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Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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090 FXUS62 KJAX 131125 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 725 AM EDT Tue Aug 13 2024 ...New AVIATION... .NEAR TERM... (Today and Tonight) Issued at 258 AM EDT Tue Aug 13 2024 A frontal zone to the northwest will begin to slide southeast into area through the day, with high pressure to the southeast. This frontal zone will sink southeast across forecast area Tonight. Some drier air will be associated with this front, so precipitation chances will be lower than normal. The best chances this afternoon will be across NE FL where better heating and moisture will persist. Any activity which does develop will largely diminish this evening. With convergence along the front, could see a few showers or storms linger a little longer Tonight. Temperatures will trend above normal through Tonight. With the front bringing in some drier air from the northwest, the best chance to reach heat advisory criteria this afternoon will be across eastern counties. && .SHORT TERM... (Wednesday through Thursday night) Issued at 258 AM EDT Tue Aug 13 2024 Deep troughing over New England will begin to cutoff from the main flow pattern on Wednesday, while ridging aloft centered over the Southern Plains states begins to build southeastward towards the lower Mississippi Valley and the northern Gulf coast. This change in the weather pattern will create deepening northwesterly flow aloft, which will allow a "backdoor" cold front to move through our area from north to south from late Wednesday morning through late Wednesday night. Meanwhile, high pressure building over the Great Lakes in the wake of this front will begin to wedge down the southeastern seaboard, resulting in a surge of onshore winds along the southeast GA coast towards noon on Wednesday, with this wind surge then spreading down the northeast FL coast during the afternoon hours. Convergence will increase along the leading edge of this wind surge, resulting in scattered to numerous afternoon showers and thunderstorms, especially for inland locations between the I-95 and I-75 corridors. Activity will shift southwestward ahead of the approaching frontal boundary and could linger into the evening hours for locations along and west of the I-75 corridor. Temperatures ahead of the front will soar to the mid and upper 90s for locations west of the I-95 corridor, except lower 90s for locations north of Waycross, where the front will pass through earlier in the day, as well as at coastal locations, where developing onshore winds will put a halt to rising temperatures. Wednesday should be the last day of Heat Index values reaching Heat Advisory criteria, mainly for locations south of Waycross. Convection should dissipate along the I-75 corridor before midnight, and lows on Wednesday night will fall to the low and mid 70s inland, while an onshore breeze keeps coastal lows in the upper 70s to around 80. High pressure will continue to wedge down the southeastern seaboard on Thursday, ushering in a slightly cooler and drier air mass into our area. Breezy northeasterly winds will prevail along the I-95 corridor, keeping highs in the mid to upper 80s, while highs further inland climb to the lower 90s. There may be enough moisture and convergence in the deepening onshore flow pattern to produce scattered showers and thunderstorms for locations along and south of the I-10 corridor, with only widely isolated coverage possible for locations south and east of Waycross in southeast GA. A much drier air mass will then overspread our region on Thursday night, with breezy onshore winds keeping coastal lows in the upper 70s to around 80. Meanwhile, decoupling winds and fair skies may allow lows to fall to the upper 60s for much of inland southeast GA by sunrise on Friday, with lower 70s expected elsewhere inland. && .LONG TERM... (Friday through Monday) Issued at 258 AM EDT Tue Aug 13 2024 Stacked ridging will be in place across our region on Friday, allowing for our local pressure gradient to gradually relax by Friday evening. Meanwhile, distant Tropical Cyclone Ernesto will reinforce an unseasonably dry air mass across our region, with only isolated late afternoon or early evening showers and thunderstorms possible for north central FL. Breezy onshore winds on Friday will keep coastal highs in the mid to upper 80s, while highs further inland generally climb to the lower 90s. Radiational cooling on Friday night will allow lows to fall to the upper 60s to around 70 at most inland locations, while a light onshore breeze keeps coastal lows in the mid to upper 70s. A potent shortwave trough digging southeastward from the Great Lakes region through the Ohio Valley on Saturday will shift ridging over our area offshore by the afternoon and evening hours. Mid-level flow will shift to northwesterly as a longwave trough begins to dig into the southeastern states, and moisture levels may recover enough to develop isolated convection during the late afternoon and evening hours, especially along the inland moving Gulf coast sea breeze. Highs will rebound slightly to the low and mid 90s for inland locations, with the afternoon sea breeze keeping coastal highs in the upper 80s to around 90. Any convection that manages to develop on Saturday afternoon at inland locations should dissipate by the mid-evening hours. Lows will fall to the 70s area-wide on