Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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956 FXUS62 KJAX 231726 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 126 PM EDT Mon Sep 23 2024 ...New AVIATION... .UPDATE... Issued at 945 AM EDT Mon Sep 23 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 Weak pressure pattern over the area with light winds and mostly clear conditions for most areas. There is weak trough of low pressure over inland southeast GA that has sparked a few showers that may continue into this afternoon but remain very isolated (10-20 percent chance). No thunder anticipated at this time given weak forcing and dry air aloft. Fog has dissipated this morning so will remove from the forecast. Another round of some fog appears likely tonight. Little change in the forecast with warmer than normal temps given the warmer conditions aloft (e.g., 850 mb at 18 C and 500 mb at -2.5 C from the 12z JAX sounding). We continue to monitor the broad tropical low pressure system trying to develop over the northwest Caribbean Sea. System looks to be moving slowly northward. More updates to this feature later today as we get better guidance and additional visible satellite imagery. Please see the NHC forecast for the latest and more detailed information. && .NEAR TERM...(through Tonight)... Outside of cloud cover along a surface trough in far northern SE GA, clear skies and calm conditions will favor the formation of patchy fog in inland areas through the rest of the morning. Locally dense fog has potential (30-60%) to develop along the I-75 & Highway-301 corridors in NE FL around dawn. Fog should lift to a low stratus deck and break up between 9/10 AM. A stagnant pressure pattern remains in place, keeping conditions mostly dry again amid anomalously warm (stable) air aloft. The aforementioned weak surface trough in SE GA is providing enough convergence along it to sprout isolated showers near the Altamaha River early this morning. That trough will move very little as it dissipates today but, with diurnal heating, there`s a slight chance (~20%) that a few spotty afternoon showers develop along once again this afternoon. Given the warm air aloft, probability of thunderstorm development is near nil. Otherwise, temperatures will warm a degree or two over yesterday`s highs with inland areas reaching the low 90s. Temp differential will generate an Atlantic sea breeze this afternoon which will keep the coast cooler, generally in the mid/upper 80s. Little change in the pattern through tonight with lows in the upper 60s to low 70s and potential for patchy inland fog. ~~ MESSAGE OF THE DAY ~~ While there is still uncertainty regarding the disturbed area of weather in the northwestern Caribbean, please take advantage of this tranquil period of weather over the next couple of days to review plans and ensure necessary supplies are assembled in the event of tropical storm or hurricane impacts later on this week. Please pay close attention to the forecast information locally as well as from the National Hurricane Center to stay abreast of the latest forecast information. For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf && .SHORT TERM...(Tuesday through Wednesday night) High pressure over the region will gradually begin to shift east towards the western Atlantic as an upper level trough over the central CONUS begins to digs south towards the Gulf coast states by the end of this forecast period. Early morning fog on Tuesday will dissipate by the early daylight hours, with another day of mainly dry conditions on Tuesday as high pressure will begin to shift towards the east. Come Wednesday, the weather pattern will be heavily influenced by the evolution of the broad area of low pressure currently located over the northwestern Caribbean Sea and the aforementioned upper level trough. The NHC currently anticipates the broad area of low pressure to develop into a tropical depression or storm with a high chance (70%) of formation during the short term. Some moisture is expected to advect over north central FL counties from Wednesday afternoon and through the overnight hours into Thursday. Temperature highs for in the mid to upper 80s along the coast, with highs in the lower 90s for inland locations on Tuesday. Cooler max temperatures on Wednesday as cloud cover will increase as moisture moves into the area. Overnight lows expected to be in the 70s across SE GA and NE FL. && .LONG TERM...(Thursday through Sunday) The forecast period is still uncertain as we continue to monitor the evolution of the broad area of low pressure over the northwestern Caribbean Sea. Guidance continues trending towards the development into a tropical system, NHC now gives chance of formations over the next 7 days as high (90%). As stated in the short term discussion, the exact path of any system that may development will be contingent on the upper trough that is expected over to influence whether the system takes a more northward or northeastern path. This of course will leave the extent of any local impacts from this system still uncertain. But an abundant amount of rainfall from the system will be possible during the end of the week, with chances of precipitation beginning to dwindle over the weekend. Be sure to restock supply kits and review family evacuation plans. Monitor official tropical forecasts from the National Hurricane Center at hurricanes.gov and local emergency management officials. && .AVIATION... (18Z TAFS) Issued at 120 PM EDT Mon Sep 23 2024 VFR/mostly clear skies at the terminals into late tonight. From around 06z-12z Tuesday, chances for MVFR vsby are indicated for JAX, VQQ, and GNV. Outside chance for IFR vsby/cigs at these terminals, with VQQ the only one with some confidence to show possible 1SM BR. Anticipate VFR all TAFs by 13z Tuesday. Sfc winds will be southeast to east 5-10 kt into early evening today, then light and variable tonight. Southeast winds re-develop after 14z Tuesday at near 5-10 kt. && .MARINE... A generally weak pressure pattern and light onshore flow continues through Tuesday. Southeasterly winds strengthen through Wednesday in response to a tropical system that is expected to develop quickly from an area of disturbed weather in the northwestern Caribbean Sea and then move northward into the eastern Gulf of Mexico. There is still uncertainty in the scale, intensity and track of the tropical system as it develops. All of those factors will influence the local coastal water conditions. At the moment, Small Craft Advisory conditions are expected to develop by Wednesday night with gales possible Thursday. Conditions are expected to improve quickly Friday and through the weekend as the tropical system rapidly tracks northward. RIP CURRENTS...Moderate risk of rip currents continues, mainly during the afternoon as the sea breeze develops, today and again Tuesday. Building breakers (3-5 feet) and increasing southeasterly flow on Wednesday enhances risk to *High* levels for at least NE FL beaches. Dangerous surf conditions are likely Thursday as influences from tropical system are most likely to begin. && .HYDROLOGY... Minor tidal flooding continues within the St Johns River basin through mid week before influences from a tropical system tracking northward across the eastern Gulf of Mexico begin. Current probabilistic forecast guidance, understandably, has considerable spread in potential forecasts given the forecast uncertainty in the possible evolution/track of the tropical system. Strong southeasterly flow in response to the tropical system may bring tidal levels back into Minor or low-end Moderate flood at times of high tide along the Atlantic coast by Thursday evening. Given the current elevated tides already ongoing in the St Johns River, the potential for Moderate Flooding and impacts are possible during at least Thursday and Friday high tides. Preparations should be considered for low-lying areas along the St Johns River, especially in the Downtown Jacksonville, San Marco, & Riverside areas along with other flood prone locations in the upper St Johns in Clay, St Johns, and Putnam counties. && .PRELIMINARY POINT TEMPS/POPS... AMG 70 91 70 88 / 10 0 0 10 SSI 75 86 76 85 / 0 0 0 10 JAX 71 89 74 87 / 0 0 0 20 SGJ 74 88 76 87 / 0 0 0 20 GNV 69 91 72 89 / 0 0 0 30 OCF 69 93 74 90 / 0 10 0 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 AM EDT Wednesday for FLZ033-038- 125-132-137-225-325. GA...None. AM...None. && $$