Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
792 FXUS62 KJAX 130147 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 947 PM EDT Sat Jul 12 2025 ...HEAT INDEX VALUES APPROACH ADVISORY CRITERIA ON SUNDAY PM... ...STRONG STORMS EXPECTED ON SUNDAY AND MONDAY AFTERNOONS... ...HEAVY DOWNPOURS POSSIBLE TUESDAY AND WEDNESDAY... 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 947 PM EDT Sat Jul 12 2025 Late evening surface analysis depicts Atlantic high pressure (1020 millibars) extending its axis westward across the FL peninsula. Aloft...deep-layered ridging was centered over the FL panhandle and the far eastern Gulf, with a trough developing just east of North Carolina`s Outer Banks. Latest GOES-East derived Total Precipitable Water imagery indicates that PWATS were generally in the 1.8 - 1.9 inch range across inland southeast GA, while values around or above 2 inches prevail elsewhere. Convection has mostly dissipated across our region, except for an isolated thunderstorm along the Ocmulgee River in southeast GA that was approaching Jeff Davis County from the northwest. Leftover debris cloud cover was gradually thinning out elsewhere, with temperatures at 02Z ranging from the mid 70s to the lower 80s, with dewpoints in the 70s at most locations. Convection approaching the Altamaha River in interior southeast GA should gradually weaken as the evening progresses, with impacts most likely remaining northwest of Baxley. Otherwise, debris cloudiness will continue to gradually thin out overnight, allowing lows to fall to the mid 70s inland and the upper 70s at coastal locations as low level winds become west-southwesterly after midnight. && .SHORT TERM... (Sunday through Monday night) Issued at 205 PM EDT Sat Jul 12 2025 Rather weak troughing/broad low pressure starts to shift south and southwestward from the Carolinas on Sunday, slowly moving towards and over the Florida Peninsula through Monday and Monday Night. This will have several implications, firstly breaking down high pressure ridging that has kept us in a mostly west to southwest flow, and secondly increasing rain/t`storm coverage across most of the area. The low will induce more of a northwesterly flow on Sunday, which will try to bring in some drier air into southeast GA and therefore tempering PoPs and convective coverage a bit in those areas, however. The more north to northwesterly flow near the surface and aloft will also result in a rather rare summer north to south storm motion Sunday. Highest convective coverage as well as the greatest threat for any strong to isolated severe storms will therefore be across northeast FL, and especially south of I-10 and towards the FL coast where the best convergence will be. Gusts up to 40-60 mph and minor flooding from heavy rainfall will be the primary hazards. Highs will remain quite warm with offshore flow, as mid 90s will be common. The highest readings likely to be across inland GA with less convective coverage and some drier air where upper 90s will be in store for some. As low pressure continues to push southward Sunday Night, this will likely keep some showers and t`storms going throughout the night over area waters and especially offshore waters, as well as over parts of northeast FL. Low temps will be mild Sunday Night, in the mid to upper 70s. Monday, broad low pressure will be located almost directly over north FL before slowly drifting southwestward towards the northeast Gulf Monday Night. The presence of the low and some weak energy aloft will maintain active convection, including increased coverage likely into southeast GA as well. The position of the low will shift flow towards the north to northeast throughout the day, with the east coast sea breeze therefore progressing far inland and likely shifting the "corridor" of highest PoPs and stronger t`storm chances inland and towards the nearly pinned west coast sea breeze during the afternoon and evening. More of a continental wind direction will hold strong enough inland for mid to upper 90s to continue Monday. However, temps from about the I-95 corridor and to the coast will nudge down a bit closer to the lower 90s where there will be more of a sea breeze influence. && .LONG TERM... (Tuesday through next Saturday) Issued at 205 PM EDT Sat Jul 12 2025 The broad and weak low will drift