Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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149 FXUS62 KJAX 151253 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 853 AM EDT Sun Sep 15 2024 ...New UPDATE... .UPDATE... Issued at 841 AM EDT Sun Sep 15 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 Rest of Today...Spoke of energy expected to rotate around the west side of developing low pressure center off the SE US coastline and push southward through SE GA and into the I-10 corridor of NE FL this afternoon and through the rest of NE FL south of the I-10 corridor this evening. This will bring an uptick in shower and isolated thunderstorm activity this afternoon along with increasing North to Northeast winds up to 15-20 mph along the Atlantic Coastal areas with wind gusts in the 25-35 mph range with lesser winds of 10-15 mph inland with gusts of 20-25 mph. A mixture of low clouds near the surface along with high clouds streaming in aloft will keep temps muted again today with highs in the lower 80s across SE GA and in the middle 80s across NE FL and these slightly below normal temps should keep any afternoon thunderstorm activity isolated, but any of this activity could still produce some heavy downpours, but movement should be slightly higher today to prevent any significant flooding issues. Tonight...The remainder of the spoke of energy should push through NE FL during the evening hours which may continue scattered showers and isolated thunderstorm activity a few hours past sunset. Otherwise expect decreasing rainfall chances and diminishing winds over inland areas, although breezy North to Northeast winds will continue through the night at Atlantic beachfront locations. Skies will continue at mostly cloudy levels and will prevent any significant fog formation, except for the usual patchy fog over inland NE FL along the I-75 corridor. Low temps in the upper 60s for inland SE GA, lower 70s for inland NE FL and middle 70s along the Atlantic Coastal areas. && .SYNOPSIS... Issued at 437 AM EDT Sun Sep 15 2024 Early morning surface analysis depicts developing low pressure (1009 millibars) located over the Gulf Stream waters adjacent to the Georgia and South Carolina coasts. Meanwhile, strong high pressure (1030 millibars) was centered over Maine and was wedging down the southeastern seaboard. Otherwise, a wavy and stationary frontal boundary situated along the Interstate 4 corridor in central FL extends westward across the FL panhandle and along the northern Gulf coast. Aloft...a persistent "Rex Block" remains in place over the eastern half of the nation, with stout ridging centered over the eastern Great Lakes region and New England, keeping Francine`s remnant trough trapped over the lower Mississippi Valley and the Deep South. A drier air mass has advected across our region, with latest GOES-East derived Total Precipitable Water imagery indicating that PWAT values have fallen back to near climatological values for mid-September, with values of 1.6 to 1.8 inches prevailing area-wide. Multi-layered cloud cover was increasing across our our area overnight, but only a few light showers or sprinkles were located near the southeast GA coast. Temperatures and dewpoints were in the 70s across northeast and north central FL as of 08Z, while dewpoints have fallen to the upper 60s across inland portions of southeast GA. && .NEAR TERM... (Today and Tonight) Issued at 437 AM EDT Sun Sep 15 2024 Low pressure will continue to gradually organize and will remain nearly stationary through tonight over the Gulf Stream waters adjacent to GA and SC. Meanwhile, strong high pressure will remain situated over New England, with this feature continuing to wedge down the southeastern seaboard today, tightening our local pressure gradient. Breezy north-northeasterly winds will continue at coastal locations this morning, with windy conditions developing this afternoon as speeds increase to 15-25 mph with occasional gusts up to 35 mph. Breezy conditions will develop at inland locations this afternoon. Deeper tropical moisture will remain offshore today, but low level onshore flow will become more convergent, with showers and a few embedded thunderstorms expected to increase in coverage along the GA coast by the mid to late morning hours, with this low-topped activity then pushing southwestward across the rest of our area as the afternoon progresses. While briefly heavy downpours are possible, the lack of deeper moisture should make activity transient in nature as it shifts southwestward, and chances for widespread thunderstorms appear to be unlikely this afternoon. Higher coverage of showers and a few embedded thunderstorms are expected to remain along and north of the Interstate 10 corridor, with another corridor of higher coverage located west of I-75 in the Suwannee Valley later this afternoon, possibly extending into the evening hours. Breezy conditions and multi-layered cloudiness will keep highs generally in the low to mid 80s, with upper 80s forecast across north central FL. Breezy onshore winds will shift to a more north-northwesterly direction at coastal locations overnight. Widely scattered showers developing to the south of the organizing low pressure center off the Carolina coast may occasionally brush locations along and east of I-95 overnight. Otherwise, low stratus clouds may develop during the predawn hours across inland portions of southeast GA, where winds will decouple, allowing lows to fall to the upper 