Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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738 FXUS62 KJAX 241559 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 1159 AM EDT Mon Jun 24 2024 ...New AVIATION... .UPDATE... Issued at 829 AM EDT Mon Jun 24 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 Forecast on track as hot and humid West to Southwest flow pattern will push Max Temps into the mid/upper 90s and combine with dew points in the 70s to produce widespread peak Heat Indices into the 105-110 range, with Heat Advisory levels (HI>=108) expected along the I-95 corridor (Atlantic Coastal Counties) and I-10 corridor (Portions of Inland NE FL) this afternoon. Expect the W-SW flow to delay the onset of the East Coast sea breeze moving inland until the late afternoon/early evening hours, which will combine with shortwave trough aloft, currently over GA/AL region that will track SE into the local area and help to trigger scattered to numerous showers/storms with isolated severe storms possible with damaging downburst winds of 50-60 mph possible with storm mergers or storm outflows that interact with the East Coast sea breeze. Slow and erratic storm motion around 10 mph or less will also promote localized flood threat in urban areas. With the late start to convection today, expect storms to continue over inland areas until around midnight, with convection fading during the early overnight hours and mainly just fair skies and humid conditions towards sunrise Tuesday morning. Warm overnight lows in the middle 70s inland and upper 70s/near 80 along the Atlantic Coastal areas. && .SYNOPSIS... Issued at 437 AM EDT Mon Jun 24 2024 Early morning surface analysis depicts a frontal boundary pushing southeastward from the Mid-Atlantic states and the Ohio and Tennessee Valleys, with the axis of Atlantic high pressure stretching westward across the FL peninsula. Aloft...the large "Heat Wave" ridge in place over the southern tier of the nation continues to retrograde westward towards the Rio Grande Valley and the Desert Southwest as troughing digs southeastward from the Great Lakes region and the Ohio Valley towards New England the Mid-Atlantic states. Latest GOES-East derived Total Precipitable Water imagery indicates that an unseasonably dry air mass remains in place across most of inland southeast GA, where PWAT values were below 1.5 inches for locations north and west of Waycross. Values elsewhere across northeast and north central FL were close to late June climatology, as PWATs were generally in the 1.8 - 2 inch range. Weak shortwave energy and remnant outflow boundaries from convection on Sunday afternoon have developed isolated showers during the predawn hours along the I-10 corridor in Baker County as well as portions of coastal Duval County, while southwesterly flow has driven a few showers into Gilchrist County from the northeastern Gulf of Mexico. Otherwise, a band of mid- level cloudiness was progressing southward across the FL/GA border, with fair skies in place elsewhere across inland southeast GA as well as across most of north central FL. Temperatures at 08Z were mostly in the 75-80 degree range, with dewpoints in the 70s area- wide. && .NEAR TERM... (Today and Tonight) Issued at 437 AM EDT Mon Jun 24 2024 Troughing aloft will continue to dig southeastward towards New England and the Mid-Atlantic coast by this afternoon, with this feature driving a weakening frontal boundary into the southeastern states. Low and mid-level west-southwesterly flow ahead of this weakening boundary will shift to northwesterly by this evening, and a ribbon of deeper moisture values preceding this boundary will traverse southeast GA late this afternoon and northeast FL this evening. West-southwesterly flow will delay the development of the Atlantic sea breeze to the early afternoon hours, with near record heat expected today for locations along and north of the I-10 corridor, where highs will climb to the mid and upper 90s all the way to the Atlantic coast. Dewpoints will mix down to the 60s this afternoon within the drier air mass across southeast GA, keeping maximum heat index values generally in the 100-105 degree range. Dewpoints will remain in the 70s elsewhere today, with these values combining with the near record heat (see Climate section below for details) along the I-10 and I-95 corridors to create heat indices in the 108-111 degree range through the late afternoon hours. A Heat Advisory has been issued for the coastal counties along the I-95 corridor as well as the inland counties all along the I-10 corridor throughout the afternoon and early evening hours before sunset. Convection should remain scattered and focused along mesoscale boundaries such as the Atlantic and Gulf coast sea breezes, as well as the St. Johns River breeze later this afternoon through around midnight tonight. Some of the higher resolution guidance is suggesting that convection will focus along the I-95 corridor in northeast FL towards sunset. Model soundings indicate that