####018012355#### FXUS62 KJAX 092216 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 616 PM EDT Thu May 9 2024 ...New UPDATE... .UPDATE... Issued at 615 PM EDT Thu May 9 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 The Tornado Watch has ended for NE FL and SE GA. Isolated strong to severe thunderstorms remain a threat through the evening, with gusty winds likely ahead of the storms as well. Timing for tomorrow's storms has not changed much, expect SE GA and the Suwannee valley area to see strong to severe thunderstorms move in around sunrise. Storms will move east and southeastward through the morning and afternoon, with potential for a second round in the evening. The second round will rely heavily on how storms progress Friday morning. Again, the main hazard for tomorrow will be damaging winds, although isolated tornadoes and hail cannot be ruled out as well. && .SYNOPSIS... Issued at 335 PM EDT Thu May 9 2024 Afternoon surface analysis depicts a wavy frontal boundary extending from the Chesapeake Bay westward across the Ohio Valley and then southwestward across the Tennessee Valley, the Ozarks and northern Texas. Meanwhile, Atlantic high pressure centered to the east of Bermuda continues to extend its axis westward across the FL peninsula. Aloft...stout ridging centered over Mexico's Yucatan Peninsula continues to flatten in response to a longwave that was digging southeastward from the Great Lakes and Upper Midwest. Otherwise, cutoff troughing continues to slowly retrograde westward across the Rockies. A strengthening jet streak at 250 millibars (around 35,000 feet) positioned to the south of the digging longwave trough was migrating from the Mid- Mississippi Valley towards the Tennessee Valley, and this jet streak and associated shortwave troughing was energizing a Mesoscale Convective System (MCS) and associated strong to severe thunderstorms that were progressing east southeastward across inland portions of southeast GA. A drier and more subsident air mass resides closer to the northern periphery of the ridge axis across northeast and north central FL, where temperatures have soared to record levels in the mid to upper 90s, while thunderstorms have cooled temperatures back to the 70s for locations north and west of Waycross. Dewpoints at 19Z ranged from the mid 60s to lower 70s. && .NEAR TERM... (through Tonight) Issued at 335 PM EDT Thu May 9 2024 Strong to severe thunderstorms associated with the southeastward moving MCS will continue to impact southeast GA through late afternoon, with activity expected to cross the FL/GA border in the 5 PM - 7 PM time frame. This MCS will continue racing southeastward early evening hours, with weakening likely as the line pushes across the Interstate 10 corridor towards sunset as it encounters the drier and more stable air mass that remains in place across north central FL. Damaging straight line wind gusts of 50-70 mph will be the primary threat for locations north of I-10, but a few isolated incidents of hail and tornadoes cannot be ruled out across southeast GA through late afternoon. The Storm Prediction Center has maintained an Enhanced Risk (level 3 out of 5) for severe thunderstorms across southeast GA, where a 10% probability of downburst wind gusts in excess of 74 mph exists, in addition to 5% probabilities for tornadoes along with enhanced probabilities for large hail. A Slight Risk was maintained for locations along and south of I-10 into the early evening hours. The longwave trough will continue to dig southeastward across the Tennessee and Ohio Valleys tonight, with strengthening westerly flow to the south of this feature propelling another shortwave trough and associated MCS across the Deep South during the overnight and predawn hours. The prior weakening MCS will push across north central and coastal northeast FL during the early to mid evening hours, with a break in between MCSs expected through the overnight hours. Short-term, high resolution guidance is in relatively good agreement in positioning this next MCS and associated strong to severe thunderstorm threat at the doorstep of the Ocmulgee/Alapaha/Suwannee Rivers around sunrise on Friday, with this activity then sweeping eastward across our area through the morning hours. Breezy west- southwesterly boundary layer flow in advance of this upstream MCS is expected to advect a stratus layer across the Suwannee Valley and inland southeast GA overnight, with these low clouds possibly crossing the I-95 corridor around sunrise. Cloud cover and warm air advection downstream of the approaching cold front should keep lows in the 70-75 degree range overnight. && .SHORT TERM... (Friday through Saturday night) Issued at 335 PM EDT Thu May 9 2024 Upper shortwave trough and associated MCS will move across the region Friday morning bringing strong to severe thunderstorms to the Ocmulgee/Alapaha/Suwannee River basins around sunrise on Friday. This activity will then sweep eastward across our area through the late-morning hours before shifting offshore. There remains uncertainty with the next round of potentially severe weather. If the morning MCS clears the area early enough, the airmass may be able to recover ahead of the approaching cold front from the northwest Friday afternoon into evening. Storms will redevelop ahead of the front but the severity of them will be determined by the airmass recovery. Regardless, damaging straight- line winds will be the main threat along with the potential for hail and isolated tornadoes. The cold front and associated convection is expected to exit to the south Friday evening with a drier airmass clearing the skies in its wake. Sunny skies and around normal temperatures in the 80s are anticipated for Saturday