFDKEY Area Forecast Discussion National Weather Service Key West FL 420 AM EDT Tue Jun 25 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 420 AM EDT Tue Jun 25 2024 After several hours with no shower activity across the area, widely scattered showers have recently developed around the Upper Keys. Temperatures along the island chain are mostly in the upper 70s to lower 80s, with dewpoints in the mid 70s, and winds on land light/variable or from the SSW at 5 mph or less. Surface analysis indicates that the Atlantic ridge axis has settled southward into the Straits during the night, with a front extending from the western Atlantic into the Southeastern states. Aloft, the weak mid/upper trough which has lingered near Florida for the past few days has shifted eastward into the Bahamas, with satellite imagery showing the associated cloudiness and convection extending from the Bahamas eastward across the Atlantic for several hundred miles. Some mid-level weakness still lingers across our region, to the south and southwest of a mid latitude trough moving offshore from the Eastern Seaboard. A very moist airmass remains in place across the Keys, as shown by the 00Z Key West sounding which measured PW of 2.35 inches. Recent MIMIC-TPW satellite imagery shows the Keys remaining embedded within a large area of 2+ inch PWs extending from the Caribbean and Greater Antilles WNW through the southern and central Gulf of Mexico. Weak WSW low level flow, ample moisture in place, and the lack of a dominant ridge aloft all should favor island cloud line development during the day, with above average potential for waterspouts. Accordingly, have maintained somewhat above climo 40 percent PoPs. Outside of cloud line activity, we generally expect less convective coverage compared to the past few days. Also have reduced thunder to slight chance, as there has been very little lightning activity across our area during the past 36 hours or so. Otherwise, expect high temps to reach the upper 80s to near 90, with sticky dewpoints in the mid 70s and light breezes making for a typically oppressive June day. The ridge axis will remain just to our south through Thursday, with continued weak WSW flow favoring daytime island cloud lines. Some mid level dry air is forecast to move into our area on Thursday, thus nudge PoPs down from 40 percent on Wednesday to 30 percent on Thursday. Nighttime typically sees less activity in this pattern, although there is always the potential for late night reactivation of lingering old cloud line boundaries. Late this week and into the weekend, the subtropical low level ridge should shift back northward, allowing for more typical midsummer gentle ESE surface flow to resume. The latest operational GFS as well as the GEFS ensemble guidance show a mid level trough developing over Florida during this time, which combined with ample moisture may encourage somewhat above climo PoPs. Convection will be possible anytime but perhaps favoring the night and morning hours in the expected easterly flow pattern. Have nudged PoPs up to 40 percent from Friday through Monday. && .MARINE... Issued at 420 AM EDT Tue Jun 25 2024 Limited overnight observations show S/SW breezes around 5 knots off the Upper Keys, with light/variable flow likely prevailing around the Lower Keys, and seas at Satan Shoal running below 1 foot. Conditions will be favorable for cloud lines and waterspouts across the nearshore waters around the Keys island chain today. From the synopsis, a weak ridge axis will extend westward from the western Atlantic across the Straits of Florida today through Thursday evening, with light to gentle southwest to west breezes prevailing over the Keys waters. Breezes may become variable at times during this period. The ridge will shift back northward late this week into the weekend, allowing gentle east to southeast breezes to resume. && .AVIATION... (06Z TAFS) Issued at 420 AM EDT Tue Jun 25 2024 VFR conditions will prevail for the upcoming TAF period. Near- surface winds will become persistent southwesterlies by sunrise, between 4 to 8 knots, which means cloud lines are possible during the day. VCSH was added to the TAF with slightly lower ceilings to account for potential nearby showers and associated possible sub-VFR conditions. && .CLIMATE... On this day in 1976, a record rainfall of 1.67" was measured in Key West. Rainfall records for Key West date back to 1873. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Jacobson Aviation/Nowcasts....AJP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest