Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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167 FXUS62 KJAX 011809 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 209 PM EDT Mon Jul 1 2024 ...STRONG STORMS AND HEAVY DOWNPOURS POSSIBLE THIS AFTERNOON AND EVENING... ...WIDESPREAD DOWNPOURS AND LOCALIZED FLOODING POSSIBLE ON TUESDAY AFTERNOON AND EVENING... ...DANGEROUS HEAT INDICES POSSIBLE FRIDAY THROUGH THE UPCOMING WEEKEND... .NEAR TERM... Issued at 209 PM EDT Mon Jul 1 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 Noon surface analysis depicts a cold front stretching from the Ozarks eastward to the Carolinas that is decelerating as it pushes into the Deep South. Meanwhile, strong high pressure (1030 millibars) was building over the Great Lakes region in the wake of this frontal boundary. Aloft..."Heat Wave" ridging remains centered along the Red River Valley of northern Texas, with this feature continuing to expand into the southeastern states. Otherwise, troughing was progressing southeastward towards the Mid-Atlantic states and coastal New England. Latest GOES-East derived Total Precipitable Water imagery indicates that deep tropical moisture prevails throughout our region, with PWATS generally in the 2 - 2.2 inch range, except for north central FL, where values were in the 1.8 - 2 inch range. Slow moving, low- topped showers were developing within this very humid air mass along portions of the U.S. Highway 301 corridor in southeast GA, while convection developing along the Gulf coast sea breeze along the FL Big Bend and Nature Coasts remains nearly stationary over Levy and Dixie Counties, while showers were developing ahead of this sea breeze boundary across southern portions of the Suwannee Valley early this afternoon. Temperatures at 16Z were mostly in the low to mid 80s across southeast GA, with values rising to the 85-90 degree range elsewhere for northeast and north central FL. Dewpoints were in the mid to upper 70s at most locations. Our area will remain within a col region aloft during this afternoon as "Heat Wave" ridging remains centered to the west of our area and troughing progresses southeastward and offshore of the Mid-Atlantic and New England coasts. The frontal boundary will get pushed southward across the Altamaha River this evening before support aloft wanes, as troughing exits into the Atlantic and ridging aloft nudges eastward over the Lower Mississippi Valley. Light winds within the aforementioned col region overhead will result in slow moving downpours developing this afternoon, with activity likely developing along a lingering low level trough that is situated along U.S. Highway 84 in southeast GA, with additional scattered convection being generated by the inland moving Atlantic and Gulf sea breeze boundaries. Short-term, high resolution model guidance continues to target the U.S. Highway 301 corridor in southeast GA for excessive rainfall potential, where a quick 2-4 inches with locally higher totals will be possible in a corridor from Nahunta and Blackshear northeastward to Jesup and Darien through this evening. Mesoscale boundary collisions may shift another axis of heavy downpours southward along the I-10 and I-75 corridors through the evening hours, where a widespread 1-2 inches with locally higher amounts will be possible for locations such as Macclenny, Lake City, Live Oak, and Gainesville. Some of this activity will attempt to shift towards the I-95 corridor after sunset before waning towards midnight. The morning sounding at Jacksonville revealed a steep lapse rate in the mid-levels, with a pocket of mild and dry air above this layer. Strong to isolated severe thunderstorms will be possible this afternoon through early this evening, with wet microbursts potentially bringing wind gusts up to the 40-60 mph range, along with frequent lightning strikes and slow moving downpours. High temperatures will generally climb to the lower 90s this afternoon before thunderstorm coverage increases. Convective coverage will diminish towards midnight, with debris cloudiness thinning out overnight across northeast and north central FL, while low stratus clouds likely develop during the predawn and early morning hours along the stalling frontal boundary across southeast GA. Lows tonight will generally fall to the mid 70s inland and the upper 70s at coastal locations. && .SHORT TERM... (Tuesday through Wednesday night) Issued at 209 PM EDT Mon Jul 1 2024 Weakening frontal boundary draped across SE GA on Tuesday will stall across the FL/GA state border and diffuse on Wednesday as surface high pressure shifts