60s. Lows elsewhere will fall to around 70 inland, ranging to the mid and upper 70s at coastal locations. && .SHORT TERM... (Monday through Tuesday) Issued at 437 AM EDT Sun Sep 15 2024 Frontal boundary remains draped across FL as its associated low pressure system shifts north-northwestward and potentially moves onshore to the Carolinas and into the Mid-Atlantic region Monday into Tuesday. NHC has a 50% chance that this low may become a subtropical or tropical storm early this week if the associated front dissipates and showers and thunderstorms become sufficiently organized. Regardless of tropical or subtropical development, local impacts for Monday will be breezy north-northeasterly winds along the coast, coastal flooding, high risk of rip currents and dangerous marine conditions. A lingering moist airmass over NE FL, convergence along the frontal boundary, and upper energy from the remnants of Francine will support daily scattered to numerous showers with embedded thunderstorms. Highs will be in the low 80s in SE GA to around 90 in north-central FL. Overnight lows will be in the upper 60s and low 70s. && .LONG TERM... (Wednesday through Saturday) Issued at 437 AM EDT Sun Sep 15 2024 Frontal boundary over northern FL on Wednesday will dissipate and shift southward as its associated low weakens over the mid- Atlantic region. Upper trough over the eastern US will place the region under north-northwesterly flow aloft advecting in some drier air for the latter half of the week. Rain chances decrease through the week bringing an end to the wet pattern. High pressure wedges down the eastern seaboard for the end of the week bringing as return of northeasterly flow. Temperatures will be around seasonal with highs in the 80s and lows in the upper 60s and low 70s. && .AVIATION... (12Z TAFS) Issued at 728 AM EDT Sun Sep 15 2024 Low CIGS in the IFR/MVFR range remain trapped at all TAF sites this morning in the light N-NE flow and once again will be very stubborn to lift or break up today as just enough sunny breaks occur to allow for diurnal heating to kick off scattered to numerous shower activity this afternoon and have added TEMPO groups to all TAF sites, but lightning chances remain too low to include any TSRA in the forecast and have removed the VCTS with this package to account for these lower probs of storm activity this afternoon. Northeast winds will increase at coastal TAF sites into the 12-16 knot range with higher gusts. Any upwards trend in rainfall this afternoon will likely fade this evening and return the Atlantic Coastal waters and VCSH will linger at the coastal TAF sites along with MVFR CIGS, while the light north flow over inland TAF sites will lead to IFR CIGS at VQQ/GNV after 06Z and potential LIFR CIGS at GNV towards the end of the TAF period. && .MARINE... Issued at 437 AM EDT Sun Sep 15 2024 Low pressure will continue to organize over the Gulf Stream waters adjacent to the Carolina coastline, with this feature potentially acquiring tropical characteristics as it pushes northward towards the Carolina coast on Monday night or early Tuesday morning. Small Craft Advisory conditions over the Georgia waters and the offshore waters north of St. Augustine this morning will overspread the rest of the northeast Florida waters by this afternoon as north-northeasterly winds strengthen to 20-25 knots and seas build. Winds may occasionally gust to around Gale Force over the Georgia waters this afternoon and evening. Seas will peak in the 5-8 foot range for the near shore waters tonight and 7-10 feet offshore. Small Craft Advisory level seas will continue on Monday night for the offshore waters, with Caution level seas of 4-6 feet forecast near shore. Waves of showers and a few embedded thunderstorms will develop across our local waters through Monday night. Winds will shift to northwesterly on Monday night while diminishing, with seas then gradually diminishing through midweek. Otherwise, a frontal boundary positioned across the Florida peninsula will lift northward over the northeast Florida waters on Wednesday, keeping chances for mainly afternoon and evening thunderstorms in place. This front will then shift south of our local waters late this week. Rip Currents/Elevated Surf: Strengthening north-northeasterly winds and increasingly rough surf conditions will keep a high rip current risk in place at all area beaches through Monday. Breaker heights will build to 3-5 feet this afternoon and will peak in the 4-6 foot range on Monday, which is just below High Surf Advisory criteria. Winds will become northwesterly on Monday night and Tuesday, with decreasing breaker heights potentially allowing for a high end moderate risk at area beaches by Tuesday. && .PRELIMINARY POINT TEMPS/POPS... AMG 82 68 81 66 / 60 20 20 10 SSI 81 72 81 71 / 50 30 20 10 JAX 84 71 83 70 / 50 30 40 10 SGJ 85 73 84 73 / 30 30 40 10 GNV 86 71 85 69 / 40 20 40 20 OCF 88 71 88 71 / 40 20 60 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 AM EDT Tuesday for FLZ033-038-132- 137-325. High Rip Current Risk through late Monday night for FLZ124-125- 133-138. Coastal Flood Advisory from 6 PM this evening to 5 AM EDT Tuesday for FLZ124-125-133-138. GA...High Rip Current Risk through late Monday night for GAZ154-166. Coastal Flood Advisory from 6 PM this evening to 5 AM EDT Tuesday for GAZ154-166. AM...Small Craft Advisory until 5 AM EDT Tuesday for AMZ450-470-472. Small Craft Advisory from 2 PM this afternoon to 5 AM EDT Tuesday for AMZ452-454-474. && $$