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Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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660 FXUS62 KJAX 151755 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 155 PM EDT Mon Jul 15 2024 ...New AVIATION... For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf .AVIATION... (18Z TAFS) Issued at 156 PM EDT Mon Jul 15 2024 Strong thunderstorms will likely impact the GNV terminal through around 20Z, with the potential for brief wind gusts in excess of 30 knots and IFR conditions during heavier downpours. Activity should then focus near or over the rest of the northeast FL terminals and SSI, where TEMPO groups were placed at each TAF site, generally between 19Z and 00Z. Periods of IFR conditions and gusty winds are expected at the Duval County terminals, SSI, and SGJ as this slow moving activity persists through around sunset before diminishing in coverage early this evening. Periods of MVFR visibilities are likely overnight at VQQ. Outside of thunderstorm activity, southeasterly surface winds will remain sustained at 10-15 knots at the SSI and SGJ coastal terminals through around 23Z. Surface winds will then shift to southerly after convection ends around or shortly after sunset, with surface speeds diminishing to around 5 knots by 06Z at the coastal terminals and less than 5 knots inland. Surface winds will then shift to southwesterly shortly after sunrise, with sustained speeds increasing to 5-10 knots by 15Z Tuesday. && .UPDATE... Issued at 1215 PM EDT Mon Jul 15 2024 Early afternoon surface analysis depicts the axis of Atlantic high pressure (1024 millibars) extending its axis across the FL peninsula and into the southeastern Gulf of Mexico. Aloft...ridging was centered off FL`s Atlantic coast, or just north of the northwestern Bahamas, while troughing was progressing eastward across the eastern Great Lakes, Ohio and Tennessee Valleys. Meanwhile, a leftover Mesoscale Convective Vortex (MCV) from widespread thunderstorm activity that occurred last evening along the Interstate 4 corridor in central FL was spinning over the Nature Coast, and this feature was activating isolated convection along the Gulf coast sea breeze along the FL Big Bend and Nature Coasts, with a few showers otherwise developing in the hot and humid air mass along the I-75 corridor in the Suwannee Valley as well as the U.S. Highway 84 corridor across inland southeast GA. Latest GOES-East derived Total Precipitable Water imagery indicates that deep moisture remains in place throughout our region, with PWATS in the 1.9 - 2.2 inch range. Multi- layered cloudiness was prevalent closer to the MCV feature across north central FL, with a healthy cumulus field otherwise developing across our area. Temperatures at the noon hour were skyrocketing to the upper 80s and lower 90s, with dewpoints in the mid to upper 70s creating heat index values that generally ranged from the upper 90s to around Heat Advisory criteria (108 degrees). The presence of deep tropical moisture and the aforementioned MCV feature will trigger scattered to numerous thunderstorms this afternoon, with activity initially focused along the inland moving Gulf Coast sea breeze along the I-75 corridor in the Suwannee Valley and north central FL, with isolated activity developing elsewhere along differential heating boundaries as well as the Atlantic sea breeze boundary. Southwesterly low level flow will tend to slow the inland progress of the Atlantic sea breeze this afternoon, setting up a collision of outflow boundaries and eventually the Atlantic and Gulf coast sea breezes for locations between U.S. Highway 301 and Interstate 95 during the late afternoon and early evening hours. Storms may pulse as mesoscale boundaries collide, with stronger activity being capable of producing downburst winds of 40-50 mph, frequent lightning strikes, and locally heavy downpours. Steering flow will remain light, resulting in slow moving storms that could result in localized flooding, especially if activity moves slowly or back-builds over urban or normally flood prone locations. Outflow boundaries will also migrate northward across inland southeast GA this afternoon, where convection may linger past sunset tonight. High temperatures this afternoon will soar to the mid and upper 90s, except for north central FL, where thicker multi-layered cloudiness should keep highs in the lower 90s. Peak Heat Index values should reach Heat Advisory criteria of 108-112 degrees behind the inland moving Atlantic sea breeze this afternoon for the coastal zones in both northeast FL and southeast GA, while peak values elsewhere mostly reach the 103-107 degree range. Debris cloudiness from this afternoon and evening`s convection will gradually thin out overnight, with lows mostly falling to the mid 70s inland, ranging to around 80 at coastal locations. && .MARINE... Issued at 1215 PM EDT Mon Jul 15 2024 The axis of Atlantic high pressure will stretch across the Florida peninsula through midweek, keeping a prevailing southerly wind flow in place across our local waters. A few strong thunderstorms will be possible late this afternoon and early this evening, mainly over the near shore waters, with stronger storms being capable of producing briefly strong wind gusts, heavy downpours, and frequent lightning strikes. Outside of thunderstorm activity, southerly winds will surge this evening before shifting to southwesterly and weakening after midnight. A similar weather pattern will prevail on Tuesday, followed by Atlantic high pressure sinking southward later this week as a frontal boundary enters the southeastern states. Seas of 3-5 feet will prevail both near shore and offshore through Tuesday night. Mainly afternoon and evening thunderstorms will increase in coverage throughout our local waters later this week as this boundary stalls to the northwest of our local waters. Seas will diminish to 2-4 feet throughout our local waters towards midweek. Rip Currents: A persistent east-southeasterly ocean swell will combine with breezy onshore winds during the afternoon hours to create a moderate rip current risk at all area beaches through at least midweek. && .FIRE WEATHER... Issued at 1215 PM EDT Mon Jul 15 2024 Southwesterly transport winds this morning will tend to shift to a more southerly direction by late afternoon, outside of developing thunderstorm activity. Stronger thunderstorms will tend to focus along the Interstate 95 corridor during the late afternoon hours, with stronger storms later this afternoon being capable of producing briefly strong wind gusts, frequent lightning strikes, and slow moving, heavy downpours. Lighter transport winds and more cloud cover over north central FL will keep daytime dispersion values generally poor today, with fair to good values expected elsewhere away from coastal locations. Light southwesterly transport winds will continue on Tuesday and Wednesday, with scattered to numerous afternoon and evening thunderstorms expected across our region. && .PRELIMINARY POINT TEMPS/POPS... AMG 76 95 75 95 / 40 60 20 70 SSI 80 92 79 93 / 50 50 40 60 JAX 75 95 76 96 / 70 70 30 70 SGJ 77 94 77 94 / 40 70 30 60 GNV 74 94 73 93 / 60 80 20 80 OCF 74 95 75 93 / 40 90 30 80 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory until 6 PM EDT this evening for FLZ124-125-133-138. GA...Heat Advisory until 6 PM EDT this evening for GAZ154-166. AM...None. && $$