textproduct: Jacksonville

KEY MESSAGES

For the latest NE FL and SE GA Daily Key Messages please visit: https:/www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

- Scattered to Numerous Afternoon & Evening Thunderstorms through the Weekend and Early Next Week

- Primary concern will be heavy downpours resulting in localized flooding

- Strong thunderstorm risk will shift inland toward the I-75 corridor this weekend

- Moderate Rip Current Risk Continues at All Area Beaches

NEAR TERM /THROUGH TONIGHT/

Highlights through Tonight:

- Waves of heavy downpours may lead to localized minor flooding this afternoon

Showers and storms continue to move eastward from the Gulf, with coverage expanding through the afternoon. With less DCAPE available, as well as southwesterly winds pinning the Atlantic sea breeze to the coast, there will be less favorable for stronger storm development. However, we can't rule out an isolated strong storm producing gusty winds, as well as heavy rain/training storms causing localized flooding problems. Areas normally flood prone, urban cities, and locations that have received a decent amount of rain the past few days are more susceptible to the flooding threat today.

Overall, storms will wane off after sunset, although we will likely see some mainly shower activity (and a few storms) near the Suwannee Valley pre-dawn.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/

Main Highlights This Period: (Friday through Saturday night)

- Strong storms are possible on Friday afternoon and early evening along the I-95 corridor

- Strong storm potential shifts inland to locations west of I-95 on Saturday afternoon and evening.

- Slower storm motion may result in a localized flood threat at inland locations on Saturday afternoon through the early evening, especially at urban or normally flood prone locations.

Troughing positioned over the eastern third of the nation on Friday, with the reinforcing frontal boundary currently pushing through the Ohio and Tennessee Valleys will stall along the southern Appalachians and the lower Mississippi Valley on Friday. Meanwhile, deep-layered Atlantic ridging centered near Bermuda will begin to extend its axis westward towards the southeastern seaboard by Friday night, forcing troughing to cutoff over the FL panhandle by Saturday afternoon. Southwesterly flow will prevail across our region on Friday, with deep tropical moisture pooling downstream of the stalled frontal boundary over southeast GA and also along the I-95 corridor in northeast FL. Convection should move onshore along the FL Big Bend and Nature Coasts early on Friday morning, with activity potentially impacting the Suwannee Valley and portions of inland southeast GA during the mid to late morning hours, with activity then progressing east-northeastward towards the I-95 corridor during the afternoon hours.

Convection will intersect a pinned Atlantic sea breeze that should be positioned near I-95 by the mid to late afternoon, resulting in storms "pulsing" to strong levels as they approach the Atlantic coast. Stronger storms along the I-95 corridor on Friday afternoon will be capable of producing downburst winds of 40-55 mph, along with frequent lightning strikes and heavy downpours. Activity may linger early on Friday evening, especially for locations along and north of I-10 that are closer to the stalled frontal boundary and deeper moisture. Highs will generally climb to the upper 80s and lower 90s on Friday, with heat indices peaking in the 100-105 degree range before convection increases in coverage later in the afternoon. Activity for locations along and north of the I-10 corridor will likely conclude by midnight, with another round of nocturnal convection developing over Apalachee Bay and the eastern Gulf potentially moving northward across far western portions of the Suwannee Valley towards sunrise on Saturday. Lows will generally fall to the low and mid 70s.

Saturday will be a transition day locally, as low and mid level flow becomes more southerly as troughing aloft cuts off to the west of our area and Atlantic ridging builds westward towards the FL peninsula and the southeastern seaboard. Deep tropical moisture will remain in place throughout our region, with prevailing southerly steering flow allowing the Atlantic and Gulf sea breezes to move further inland and collide near the U.S. Highway 301 corridor by the late afternoon. Convection may begin towards noon along the inland moving sea breeze boundaries along the I-95 and I-75 corridors, with coverage and intensity of storms increasing at inland locations throughout the afternoon. Mesoscale boundaries will again collide and allow for storms to "pulse" and become strong, with isolated severe storms not out of the question for inland locations. Slower storm motion on Saturday afternoon and evening may increase the threat for localized flooding, especially if downpours focus at urban or normally flood prone, low lying locations.

Highs will again climb to the upper 80s and lower 90s on Saturday, with peak heat indices of 100-105 degrees occurring before convection increases in coverage by the mid afternoon hours. Convection that congregates at inland locations should diminish before midnight on Saturday night, with developing onshore low level flow potentially bringing a few showers or even an embedded thunderstorm towards the Atlantic coastal communities during the predawn hours on Sunday. Light onshore winds will likely keep coastal lows in the upper 70s to around 80, while inland lows mostly fall to the lower 70s.

