Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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120 FXUS62 KJAX 041206 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 806 AM EDT Thu Jul 4 2024 ...New UPDATE, AVIATION... .UPDATE... Issued at 759 AM EDT Thu Jul 4 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 Extended the Heat Advisory into all areas of the Suwannee Valley west of Interstate 75. With their proximity to Gulf moisture felt the humidity factor warranted an extension. && .NEAR TERM... (Today through Tonight) Issued at 400 AM EDT Thu Jul 4 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 Pattern for daytime convective development will continue through today with showers and storms forming in the vicinity of the I-95 corridor and then building inland as initially easterly flow will weaken and shift to become more out of the north and northeast as the remains of the frontal boundary to the north dissolves and high pressure and drier air forms along the eastern seaboard, moving southward. PWAT values ahead of the dry air boundary will measure between 2.1 and 2.6 inches which can lead to storms capable of producing heavy rains and localized flooding. High temperatures today will rise into the lower to mid 90s for inland areas and in the upper 80s and lower 90s along the coast. Overnight low temperatures are expected to drop down into the mid 70s for inland areas and in the upper 70s and lower 80s along the coast. Heat index values will rise to be above 100 degrees today with a Heat Advisory (for heat index of around 108-110) set for north central Florida and adjacent counties. && .SHORT TERM... (Friday through Saturday night) Issued at 400 AM EDT Thu Jul 4 2024 During this period, mid level high pressure at 500 mb will dominant the region while the lo level ridge drops a bit further south and southeast. Drier air will continue to filter in from the northeast on Friday resulting in lower rain chances for the coastal areas possibly just supporting slight rain chances there. Further inland, we continue to show chance to likely POPs as the sea breezes merge across the inland areas near and west of Highway 301 and I-75. A combination of max temps in the mid 90s and rich dewpoints inland zones on Friday could result in another case for some heat advisories. Isolated to scattered mainly evening convection expected Friday night mainly across the inland zones. Lows in the mid 70s to near upper 70s toward the coast are expected. Saturday, some subtle pattern change as a mid level trough around 700 mb is forecast to come across AL and GA and help shove the drier air along the eastern zones offshore. This in combination with PWATs of about 2.2 inches or better will bring on more scattered and numerous showers and storms to the forecast area, possibly including the coastal zones. Max temps rise to mid 90s and heat advy criteria could be met in some locations for brief periods of time. As far as t-storm environment, the local measured temps at 500 mb are rather warm. JAX observed soundings have been averaging 500 mb temps at -4 to -5 C for several days (about 2.5 deg warmer than normal) and 850-500 mb lapse rates are about 5 C/km. This will not change appreciable through Saturday and in fact may nudge even warmer. PWAT values have also been averaging at least 2 inches since June 28th. This will continue to support warm rain processes, thus more heavy rainfall potential (mainly inland zones) given the rather high PWAT air in place and slow storm motion. Certainly, water loading and some localized dry pockets aloft may result in gusty winds of about 35-50 mph in stronger storms. && .LONG TERM... (Sunday through Wednesday) Issued at 400 AM EDT Thu Jul 4 2024 Models generally agree on low level ridge across north central FL largely dominating the area and low level troughing across the southeast states. The synoptic flow is weak enough for sea breezes each day and more than sufficient moisture for daily scattered to numerous showers and storms. Will keep POPS of about 40-70 percent each day. The hot and humid conditions are still anticipated with little change in the dewpoints and the max temps of mid 90s. Thus, we may see some areas with heat related headlines during this period. && .AVIATION... (12Z TAFS) Issued at 759 AM EDT Thu Jul 4 2024 Yet another day of sea breeze front convergence across the north Florida and southeast Georgia region. For now, have kept thunder as VCTS but will likely amend around 15 utc to introduce TEMPO Groups. That will give us some time to look at how the daytime heating is progressing. && .MARINE... Issued at 400 AM EDT Thu Jul 4 2024 The weakening frontal boundary will move southward and dissipate over the local waters today, with prevailing onshore winds continuing as weakening high pressure lingers off the eastern seaboard. Storm coverage will decrease Friday through Saturday, with prevailing winds then shifting to southwesterly during the weekend ahead of the next slowing frontal boundary approaching from the north. Rip Currents: Given the area rescues and surf noted yesterday of up to 2-4 ft, High Risk was elected to be posted for NE FL beaches today and then becoming Moderate on Friday. Moderate Risk for SE GA beaches through Friday. && .CLIMATE... Issued at 400 AM EDT Thu Jul 4 2024 Above average max/min temps expected through Saturday with the record high mininim not too far off the forecast min temps in the mid 70s. July 4: KJAX: 78/1997 KGNV: 77/1897 July 5: KGNV: 75/2023 July 6: KJAX: 79/1902 KGNV: 78/1900 && .PRELIMINARY POINT TEMPS/POPS... AMG 93 74 95 75 / 40 10 50 30 SSI 90 78 92 79 / 30 10 20 10 JAX 92 75 94 75 / 40 20 30 10 SGJ 91 77 92 76 / 40 20 30 10 GNV 92 73 94 74 / 60 30 60 20 OCF 93 75 93 75 / 70 40 60 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory from 11 AM this morning to 6 PM EDT this evening for FLZ021-035-038-136-137-140-220-236-237-240-340-522. High Rip Current Risk through late tonight for FLZ124-125-133- 138. GA...None. AM...None. && $$