Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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870 FXUS62 KJAX 181815 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 215 PM EDT Sat May 18 2024 ...New AVIATION... .UPDATE... Issued at 1045 AM EDT Sat May 18 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 forecast remains on track with numerous showers and storms developing throughout southeast GA into the late morning and early afternoon. As this activity develops, northeast FL will continue to see more sun and become more unstable, with the airmass more favorable for northeast FL late morning and this afternoon for scattered to numerous showers and storms to develop. Gusty winds, heavy rainfall, and hail are the main threats given the environmental bulk shear of 40-50 kt in place. The low level flow is relatively unidirectional so the tornado threat is not high (background SRH 0-3KM generally about 150 or less), but not out of the question with some backing of the winds that an isolated tornado develops later today, with the more favored area in about 3-6 hours further south, closer to the southeast GA/northeast FL state line, of the where the current convection is located. The threat of strong or severe storms looks to decrease after about 6 pm as the airmass gets worked over. Also, an isolated flooding threat in the near term for inland southeast GA. Overall, little change in the forecast and expect to see an uptick in showers and storms both intensity and coverage near and southeast of a line from Jesup to Douglas over southeast GA and into northeast FL as outflows and cells propagate southeastward into more unstable airmass. && .NEAR TERM... Issued at 350 AM EDT Sat May 18 2024 Showers have nearly ended across our area from late night T`storms that moved eastward across the SE GA and the FL/GA state line to the coast and then offshore. Southerly flow, mostly light 5-10 mph with a few higher breezes to 15-20 mph are keeping temperatures warm in the mid 70s with very moist dewpoints around 70 and some low stratus clouds may develop through sunrise over SE GA and inland NE FL. Today, a compact mid level trough over Ozark Plataea/mid MS valley will progress east through the TN river valley. A cold front will move eastward across the FL panhandle with deep moisture feeding into the area from the Gulf ahead of the front and spur a wave of T`storms that will shift east northeast first across interior SE GA from south GA and the FL panhandle late this morning into midday, with greater uncertainty on T`storm evolution into NE FL later this afternoon, but the The storm prediction center has a Slight risk (category 2 out of 5) for isolated to scattered severe T`storms for SE GA and much of NE FL as many ingredients will be in place including strong deep southwesterly shear values 50-60 knots 0-6km under divergent 250 mb jet streak crossing the deep south. Highs warming into the upper 80s to lower 90s will aid strong instability well ahead of the front and support a threat for gusty winds in excess of 60 mph with more intense cells, hail, and even isolated tornadoes as embedded supercell structures may contain stronger mesocyclones that could promote a tornado or two. With deep moisture, efficient rainfall rates will create localized heavy rainfall amounts that could lead to minor flooding concerns (see hydrology section). Otherwise, mostly cloudy skies will remain over SE GA with more partly cloudy skies initially over NE FL and thus warmer highs as mentioned. Southwest winds will pin the Atlantic seabreeze to the immediate NE FL coast if not just offshore through much of the afternoon. Tonight will be moist and muggy with another round of showers and T`storms as the cold front shifts through the area after midnight Lows will be in the low 70s over NE FL and the upper 60s over SE GA with light southwest winds under mostly cloudy skies. && .SHORT TERM... (Sunday through Monday night) Issued at 350 AM EDT Sat May 18 2024 The aforementioned cool front will slow and stall across NE FL through most of Sunday before a reinforcing frontal boundary slides in from the north Sunday night. Meanwhile aloft, a trough will begin its pivot maneuver across the Florida. Cold air aloft associated with the trough and embedded shortwaves will crank up diurnal instability with higher-end guidance around 1500-2000 j/kg CAPE. This instability and modest westerly deep shear may result in scattered strong and possibly marginally severe t`storms, with particular focus along the stationary front lying south of I-10 in NE FL. Given the unidirectional flow, the primary concern will be strong outflow winds and small hail - tornadoes are very unlikely. Showers and storms will fizzle through Sunday night as a cooler, more stable airmass arrives. An additional concern will be training storms along the stalled boundary, which may result in flood concerns particularly at locations south of I-10. Monday, high pressure will build in from the north, setting up a northeasterly flow regime. Lingering moisture may result in enough daytime instability to initiate isolated to widely scattered showers, maybe an isolated storm, along the I-75 corridor as the Gulf sea breeze attempts an inland push. Again, any daytime activity will fade during the evening Monday. Combo of showers/storms and cloud cover will limit temps the mid/upper 80s Sunday with a readings trending 3-5 degrees cooler into Monday as the reinforcing front arrives. && .LONG TERM... (Tuesday through Friday) Issued at 350 AM EDT Sat May 18 2024 Though there could be a few lingering showers or even an isolated storm across the southern zones Tuesday afternoon, the rest of period should be rain-free as dry airmass tanks PWATs around an inch -- a typical amount for this time of year. Upper ridging will lean in from the west next week, resulting in another increase in temps with highs pushing back into the low 90s. Hot and humid conditions will be the main concern as triple-digit heat index values make another earlier-than-normal appearance. && .AVIATION... (18Z TAFS) Issued at 200 PM EDT Sat May 18 2024 TAFs are generally on track with showers and storms affecting the terminals today. Storms have moved through SSI and some lingering showers will be possible there rest of the afternoon, with northeast FL TAFs expected to see convection so have VCTS and TEMPO groups into the evening hours. The primary times for TSRA is from now through about 22z, with gusty winds around 30-40 kt and briefly lower visibility. Still a risk of showers and isolated thunderstorms tonight but for now carrying VCSH for the overnight hours. Sunday, a risk of some showers and possibly a thunderstorm toward the end of the TAF period. Prevailing west to southwest winds 8-12 knots and becoming lighter and southerly by midnight. Mainly westerly flow for Sunday at about 10 kt. && .MARINE... Issued at 350 AM EDT Sat May 18 2024 A slow moving cold front will gradually push across the coastal waters late tonight through Sunday, renewing chances for storms. Winds will turn northerly as high pressure wedges against a low pressure situated northeast of the waters early next week. High pressure builds directly over the waters during the middle part of next week. Rip Currents: Low Risk of rip currents at all area beaches today and Sunday. && .HYDROLOGY... Issued at 350 AM EDT Sat May 18 2024 While some locally heavy rainfall occurred along the FL/GA state line overnight, much of NE FL recovered very little rain Friday. With the approach of the cold and expected T`storms later today and again tonight, expecting widespread 1-2 inch totals over SE GA and inland NE FL with locally heavier amounts of 3 inches in isolated locations where more intense storms travel or train over with overall less amounts towards the NE FL coast. Minor flooding is possible in low lying and urban areas and flood prone roads. && .PRELIMINARY POINT TEMPS/POPS... AMG 68 85 65 83 / 60 60 20 20 SSI 71 85 67 79 / 70 70 30 30 JAX 71 88 67 82 / 70 70 30 40 SGJ 71 88 69 81 / 70 70 40 40 GNV 70 86 66 86 / 60 70 20 50 OCF 72 86 69 86 / 60 70 20 50 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$