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 Afternoon & Evening Thunderstorms Today & Friday. Hazards: Wind Gusts of 35-45 mph, Frequent Lightning & Heavy Downpours

- Increasing Coverage of Afternoon & Evening Thunderstorms This

- Heavy Rainfall & Localized Flooding Possible on Sunday and Monday. Best Chance for Northeast & North Central FL

- Moderate Rip Current Risk at the Northeast FL Beaches

- Heat Advisory Conditions Possible Towards the Middle of Next Week

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Seasonably Hot and Humid Summertime Weather Continues.

- Scattered Afternoon and Early Evening Showers and Thunderstorms This Afternoon and Early evening.

Surface high pressure located to the west of the area along the central Gulf coast will continue light west northwest flow over the area while strong heating and overall weak pressure pattern leads to the Atlantic and Gulf seabreezes moving inland through the afternoon. Isolated to scattered thunderstorms early this afternoon across most of the area will become scattered to numerous along the over eastern areas as the seabreezes merge between US-17 and highway 301 corridors. Given warmer than average mid level temperatures near -5 Celsius from the morning KJAX sounding, lack of wind shear aloft, and a fairly moist low and mid levels not expecting stronger thunderstorms to approach severe levels. However, any stronger storms forming along seabreeze collisions and outflows could produce gusty winds up to 35-45 mph. Light winds will promote slow, erratic storm motions and longer duration locally heavy downpours supporting some potential for minor flooding later this afternoon in low lying and urban locations. Highs will reach the low 90s this afternoon with mid 90s along the St Johns river basin south of Jacksonville. Heat index values will be limited below advisory levels to the 100-105 range.

Tonight, thunderstorms will dissipate after sunset with mid to high level debris clouds drifting back to the northwest, mainly away from the coast this evening with scattered showers persisting until midnight away from the coast and light west to southwest winds well inland and southerly near the coast 4-8 mph winds. Skies will trend mostly clear late overnight with calm winds inland and light southwest winds at the coast maintaining around 5 mph. Lows will be a little above normal in the low to mid 70s inland and the mid to upper 70s along the coast.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/

Main Highlights During Friday and Saturday:

- Heavy Rain and Localized Flood Concerns for NE FL this Weekend - Daily bouts of showers and storms

A Tropical Upper Tropospheric Trough (TUTT) will likely closing off into an upper low on Friday while drifting slowly northwestward into the northeastern Gulf of America. Cooling temperatures aloft associated with this feature, combined with deep tropical moisture (PWATs near or above 2 inches), will increase afternoon and evening thunderstorm coverage compared to recent days. With prevailing northwesterly flow, the Atlantic sea breeze will push inland, focusing the primary corridor of convection near and west of the US- 301 corridor, with the highest coverage across inland northeast Florida and north central Florida.

The upper low is forecast to linger over the northeastern Gulf through Saturday before lifting northeastward late in the weekend as a northern-stream trough approaches the eastern United States. A weak surface low may attempt to develop beneath the upper feature and acquire some subtropical or tropical characteristics as it moves northeast on Sunday. However, confidence in surface low development remains low, with the National Hurricane Center maintaining only a 20 percent chance of tropical development and recent guidance trending less favorable.

Regardless of tropical development, a deep tropical airmass will overspread the region through the weekend, supporting numerous showers and thunderstorms each afternoon and evening, with the greatest coverage expected Sunday. The primary hazard will be periods of heavy rainfall capable of producing localized flooding, especially across northeast and north central Florida where repeated rounds of convection are most likely. Frequent lightning and locally gusty winds will accompany the stronger storms.

Temperatures will remain seasonably hot on Friday and Saturday, with highs in the lower to middle 90s and peak heat index values of 102 to 107 degrees. Increasing cloud cover and widespread convection should hold highs closer to the upper 80s to lower 90s by Sunday while maintaining humid conditions.

LONG TERM /SUNDAY THROUGH THURSDAY/

Main Highlights For Next Week:

- Scattered to Numerous Afternoon Thunderstorms - Potential heat advisory conditions by the middle of next week

he upper low may gradually lift northeastward early next week into the northeast Gulf of America, although some uncertainty remains regarding its exact timing. Regardless, deep tropical moisture will persist across the region through at least Monday as west to southwesterly flow develops behind the departing system. This will support scattered to numerous afternoon and evening showers and thunderstorms, with the greatest coverage Sunday and Monday. Periods of heavy rainfall capable of producing localized flash flooding will remain the primary concern, especially where storms repeatedly track over the same locations.

