Area Forecast Discussion
Issued by NWS Miami, FL
Issued by NWS Miami, FL
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005 FXUS62 KMFL 171500 AFDMFL Area Forecast Discussion National Weather Service Miami FL 1100 AM EDT Tue Sep 17 2024 ...New UPDATE... .UPDATE... Issued at 1045 AM EDT Tue Sep 17 2024 Earlier convection over southern Florida has given way to a morning lull with plenty of cloud cover to dampen diurnal heating. Much of the area remains in the lower 80s though Southwest Florida is a few degrees warmer since the rain ended earlier there. The 12z MFL sounding shows a moist, saturated atmospheric column with a precipitable water value well above 2 inches. With mid to upper level tough axes over the region, there will be both an upper level jet and a developing low level jet over the eastern portions of South Florida. Strong to severe storms will be possible this afternoon, particularly around the Atlantic sea breeze boundary. After monitoring recent high tide gauge levels, it appears that an upgrade from a Coastal Flood Statement to a Coastal Flood Advisory was necessary. Also went ahead with an extension of time into Thursday. Several tide gauges rose well above 1.5 feet this morning and the forthcoming high tides will likely be higher. && .SHORT TERM... (Today through Wednesday) Issued at 245 AM EDT Tue Sep 17 2024 The consolidation of a mid-level low across the southeastern United States today, comprised of two previous lobes of 500mb vorticity (ex-PTC 8 and ex-Francine) will usher in a period of troughing across a large swath of the eastern United States by late Monday. This will maintain cooler temperatures aloft (-6C to -7C at 500mb) and facilitate the development of stronger southwesterly 500mb flow across the region. The mid-level portion of the atmospheric column does appear to moisten slightly today with the CAMs (Convection Allowing Models) such as the HRRR, RAP, etc depict less dry air in the mid-levels today on the overnight model soundings. At the surface, light and variable surface winds will continue to prevail at the surface which may facilitate the development of fairly patchy inland fog this morning that should quickly burn off after sunrise. Our area will remain situated to the south of a persistent stationary front draped across Central Florida which will keep us on the warm and unstable side of the boundary. With the onset of sunrise and diurnal heating, humid and warm conditions will be realized across the area as we quickly heat up into the upper 80s and lower 90s. With the mid-level low over the southeast United States and light surface flow, incipient updrafts/cores during the early afternoon hours will create outflow boundaries that will interact with the Gulf and Atlantic sea-breezes. As these updrafts create cold pools and radially- outward propagating outflow boundaries interact, scattered to potentially numerous convection will overspread the region through the remainder of the afternoon into the early evening hours. Combining the mesoscale and synoptic factors listed above, there is once again the potential for a few strong to marginally severe storms across the area today. Heavy rainfall, gusty winds, and frequent to excessive lightning will be possible with any storms today. Strong to marginally severe wind gusts will be possible once again with the most robust thunderstorms today. A threat of localized flooding persists as well, especially where boundary collisions come together and heavy rainfall is prolonged over urban areas. HREF`s LPMM once again depicts the potential of a few localized pockets of 1-2 inches which could result in some urban flooding once again. The mid-level low across the southeastern United States will gradually lift northeastward through the mid-week period which will veer 500mb flow across the region to a westerly then northwesterly direction. The elongation of troughing over the eastern United States will keep 500mb temperatures in the -6C to -7C range during the mid-week period with forecasted daily afternoon lapse rates in the 5.5 to 6.0 C/km range. At the surface, we will remain situated to the south of the weak yet quite persistent stationary boundary still draped across Central Florida. Ample precipitable water (PWAT) values of 2.0+ inches and a fairly moist saturated column will result in daily afternoon rain chances near climatological norms. The prevailing weak surface winds and the generally westerly flow aloft will keep a rain pattern favoring SoFlos interior and eastern metro areas. Deeper convection will again focus along sea breeze and outflow boundaries mainly in the afternoon hours, with the continued potential of a few isolated strong to marginally severe pulse storms when ascent is briefly maximized along those aforementioned mesoscale boundaries. High temperatures each afternoon will remain just above seasonal norms with heat indices remaining just below heat advisory thresholds. The overspread of convective cold pools across the region will help cool the region off during the mid to late afternoon hours. && .LONG TERM... (Wednesday night through Monday) Issued at 245 AM EDT Tue Sep 17 2024 With the continued propagation on the mid-level low across the northeastern United States and western Atlantic waters, 500mb flow over the region will remain out of a light northwesterly direction on Thursday and Friday. Like a broken record, the pesky stationary boundary over will remain to the north of the region resulting in light winds at the surface. The mesoscale phenomenon will once again dictate where convection develops and propagates with the northwesterly flow favoring the Atlantic sea-breeze for convective initiation each afternoon. 500mb temperatures will remain in the -6C to -7C range as we remain on the periphery of the influence of the departing mid-level low/troughing. By this weekend, the influences of mid-level ridging across the central United States will gradually nose into the region. Model guidance hints at the potential of a surge of drier mid-level air into the region which may act to limit spatial coverage of convection this weekend. Temperatures will remain near seasonal norms for this time of year with high temperatures in the upper 80s to near 90 currently forecast. && .AVIATION... (12Z TAFS) Issued at 725 AM EDT Tue Sep 17 2024 Morning showers will give way to a VFR convective lull before storms return for the afternoon. Light winds through much of the period with sea breezes developing and moving inland late morning into the afternoon. Short-fused AMDs for IFR/LIFR may be necessary for storms later today. Activity should diminish late evening into the overnight. && .MARINE... Issued at 245 AM EDT Tue Sep 17 2024 Generally light winds will prevail across the area through most of this week as a weak surface boundary remains just to the north of the area. Seas across the northern Atlantic waters will gradually lessen as northerly swell declines through mid-week. Scattered showers and thunderstorms will be possible each day through the period and could lead to locally higher winds and seas. && .BEACHES... Issued at 245 AM EDT Tue Sep 17 2024 Decreasing northerly swell will result in a high risk of rip currents for the Palm Beaches coast once again today with a moderate risk of rip currents elsewhere on the east coast of South Florida. There will also be the continued potential for minor to moderate coastal flooding around periods of high tide due to astronomically higher tides associated with this full moon through mid-week. High Tide Times: Naples: 12:56 PM Tue, 1:25 AM Wed, 1:46 PM Wed Lake Worth: 7:46 AM Tue, 8:14 PM Tue, 8:38 AM Wed Port Everglades: 8:06 AM Tue, 8:31 PM Tue, 8:58 AM Wed Virginia Key: 8:53 AM Tue, 9:18 PM Tue, 9:45 AM Wed && .PRELIMINARY POINT TEMPS/POPS... Miami 91 77 91 77 / 70 50 70 50 West Kendall 91 75 90 74 / 70 50 70 50 Opa-Locka 91 77 91 77 / 70 50 70 50 Homestead 90 76 90 76 / 70 50 70 50 Fort Lauderdale 90 77 88 77 / 60 50 70 50 N Ft Lauderdale 91 77 89 77 / 60 50 70 50 Pembroke Pines 93 78 90 77 / 60 50 70 50 West Palm Beach 92 76 90 77 / 50 40 70 40 Boca Raton 93 77 91 77 / 60 40 70 50 Naples 90 78 91 77 / 50 30 60 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 2 PM EDT Thursday for FLZ069-075- 168-172>174. High Rip Current Risk through Wednesday evening for FLZ168. AM...None. GM...None. && $$ SHORT TERM...Hadi LONG TERM....Hadi AVIATION...RAG