487 FXUS62 KJAX 131857 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 257 PM EDT Fri Jun 13 2025 ...WIDESPREAD AFTERNOON AND EVENING STORMS THROUGH THE WEEKEND... ...THUNDERSTORM COVERAGE MAY WANE SLIGHTLY EARLY NEXT WEEK... ...HEAT INDEX VALUES CLIMB TO NEAR 105 NEXT WEEK... For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf .SYNOPSIS... Issued at 257 PM EDT Fri Jun 13 2025 Afternoon surface analysis depicts Atlantic high pressure (1025 millibars) centered near Bermuda, with this feature extending its axis westward across our region. Aloft...ridging was centered over the northwestern Bahamas and the FL peninsula, while a slow moving trough was progressing across the Ozarks and the Mid- Mississippi Valley. Latest GOES-East derived Total Precipitable Water imagery indicates that deep tropical moisture remains entrenched across our area, with PWATs generally around 2 inches. Scattered showers and thunderstorms were overspreading locations along and north of the I-10 corridor this afternoon, with more isolated coverage thus far for areas closer to the deep-layered ridge axis across north central FL. Brisk low level southerly flow, noted in this morning's sounding at Jacksonville, was steering convection generally northward around 15-20 mph. Temperatures at 19Z have climbed to the lower 90s at inland locations where conditions remain dry, with 80s elsewhere. Dewpoints remain in the 70s area-wide. && .NEAR TERM... (through Tonight) Issued at 257 PM EDT Fri Jun 13 2025 An abundance of tropical moisture across our region will continue to foster and increasing coverage of showers and thunderstorms over much of our area through this evening. Colliding mesoscale boundaries may result in a few storms pulsing, with a few wet microbursts possibly producing brief wind gusts in the 40-50 mph range, along with frequent lightning strikes and torrential downpours. Storm motion around 15 knots should limit the potential for widespread flooding, but a few instances of "training" downpours, falling repeatedly over the same locations, could result in localized flooding later this afternoon through early this evening, especially if these repeated downpours occur at urban or normally flood prone, low-lying locations. The Weather Prediction Center has thus included most of our area within a "Marginal" Risk (level 1 out of 4) for Excessive Rainfall this afternoon and evening. Convection late this afternoon that will likely concentrate along the U.S. Highway 301 corridor should shift back towards I-95 early this evening as anvils get steered by the higher altitude southwesterly flow pattern. Most activity will dissipate or shift offshore by midnight, with debris cloudiness gradually thinning out during the predawn hours. Low level south to southwesterly flow will keep lows in the low to mid 70s inland, ranging to the mid and upper 70s at coastal locations. && .SHORT TERM... (Saturday through Sunday night) Issued at 257 PM EDT Fri Jun 13 2025 Surface high pressure will be centered to the east northeast Saturday, and more directly to the east Saturday night through Sunday night. The position of the high will make subtle changes in the low level flow, but the result will roughly be the same. The east coast sea breeze will push past I-95, and diurnal convection will initiate across the area. The axis of the upper ridge will be just south of the region. With light flow from the southwest in the afternoons, and the flow north of upper ridge also from the southwest, storms which develop will drift to the east northeast. So, even if the convection develops west of an area due to the sea breeze, that area could have it move back in later in the day. Afternoon convection coverage will be scattered to numerous. Precipitation will diminish during the evening hours with loss of diurnal heating. Temperatures will trend a little above normal this period. && .LONG TERM... (Monday through next Friday) Issued at 257 PM EDT Fri Jun 13 2025 Surface high pressure will be east of the region through Wednesday, with daily convection expected due to diurnal heating and sea breeze interactions. The position of the upper ridge overhead will provide subsidence to help limit strength of activity. Temperatures will run about 5 degrees above normal through Wednesday. The pattern changes for Thursday into Friday. The surface high will become centered more to the east southeast, as a surface trough moves into the southeastern US. An upper trough will also dig into the southeastern US late in the week as well, helping to increase instability with increased potential for stronger storms. Scattered to numerous showers and storms late in the week. Temperatures will be about 5 to 7 degrees above normal Thursday into Friday. && .AVIATION... (18Z TAFS) Issued at 139 PM EDT Fri Jun 13 2025 Showers and thunderstorms will continue to impact the Duval County terminals and SSI through the afternoon hours, with a lower confidence for convective development near the SGJ and GNV terminals later this afternoon and this evening. TEMPO groups for brief wind gusts up to 25 knots and IFR visibilities during heavier downpours were used at the Duval County terminals and SSI, with PROB30 groups placed in the GNV and SGJ TAFs after 20Z through the early evening hours tonight. Due to lower confidence in potential impacts at SGJ and GNV, MVFR conditions were indicated in the PROB30 groups for SGJ and GNV. Convection should dissipate or push offshore of the coastal terminals before 04Z, with VFR conditions then prevailing at the regional terminals through at least 06Z. MVFR visibilities will likely develop towards 07Z at VQQ and continuing through the predawn hours on Saturday. Outside of ongoing thunderstorm activity, southerly surface winds will remain sustained at 5-10 knots at the inland terminals, while onshore winds increase to 10-15 knots at the coastal terminals. Surface winds will then shift to southerly at 5-10 knots after sunset as convective coverage decreases across our area, followed by winds shifting to southwesterly after sunrise. && .MARINE... Issued at 1129 AM EDT Fri Jun 13 2025 Atlantic high pressure centered near Bermuda will continue to extend its axis across our local waters through the weekend. This weather pattern will create a prevailing southerly wind flow, with afternoon sea breezes over the near shore waters bringing speeds up to Caution levels, while a southerly wind surge results in Caution conditions offshore this evening. Late afternoon and evening thunderstorms are likely across our local waters through Saturday, with coverage then expected to decrease slightly from Sunday through the middle portions of next week. Seas of 2 to 4 feet will prevail throughout our local waters outside of thunderstorm activity during the next several days. Rip Currents: Breezy onshore winds developing following the passage of the sea breeze this afternoon will combine with a weak east-southeasterly swell and a southerly long shore current to create a moderate risk at all area beaches through the weekend. && .FIRE WEATHER... Issued at 1129 AM EDT Fri Jun 13 2025 Breezy southerly transport winds will create good daytime dispersion values at most inland locations this afternoon, with breezy onshore winds this afternoon at coastal locations yielding fair daytime dispersion values. Transport winds will shift to southwesterly during the weekend, with gradually decreasing speeds generally yielding fair values on Saturday. Elevated mixing heights on Sunday will create good daytime dispersion values across inland portions of southeast GA, with fair values forecast elsewhere. Scattered to numerous mainly afternoon and evening showers and thunderstorms will continue through the weekend, with a gradual decrease in coverage expected during the early and middle portions of next week. && .PRELIMINARY POINT TEMPS/POPS... AMG 73 89 72 90 / 70 60 20 70 SSI 77 85 76 90 / 60 70 40 70 JAX 74 91 74 92 / 50 70 30 80 SGJ 76 89 75 90 / 50 60 40 80 GNV 73 91 73 92 / 50 60 20 90 OCF 73 91 73 92 / 60 60 20 90 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$