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Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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934 FXUS62 KJAX 081228 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 828 AM EDT Sat Jun 8 2024 ...New UPDATE... ...NEAR RECORD HEAT THIS WEEKEND... .UPDATE... Issued at 817 AM EDT Sat Jun 8 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 Continued hot and mostly dry today except for 20-35% chances of afternoon showers and possibly a rouge thunderstorm roughly along and south of a St. Augustine to Gainesville line. This is where near climo PWATs of 1.5 inches will coincide over an unstable low level airmass where sea, lake and river boundary collisions focus roughly between 3 pm - 8 pm. Elsewhere, post-frontal dry air will bring mostly dry and sunny skies as high temps soar into the mid to upper 90s making for heat index values in the 100-106 deg range across NE FL where higher moisture will linger with heat index values 95-100 deg near and north of the I-10 corridor where drier air will mix down this afternoon (dew pts mid 50s to near 60). As a reminder, local heat advisory criteria is for the heat index to reach 108-112 degrees F. && .SYNOPSIS... Issued at 401 AM EDT Sat Jun 8 2024 Overnight surface analysis depicts a weakening frontal boundary along the FL/GA border, with weak pressure pattern in place on either side of the boundary across the southeastern states. Aloft...a weakening trough was progressing southeastward across our area, with ridging building over eastern Texas and the lower Mississippi Valley in the wake of this trough. Latest GOES- East derived Total Precipitable Water imagery indicates that a much drier air mass continues to advect southeastward into our region, with PWATS falling below one inch for locations north of Waycross in southeast GA, while values remain around 1.5 inches across north central FL. Only a few patches of mid-level clouds were migrating across our skies along and ahead of the weakening frontal boundary, with fair skies otherwise prevailing throughout our region. A light west- southwesterly breeze prevails to the south of the frontal boundary across northeast and north central FL, where temperatures at 08Z generally remain in the 75-80 degree range, with dewpoints in the 70s. North of this boundary, a light northwest to northerly breeze prevails, with cool air advection dropping temperatures to the upper 60s and lower 70s for inland locations from Waycross northward, while dewpoints were falling to the 55-60 range for locations to the northwest of Waycross, while values elsewhere remain in the 65-70 range. && .NEAR TERM... (Today and Tonight) Issued at 401 AM EDT Sat Jun 8 2024 Ridging aloft will build eastward along the northern Gulf coast in the wake of the departing trough today, resulting in rising heights and a drier northerly flow aloft. The departing trough will allow the frontal boundary to dissolve along the Interstate 10 corridor this afternoon, with a weak pressure pattern allowing both the Gulf and Atlantic sea breezes to develop late this morning and move inland this afternoon. Just enough moisture will be in place across north central and coastal northeast FL to allow for isolated to widely scattered, low-topped convection to develop late this afternoon as mesoscale boundaries such as the St. Johns River breeze collide with the Atlantic and Gulf coast sea breezes, with this activity being confined for locations south of I-10. The drier air mass will allow dewpoints to remain in the 50s today for inland locations along and north of I-10, while dewpoints elsewhere inland fall through the 60s this afternoon, which will help keep heat index values below Advisory levels across our area this afternoon. This unseasonably dry air mass and plenty of sunshine will again boost high temperatures up to near daily records (see Climate section below for details), with mid to upper 90s expected again nearly area-wide. Breezy onshore winds developing behind the inland moving Atlantic sea breeze boundary will likely drop temperatures back to the 80s by late afternoon for coastal locations, but rebounding humidity values behind this boundary will push heat index values to the 100-105 degree range during the early to mid afternoon hours along the coast. The increasingly dry and subsident air mass should keep convection that develops this afternoon transient and generally weak in nature, with only briefly heavy downpours and lightning strikes being the primary threats today within southern portions of the St. Johns River Basin and north central FL. Any convection that manages to develop for locations south of the I-10 corridor late this afternoon will quickly diminish around or shortly after sunset. Fair skies, decoupling winds, and a subsident air mass could promote patchy fog development during the predawn and early morning hours on Sunday, mainly for locations in the Suwannee Valley and north central FL. Lows will fall to the mid and upper 60s across inland southeast GA and northern portions of the Suwannee Valley, ranging to the low and mid 70s at coastal locations. && .SHORT TERM... (Sunday through Monday night) Issued at 401 AM EDT Sat Jun 8 2024 Dry conditions continue into Sunday ending the week with highs reaching well into the upper 90s area wide. Heat index values will be near heat advisory levels along the St Johns river