Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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518 FXUS62 KJAX 191743 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 143 PM EDT Sun May 19 2024 ...New AVIATION... .UPDATE... Issued at 955 AM EDT Sun May 19 2024 For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf Areas of low clouds over southeast GA will slowly break up in the next couple of hours, while the westerly flow in the low levels helps mix out patchy low clouds in northeast FL as well. High clouds are moving out and anticipate strong heating today with scattered to broken cumulus developing. Have tweaked high temps up a couple of degrees for the update. The forecast overall looks good with scattered to numerous showers and storms developing, with greater coverage generally over southeast GA near the slow moving cool front. Amid cool temps aloft of -10c to possibly -12c at 500 mb, this will generate some moderately high CAPE values of about 2500 J/kg, maybe near 3000 J/kg per modified sounding. This along along with some shear values of about 20-30 kt will support isolated strong to severe storm activity this afternoon and evening. Winds aloft are generally unidirectional which is basically keeping the shear values lower than yesterday. One of the main threats is strong gusty winds given the high DCAPE values of about 900-1100 J/kg anticipated. A couple of areas in the greater strong storm threat are over southeast GA near the Altamaha Basin down to into coastal southeast GA, and then also isolated strong activity possible near I-75 over northeast FL. Confidence is low to moderate at this time. Some adjustments were made to the POPs for rest of today and into the overnight hours, but rest of the forecast in good shape. && .NEAR TERM... Issued at 355 AM EDT Sun May 19 2024 A wave of showers and thunderstorms ahead of a slow moving, nearly stalled cold frontal boundary from the west has brought some late night and early morning rainfall to portions of eastern SE GA along and south of US highway 84 to areas over NE FL from Gainesville northeast to the Jax Beaches. These showers and storms will end by sunrise. Cold front will stall near NE FL today with partly cloudy skies late this morning through afternoon and west to southwesterly winds 8-12 mph, a bit breezier across north central FL towards the Gulf coast 10-15 mph. Strong heating due to the high sun angle for mid to late May (nearly one month before the upcoming summer solstice) will raise high temperatures into the upper 80s with isolated 90 degree readings along the St Johns river basin and I-95 corridor over NE FL as the Atlantic seabreeze stays pinned near the immediate coast. A positively tilted mid level trough currently over northern GA will shift southeast into the area through this afternoon with shortwave energy rounding the base of the trough that will become closed with southeast extent. This will cool mid level lapse rates over the area with thunderstorms developing over north central Fl this afternoon with a secondary focus over SE GA north of Waycross late this afternoon that will move southeast into the Jacksonville area by around sunset and then shift off the NE FL coast before midnight. Dewpoints around 70 along the coast and upper 60s inland will create strong CAPE values over 2,000 J/KG while the closed trough will cool mid level temperatures to -11 to -13 C which will steepen mid level lapse rates. Strong 0-6km shear of 30-40 knots will also be present and the Storm Prediction Center has a Marginal threat of Isolated Severe T`storms for most of the area as the ingredients mentioned will support large Hail and isolated strong to severe wind gusts up to 60 mph. Not expected widespread heavy rainfall today, but pockets of 1 inch totals will occur closer to the coast where best focus for storms will be with a few higher isolated amounts to 2 inches possible. Storms should exit into the Atlantic by midnight and the cold front will clear southeast of the area overnight with northerly to northeasterly winds winds turning northerly 5-10 mph inland and breezier at the coast 10-15 as high pressure builds down from the Mid Atlantic and northeast coastline. Low stratus clouds will sink south along the Southeast coast into SE GA with lows in the mid 60s over SE GA and the upper 60s over NE FL. && .SHORT TERM... (Monday through Tuesday night) Issued at 355 AM EDT Sun May 19 2024 Upper trough will move over forecast area Monday, then gradually shift just S of forecast area Monday night, continuing further S Tuesday. Latest consensus guidance suggests continued potential for scattered showers/ t-storms Monday with onshore flow pattern. Guidance suggests showers mainly offshore Monday night, but potential for coastal showers moving onshore ne FL Tuesday with continued onshore flow. Onshore flow pattern will result in somewhat lower high temperatures eastern counties with upper 70s/lower 80s coast and I-95 corridor, a little warmer further inland. && .LONG TERM... (Wednesday through Saturday) Issued at 355 AM EDT Sun May 19 2024 Upper ridge of high pressure will build over the forecast area during this period, resulting in mainly dry and warm conditions. An exception could be on Saturday when a weak shortwave passes over the area, which consensus guidance suggests could lead to scattered showers/t-storms. Near normal temperatures are expected on Wednesday, with highs lower 80s coast, mid-upper 80s inland. Slightly above normal temperatures are expected Thursday through Saturday with high temperatures upper 80s coast, lower 90s inland with low temperatures through the period in the 65-70 range. && .AVIATION... (18Z TAFS) Issued at 140 PM EDT Sun May 19 2024 VFR clouds around at this time with scattered to broken cumulus around 3500-4500 ft. First signs of convection so far over inland southeast GA, but deepening cumulus field will result in chance of showers and storms rest of the aftn with TEMPO groups in place, with lowest confidence for SGJ and GNV at this time. Could be strong gusty winds that accompany storms around SSI and then near JAX by 22z and 00z, respectively. Showers and storms expected to diminish in coverage and intensity after 02z-04z time frame as frontal boundary sags southward. Low clouds will begin to develop overnight into Monday morning that may be close to IFR but mainly MVFR. Sfc winds prevail from the west about 8-12 kt and will shift to northerly and northeast by Monday morning. && .MARINE... Issued at 355 AM EDT Sun May 19 2024 A slow moving cold front will stall over the coastal waters today with numerous showers and thunderstorms late this afternoon into the early evening hours. Some of these storms may contain strong gusty winds and heavy downpours. Westerly winds will turn southerly this afternoon due to the Atlantic seabreeze and then become breezy from the north and northeast overnight into Monday as a secondary cold front pushes south of the waters and high pressure wedges down from the Mid Atlantic coast against a low pressure through early next week. High pressure builds directly over the waters during the middle part of next week. Rip Currents: Low risk of Rip Currents today at all area beaches. A moderate risk of rip currents is forecast for NE FL and SE GA beaches Monday. && .PRELIMINARY POINT TEMPS/POPS... AMG 65 84 63 86 / 20 10 0 0 SSI 69 79 69 81 / 50 20 0 10 JAX 67 82 65 83 / 60 40 10 20 SGJ 68 81 69 82 / 60 40 20 30 GNV 67 84 63 86 / 40 60 0 20 OCF 68 85 65 86 / 10 50 10 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$