Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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782 FXUS62 KJAX 150534 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 134 AM EDT Wed May 15 2024 ...New AVIATION... .UPDATE... Issued at 939 PM EDT Tue May 14 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 Overall forecast is in good shape with only minor adjustments to increase the QPF/rainfall forecast up a little for the predawn hours and into midday as waves strong to isolated severe T`storms develop after midnight tonight as a jet streak moves in from the Gulf. SW surface winds 5-10 mph will remain overnight with increasing low level southwest winds 40-45 knots head of a approaching cold front will help to destabilize the environment late tonight and raise elevated CAPE values towards 2,000 J/kg with about 500-800 J/kg of CAPE within the Hail growth zone of -10C to -30C aloft aiding a threat of potentially large hail with more intense storms. Strong bulk shear values of 50 knots will also help support a gusty wind threat 40-60mph along with heavy downpours that will bring more than a an inch of rain for areas south of I-10 with locally heavy rainfall amounts of 2-3 inches possible where heavier storms develop. An isolated tornado threat cannot be ruled out either due to the enhanced low level shear. Lows overnight will be above normal in the upper 60s and lower 70s. Showers and embedded thunderstorms will continue Wednesday morning before shifting south and east to the NE FL coast by midday and then ending for all areas by afternoon as the cold front moves into the area and begins to slow it`s progression. Ahead of the front, winds will be southwest 10-15 mph with gusts to 25-30 mph. Bumped up highs a bit to account for convection ending a bit sooner Wednesday with upper 80s for much of the area and cooler over north central FL into the mid 80s where convection and clouds persist longer through the early afternoon. && .SYNOPSIS... Issued at 314 PM EDT Tue May 14 2024 Afternoon surface analysis depicts a warm front lifting northward through the Carolinas and north GA, with a wavy cold front extending from north to south across the Tennessee and Lower Mississippi Valleys. Aloft...closed upper troughing centered over the Mid-Mississippi Valley was moving slowly eastward, with ridging centered over Cuba and the northwestern Caribbean Sea. This weather pattern was creating deep southwesterly flow across our area, with this flow propelling the shortwave trough and associated weakening Mesoscale Convective System (MCS) that impacted our area earlier this morning offshore and east of Cape Canaveral this afternoon, with another MCS moving eastward across the east central Gulf of Mexico, or south of the FL panhandle coast, this afternoon. Subsidence in the wake of the departing MCS was allowing for filtered sunshine to overspread our area this afternoon from west to east, as thick debris cirrostratus cloud cover along the I-95 corridor thins out as convection moves further away from our area. Breezy south-southwesterly winds prevail across northeast and north central FL in the wake of the MCS, with lighter winds for locations north of Interstate 10. Temperatures at 19Z were generally in the 80s area-wide, except upper 70s beneath the thicker departing cirrostratus across coastal Flagler County. Dewpoints were mostly in the upper 60s and lower 70s throughout our region. && .NEAR TERM... (through Tonight) Issued at 314 PM EDT Tue May 14 2024 Subsidence in the wake of the departing MCS should keep a lid on convective activity across our region through the evening hours, with a few showers possibly developing towards midnight ahead of the next developing MCS that is expected to impact our region overnight. This next MCS will be aided by a 90-knot jet streak at 250 millibars (around 35,000 feet) that will be developing at the base of the trough that will be digging into the Tennessee Valley overnight, which will also force a 40-50 knot low level southwesterly low level jet around 850 millibars (around 5,000 feet) that will become aligned along the Interstate 10 corridor towards sunrise. The digging trough will push a cold front eastward across the FL panhandle overnight. Increasingly divergent flow aloft as a result of strengthening winds aloft should create an expanding area of convection along or just north of the Interstate 10 corridor just after midnight tonight, with an increasing potential for strong to isolated severe thunderstorms expected during the overnight and predawn hours, mainly across northeast FL. Heavy downpours may extend into coastal southeast GA during the overnight and predawn hours before convection begins a southeastward push towards sunrise on Wednesday. The main threats with strong to isolated severe convection overnight will be downburst winds of 40-60 mph and hail, and an isolated tornado cannot be ruled out, especially for locations south of I-10. Widespread 1-2 inch rainfall totals will be possible by sunrise for coastal southeast GA and the I-10 corridor