basin to the NE FL coast generally to the south of Jacksonville ranging 102-106 degrees. Overnight temperatures will drop into the low 70s, keeping warmer along the coast. Monday morning a cold front will begin making its way into the region from the north but, with weak short waves aloft and PWAT values of 1.3 to 1.7 inches, chances will be around 30-40% for scattered storms and precipitation focused in the afternoon and evening hours. Daytime temperatures will be in the low to mid 90s for SE GA and mid to upper 90s with some areas closer to the coast possibly seeing 100 degrees for NE FL. Heat indices will be around 100 degrees along and east of US 17. Temperatures will cool overnight into the low to mid 70s inland sticking in the upper 70s along the coast. && .LONG TERM... (Tuesday through Saturday) Issued at 401 AM EDT Sat Jun 8 2024 The cold front stalls along the FL/GA border Tuesday morning and rebounds into SE GA Tuesday night becoming a stationary front for the rest of the week. Moisture begins to pile in Wednesday evening increasing PWAT values above 2 inches into next weekend. Expect showers and thunderstorms each day with the highest percentages in the afternoon due to diurnal heating and sea-breeze convergence. Temperatures will cool into the mid to upper 80s by Thursday. && .AVIATION... (12Z TAFS) Issued at 705 AM EDT Sat Jun 8 2024 Westerly winds prevail this morning 4-8 kts with a frontal passage, then winds will transition at coastal terminals early this afternoon as the east coast sea breeze shifts inland, with gusts near 15 kts into the early evening. The best chance of afternoon showers or maybe a lone storm will occur near GNV to SGJ 19z-23z as drier air will limit rain chances today. After sunset, winds will weaken and transition back to WSW with a land breeze at coastal terminals to near calm inland. Included TEMPO IFR after 07z for VQQ for shallow ground fog and based on persistence. && .MARINE... Issued at 401 AM EDT Sat Jun 8 2024 A weakening frontal boundary pushing across the GA waters early this morning will stall and dissipate this evening across the northeast FL waters. A weak pressure pattern will prevail across our local waters this weekend, with prevailing offshore winds during the morning hours, followed by afternoon sea breezes near shore and evening wind surges offshore. Winds will remain below Caution levels through the period, with seas of 2-4 feet prevailing both near shore and offshore. A cold front will then approach our local waters from the northwest on Monday, resulting in scattered showers and thunderstorms during the late afternoon and evening hours. This front will stall across our region, with a surge of tropical moisture pushing northward from the Caribbean Sea and the Gulf of Mexico over our area, resulting in waves of widespread showers and thunderstorms throughout our local waters beginning on Tuesday afternoon and continuing for the rest of the week. Rip Currents: Developing onshore winds this afternoon will combine with a lingering east southeasterly ocean swell to keep a lower end moderate risk in place at area beaches. Breezy offshore winds on Sunday will delay the development of the afternoon sea breeze, with low wave heights likely resulting in a low risk at all area beaches. This low risk should continue into early portions of the upcoming week. && .FIRE WEATHER... Issued at 401 AM EDT Sat Jun 8 2024 A drier air mass filtering into our region will result in minimum relative humidity values falling to critical thresholds this afternoon for inland locations along and north of Interstate 10, while values fall to around 30 percent for inland locations south of I-10. West-southwesterly transport winds will remain sustained around 10 mph today and will combine with elevated mixing heights to create good daytime dispersion values at most locations today. Breezy onshore surface winds will develop by the mid to late afternoon hours along the I-95 corridor in the wake of the Atlantic sea breeze boundary, with breezy westerly surface winds expected late this afternoon across north central FL in the wake of the Gulf coast sea breeze. The dry air mass will linger across our region on Sunday, and westerly transport winds will strengthen after sunrise, becoming breezy during the afternoon hours, creating marginally high to high daytime dispersion values at most locations. These breezy westerly transport winds will continue on Monday and will combine with elevated mixing heights to create high to very high daytime dispersion values, especially for locations along and east of I-75 during the afternoon hours. Also of note, NWCG Predictive Services has NE FL and coastal SE GA highlight under a Moderate to High wildfire risk today and Moderate to High for SE GA and NE FL on Sunday due to the hot weather and dry conditions. && .CLIMATE... Issued at 401 AM EDT Sat Jun 8 2024 Record high temperatures at our designated climate sites through Monday: June 8 June 9 June 10 ----------------------------------- Jacksonville 99/1993 101/1872 100/1954 Gainesville 98/1907 99/1907 99/1899 Alma, GA 100/1993 99/1993 103/1954 Craig Airport 97/1985 97/2006 99/2006 && .PRELIMINARY POINT TEMPS/POPS... AMG 96 67 97 73 / 0 0 0 10 SSI 93 74 96 77 / 10 0 0 10 JAX 98 73 99 73 / 10 0 0 0 SGJ 95 76 98 75 / 10 10 10 0 GNV 98 72 97 70 / 20 0 10 0 OCF 97 73 96 73 / 30 10 20 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$