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. Highest coverage over north central Florida this weekend. Storm Hazards: Lightning, Gusty Winds, & Localized Flooding

- High Risk for Rip Currents Today Northeast FL Beaches. Moderate Risk this Weekend Southeast GA

- Hot Again Sunday: Daily Peak Heat Indices: 105-109F. Building heat next week potential heat advisory conditions

UPDATE

Stratiform showers with occasional residual anvil lightning remain primarily confined to Flagler County this evening, with this activity expected to dissipate after sundown. A few isolated post-sea breeze showers will also persist across the First Coast and should gradually weaken and dissipate through the evening. Farther north, a few additional showers may briefly develop across interior southeast Georgia as the east coast sea breeze continues its westward progression toward the Waycross area.

Most convection will diminish rapidly after sunset with the loss of daytime heating. However, a few lingering light showers may persist along the westward-moving east coast sea breeze boundary before it eventually dissipates. Considerable cloud cover will linger through midnight before clearing skies gradually develop after midnight.

Toward daybreak, strengthening southwesterly flow may allow a few showers to move into portions of western Marion and Alachua Counties. Overnight lows will fall into the mid 70s inland, with upper 70s expected along the coast.

SHORT TERM /THROUGH MONDAY NIGHT/

Sunday & Monday...

Main Highlights This Period:

- Daily Max Heat Indices 105-110, Heat Advisory Potential - Daily Afternoon & Early Evening Storms - Elevated Rip Current Risk Sunday

A pattern shift to southwest steering flow begins Sunday and continues Monday as the mid level ridge axis extends across south- central FL. This will bring a dominant west coast sea breeze convective regime across the local area and focus the higher afternoon and evening thunderstorm chances across areas east of Highway 301 and toward the coast each day. Southwest flow off of the Gulf will bring a few morning showers then late morning thunderstorm chances inland by about noon across the Suwannee River Valley, with more scattered to numerous showers and storms blossoming from west to east across inland areas into the afternoon. Sea breeze and boundary mergers will converge near and west of Highway 301 and toward the Atlantic coast during the late afternoon with storms tracking back toward the local coast into the evening each day. Convection fades inland each evening with localized radiation fog where recent rainfall occurs. With warm mid levels and weak steering flow < 10 kts for most locations, the main storm hazards will be localized, briefly flooding rainfall and wet downburst winds of around 40 mph due to heavy precipitation loading. Better storm chances on Sunday, with lower chances Monday as some drier mid/upper level air invades from the west-southwest.

Temperature moderate to above average with highs in the mid to upper 90s, even the low/mid 90s at the beaches with a delayed east coast sea breeze start compared to recent days. This building heat combined with elevated dew pts will created heat index values in the 105-110 deg range each day, near to just above Heat Advisory criteria for zones east of Highway 301 and toward the coast. Muggy overnight lows range in the 70s inland to near 80 coast.

LONG TERM /TUESDAY THROUGH SATURDAY/

Main Highlights This Period:

- Above Average Temperatures with High Heat Index Values - Daily Thunderstorm Chances

Prevailing southwest steering flow continues through the week with increasing moisture from the north across southeast GA mid-week which will increase daily shower and thunderstorm coverage. At this time daily rain chances range from 20-50%, with the higher afternoon and evening chances toward the east coast. Evening storms press offshore then showers resurrect near the Gulf Coast and shift inland each morning.

With the upper ridge across FL and westerly flow, higher thicknesses will continue above average temperatures with highs in the mid/upper 90s and daily heat index values 105-112 degF, reaching local Heat Advisory criteria in some locations. At this time, the area of greater heat risk appears to focus along the Highway 301 corridor toward the Atlantic coast across northeast Florida, with "extreme risk" highlighted at wpc.ncep.noaa.gov/heatrisk Tue-Fri.

AVIATION /00Z SUNDAY THROUGH 00Z MONDAY/

The few lingering showers and storms will clear in the next hour or so. Light to calm winds will develop during the overnight hours, which could allow for lower vsbys to develop over inland sites. Winds will continue mainly from the southwest on Sunday with showers and storms moving from west to east. Convective activity will likely increase after 18Z as the sea breezes begin to merge. Likely impacts to TAF sites still is not certain, so put PROB30 groups for now, with further refining in upcoming TAF packages.

MARINE

High pressure builds across central and south Florida this weekend into early next week with a transition to a prolonged south to southwest flow over the local waters through next week. This will increase afternoon and evening thunderstorm chances over the local waters. Nightly wind surges return with near exercise caution levels developing by Sunday night.

Rip Currents:

High risk remains in effect, mainly due to the higher probability of Rip Current incidents due to the heavy beach attendance for the Independence Day holiday. Surf will be generally 1-3 feet with minor swell which will generally diminish the occurrence of rips on a widespread concern but typical areas near jetties, sandbars, inlets, and piers will be favored for rip currents this afternoon. Similarly, looks like a moderate to locally high risk for Sunday.

FIRE WEATHER

Showers and isolated storms moving inland from the Gulf Coast through late morning. The east coast sea breeze will develop and drift inland toward the I-95 corridor mid to late afternoon. The best chance of afternoon and evening storms each day will focus between Highway 301 and the Atlantic coast. Dispersion will be elevated across inland southeast GA and parts of the Osceola NF on Monday. Daily heat index values will approach 105-110 deg. Afternoon minimum humidity will continue above critical values.

Fog Potential and other remarks: Patchy inland fog each morning around sunrise is possible, especially where rainfall recently occurred. Thunderstorms will be capable of producing 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 75 96 75 95 / 10 40 30 20 SSI 79 95 79 94 / 0 50 30 40 JAX 76 96 77 95 / 10 60 30 50 SGJ 77 94 77 94 / 10 40 20 50 GNV 75 93 74 93 / 30 40 10 40 OCF 75 92 75 92 / 30 40 20 40

JAX WATCHES/WARNINGS/ADVISORIES

FL...High Risk for Rip Currents until 2 AM EDT Sunday for FLZ124-125-138- 233-333. GA...None. MARINE...None.