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. Storm Hazards: Lightning, Gusty Winds, & Localized Flooding

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

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

NEAR TERM /THROUGH TONIGHT/

Main Highlights through Tonight:

- Scattered Strong Pulse Storms for Inland NE FL this afternoon. - Minor and Localized Flooding Possible with Strong Storms. - Elevated Rip Current Risk at Area Beaches Today

The transition to a more typical summery pattern is underway as south-southeasterly moisture feed continues to pump precipitable water values above 1.75" in the Suwannee Valley and generally along and south of I-10 to 2"+ across Marion County. This uptick in available deep moisture and instability has already seeded a few areas of expanding coverage in the high-grade moisture across north- central FL. Coverage will expand across NE FL as the Atlantic and Gulf sea breezes trek inland. Stronger pulse storms are more likely to develop along sea breeze, outflow, cellular collision as coverage expands mainly across inland NE FL, along and west of the St Johns River. While the stronger storms will be favored across NE FL, isolated storms will be possible as far north as US 82 in SE GA.

A generally weak steering underscores the localized flood potential as peak rain rates around 3-4" hour will be possible with the more robust storms, likely along the US 301 corridor where the sea breezes will merge early this evening 6-8 PM. Considering all of the outdoor festivities, frequent lightning will be a higher than typical risk today. Heavy water loaded pulses will also be capable of gusty outflows up to 45 mph as they collapse.

Convection will generally weaken and fade after the loss of heating but the residual showers will be steered east-northeastward toward the Atlantic coast during the evening hours. Lingering scattered clouds will linger beyond midnight as conditions dry out completely. During the predawn hours, southwesterly flow may push in showers into portions of western Marion and Alachua counties. Lows reading in the mid 70s inland and upper 70s near the coast.

SHORT TERM /SUNDAY 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 FRIDAY/

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 /18Z SATURDAY THROUGH 18Z SUNDAY/

Primary TSRA concerns this afternoon remains focused across Northeast FL, generally west of the I-95 corridor. High confidence of slow-moving +TSRA at KGNV between 19z-23z remains the most likely with potential convective impacts possible at KVQQ and KJAX through 23z. Per usual, in the vicinity of +TSRA erratic wind gusts up to 30+ knots is possible.

Otherwise, no forecast augments made with the afternoon forecast. Outside of convection, cloud bases around 4-5 kft are expected with winds light winds from the WNW shifting east around 10 knots with the Atlantic sea breeze.

This evening as convection settles, "blow back" showers from residual TSRA may lead to -SHRA along the I-95 corridor through 03z. Southwesterly winds will develop overnight and spark widely scattered showers by 15z.

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 Sunday evening.

PRELIMINARY POINT TEMPS/POPS

AMG 96 75 96 75 / 10 10 40 30 SSI 89 79 95 79 / 0 0 50 30 JAX 95 76 96 77 / 30 10 60 30 SGJ 89 77 94 77 / 20 10 40 20 GNV 95 75 93 74 / 60 30 40 10 OCF 92 75 92 75 / 70 30 40 20

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.