Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
945 FXUS62 KJAX 140159 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 959 PM EDT Sun Jul 13 2025 ...STRONG STORMS THIS EVENING ACROSS NORTH CENTRAL FL... ...HIGH HEAT INDICES ON MONDAY AFTERNOON... ...STORM COVERAGE SHIFTS INLAND ON MONDAY AFTERNOON WITH LOCALIZED FLOODING POSSIBLE ALONG THE I-75 CORRIDOR... For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf .UPDATE... Issued at 959 PM EDT Sun Jul 13 2025 Late evening surface analysis depicts weak low pressure (1015 millibars) situated along a trough over the Gulf Stream waters adjacent to coastal South Carolina and Georgia. Aloft...ridging has been slowly retrograding westward along the northern Gulf coast, with the nose of this feature extending northeastward along the spine of the southern Appalachians. Meanwhile, cutoff troughing located to the northwest of Bermuda was extending its axis southwestward along the Gulf Stream waters off the southeastern seaboard. Latest GOES-East derived Total Precipitable Water imagery indicates that a drier air mass continues to advect southeastward across inland southeast GA, where PWATs were falling to the 1.6 - 1.8 inch range, while values elsewhere were mostly in the 1.9 - 2.2 inch range. Leftover outflow boundaries from afternoon convection over northeast FL have collided over north central FL and southern portions of the St. Johns River basin this evening, with an unstable northwesterly flow allowing for storms to pulse and become strong to severe, mainly along the U.S. Highway 301 and 17 corridors to the southeast of Gainesville and Palatka. Additional convection was also sliding southward along coastal southeast GA late this evening. Fair skies prevail within the drier air mass across inland southeast GA, where temperatures remain in the low to mid 80s as of 02Z, with dewpoints recovering into the 70s this evening. Temperatures elsewhere were mostly in the 75-80 range. Convective outflows may continue to ignite convection across coastal locations and north central FL through around midnight before coverage and intensity diminish overnight. Debris clouds will otherwise thin out overnight, with lows mostly remaining in the mid to upper at most locations overnight. && .SHORT TERM... (Monday through Tuesday night) Issued at 146 PM EDT Sun Jul 13 2025 A broad area of low pressure is forecast to be off the southeast U.S. coast Monday morning, with an associated the mid/upper low pressure system located over the northwest Bahamas. A sfc trough extending from the low arcs northwest into GA. The sfc system is forecast to move west to west-southwest through the FL peninsula Monday through Monday night and then into the eastern Gulf Tuesday afternoon. Weak troughing, oriented from south to north over our forecast region, still likely on Tuesday even as the broad low moves west of the area late in the afternoon. Mean layer flow up to about 20 kft is northerly on Monday and shifts to northeasterly on Tuesday. On both days, highest chances for showers and storms are expected across inland areas as the Atlantic sea breeze will have little resistance moving inland, but especially on Tuesday as the low level flow become northeast and east. A few strong storms are likely with heavy rainfall, gusty winds, and frequent lightning. Models suggest Monday having the higher threat of heavy rainfall over inland areas south of I-10. WPC has marginal to a slight risk of excessive rain south of a line from about Palm Coast to Waldo to Fort White. Storm severity looks somewhat weaker by Tuesday as temps aloft are warmer and sfc temps may be more in the lower 90s which would suggest overall weaker updraft strength. The axis of better precip will also shift a little further inland on Tuesday due to northeasterly mean layer flow. Monday will be the hotter of the two days, with heat indices approaching advisory levels. Too close to call on issuing an advisory at this time. Forecast will show values of about 104 to 108 in most locations. Heat advisory criteria is 108-112. && .LONG TERM... (Wednesday through next Sunday) Issued at 146 PM EDT Sun Jul 13 2025 The broad area of low pressure will be in the Gulf on Wednesday with mean layer flow from the south and southeast. High pressure ridge axis will located further north than normal into parts of GA and SC Wednesday. As the sfc low tracks further away from the area Thu and Fri, this high pressure ridge will build further into the area by the end of