Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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653 FXUS62 KJAX 131542 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 1142 AM EDT Mon May 13 2024 ...New UPDATE... ...ISOLATED STRONG TO MARGINALLY SEVERE STORMS POSSIBLE SOUTH OF I-10 THIS AFTERNOON AND EVENING... .UPDATE... Issued at 1117 AM EDT Mon May 13 2024 A couple of tweaks to discuss this morning on the forecast through this afternoon: 1) The PoPs and cloud cover were both increased for the inland zones, mainly north of I-10, to account for the earlier batch of light and stable rain associated with the lift being supplied by a shortwave impulse propagating through the zonal flow. A few storms are possible as this wave pushes across the area this afternoon, mainly south of I-10 and west of the St Johns River where marginal instability will build as SSE flow advects higher dewpoints into north-central FL. 2) Due to the thickening high cloud cover, temperatures were trended downward to reflect the latest observations and cool expected high temps to the upper 70s and low 80s across southeast GA. -------------------------------------------------------------- Otherwise, the Atlantic sea breeze is still expected to push inland and interact with the Gulf sea breeze west of the Highway 301 corridor this afternoon, mainly trigger garden-variety convection. For this evening, SPC has maintained a Marginal Risk (Level 1 of 5) for the area while WPC has nudged a Slight Risk (15% chance of flooding) a bit eastward into portions of the Suwannee Valley. Both of these Risks are aimed at the severe and heavy rain threats associated with thunderstorms during the evening hours as a warm front begins to lift into the region. For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf && .NEAR TERM... Issued at 300 AM EDT Mon May 13 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 A few sprinkles are moving across the region as of 06-07Z, in response mainly to a pseudo warm front passing overhead as weak high pressure moves northeastward. This is setting the stage for the start of an active few days, as a more robust warm front approaches the region this afternoon and evening. The timing of this also coincides with the diurnal heating cycle and therefore an onshore sea breeze, which should help to induce convection over northeast FL. At the same time, shortwave energy/diffluence aloft associated with a larger upper trough over the south/central US streams east/northeast along the Gulf coast and across southeast GA. The combination of all these features will result in increasing shower and t`storm coverage throughout the afternoon and evening, likely continuing into at least the first half of tonight. Although plentiful ingredients are in place, the main limiting factor will be instability, as SB/MUCAPE is expected to be generally around 1000 J/kg, decreasing further north and east and especially over southeast GA. Despite this, with the modest dynamics and frontal boundary, the SPC still places the entirety of the CWA in a "marginal" risk for severe storms. The main threats will be gusty winds, hail, and heavy rainfall - though an isolated tornado cannot be ruled out as well. Looking like the best "overlap" of ingredients will be around I-10 southward, though southeast GA certainly cannot be totally overlooked as well. Temps today will be a bit tricky due to the amount of cloud cover likely to be in place (which also will play a big factor in the amount of buoyancy available). However, expecting mid 80s to low 90s south of about I-10 and low 80s and some upper 70s over southeast GA. Expecting a break for most about after midnight through the morning hours, with a mild night of upper 60s to low/mid 70s. && .SHORT TERM... (Tuesday through Wednesday night) Issued at 300 AM EDT Mon May 13 2024 Tuesday...Warm frontal boundary still on track to be somewhere near the FL/GA border early in the day with likely ongoing convective complex along this boundary close to/or just west of the local area and expect this feature to push across the entire area at some point during this time frame with heavy rainfall and isolated strong to severe storms expected. Rainfall totals still expect to be highest along and to the north of the warm frontal boundary with localized 2-4 inch amounts across SE GA and 1-2 inch amounts across NE FL. Damaging winds will remain the main storm threat, but large hail and/or isolated tornadoes cannot be ruled out. Max temp forecast a bit tricky due to possible timing issues with storm activity but widespread highs in the 80s expected, with some lower 90s possible across NE FL south of a line from Ocala to St. Augustine. Even without storm activity expect the gradient wind flow to be out of the Southwest from 15-25 mph with gusts to 35 mph at times, strongest in the warm sector across NE FL. Tuesday Night...Mid