downdraft CAPE values will rise to the 1,000-1,500 j/kg range across northeast and north central FL, so a few storms may pulse and become strong later this afternoon and this evening, with downburst wind gusts of 40-50 mph, frequent lightning strikes, and heavy downpours possible. Activity could linger through around midnight as the ribbon of deeper moisture migrates southward towards the I-10 corridor, while a drier air mass again advects into southeast GA overnight as low and mid level flow shifts to northwesterly. Debris cloudiness will gradually thin out during the predawn hours on Tuesday, with lows only falling to the mid and upper 70s at most locations. && .SHORT TERM... (Tuesday and Wednesday) Issued at 437 AM EDT Mon Jun 24 2024 Drier air (PWATs around 1.5") lingering over parts of SE GA will keep rain chances and cloud cover a bit lower than across NE FL on Tuesday, with higher coverage in diurnal thunderstorms over north central FL as the sea breezes push inland and interact. High precip chances will continue Wednesday as light southerly flow allows for a repeat of sea breeze formation and interactions. Southerly winds and mostly sunny skies will help temperatures soar into the mid to upper 90s both days, with heat indices reaching above 100 degrees for most of the area. The majority of the area is expected to remain just below heat advisory criteria, though some spots could see heat indices flirting with that threshold at times, especially around the St. Johns River to the coast and Suwannee Valley. && .LONG TERM... (Thursday through Sunday) Issued at 437 AM EDT Mon Jun 24 2024 Hot temperatures will continue through the end of the week, with highs generally in the 90s, with lows in the 70s. Weak southerly winds through the period will promote diurnal showers and embedded thunderstorms as both the Gulf and Atlantic sea breezes develop and interact inland. && .AVIATION... (18Z TAFS) Issued at 1151 AM EDT Mon Jun 24 2024 West-Southwest flow is kicking off some convergent showers along the Big Bend Gulf Coast that are pushing slowly inland towards GNV and will likely see some isolated convection (VCTS) kick off there at the beginning of the TAF period, while all of the Atlantic Coastal TAF sites will need to wait for the East Coast sea breeze to push in late this afternoon/early evening before TEMPO groups will likely be needed in the 21-02Z time frame for potential MVFR CIGS/VSBYS and gusty winds. Convection will fade in the 03-06Z time frame with VCSH becoming lingering VFR mid/high clouds during the overnight hours. Expect some light MVFR fog possible at GNV/VQQ around sunrise Tuesday morning, especially if rainfall occurs at those locations this afternoon/evening. Any convection expected on Tuesday will likely occur after the current TAF period and will leave out of the current TAF package. && .MARINE... Issued at 437 AM EDT Mon Jun 24 2024 A surface trough progressing across the southeastern states will stall to the northwest of our area tonight and Tuesday. Southwesterly winds will prevail across our local waters, with a southerly evening wind surge bringing speeds up to Caution levels tonight for the offshore waters. Seas of 2 to 4 feet both near shore and offshore today will build to 3-5 feet tonight offshore. Daily rounds of showers and thunderstorms over land areas will progress eastward across our local waters each day this week, with another trough expected to enter the southeastern states later this week that will also stall to the northwest of our local waters. Prevailing winds will then shift to southeasterly by Friday and Saturday as high pressure builds off coastal New England in the wake of the stalled surface trough. Seas of 2 to 4 feet are expected to prevail throughout our local waters from Tuesday through the upcoming weekend. Rip Currents: Breezy onshore winds this afternoon will combine with a lingering east-southeasterly ocean swell to create a lower-end moderate rip current risk at all area beaches today. The risk is expected to become low on Tuesday at the southeast GA beaches as surf heights diminish below 2 feet, while a lower-end moderate risk may persist during the afternoon hours on Tuesday at the northeast FL beaches. && .CLIMATE... Issued at 437 AM EDT Mon Jun 24 2024 Record high temperatures through Wednesday at our designated climate sites: June 24 June 25 June 26 -------------------------------- Jacksonville 101/1914 99/2016 101/1952 Gainesville 101/1950 102/1950 103/1950 Alma, GA 100/1998 100/1998 100/1954 Craig Airport 98/2019 101/1998 95/2014 && .PRELIMINARY POINT TEMPS/POPS... AMG 99 74 98 74 / 40 20 50 20 SSI 94 78 92 78 / 40 30 50 20 JAX 99 76 96 75 / 50 50 70 20 SGJ 96 76 93 76 / 40 40 70 40 GNV 97 74 94 73 / 60 40 70 30 OCF 96 74 94 75 / 60 50 70 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory until 7 PM EDT this evening for FLZ021-023-024-030- 031-033-035-038-120-124-125-132-133-137-138-220-225-232-322- 325-422-425-522. GA...Heat Advisory until 7 PM EDT this evening for GAZ153-154-165-166. AM...None. && $$