off the mid-Atlantic coast. Meanwhile, upper ridging builds over the SE US shifting flow to north-northeasterly. Models have slightly delayed the influx of drier air from the north allowing deep tropical moisture (PWATs 2.2-2.5 in.) to remain over the area through Wednesday. Scattered to numerous showers and storms develop each day along the sea breezes and the frontal boundary. This boundary and mesoscale collisions will provide the focus for stronger convection, with gusty winds and heavy rain as the main threats. Areas that have received heavy rain over the past couple of days may be more susceptible to flooding from slow-moving storms. High temperatures will be in the 90s for most inland areas and in the upper 80s along the coast and for areas behind the frontal boundary. Overnight low temperatures will drop into the 70s. && .LONG TERM... (Thursday through Sunday) Issued at 209 PM EDT Mon Jul 1 2024 Upper ridging remains over the SE US through the end of the week before shifting southeastward as an upper trough digs into the Plains this weekend. Daily chances for showers and storms along the sea breezes continue into the weekend but convection becomes more scattered with drier north-northeasterly flow. The greatest chances for storms will be over north-central FL where PWATs remain 2+ inches. Ridging and drier air will allow high temperatures to quickly rise into the mid/upper 90s through the weekend. Heat indices will likely rise into heat advisory criteria by the weekend. && .AVIATION... (18Z TAFS) Issued at 209 PM EDT Mon Jul 1 2024 Showers and thunderstorms will increase in coverage at the regional terminals this afternoon, with activity potentially lingering into the evening hours. TEMPO groups have been placed in each terminal`s TAF through the early evening hours, with IFR visibilities expected during heavier downpours at SSI, JAX, VQQ, and GNV. MVFR visibilities will be possible if downpours reach SGJ and CRG. Activity should diminish by 04Z Tuesday, with MVFR to IFR visibilities possible overnight at VQQ, with lower confidence for low stratus ceilings at SSI, JAX and GNV through around 14Z. MVFR ceilings are then expected after sunrise through the morning hours on Tuesday, with showers and thunderstorms then potentially developing after 16Z along inland moving sea breeze boundaries. Southwesterly surface winds will prevail at the inland terminals, except east southeasterly at the coastal terminals behind the inland moving Atlantic sea breeze boundary. Prevailing winds will shift to southerly after convection subsides late this evening, with speeds diminishing by midnight. The exception will be at SSI, where onshore winds will develop during the predawn hours, with speeds increasing to 5-10 knots towards sunrise. && .MARINE... Issued at 209 PM EDT Mon Jul 1 2024 A frontal boundary will approach our local waters from the north tonight. Breezy south to southwest winds will prevail ahead of this approaching frontal boundary through tonight. The frontal boundary will stall over the Georgia waters on Tuesday and dissipate, with increasing chances for mainly afternoon and nighttime showers and thunderstorms across our local waters. Prevailing winds will shift to east and southeast beginning on Tuesday through Wednesday as high pressure builds down the southeastern seaboard. Seas of 2-4 feet will prevail both near shore and offshore during the next several days. High pressure will then weaken as it shifts southward towards our local waters later this week. Rip Currents: Onshore winds developing in the wake of the inland moving Atlantic sea breeze will combine with a persistent, long period easterly ocean swell to create a lower end moderate rip current risk at all area beaches through at least Tuesday. && .HYDROLOGY... Issued at 400 AM EDT Mon Jul 1 2024 Deep tropical moisture over the region will lead to heavy downpours from convection especially along and ahead of an approaching frontal boundary/trough from the north. WPC has placed SE GA in a slight risk of excessive rainfall today. Localized areas could see rain amounts of 3 inches, with higher amounts of 5 inches possible. A Flood Watch was introduced for a few southeast GA counties for this threat. Refinements to the watch may be needed later today. && .PRELIMINARY POINT TEMPS/POPS... AMG 74 88 74 91 / 60 70 30 60 SSI 79 88 78 89 / 50 40 40 60 JAX 75 91 76 92 / 60 60 30 70 SGJ 77 92 78 91 / 40 40 30 60 GNV 74 92 74 92 / 50 60 40 70 OCF 74 93 76 93 / 40 60 40 70 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...Flood Watch until 10 PM EDT this evening for GAZ136-151>153. AM...None. && $$