to upper level trough sweeps into SE GA through the night with dry slot of air aloft pushing the frontal boundary with numerous showers and isolated strong/severe storms with heavy rainfall from SE GA during the evening hours slowly southward into NE FL during the overnight hours with waves of storms moving along this boundary during this time frame. Training of storms over already wet soils in some areas from this pattern set up may require the issuance of a Flood Watch for some areas on Tuesday ahead of this event. Low temps generally near 70 with gusty Southwest winds continuing at 10-20 mph with gusts to 30 mph at times. Wednesday...Models trending towards dry slot aloft pushing in faster and driving trailing frontal boundary with showers/storms and heavy rainfall south of the region quicker than previous model runs, but for now have kept rainfall chances mainly during the morning hours across all areas, then shifting southward through NE FL during the early to mid afternoon hours with some partial clearing by the end of the day as frontal boundary pushes into Central Florida. Max temps generally in the mid/upper 80s with winds shifting to the West at 15-20 mph with gusts to 30 mph at times. Wednesday Night...Drier airmass overspreads the local area with mainly dry conditions after sunset and skies becoming mostly clear and temps falling into the 60s area-wide behind the frontal passage. && .LONG TERM... (Thursday through Sunday) Issued at 300 AM EDT Mon May 13 2024 Thursday...Lingering dry airmass in place between weather systems will continue mainly dry conditions with above normal temps reaching into the upper 80s/lower 90s over inland areas with West- Northwest winds at 10-15 mph and East Coast sea breeze remains pinned closer to the Atlantic Coast along the I-95 corridor. Friday/Saturday...Another similar scenario with warm frontal boundary lifting back northward on Friday and trailing frontal boundary pushing southward through the region on Saturday with heavy rainfall and isolated strong to severe storm potential area- wide and rainfall chances already in the 50-70% range. Above normal temps will continue. Sunday...Lots of long range model uncertainty as some models push drier air into the region, while some stall the frontal boundary in the vicinity so for now the model blends are just placing normal diurnal scattered convection due to local sea breeze activity as above normal temps continue. && .AVIATION... (12Z TAFS) Issued at 649 AM EDT Mon May 13 2024 Overall thinking has not changed significantly since the last forecast. VFR is expected to continue through early this afternoon as cloud decks above 030 move in later this morning. Expecting convection to increase this afternoon and evening, with TEMPO groups now added for similar timing to the earlier forecast as well as a continued gusty wind potential. Isolated storms may be strong to severe, with gusts up to 40-60+ knots. More detail to TEMPO groups will be added throughout the day as the event unfolds. SHRA/-RA lingers tonight as more significant convection moves offshore. MVFR conditions will be likely for most of the night for this same period, and IFR also appears possible through the end of the forecast period. && .MARINE... Issued at 300 AM EDT Mon May 13 2024 Southeasterly winds increase through today as a warm front lifts northward toward the coastal waters. This will result in Small Craft Advisory conditions this evening and overnight tonight. Showers and storms will spread over our local waters this afternoon and into the evening ahead of the aforementioned warm front. Tuesday, the front stalls just north of the local waters as several rounds of heavy showers and storms push across the area through Wednesday. Conditions improve on Thursday as weak high pressure and offshore flow develops. Rip Currents: Rip current risk will be low to moderate given the offshore or along shore wind developing today and into Tuesday. && .HYDROLOGY... Issued at 240 PM EDT Sun May 12 2024 From Monday to Wednesday, forecast storm total rainfall amounts are from 2 to 3 inches for southeast GA to about 1 to 2 inches for northeast FL. This may be enough to raise river levels a bit but for now no minor river flooding is forecast. The high- end potential total rain is over 5 inches in some locations, mainly favoring nrn half of the area, so we will need to monitor trends in the guidance for further updates to the forecast rainfall. && .PRELIMINARY POINT TEMPS/POPS... AMG 79 67 83 69 / 90 80 100 70 SSI 81 70 84 72 / 80 80 90 70 JAX 83 69 89 71 / 70 80 90 70 SGJ 83 71 91 71 / 60 70 80 60 GNV 87 69 89 71 / 70 70 80 70 OCF 89 71 92 71 / 60 60 70 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...Small Craft Advisory from 5 PM this afternoon to 11 AM EDT Tuesday for AMZ450-452-454. Small Craft Advisory from 5 PM this afternoon to 2 PM EDT Tuesday for AMZ470-472-474. && $$