Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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355 FXUS62 KJAX 281822 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 222 PM EDT Fri Jun 28 2024 ...New NEAR TERM, SHORT TERM, LONG TERM, MARINE... .NEAR TERM... Issued at 218 PM EDT Fri Jun 28 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 Thunderstorms are develop over duval county as initial round of showers/isolated T`storms have progressed off the St Johns and Flagler county coastlines pushing some outflow boundaries north. Expect numerous thunderstorms to affect downtown Jacksonville, the Jax beaches with further developments north along I-95/US17 corridors into SE GA. Slow storm motion and above normal moisture levels will create locally heavy rainfall amounts that will create minor flooding over urban and low lying areas. AS mid level temperatures are warmer than typical for late June around -6C, not expecting severe downburst winds, but strong wind gusts 40-50 mph are most likely with strongest convection into mid afternoon. However, frequent lightning will occur with storms due to strong diurnal heating and a very moist airmass as dewpoints are commonly ion the mid 70s. A funnel cloud or waterspout may develop briefly as storms initially tower along the Atlantic seabreeze or outflow boundaries, but the environment overall does not support a threat for tornadoes. Highs have already peaked in the low 90s and will likely remain steady or fall with clouds and convection increasing over next few hours. Tonight, leftover T`storm outflow boundaries may push north into SE GA areas closer to the Altamaha river basin in the early evening hours with mostly cloudy skies from mid and high level debris clouds thinning out gradually overnight. Lows will range into the low 70s for inland SE GA, mid 70s over inland NE FL, and the upper 70s along the coast. && .SHORT TERM... (Saturday through Sunday night) Issued at 218 PM EDT Fri Jun 28 2024 Deep moisture will remain entrenched across the region through the weekend, supporting diurnal convection each afternoon. Steering flow will begin to weaken and become stagnant as low-level ridging consolidates over then northern GOMEX and an easterly wave aloft slowly slides into the southern FL peninsula. Given the lack of flow, both sea breezes will progress inland and collide between I-75 and HWY-301 each afternoon; the St Johns River breeze and its interaction with the Atlantic sea breeze will also be a focus for more robust convection. As far as instability is concerned, there will be enough (MLCAPE values peaking between 1500-2000) to support a few strong pulse storms each day. It`s unlikely that the somewhat cooler temps aloft associated with the easterly wave will extend far enough north into NE FL to further amplify instability. The primary storm concerns will be strong, gusty outflows. Localized flooding, especially in urban areas, will also be a threat as storm motions will be very slow (<5mph) and even stationary at times. PWATs remaining around the 90th percentile (2"+) may yield rain rates between 3-5" per hour. Anticipate convection to wane after sunset on Saturday, with perhaps a few lingering showers or isolated storms inland through the mid evening. Similar trends are expected across NE FL Sunday night as well but convection may last later into the night across SE GA as outflow from local diurnal convection interacts with a prefrontal trough pushing southward through GA. Hot and humid conditions persist through the weekend with highs in the low to mid 90s inland and in the upper 80s to low 90s at the beaches thanks to a more active sea breeze pushing across the mild waters (shelf water temps now in the mid 80s). Humidity will push the "feels like" (Heat Index) temps into the 100-107 range each day, just below Advisory levels. && .LONG TERM... (Monday through next Friday) Issued at 218 PM EDT Fri Jun 28 2024 Anomalous deep moisture continues and increases with pooling ahead of a slowing front that should stall to the north early next week. Weak surface troughing within the vicinity of the decaying boundary will be a convective focus Monday across SE GA before dissipating entirely through Tuesday. Numerous showers and afternoon storms are likely through Wednesday before drier air attempts to wrap around the eastern side of an intense upper ridging by Independence Day, limiting storm coverage along the sea breezes. Temperatures will be around or perhaps below normal, especially across SE GA, to start the week due to convective activity and associated cloudiness. Under the influence of the intense ridge, temperatures should begin to push above normal by Independence Day and into next weekend. && .AVIATION... (18Z TAFS) Issued at 128 PM EDT Fri Jun 28 2024 The 18Z TAF forecast will begin with tempo MVFR restrictions for ceilings/visibility and gusty winds up to 30 knots at duval county and SSI terminals over the 18-22Z window as thunderstorms develop quickly between collision of the Atlantic seabreeze and initial scattered showers/isolated thunderstorms from the southwest associated with Gulf seabreeze. Storms will wrap up by 21Z at GNV but VCTS will linger around 00Z along the NE FL coastal TAF sites up to SSI. VFR conditions prevail late tonight and into Saturday. Light variable winds become calm inland overnight under thinning cloud cover. High pressure ridge just south of the region will allow for lighter and variable winds to start Saturday with the Atlantic Seabreeze moving onshore again after 15/16Z Saturday with VCTS noted to end the period at all terminals as scattered ceilings rise from 2.5 kft to 3.5 kft. && .MARINE... Issued at 218 PM EDT Fri Jun 28 2024 High pressure ridging south of the waters will promote south to southwesterly winds into early next week. Scattered to numerous showers and thunderstorms will develop along the near shore waters each afternoon and linger into early evening each day due to storm growth along the Atlantic seabreeze. Impacts from thunderstorms will include wind gusts up to 30 to 35 knots in stronger storms along with brief waterspouts. but may be locally higher in storms. A cold front will approach the waters, then dissipate Wednesday with winds more east to southeasterly. Rip Currents: A low end moderate risk of rip currents will be in place this afternoon/evening behind the Atlantic seabreeze for our NE FL and SE GA beaches. A low end moderate risk will again be in place Saturday at all area beaches. && .PRELIMINARY POINT TEMPS/POPS... AMG 93 73 94 76 / 70 50 40 30 SSI 90 76 90 78 / 60 40 40 40 JAX 92 74 93 76 / 80 60 60 30 SGJ 92 74 91 76 / 80 50 60 40 GNV 91 73 92 73 / 80 40 70 30 OCF 92 73 92 75 / 80 40 70 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$