with lows dipping into the upper 50s and 60s. && .LONG TERM... (Sunday through next Thursday) Issued at 335 PM EDT Thu May 9 2024 Warm and dry conditions on Sunday quickly give way to a wet and unsettled pattern for next week as upper shortwaves parade across the region. A wave of low pressure will move eastward across the northern Gulf lifting a stationary front across southern FL up the peninsula Monday into Tuesday as a warm front. As the warm front lifts across the region, a moist and unstable airmass will become established which will support an increasing thunderstorm potential throughout next week. High temperatures will generally be around normal in the 80s and then trend upward on Wednesday. && .AVIATION... (18Z TAFS) Issued at 232 PM EDT Thu May 9 2024 VFR conditions will prevail at the regional terminals through at least 20Z. A Mesoscale Convective System (MCS) is expected to race southeastward towards the terminals late this afternoon through around sunset, bringing the potential for strong to severe thunderstorms to SSI and the Duval County terminals after 21Z. We have included TEMPO groups for wind gusts of 30-45 knots, along with IFR visibilities and MVFR ceilings as this squall line potentially moves across these terminals through 01Z. The MCS/broken squall line will then weaken after 01Z, with confidence too low to indicate anything other than vicinity thunderstorm coverage at GNV and SGJ at this time. MVFR to IFR ceilings will then overspread the regional terminals after 04Z through the early morning hours on Friday. Another MCS is then expected to impact our region after 12Z Friday, with this convective complex expected to move rapidly eastward during the morning hours. We included PROB30 groups from 13Z-18Z at each terminal for the potential of 20-40 knot wind gusts, along with MVFR to IFR conditions during heavier downpours. Gusty southwesterly surface winds sustained around 15 knots, with surface winds shifting to southerly at 10-15 knots at SGJ after 19Z due to a pinned Atlantic sea breeze boundary near the coast. A period of breezy northerly surface winds can be expected in the 00Z-04Z time frame in the wake of the squall line/MCS passage. Otherwise, southwesterly winds of 5-10 knots will resume around or after 06Z Friday. Outside of thunderstorm activity on Friday morning, west- southwesterly surface winds will increase to 15-20 knots and gusty before 15Z. && .MARINE... Issued at 335 PM EDT Thu May 9 2024 A squall line of strong to severe thunderstorms will traverse the Georgia waters during the mid to late afternoon hours today, with this line reaching the northeast Florida waters during the late afternoon and early evening hours. This squall line is expected to weaken after sunset as it approaches the waters from St. Augustine southward. Strong to severe thunderstorms will be capable of producing damaging wind gusts, hail, and frequent lightning strikes. Outside of thunderstorm activity, seas of 3-5 feet will prevail both near shore and offshore through tonight. Otherwise, a cold front will enter the southeastern states tonight and will progress southeastward across our local waters on Friday afternoon and evening. Additional rounds of strong to severe thunderstorms will be possible after sunrise and again during the afternoon hours ahead of this front. Winds will shift to northwesterly in the wake of the frontal passage on Friday night and Saturday morning, with weak high pressure the expected to build eastward from the Ozarks on Saturday night, reaching the coastal Carolina region by Monday afternoon. This weather pattern will result in onshore wind development on Sunday afternoon, with onshore winds then strengthening on Monday night ahead of an approaching warm front. Showers and thunderstorms will overspread our local waters by late Monday night as this warm front lifts northeastward across our area. Rip Currents: Gusty offshore winds should result in a low risk at all area beaches on Friday and Saturday. && .FIRE WEATHER... Issued at 335 PM EDT Thu May 9 2024 Low cloud cover is expected to overspread our region late tonight through early Friday morning. Strong west-southwesterly surface and transport winds on Friday will result in high daytime dispersion values for north central FL, with good values expected elsewhere across northeast FL despite abundant cloud cover and increasing rain chances, with fair values forecast across southeast GA. Rounds of strong to severe thunderstorms are expected from the Interstate 10 corridor northward through the early evening hours today, and then area-wide on Friday morning and again on Friday afternoon. Strong to severe thunderstorms will be capable of producing damaging wind gusts, hail, and frequent lightning strikes. An isolated tornado cannot be ruled out during the severe weather potential through early evening. A cooler and drier air mass will then filter into our region during the weekend, with minimum relative humidity values falling to around 30 percent at most inland locations during the afternoon hours on Saturday and Sunday. Breezy northwesterly transport winds and elevated mixing heights on Saturday could result in elevated daytime dispersion values. && .CLIMATE... Issued at 1232 PM EDT Wed May 8 2024 Daily record Maximum Temperatures at the local climate sites for... Thursday, May 9th...JAX 96/1962...CRG 93/2008...GNV 95/2011...AMG 95/1962 Friday, May 10th...JAX 94/2017...CRG 95/2003...GNV 95/2011...AMG 95/2011 && .PRELIMINARY POINT TEMPS/POPS... AMG 71 83 60 81 / 60 70 10 0 SSI 73 84 64 80 / 80 70 20 0 JAX 73 87 64 84 / 80 80 30 0 SGJ 74 91 67 83 / 20 60 30 10 GNV 73 88 64 87 / 20 60 30 10 OCF 72 89 68 89 / 20 50 30 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$