Area Forecast Discussion
Issued by NWS Miami, FL
Issued by NWS Miami, FL
957 FXUS62 KMFL 202226 AFDMFL Area Forecast Discussion National Weather Service Miami FL 626 PM EDT Thu Aug 20 2026 ...New AVIATION... .KEY MESSAGES... Updated at 625 PM EDT Thu Aug 20 2026 - Slightly lower high temperatures expected today but heat indices of 105-110 are still anticipated this afternoon. Heat Advisory in effect from 11AM to 6PM. - Scattered thunderstorms expected after midday this afternoon and into the evening will provide some relief from the heat. && .UPDATE... Issued at 246 PM EDT Thu Aug 20 2026 The forecast remains on track this afternoon with isolated showers and thunderstorms developing along sea breeze boundaries. A continued moistening trend is underway across the region, with the 12Z MFL sounding and recent ACARS data showing PWAT values closer to climatological norms for mid-August (1.6-1.8 inches). Convection is expected to increase in coverage through the afternoon and early evening, favoring the eastern half of the peninsula under a prevailing westerly flow. Meanwhile, increasing humidity combined with high temperatures is maintaining Major HeatRisk conditions across most urban areas today. Residents are encouraged to continue exercising heat safety by staying hydrated, taking frequent breaks in the shade or indoors, and checking on vulnerable individuals. Shower and thunderstorm activity will gradually diminish after sunset, with overnight lows settling into the mid-70s across the interior while remaining a few degrees above normal closer to the coasts. && .SHORT TERM... (Today through Friday) Issued at 109 AM EDT Thu Aug 20 2026 As the Saharan dust continues to filter out of the area for the end of this week, deeper moisture will simultaneously begin to work back into South Florida for the end of the week as a couple of upper level disturbances in the Caribbean help infiltrate extra tropical moisture. These upper level lows are not expected to reach South Florida, but will still provide this deeper moisture advection. Similarly, an upper-level trough will enhance underneath strong jet dynamics as a result of a stout ridge across the Southwestern US. As the trough deepens and digs southwards, prevailing wind flow will shift to more of a southerly direction across the forecast area. This will result in a pooling of the deep moisture for the end of this week and likely beyond. As a result of the pattern above and the dissipation of the dust plume, temperatures should fall closer to normal in the low to mid 90s for today and tomorrow while convection also initiates a couple hours earlier and starts to become more widespread in the afternoon and evening hours. Given the prevailing southwesterly flow today and eventually southerly flow on Friday and into the weekend, the Atlantic sea breeze will not advance as far inland as it typically does, which is expected to result in the more widespread coverage of showers and thunderstorms to occur across Southeast Florida. Some storms will be capable of producing strong wind gusts as high as 40- 50 mph but severe parameters are rather limited for this end of of week time period. Main concerns will be for heavy rainfall lowering visibilities on roadways, strong wind gusts and localized flooding as a result of training storms or convection re-developing over the same locations. In terms of heat, it should not be quite as hot as the last couple of days given the dust plume dissipating. However, with deeper moisture arriving there will still be dew points in the upper 70s for most of the region and high temps achieving the low to mid 90s prior to rain occurring across the region in the afternoon. Therefore, opting to go with a Heat Advisory again for today from 11AM - 6PM for all of South Florida. If rainfall becomes widespread earlier than 6PM and causes sudden decreases in heat levels, then this advisory could be canceled prior to 6PM. && .LONG TERM... (Friday night through Wednesday) Issued at 109 AM EDT Thu Aug 20 2026 The extended period will see a much needed return to a more typical summertime pattern. An upper level ridge will remain anchored over the western US while the eastern US will remain under the influence of a mid-level trough set up across most of the Eastern Seaboard through at least early next week. Expect mainly diurnally driven sea- breeze convection each day with seasonable PoPs (40-60%) favoring the afternoon and early evening hours, and then widely scattered coastal showers during the overnight period. Highest rain chances and most widespread coverage is expected across interior South Florida where the sea breezes and outflow boundaries collide. Temperatures will remain above normal through the weekend and into early next week. Max heat indices will remain around advisory criteria each day, so additional heat headlines will remain possible. && .AVIATION... (00Z TAFS) Issued at 625 PM EDT Thu Aug 20 2026 Mainly VFR conditions will prevail through the forecast period. L/V winds at east coast terminals overnight will increase out of the east after 16Z. Scattered afternoon showers and thunderstorms may require short-fused AMDs and TEMPOs for east coast terminals after 20Z. At KAPF, westerly winds around 12 kts will become L/V overnight, then increase out of the west after 16Z. && .MARINE... Issued at 109 AM EDT Thu Aug 20 2026 Gentle west-northwest winds expected across the Gulf waters today with southerly winds across the Atlantic. These winds are expected to shift a little more southwesterly for the Gulf and southeasterly for the Atlantic on Friday. Seas will remain at 1-2 feet or less. Scattered showers and thunderstorms are possible late each day and in the late night hours which may result in locally hazardous winds and seas. && .PRELIMINARY POINT TEMPS/POPS... Miami 81 93 79 93 / 20 50 20 50 West Kendall 79 92 77 92 / 20 40 10 50 Opa-Locka 80 93 80 93 / 20 50 20 50 Homestead 79 92 78 92 / 10 30 10 40 Fort Lauderdale 81 92 80 92 / 20 50 20 50 N Ft Lauderdale 81 93 80 93 / 20 50 20 50 Pembroke Pines 81 93 80 93 / 20 50 20 50 West Palm Beach 80 94 78 93 / 10 50 20 50 Boca Raton 80 92 79 92 / 10 50 20 50 Naples 79 91 79 91 / 20 30 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && $$ SHORT TERM...Redman LONG TERM....Redman AVIATION...DPB