Sometime late Monday or Tuesday next week per Google Deepmind and some ECMWF AI ensemble members, the upper low should move away as mid-level ridging gradually builds eastward from the west-northwest, resulting in a more typical summertime pattern. While scattered afternoon and evening thunderstorms will continue each day, coverage should gradually decrease. At the same time, increasing heights aloft will allow temperatures to climb back into the middle 90s, with oppressive humidity pushing peak heat index values into the 105 to 110 degree range by midweek. Heat Advisory conditions may become increasingly likely, particularly across inland locations where storm coverage is lower and temperatures climb the highest.

AVIATION /18Z THURSDAY THROUGH 18Z FRIDAY/

VFR conditions to begin the TAF period will change later this afternoon as scattered thunderstorms become more numerous with MVFR restrictions due to lowered visibility from heavy downpours as the Atlantic seabreeze moves across CRG/JAX early to mid afternoon and the Gulf seabreeze shifts across GNV by the mid to late afternoon hours.

Surface high pressure west of the area along the northern Gulf coast will keep light northwest to west northwest winds mostly 5-8 knots and scattered thunderstorms develop over much of the area while the Atlantic Seabreeze currently moves onshore and shifts west of CRG by 19Z and KJAX before 21Z. Have tempo groups this afternoon for MVFR restrictions mostly due to lowered visibility from locally heavy downpours. MVFR visibility from heavy rainfall with storms with the window starting and ending earlier near the coast and a bit later at GNV and VQQ through 02Z.

Thunderstorms will dissipate with loss of heating after 00Z, lingering inland through 02Z. Mid to high level leftover storm clouds will persist and VCSH will continue through 04Z with light southerly winds turning southwesterly around 5 knots along coast and trending calm inland after 06Z with light northwest winds Friday morning after 13Z.

MARINE

High pressure will remain to the west near the northern Gulf coast through Friday with west to northwest winds turning east to southeasterly each afternoon due to daily seabreeze circulation. Afternoon thunderstorms near the coast may drift to the nearshore waters during the early evening today and Friday. A weak trough will develop over the area Saturday with prevailing wind flow from the southwest with a southerly wind surge in the evening hours elevating winds to near caution levels.

Surface troughing will strengthen Sunday and Monday, with weak low pressure possibly developing over the northeast Gulf. The National Hurricane Center has maintained a low chance, or 20 percent, of weak tropical cyclone formation in the northeast Gulf. Showers and thunderstorms will increase in coverage this weekend, and this weak low pressure center may then progress northeastward across our local waters early next week.

Rip Currents:

Onshore winds developing this afternoon behind the inland moving sea breeze could create a lower end moderate risk at the northeast FL beaches, where surf heights may increase to around 2 feet. Meanwhile, low surf heights at the southeast GA beaches should maintain a low risk through at least Friday. Southerly wind surges during the evening hours this weekend may build surf heights to 2-3 feet at the northeast FL beaches.

FIRE WEATHER

- Fair To Good Dispersions Friday And This Weekend

Wind speeds are forecast to remain below 15 mph through the end of the week. No minimum RH concerns are forecast, with afternoon smoke dispersion values anticipated to be generally fair to good Friday and this weekend. Moisture steadily increases across region into the weekend, with rain and storm chances incrementally increasing through the weekend. Any storms that manage to develop will be capable of producing frequent lightning strikes, high wind gusts, and heavy downpours.

Fog Potential and Other Remarks: Significant fog development is not expected for the next several nights. Gusty and erratic winds will be possible in and near thunderstorms, with occasional outflow boundaries capable of producing sudden wind shifts well away from ongoing convection.

PRELIMINARY POINT TEMPS/POPS

AMG 91 75 94 74 / 20 10 30 30 SSI 93 79 93 79 / 30 10 10 10 JAX 93 75 95 75 / 50 20 40 10 SGJ 92 76 93 76 / 50 10 30 10 GNV 92 74 93 73 / 40 20 60 50 OCF 92 75 93 74 / 50 20 80 50

JAX WATCHES/WARNINGS/ADVISORIES

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