Area Forecast Discussion
Issued by NWS Miami, FL
Issued by NWS Miami, FL
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660 FXUS62 KMFL 191420 AFDMFL Area Forecast Discussion National Weather Service Miami FL 1020 AM EDT Thu Sep 19 2024 ...New UPDATE... .UPDATE... Issued at 1008 AM EDT Thu Sep 19 2024 Conditions across South Florida this morning are looking pretty similar to yesterday`s setup as troughing prevails aloft and a front remains stalled over northern Florida. This morning`s 12Z sounding shows comparable parameters, with SBCAPE ~2000 J/kg, PWAT of 2.02 inches, DCAPE ~ 600, low shear and weak mid-level flow. The CAMs seem to be capturing the resulting forecast decently, with scattered to numerous showers and thunderstorms possibly developing early this afternoon (PoPs 50-60%). Initiation will most likely happen along sea breeze boundaries. Activity will most likely be slow-moving given weak steering winds, which brings up the possibility for localized or even flash flooding in vulnerable areas and areas where the soils are already saturated from several rounds of rain over the past few days. Temperatures will remain near climatological averages, at or below 90 degrees for much of South Florida. Heat indices will struggle to rise over the low 100s as convection and cloud coverage limit sun exposure. && .SHORT TERM... (Today through Friday) Issued at 310 AM EDT Thu Sep 19 2024 Models remain fairly consistent in keeping a mid level trough/low complex over the SE CONUS through at least today, keeping a generally unsettled pattern across SoFlo. 00Z MFL sounding data and model PWATs show values back to around 2 inches, with plenty of atmospheric moisture available for localized heavy showers to develop later today. Meanwhile, pressure gradients across the area remain weak, with sfc winds generally light and variable at times. Therefore, expect afternoon sea breeze and outflow boundaries to again become focal points for deeper convection, with potential for strong to locally damaging wind gusts with the strongest thunderstorms. Highest POPs remain around 70 percent, including most of the Atlantic coast metro areas. The weak storm motion can significantly contribute to localized heavy downpours, which could result in localized flooding. For Friday, ensembles and global model solutions show fair agreement in pushing a frontal boundary across the peninsula and down to SoFlo later in the day. The front seems to become stationary either over the southern tip of the state, or pushing into the Florida Keys late Friday afternoon. Regardless, it should bring an initial decrease in moisture, with POPs on a modest downward trend heading into the weekend. Temperatures are expected to again reach the upper 80s lower 90s this afternoon and again on Friday, even with the lingering cloud cover and rain activity, along with heat index values in the low- mid 100s. && .LONG TERM... (Friday night through Wednesday) Issued at 310 AM EDT Thu Sep 19 2024 Moving into the upcoming weekend, the upper level trough will continue to dig southward into the southeastern CONUS. It will maintain a W/NW flow over the region aloft as the trough`s backside moves over Florida`s Peninsula. Meanwhile, the plume of moisture remains over South Florida as the stationary front meanders across the southern peninsula. Most convection will be driven by the sea breezes and outflow boundaries, following the afternoon`s diurnal heating and influence of widespread heavy PWATs (1.7-1.9"). The primary hazards will be heavy rainfall, strong winds, and localized flooding, especially over urban areas. While PWATs have dropped below 2.0", with plentiful moisture and saturated grounds, any slow- moving storms may lead to flash flooding. As we move into Sunday and early next week, an expansive ridge will stretch across the Gulf of Mexico and Florida as the trough moves into the Atlantic. As this occurs, it will allow for drier air to advect into the region. Currently, the extended models indicate a chance for showers, with a drop in PoPs (30-50%) and lower PWATs (1.4-1.7"), due to this incoming drier air mass. However, further into the extended, less confidence in the regional impact from rain, so PoPs are capped at 60% through day 7. This may allow for a drop below climatological rainfall normals early next week. Looking into the extended forecast, we will continue to monitor the tropics. In the upcoming days, the area to watch will be in the western Caribbean as there is potential for a body of low pressure to form. The National Hurricane Center`s 2AM outlook has a 40% chance of tropical formation in the next 7 days. As it remains far too early for many upcoming details, we will continue to keep an eye on the latest tropical forecasts. Temperatures will be near seasonal normals throughout the long term forecast. Afternoon high temperatures will be in the upper 80s to low 90 and overnight lows in the 70s. With the potential for daytime dew points to drop into the low to mid 70s, the drier air may provide a relief from sticky humidity and heat advisories. However, with less cloud coverage and lighter rainfall, it will still allow for oppressive heat and warm temperatures. && .AVIATION... (12Z TAFS) Issued at 746 AM EDT Thu Sep 19 2024 Mostly VFR conditions at the start of the period as light surface winds prevail across the region. Later this afternoon, periods of MVFR/IFR will be likely as slow-moving SHRA/TSRA develop and move over all TAF sites. Conditions should begin to improve shortly after sunset, but some stratiform rain coverage could linger into the late night hours. && .MARINE... Issued at 310 AM EDT Thu Sep 19 2024 Winds remain generally light across the coastal waters today as a weak surface boundary remains just to the north of the area, with continuing scattered to numerous showers and thunderstorms possible each day. The boundary reaches the area on Friday, bringing a decrease in thunderstorm activity through the weekend and into early next week. However, periods of locally higher seas and gusty winds may accompany any thunderstorm that forms. && .BEACHES... Issued at 310 AM EDT Thu Sep 19 2024 Expect minor to moderate coastal flooding to continue during periods of high tide. These elevated tides will continue to affect all coastal areas of South Florida through Friday morning, for which a coastal flood advisory remains in effect. For the upcoming weekend, a decrease in northerly swell should help in decreasing the potential for coastal flooding. However, an elevated risk of rip currents could continue for the Palm Beaches during the next several days. NAPLES HIGH TIDE TIMES... 1:56 PM today. LAKE WORTH HIGH TIDE TIMES...931 AM today, 949 PM tonight. && .PRELIMINARY POINT TEMPS/POPS... Miami 90 75 89 76 / 70 60 50 40 West Kendall 92 73 90 73 / 70 60 50 40 Opa-Locka 92 74 89 76 / 70 60 50 40 Homestead 90 74 89 76 / 70 60 50 40 Fort Lauderdale 90 75 88 76 / 70 60 50 40 N Ft Lauderdale 91 76 89 76 / 70 60 50 40 Pembroke Pines 92 75 91 76 / 70 60 50 40 West Palm Beach 92 75 89 76 / 60 50 40 30 Boca Raton 92 75 90 76 / 70 60 50 40 Naples 89 77 90 76 / 40 40 30 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 2 PM EDT Friday for FLZ069-075-168- 172>174. AM...None. GM...None. && $$ SHORT TERM...99 LONG TERM....JS AVIATION...ATV