Area Forecast Discussion
Issued by NWS Miami, FL
Issued by NWS Miami, FL
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455 FXUS62 KMFL 191728 AFDMFL Area Forecast Discussion National Weather Service Miami FL 128 PM EDT Thu Sep 19 2024 ...New SHORT TERM, AVIATION, MARINE, BEACHES... .SHORT TERM... (Rest of today through Friday) Issued at 120 PM EDT Thu Sep 19 2024 Scattered to numerous showers will be likely across portions of South Florida this afternoon as as troughing prevails aloft and a front remains stalled over northern Florida. This is helping pool moisture over the region as evidenced by MLF`s 12Z sounding which showed PWATs of 2.02 inches, well above average for this time of year. The sounding also showed light sfc-3km westerly flow and ample instability (SBCAPE >2000 J/kg), along with light WSW flow aloft. Given this setup, expect afternoon sea breeze and outflow boundaries to become the focal points for deeper confection. The main concern for today remains heavy rainfall with slow moving storms which could lead to localized flooding for portions of South Florida. In fact, the HREF LPMM shows isolated areas along the East Coast metro possibly getting 4-6 inches of rain, and there are areas that have already received 2-4 inches of rain over the past couple of days, which has made for waterlogged soils. To that effect, WPC has placed most of the East Coast metro under a marginal (1/5) risk for excessive rainfall this afternoon. The frontal boundary will slowly drift southward across our region tomorrow, ushering in some slightly drier mid-level air over the area. This drier air mass could help limit shower and storm coverage tomorrow. However, with troughing lingering over the peninsula and light low level flow, there is still a chance for sea breeze driven convection to pick up tomorrow afternoon. We kept PoPs in the 40-50% range. Although temperatures and heat indices will remain above normal, convection and cloud coverage should help keep them below advisory criteria through the period. && .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... (18Z TAFS) Issued at 120 PM EDT Thu Sep 19 2024 Brief periods of MVFR/IFR conditions could be likely for all sites as slow moving SHRA/TSRA begin to develop. The sea breeze will begin to work in over the sites around 18Z, and winds could become gusty within storms and outflow boundaries. Conditions should begin to improve shortly after sunset, but some stratiform rain coverage could linger for a few hours after 00Z. && .MARINE... Issued at 120 PM 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 120 PM 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 reduce the risk for moderate flooding, but some minor flooding could still be possible. Additionally, 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, 1:44 AM tomorrow morning, 2:57PM tomorrow afternoon LAKE WORTH HIGH TIDE TIMES...949 PM tonight, 10:24 AM tomorrow morning && .PRELIMINARY POINT TEMPS/POPS... Miami 76 89 76 89 / 50 60 40 40 West Kendall 74 90 73 90 / 50 60 40 50 Opa-Locka 75 90 76 91 / 50 50 40 40 Homestead 75 89 76 89 / 50 60 40 50 Fort Lauderdale 75 88 76 89 / 50 60 40 40 N Ft Lauderdale 75 89 76 89 / 50 60 40 40 Pembroke Pines 75 91 76 92 / 50 50 40 40 West Palm Beach 75 89 76 90 / 50 50 30 30 Boca Raton 75 90 76 91 / 50 60 40 30 Naples 77 90 76 92 / 40 40 30 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 PM EDT Friday for FLZ069-075-168- 172>174. AM...None. GM...None. && $$ SHORT TERM...ATV LONG TERM....JS AVIATION...ATV