the week. Elevated rain chances expected Wednesday to Friday with some moderation in chances nearer to normal by Sat due to subsidence affects from the mid level high which will move into central FL end of the week. Temperatures will be near to a little above normal this period with heat indices in the range of 100-105 each day, with heat advisory criteria possibly being met in some locations. && .AVIATION... (00Z TAFS) Issued at 756 PM EDT Sun Jul 13 2025 Strong thunderstorms will impact SSI and the Glynn County airfields through around 01Z, with brief surface wind gusts up to 30 knots and IFR conditions during heavier downpours. Thunderstorms may also impact GNV through around 02Z, with brief surface wind gusts up to 30 knots and IFR conditions during heavier downpours. Briefly heavy showers are otherwise possible through around 02Z at the Duval County terminals, with confidence high enough to include a TEMPO group at JAX for MVFR conditions through around 01Z. VFR conditions should then prevail at the regional terminals towards 03Z, with brief periods of MVFR visibilities possible overnight at VQQ. Showers and thunderstorms will focus inland on Monday afternoon and evening, with PROB30 groups for briefly gusty winds and MVFR to IFR conditions during heavier downpours included after 18Z at GNV and VQQ. Confidence was only high enough for vicinity coverage at JAX and CRG, generally during the early afternoon hours. Only vicinity showers were mentioned at the SSI and SGJ coastal terminals on Monday. Southerly surface winds sustained at 5-10 knots early this evening will shift to westerly while gradually diminishing overnight. Northwesterly surface winds will develop shortly after sunrise, with speeds increasing to 5-10 knots by 14Z. Surface winds will then shift to northeasterly at the coastal terminals by 16Z, where speeds will increase to around 10 knots. The Atlantic sea breeze will progress inland during the afternoon hours, shifting surface winds to northeasterly at the inland terminals by late afternoon. && .MARINE... Issued at 959 PM EDT Sun Jul 13 2025 Troughing developing over the Gulf Stream waters tonight will shift slowly westward on Monday, crossing our local waters on Monday night. Showers and thunderstorms over the Georgia waters early this evening will diminish before midnight, with activity on Monday mainly confined to the offshore waters. Seas around 2 feet will prevail both near shore and offshore through Monday night. Showers and thunderstorms will increase in coverage on Tuesday and Wednesday as troughing shifts westward across the Florida peninsula and into the eastern Gulf, with low pressure potentially organizing later in the week near the northern Gulf coast. Prevailing northeasterly winds on Monday will shift to southerly by late Tuesday as troughing shifts west of our local waters, with south-southeasterly winds briefly strengthening to Caution levels of 15-20 knots near shore on Wednesday afternoon. Seas will build to the 3-4 foot range offshore by midweek. Rounds of showers and thunderstorms will continue through late in the week as southerly winds prevail. Rip Currents: Developing northeasterly winds on Monday will likely result in a low-end moderate rip current risk at all area beaches. && .FIRE WEATHER... Issued at 959 PM EDT Sun Jul 13 2025 Surface and transport winds will shift to northwesterly towards sunrise on Monday, followed by winds shifting to northerly towards noon and then northeasterly during the afternoon hours, with breezy onshore surface winds developing at coastal locations during the afternoon hours. These winds will combine with elevated mixing heights to create high daytime dispersion values on Monday afternoon for inland locations west of the U.S. Highway 301 corridor, with good values elsewhere inland and fair values at coastal locations. Northeasterly surface and transport winds on Tuesday morning will shift to easterly during the afternoon hours, with good to marginally high daytime dispersion values forecast inland and fair values at coastal locations. Surface and transport winds will then shift to south-southeasterly on Wednesday, with good to marginally high daytime dispersion values forecast area-wide. && .PRELIMINARY POINT TEMPS/POPS... AMG 75 98 74 93 / 20 60 20 60 SSI 78 91 78 88 / 30 30 10 50 JAX 76 95 75 92 / 20 50 20 70 SGJ 75 91 77 89 / 40 30 20 70 GNV 75 97 73 93 / 60 80 40 80 OCF 75 96 73 91 / 60 80 40 90 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$