before activity shifts south of I-10 after sunrise. Lows tonight will only fall to the upper 60s across inland southeast GA and lower 70s elsewhere. && .SHORT TERM... (Wednesday through Thursday night) Issued at 314 PM EDT Tue May 14 2024 The active weather pattern continues through Wednesday, with another round expected overnight tonight and through Wednesday afternoon. Strong to isolated severe potential will be highest in the morning south of I-10 with the primary hazards being gusty winds, locally heavy rainfall, and isolated tornadoes. By early afternoon, the bulk of the storms will be offshore/south of the area, with lingering isolated thunderstorms possible through the afternoon over north central FL. High temperatures will trend near normal Wednesday, reaching the mid to upper 80s area-wide. A brief break in this wet pattern is expected for Thursday as the front sits just south of the area over central Florida. Clear skies will allow for good daytime heating with highs reaching to upper 80s to lower 90s. Beachside will be able to heat up into the upper 80s/near 90 as well due to elevated west/northwest winds preventing an east coast sea breeze from moving far inland. && .LONG TERM... (Friday through next Tuesday) Issued at 314 PM EDT Tue May 14 2024 Precipitation chances will return Friday afternoon/evening and last through Monday as the front lifts northward Friday, followed by a trialing cold front incoming from the northwest this weekend. The highest rain chances will be on Saturday ahead of the frontal passage, numerous showers and isolated thunderstorms are forecast. More uncertainty in the forecast comes on Sunday and Monday, depending on where the front`s position is, for now scattered rain and thunderstorm chances are in the forecast both days. High temperatures will range from the mid 80s to lower 90s each day during this period, with mild lows in the mid 60s to lower 70s. && .AVIATION... (06Z TAFS) Issued at 124 AM EDT Wed May 15 2024 SHRA and TSRA are developing at this hour, and are expected to increase in coverage for most through the next several hours. TSRA is expected for at least all FL terminals, though have continued to include at SSI as well. Recent trends in guidance have been for a southern shift in TSRA coverage, though confidence is too low to remove SSI from TSRA consideration. GNV and SGJ are will have the highest chances for TSRA as well as strong to severe TSRA, which will last into the late morning to afternoon hours. Some storms this morning could be capable of large hail and gusts of 35-55 knots. Heavy rainfall and lower ceilings will also cause periods of MVFR and isolated IFR, as indicated in TEMP groups. TSRA and especially strong/severe TSRA threat subsides from north to south at terminals this afternoon and into the evening, with only some isolated SHRA lingering before sunset. VFR is expected to return for the final 3 to 6 hours of the forecast period. && .MARINE... Issued at 314 PM EDT Tue May 14 2024 Southwesterly winds will strengthen overnight ahead of an approaching cold front, with widespread showers and the potential for strong to severe thunderstorms expected developing over our local waters after midnight. Strong to severe thunderstorms will be capable of producing damaging wind gusts, hail and waterspouts late tonight and Wednesday morning. Activity will then shift southeastward late on Wednesday morning as the frontal boundary shifts southward. Outside of thunderstorm activity, winds will increase to Caution levels of 15-20 knots throughout our local waters by Wednesday morning, with Caution conditions continuing offshore on Wednesday night. Seas of 3-5 feet are expected both nearshore and offshore through Wednesday. Conditions will improve from north to south on Wednesday afternoon and evening as the frontal boundary shifts southward, with breezy westerly winds expected outside of thunderstorm activity that will gradually subside by Thursday afternoon as weak high pressure settles over the southeastern states. Seas will remain in the 3-5 foot range offshore on Wednesday night, with near shore seas subsiding to 2-4 feet. Winds will then shift to southerly on Friday ahead of the next frontal boundary that will impact our area this weekend. Showers and thunderstorms will likely impact our local waters from Saturday afternoon through Sunday morning, with a few strong storms possible. Winds will then shift to northwesterly by Sunday afternoon and night as this front pushes offshore. Seas of 2-4 feet are expected throughout our local waters from Thursday through the upcoming weekend. Rip Currents: A southeasterly ocean swell and choppy surf conditions will keep a lower end moderate risk in place at area beaches through Wednesday. Light prevailing offshore winds should result in a low risk by Thursday. && .PRELIMINARY POINT TEMPS/POPS... AMG 88 65 88 67 / 20 0 0 0 SSI 88 69 86 71 / 50 0 0 0 JAX 88 67 90 68 / 60 0 0 0 SGJ 87 69 90 69 / 80 0 0 0 GNV 86 67 89 67 / 70 0 0 0 OCF 84 67 89 67 / 80 0 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$