southwestward into the Gulf Tuesday and into Wednesday as high pressure starts to rebuild from the east to northeast through the end of the week. The National Hurricane Center (NHC) has placed a 20% chance of tropical or subtropical development somewhere over the north/northeast Gulf during the longer term, though impacts, if any, do not look significant and likely west of our area at this time. We will of course continue to keep a close eye on trends and forecasts accordingly. Otherwise, the long term looks to mostly consist of near to above average shower/t`storm chances and an onshore flow regime. Temperatures overall will trend near normal, though start to nudge upward towards late week as flow becomes more southeast as compared to east/northeast. && .AVIATION... (00Z TAFS) Issued at 744 PM EDT Sat Jul 12 2025 Light showers near SGJ will dissipate before 01Z. Otherwise, VFR conditions will prevail at the regional terminals through at least 06Z Sunday. Periods of IFR visibilities are expected overnight at VQQ. A brief period of MVFR ceilings between 2,000 - 3,000 feet will be possible at the terminals during the late morning hours on Sunday, but confidence was too low to include anything other than scattered ceilings at this time. Showers and thunderstorms will develop after 17Z along the Atlantic sea breeze boundary near the SGJ and SSI coastal terminals, with activity then expected to shift inland after 19Z, with coverage and intensity of convection expected to increase during the mid to late afternoon hours. Thunderstorms should shift west of the I-95 corridor by 23Z, with activity potentially lingering into the early evening hours at VQQ and GNV. PROB30 groups were included at each terminal on Sunday afternoon for brief wind gusts up to 30 knots and IFR visibilities during heavier downpours. Southerly surface winds sustained at 5-10 knots early this evening will shift to southwesterly by midnight, with speeds remaining around 5 knots at the coastal terminals overnight. Surface winds will then shift to west-northwesterly shortly after sunrise, with speeds increasing to 5-10 knots by 14Z. The inland moving Atlantic sea breeze boundary will shift winds to east-southeasterly after 17Z at SGJ, with speeds increasing to 10-15 knots, while southerly winds of 10-15 knots are forecast at SSI after 18Z. && .MARINE... Issued at 947 PM EDT Sat Jul 12 2025 Atlantic high pressure extending its axis westward across the FL peninsula will shift southward on Sunday as a weak trough develops near the Gulf Stream waters. This trough will then slowly migrate westward across our local waters on Monday, with this feature shifting into the northeast Gulf by Tuesday. Showers and thunderstorms will likely increase across our local waters beginning later on Monday and Tuesday, with prevailing winds shifting to southerly by Tuesday as this trough slowly organizes over the eastern Gulf towards midweek. Seas of 2 to 3 feet will prevail both near shore and offshore through Tuesday, followed by seas building slightly to 3-4 feet offshore towards midweek as southerly winds increase. Rip Currents: A low risk is expected on Sunday at area beaches. Lower-end moderate risks are anticipated on Monday and Tuesday as more consistent onshore winds develop. && .FIRE WEATHER... Issued at 947 PM EDT Sat Jul 12 2025 Surface and transport winds will shift to northwesterly after sunrise on Sunday, with onshore surface winds developing at coastal locations by the early afternoon hours. Elevated mixing heights will likely result in high daytime dispersion values across most of inland southeast GA, with good values forecast elsewhere inland. Fair daytime dispersion values are expected at coastal locations. North-northwesterly surface and transport winds will prevail on Monday, with onshore surface winds again developing at coastal locations by early afternoon. Elevated mixing heights will create high daytime dispersion values for locations west of the I-95 corridor, with good values expected elsewhere, except fair values at coastal locations. && .PRELIMINARY POINT TEMPS/POPS... AMG 74 98 75 96 / 10 30 30 50 SSI 77 94 78 92 / 20 40 20 40 JAX 76 97 75 95 / 30 60 40 70 SGJ 77 93 76 92 / 40 70 20 70 GNV 76 94 74 96 / 30 70 20 90 OCF 75 93 75 94 / 20 80 40 90 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$