Saturday night. Troughing aloft will become established over the southeastern states by Sunday and Monday, driving a frontal boundary into the Deep South. West-southwesterly flow will deepen over our region, activating convection along the inland moving Gulf Coast sea breeze boundary. At least scattered afternoon and evening thunderstorms are expected to traverse our region, with a few strong storms possible along the I-95 corridor during the late afternoon or early evening hours as activity interacts with a pinned Atlantic sea breeze boundary. Highs will soar to the low and mid 90s throughout our region, with Heat Index values likely climbing back towards Heat Advisory criteria (108 degrees) by early next week. Lows will remain in the 70s area-wide. && .AVIATION... (12Z TAFS) Issued at 725 AM EDT Tue Aug 13 2024 Thunderstorm chances are forecast to be below normal this afternoon, with only isolated to scattered storms forecast. At this time, have forecast a VCTS during time when best chance for storms will occur. Later forecast updates, can then refine this timing as activity develops, and add restrictions where appropriate. && .MARINE... Issued at 258 AM EDT Tue Aug 13 2024 A frontal boundary will slowly move southeast across the area through Wednesday. This boundary will move off to the southeast Wednesday night, as high pressure builds down the east coast of the US. This ridge of high pressure will remain across the coast through Friday, then will begin to push out over the western Atlantic waters. Tropical Storm Ernesto is well to the southeast of area waters Today, and will track northwest through Thursday, before turning to the north and passing well to the east through the weekend. While Ernesto`s track will be well to the east, it will push elevated seas toward region. Small craft advisory level seas will be possible as a result over outer waters Friday and Saturday. Monitor the National Hurricane Center for the latest forecast track information on Ernesto. Rip Currents: Moderate through Wednesday. Rip current risk will trend toward high for this weekend due to distant Ernesto. && .FIRE WEATHER... Issued at 258 AM EDT Tue Aug 13 2024 Westerly transport winds will prevail today, with surface winds becoming onshore this afternoon along the Interstate 95 corridor as the Atlantic sea breeze boundary pushes inland. Good daytime dispersion values are forecast at most inland locations, while fair values prevail at coastal locations as well as across north central Florida. Transport winds will shift to northwesterly on Wednesday morning and then northeasterly by late Wednesday afternoon, with breezy northeasterly surface winds developing at coastal locations during the afternoon hours. Marginally high daytime dispersion values will be possible for inland locations along the I-10 corridor as well as portions of inland southeast Georgia on Wednesday. Breezy northeasterly surface and transport winds will then overspread our region on Thursday, creating good daytime dispersion values area-wide, with marginally high values possible at inland locations. && .HYDROLOGY... Issued at 258 AM EDT Tue Aug 13 2024 Water levels continue to slowly rise along lower portions of the Santa Fe River near the Three Rivers Estates gauge, where a crest near a major flood is forecast later this week and into the upcoming weekend. Meanwhile, minor flooding is forecast at the gauge near Hildreth, where a crest is forecast late this week or during the upcoming weekend. Further upstream, water levels have crested in a moderate flood near the gauge at Fort White. Moderate flooding will continue around this gauge through at least Friday. Water levels along middle and lower portions of the Santa Fe remain in a minor flood, with levels forecast to fall below flood stage near the gauge at High Springs late this week. Moderate flooding will continue through late this week along the St. Marys River near the gauge at Macclenny. Moderate flooding also continues at the downstream gauge near Traders Hill. Minor flooding continues along upper portions of the Suwannee River, where water levels are forecast to fall below flood stage later this week near the gauge at White Springs. Water levels are cresting in a moderate flood near the gauge at Benton. Rises will continue along lower portions of the Suwannee River during the next week, with minor flooding forecast at several gauges from around the gauge at Luraville and points downstream. Water levels have fallen back to minor flood levels along lower portions of the Satilla River near the gauge at Atkinson. Minor flooding will continue along lower portions of the Satilla River during the next several days. Water levels have fallen below flood stage further upstream near the gauge at Waycross. Water levels have fallen to minor flood levels along lower portions of the Altamaha River near the Everett City gauge. Water levels are forecast to fall below flood stage at this gauge by this evening. && .PRELIMINARY POINT TEMPS/POPS... AMG 96 74 92 72 / 20 10 40 30 SSI 93 78 92 80 / 20 20 40 30 JAX 96 77 94 75 / 20 20 50 20 SGJ 94 77 92 79 / 20 30 40 20 GNV 94 75 95 75 / 30 10 60 40 OCF 94 76 95 75 / 30 10 50 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory from 11 AM this morning to 6 PM EDT this evening for FLZ023-024-030-031-033-038-120-124-125-132-133-138-220- 225-232-322-325-422-425. GA...Heat Advisory from 11 AM this morning to 6 PM EDT this evening for GAZ153-154-162-163-165-166-264-350-364. AM...None. && $$