LONG TERM /SUNDAY THROUGH THURSDAY/

Main Highlights This Period: (Sunday through Wednesday)

- Strong storm potential shifts towards the I-75 corridor on Sunday and Monday afternoons.

- Gradual decrease in afternoon and evening thunderstorm coverage for locations along and north of I-10 by Tuesday.

- Temperatures climb to the mid 90s by midweek at inland locations as afternoon thunderstorm coverage decreases.

Atlantic ridging will continue to shift westward on Sunday, allowing cutoff troughing over the FL panhandle on Saturday to retrograde slowly westward along the northern Gulf coast on Sunday and Monday. Meanwhile, surface high pressure building over the Mid-Atlantic region on Sunday will only gradually weaken as it settles slowly southward towards the Deep South early next week. This change in the weather pattern will result in prevailing easterly flow across our area throughout this period, which will focus afternoon and evening convection along the I-75 corridor on Sunday and Monday. Stronger storms will be possible for inland southeast GA and the I-75 corridor during the late afternoon and early evening hours. Isolated to widely scattered showers and a few embedded thunderstorms may advect onshore along the Atlantic coast and I-95 corridor during the early to mid-morning hours on Sunday and Monday. Prevailing onshore winds should keep coastal highs in the upper 80s to around 90 on both days, while inland highs climb to the low and mid 90s. Convection should exit west of the Suwannee and Alapaha Rivers during the early to mid afternoon hours, and lows will range from the low to mid 70s inland to the upper 70s to near 80 at coastal locations.

Ridging aloft will strengthen over the southeastern states by Tuesday and Wednesday, with an increasingly subsident atmosphere likely limiting afternoon and evening convective coverage to isolated for inland locations along and north of I-10. Deeper moisture should remain in place on Tuesday for areas south of I-10, keeping scattered to numerous afternoon and evening thunderstorms in the forecast, especially for locations along the I-75 corridor. A drier air mass may then advect westward across our entire area towards midweek, which should result in less convective coverage. Onshore winds could still advect a few showers onshore along the Atlantic coastal communities early next week before this drier air arrives towards midweek. Less convective coverage should allow inland highs to reach the mid 90s by Tuesday and Wednesday, while onshore winds keep coastal highs in the upper 80s to around 90. Lows will continue to fall to the low and mid 70s inland, with upper 70s to near 80 forecast at coastal locations.

AVIATION /00Z FRIDAY THROUGH 00Z SATURDAY/

Lingering showers and storms over the area could bring strong gusts to the JAX TAF sites early this evening. As storms clear the area, VFR conditions will develop with the lone exception being VQQ with the typical lower vsbys around 08Z. Showers and storms will likely begin once again around 18Z as the sea breezes push inland, PROB30 groups for now in the TAFs.

MARINE

Offshore winds will prevail through Friday night, then shift onshore over the weekend as high pressure builds to the north over the weekend, then to the northeast and into the western Atlantic early next week. Thunderstorms will push over the waters early this evening, with showers and thunderstorms once again Friday afternoon as offshore winds continue. Decreasing chances for showers and storms over the weekend and into next week as onshore flow develops.

Rip Currents: A very low end Moderate Risk of rip currents is expected this afternoon after the sea breeze develops. Similar expectation on Friday. Prevailing winds turn onshore this weekend, leading to a more solid Moderate risk.

FIRE WEATHER

Scattered to numerous showers and thunderstorms will progress across our during the afternoon and early evening hours through Friday. Activity may begin during the late morning hours along the I-75 corridor and north central Florida before activity pushes eastward across the rest of our area during the afternoon and early evening hours. Strong thunderstorms will be possible each afternoon, mainly along the Interstate 95 corridor. Afternoon and early evening showers and thunderstorms will then shift to locations west of the I- 95 corridor this weekend through Monday, with isolated activity possible along and east of I-95 during the morning hours. Strong thunderstorms will be possible for locations west of I-95 each afternoon from this weekend through Monday. Southwesterly surface and transport winds will prevail through Friday, followed by surface and transport winds shifting to southeasterly on Saturday and then easterly on Sunday and Monday. Fair to good daytime dispersion values will prevail through Friday. Lighter surface and transport speeds on Saturday will yield poor to fair daytime dispersion values, followed by generally fair values on Sunday and Monday.

Fog Potential: Significant fog is unlikely during the next several days. Gusty and erratic winds can be expected in and near thunderstorms.

PRELIMINARY POINT TEMPS/POPS

AMG 72 90 72 90 / 40 80 40 80 SSI 76 89 76 88 / 20 60 50 60 JAX 73 91 72 90 / 20 60 50 70 SGJ 74 91 74 90 / 20 50 50 50 GNV 72 90 72 91 / 10 80 40 80 OCF 72 91 73 92 / 10 70 40 80

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...None.