Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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838 FXUS62 KJAX 191243 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 843 AM EDT Thu Sep 19 2024 ...New UPDATE... .UPDATE... Issued at 842 AM EDT Thu Sep 19 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 Frontal boundary will slide just south of the forecast area this afternoon. The greatest chance for a few showers and storms Today will be across north central FL counties due to frontal convergence, and for areas along I75 corridor due to Gulf coast sea breeze convergence. Partly to mostly sunny skies this afternoon, with highs in the mid to upper 80s. Areas south of GNV could reach highs into the lower 90s. && .NEAR TERM... Issued at 349 AM EDT Thu Sep 19 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 weak cold front over SE GA this morning will continue to shift southward and into central FL this afternoon. A drier (PWATs 1.3-1.5 in.) and more stable north-northwesterly flow builds over the region squashing convective coverage to be mainly isolated. Convection today will be limited to along the inland moving sea breezes, the only source of lift, this afternoon into evening. Highs today will range from the upper 80s to around 90. Any convection that manages to develop will wane this evening with the loss of daytime heating. A drier and more subsident air mass may allow another round of patchy inland fog to develop early Friday morning. Overnight lows will fall to the upper 60s in inland SE GA to the lows 70s elsewhere. && .SHORT TERM... (Friday through Saturday night) Issued at 349 AM EDT Thu Sep 19 2024 Troughing will persist along the U.S. eastern seaboard on Friday and Saturday, while stout ridging aloft resides over Texas. This weather pattern will result in deep northerly flow across our area, and our local pressure gradient will begin to tighten during the afternoon hours on Friday as low pressure strengthens off coastal New England and high pressure builds down the spine of the Appalachians, resulting in breezy onshore winds developing along the I-95 corridor during the afternoon hours. This breezy and convergent low level flow could develop a few showers and thunderstorms along an inland moving Atlantic sea breeze boundary during the afternoon hours, with activity then potentially becoming widely scattered over north central FL and southern portions of the Suwannee Valley during the late afternoon hours as the Atlantic sea breeze boundary collides with a pinned Gulf coast sea breeze along and west of the I-75 corridor. A drier air mass and plenty of morning and early afternoon sunshine will boost highs to the upper 80s to around 90 for locations along and west of I-95. Breezy onshore winds will keep coastal highs in the mid 80s. An onshore breeze will continue at coastal locations on Friday night, keeping lows in the low to mid 70s. Winds at inland locations will decouple by late in the evening, with a seasonably dry air mass and fair skies allowing lows to fall to the mid and upper 60s by sunrise on Saturday. Breezy northeasterly winds will prevail on Saturday along the I-95 corridor, with these breezy conditions spreading inland during the afternoon hours. There may be just enough moisture and low level convergence for a few showers to advect onshore along the northeast FL coast, with activity potentially shifting inland towards north central FL during the late afternoon hours, where an isolated thunderstorm cannot be ruled out. A seasonably dry and subsident air mass will prevail for southeast GA and the Suwannee Valley. Highs on Saturday will again climb to the upper 80s to around 90 for inland locations along and west of I-95, with breezy onshore winds keeping coastal highs in the mid 80s. Any showers or thunderstorms that manage to develop on Saturday afternoon for locations south of I-10 will dissipate around sunset, with fair skies expected overnight area-wide. Decoupling winds at inland locations will allow lows to fall to the mid to upper 60s at most inland locations, with breezy onshore winds keeping coastal lows in the low to mid 70s. && .LONG TERM... (Sunday through Wednesday) Issued at 349 AM EDT Thu Sep 19 2024 Ridging aloft will continue to flatten but will expand eastward along the northern Gulf Coast on Sunday as a potent shortwave trough progresses across the eastern Rockies and enters the High Plains states. This ridge will then become centered along the northern Gulf coast states on Monday and then directly overhead by Tuesday. Long-term models then diverge on the evolution of the trough that will progress from the High Plains towards the Upper Midwest on Tuesday and then the Great Lakes region by midweek, as the base of this trough may become cutoff over west Texas. This will have important implications for a potentially developing tropical cyclone over the northwestern Caribbean Sea during the early to middle portions of next week. Confidence in the evolution of this weather pattern remains low in the extended portion of the forecast, with global models trending slower with the potential for a tropical cyclone to emerge into the Gulf of Mexico at some point next week. A dry and subsident air mass will prevail locally beneath the ridge, with only isolated afternoon showers possible along the inland moving Atlantic sea breeze boundary for locations in north central FL and southern portions of the St. Johns River basin on Sunday and Tuesday, with dry weather expected area-wide on Monday. Highs will continue to climb to the upper 80s to around 90 at inland locations, while persistent breezy onshore winds keep coastal highs mostly in the mid 80s. Lows will continue to fall to the mid and upper 60s inland, while onshore winds keep coastal lows in the low to mid 70s. Breezy easterly winds are currently forecast on Wednesday, and a moistening trend may commence from south to north, which may result in isolated to widely scattered showers and thunderstorms, especially for locations south of I-10. Highs should again reach the mid to upper 80s, with lows falling to around 70 inland and the mid to upper 70s at coastal locations. && .AVIATION... (12Z TAFS) Issued at 642 AM EDT Thu Sep 19 2024 A few showers have developed along the frontal boundary over NE FL and may pass in the vicinity of SGJ between 11-12Z. Patchy fog and low stratus over inland TAF sites will lift and dissipate after 12Z. Calm winds this morning become north- northwesterly as the front shifts into central FL by this afternoon. Easterly winds develop at the coastal and Duval TAF sites between 17-20Z as the weak Atlantic sea breeze shifts inland. Low chances for rain this afternoon with maybe a shower passing by a TAF site but chances are too low to include at this time. && .MARINE... Issued at 349 AM EDT Thu Sep 19 2024 A weak cold front over the coastal waters will shift south of the waters later this morning. Light northwesterly winds shift to east-northeasterly as the sea breeze shifts inland this afternoon. Stronger high pressure will build down the east coast Friday into early next week. This will lead to an increase in Northeast winds and seas for this weekend reaching Small Craft Exercise Caution levels. Caution levels will likely continue into early next week for the offshore waters. Rip Currents: Moderate rip current risk for NE FL and SE GA beaches continues through Friday. Risk will likely increase this weekend with higher tides combined with the return of onshore winds. && .HYDROLOGY... Issued at 349 AM EDT Thu Sep 19 2024 High tides have now been peaking in minor flood stage within the St. Johns river basin which prompted the downgrade of the Coastal Flood Warning to an advisory. Minor coastal flooding will continue at times of high tide for the St. Johns river through at least Friday. Peak tidal levels for this full moon cycle will continue through Sept. 21st. Minor coastal flooding likely returns on Friday for the NE FL Atlantic coast and ICWW with the peak tides and developing northeasterly winds. && .PRELIMINARY POINT TEMPS/POPS... AMG 88 69 87 66 / 10 0 20 0 SSI 84 73 84 72 / 10 10 10 0 JAX 88 70 87 69 / 10 10 20 0 SGJ 87 74 85 73 / 10 10 20 10 GNV 90 71 88 68 / 20 10 30 0 OCF 91 71 89 69 / 20 20 20 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 AM EDT Saturday for FLZ033-038- 125-132-137-225-325. Coastal Flood Advisory from 5 AM Friday to 5 AM EDT Saturday for FLZ124-133-138. GA...None. AM...None. && $$