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

- Daily Afternoon & Evening Thunderstorms. Today: Inland Northeast FL. Weekend: Increasing Chances Area-Wide

- High Risk of Rip Currents Northeast FL Beaches Today, Moderate Risk Southeast GA Beaches

- Hot Holiday Weekend, Potential Max Heat Indices: 105-108F

- Minor River Flooding for Satilla River

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Highest Strong Thunderstorm Potential Near I-75 Today

- Elevated Rip Current Risk at Area Beaches

Low level flow remains generally out of the east today, as high pressure is still situated north of the area. Moisture levels remain near normal, with PWATs of about 1.75 inches, though 12Z sounding this morning continued to show pockets of drier air aloft which is especially present on satellite estimates across southeast GA. Some drier air and warmer air aloft is expected to taper chances for thunderstorms today, which the highest chances for t'storms and especially stronger t'storms to be towards the I-75 corridor and areas to the west as the Atlantic sea breeze pushes towards the west coast breeze. Expecting mainly dry conditions across southeast GA through this afternoon, and ongoing showers with occasional thunder to shift further inland over northeast FL this afternoon, and towards the I-75 corridor by early evening. Temps will top out in the mid 90s inland, and upper 80s to low 90s closer to the coast.

Overnight lows will run in the low to mid 70s inland and mid to upper 70s near the coast/St. Johns River, with some patchy fog also possible for inland areas early Saturday morning. Though lower chances compared to the last few days, a weak coastal trough will continue to bring a slight chance for an isolated shower late tonight and into early Saturday.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Main Highlights This Period:

- Afternoon thunderstorms focused over inland Northeast Florida. - Elevated Rip Current Risk at Area Beaches Saturday

High pressure across the Southeast U.S. is weakening as mid-level troughing digs through the Northeast and Midwest. Meanwhile, surface high pressure will gradually build over the western Atlantic, with its axis extending into South Florida by late this weekend.

Given a weak pressure gradient on July 4th, the east coast sea breeze will be slightly delayed, migrating inland toward Highway 301 by late afternoon. This will favor a sea breeze collision across interior sections of SE GA and NE FL. Scattered showers and thunderstorms will develop by early to mid-afternoon, becoming numerous across inland NE FL and North Central FL particularly along and south of the I-10 corridor where sea breeze and outflow interactions will maximize convergence and where precipitable water values are 2 inches or greater. Slow storm motions and abundant moisture will support torrential rainfall and a localized flooding threat, while stronger storms may also produce frequent cloud-to- ground lightning and gusty, erratic winds. Convective activity will gradually diminish after sunset, though isolated to scattered showers and storms may linger during the mid to late evening hours across the interior.

A southwesterly low-level flow will become more established on Sunday as the Atlantic high shifts east of the Florida Peninsula. This pattern will pin the Atlantic sea breeze near the coast while transporting deeper tropical moisture with precipitable water values rising to 2.02.5 inches into the region, supporting a more active convective pattern. Storm coverage will expand across nearly the entire forecast area, with primary hazards remaining heavy rainfall, localized flooding, lightning, and isolated strong wind gusts.

Heat and humidity will remain significant concerns through the holiday weekend. Inland highs will reach the mid-to-upper 90s, with upper 80s to lower 90s along the coast. Overnight lows will provide little relief, falling into the lower-to-mid 70s inland, while remaining in the upper 70s to around 80 near the coast and the St. Johns River. Peak afternoon heat indices of 105 to 109 degrees will be on the precipice of Heat Advisories.

An elevated rip current risk will continue at area beaches Saturday.

LONG TERM /MONDAY THROUGH THURSDAY/

Main Highlights This Period:

- Storm Chances Continue thru Next Week - Above Average Temperatures with High Heat Index Values

A broad subtropical ridge anchored east of the Florida peninsula over the western Atlantic will maintain persistent south to southwesterly flow through much of next week. This regime will keep the Atlantic sea breeze confined to the coastline while continuously advecting deep tropical moisture into the region, keeping precipitable water values generally above 2 inches.

Expect scattered showers and thunderstorms each afternoon and evening. Convective coverage will focus along the inland-moving Gulf Coast sea breeze, remnant outflow boundaries, and other mesoscale convergence zones. A weak frontal boundary may approach the Southeastern states around Wednesday, its influence on NE FL and SE GA should be negligible, leaving the prevailing southwesterly flow pattern intact with perhaps better pooling of higher moisture content midweek next week.

Temperatures will remain above seasonal normals. Afternoon highs will generally peak in the mid 90s, with a few upper 90s possible across inland SE GA, while overnight lows stay in the mid to upper 70s. Persistent heat and high humidity will result in peak heat indices of 105 to 110 degrees, making Heat Advisories likely on some days.

AVIATION /18Z FRIDAY THROUGH 18Z SATURDAY/

Widely scattered SHRA will continue to push inland through this evening with the Atlantic sea breeze, bringing slight chances for TSRA for coastal northeast FL sites and higher chances for inland areas. VFR will be expected otherwise outside of any convection, expecting to return from east to west. SSI is expected to avoid TSRA altogether today, with TEMPO updates likely throughout the afternoon for convective updates. A few showers may affect coastal terminals overnight tonight, though significant restrictions are not expected at this time.

MARINE

Easterly flow continues today with high pressure northeast of the region and a trough axis extending across central Florida. Passing coastal showers will continue today and especially tonight. High pressure builds across central and south Florida this weekend into early next week with a transition to south to southwest flow over the local waters and higher afternoon and evening thunderstorm chances over the local waters. Nightly wind surges return with near exercise caution levels developing by Sunday night.

Rip Currents:

Onshore flow around 10-15 mph, combined with surf up to 2-3 ft will result in an a high risk for the northeast FL coast, with a high end moderate risk over southeast GA beaches. Risk is expected to remain at least moderate through the weekend.

FIRE WEATHER

Scattered showers and storms will build in this afternoon with the majority of the convection occurring over north central Florida and for areas along and south of the I-10 corridor. Onshore easterly winds will build with daytime heating allowing the breezy diurnal sea breeze to reach further inland, becoming light and variable overnight. Scattered storms are anticipated for Sunday with developments being most heavily concentrated over north central Florida.

Persistent south-to-southwesterly flow will persist Monday through Wednesday, supporting daily rounds of scattered afternoon and evening thunderstorms.

Fog Potential: Patchy fog developments are expected over inland areas overnight and then dispersing before mid morning. Any stronger thunderstorms will be capable of producing frequent lightning, torrential rainfall, and erratic wind gusts during the afternoon and evening.

HYDROLOGY

Satilla River at Atkinson will remain in Minor Flood through the Sunday and is forecast to lower into action stage Sunday evening.

PRELIMINARY POINT TEMPS/POPS

AMG 96 73 98 76 / 10 0 10 0 SSI 90 79 92 79 / 10 0 0 0 JAX 92 74 96 77 / 20 10 20 0 SGJ 90 76 92 77 / 30 0 30 10 GNV 95 74 95 74 / 40 20 50 20 OCF 94 75 93 75 / 50 30 60 20

JAX WATCHES/WARNINGS/ADVISORIES

FL...High Risk for Rip Currents through late tonight for FLZ124-125-138- 233-333. GA...None. MARINE...None.