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

- Increasing Daily Thunderstorm and Heavy Downpour Coverage. Waves of Heavy Downpours May Increase the Threat for Localized Flooding this

- Weekend and into Next Week

- Moderate Rip Current Risk all Area Beaches through Monday

- Coastal and Marine Hazards Increase Next Week. Strong & Gusty Northeast Winds Arrive Monday Night. Gale Conditions Likely for the Atlantic Waters Tuesday through Wednesday. Deadly Rip Currents, Rough Surf & Substantial Beach Erosion Likely. Moderate Tidal Flooding Risk Tuesday through Thursday Along the Atlantic Coast,

- Intracoastal Waterway & Tidal Tributaries of the St. Johns & St. Marys River Basins

NEAR TERM /THROUGH SATURDAY/

Main Highlights Today and Tonight:

- Numerous to widespread showers and scattered thunderstorms this afternoon and into the evening.

- Localized heavy downpours may lead to brief periods of flooding, especially for inland areas.

Afternoon surface analysis depicts high pressure (1022 millibars) now centered near Bermuda, with this feature extending its axis westward along the southeastern seaboard. Meanwhile, a cold front extends from New England southwestward through the Ohio and Tennessee Valleys and across eastern Texas. Otherwise, strengthening high pressure (1030 millibars) was building across the Upper Midwest and the Plains states in the wake of this front. Aloft...deep- layered ridging situated along the southeastern seaboard has deflected a shortwave trough northeastward towards the Great Lakes region, with a cutoff trough lingering behind this departing system over west Texas. Latest GOES-East derived Total Precipitable Water imagery indicates that deep tropical moisture has overspread our area, with PWATs above 2 inches area-wide, with values of 2.2 - 2.4 inches generally located along and south of the Interstate 10 corridor. Widespread showers and embedded thunderstorms that have been impacting the I-95 and U.S. Highway 301 corridor this afternoon are expanding inland towards I-75 and interior portions of southeast GA, where a band of very heavy downpours is currently training from the Okefenokee Swamp northward through Waycross and Blackshear, extending northward to just east of Baxley. Activity elsewhere has been moving briskly northward around 20 mph, producing brief wind gusts of 30-40 mph, in addition to occasional lightning strikes. Temperatures at inland locations that have not received rainfall remain mostly in the mid to upper 80s as of 19Z, while locations elsewhere have cooled to the 70s. Dewpoints were in the 70s area- wide.

Stout ridging along the southeastern seaboard will shift south and eastward overnight, allowing mid and high altitude winds to veer to south and then southwesterly overnight. This weather pattern will maintain a feed of deep tropical moisture into our area, and embedded shortwave energy in this flow over the eastern and southeastern portions of the Gulf will advect across our area tonight. Outflow boundaries pushing westward across interior portions of southeast GA as well as towards the I-75 corridor in the Suwannee Valley and north central FL will continue to ignite convection through late this afternoon, with the potential for band of downpours to train from south to north through early this evening at these inland locations. Shortwave energy approaching out area from the eastern Gulf should guide the next round of convection northward from central FL along the I-95 and U.S. Highway 17 corridors in north central and northeast FL late this afternoon through early this evening, with this activity then making its way across coastal southeast GA through the evening hours. Briefly heavy downpours can be anticipated with this next round of showers and embedded thunderstorms through around sunset this evening. Convection should then move away from our area while weakening at inland locations towards midnight. Low clouds and possibly some fog will likely develop during the predawn and early morning hours on Saturday, especially at inland locations. Temperatures will remain in the 70s area-wide overnight in this warm and unseasonably humid air mass.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/

Main Highlights This Period: Saturday through Sunday night

- Above normal rain chances through the weekend. Localized heavy downpours and flooding possible.

The region will be between an area of high pressure to the northeast, and an inverted trough over the Gulf this period. A frontal boundary will extend northeast from the Gulf trough, and be located just north of the local area this for most of this period. The front is expected to sink south across area Sunday night. A very moist airmass will be in place over the weekend, with waves moving east along the frontal zone to the north. The greatest chance for precipitation will be over SE GA closer to the frontal zone, but above average chances will exist across the forecast area.

While a few strong storms can not be ruled out this period, the main hazard will be the potential for heavy rainfall and localized flooding.

Temperatures will trend above average this period.

LONG TERM /MONDAY THROUGH FRIDAY/

Main Highlights This Period: Monday through Friday

- Strong northeast flow pattern Tuesday through Thursday, with potential for Minor to Moderate Tidal Flooding, Deadly Surf, and Gusty Coastal Conditions.

- Potential for rounds of heavy rainfall, and a few strong to severe thunderstorms can not be ruled out

The front will slowly push just to the south of the local area Monday into Tuesday, as high pressure builds to the north. Waves of rain are expected to continue to move east along this boundary over the forecast area.

An area of low pressure is expected to develop on the frontal zone to the northeast Tuesday, then slowly move to the east northeast Wednesday into Thursday. The gradient between the low, and high pressure to the north will bring a surge of winds down the coastal waters. The proximity of this low will enhance precipitation coverage, especially at the coast. Coastal winds will also be elevated Tuesday through Thursday, with wind advisory level gusts possible at the beaches.

High pressure ridge will build closer from the north Friday, but the frontal zone will remain just to the south, so precipitation chances will continue.

Temperatures will trend below average this period.

AVIATION /00Z SATURDAY THROUGH 00Z SUNDAY/

Showers will continue to move through the forecast area tonight, becoming more dispersed by around 03z however an occasional errant shower may still be possible through 10z. Reduced visibility and IFR ceilings for sites are anticipated for the early morning hours on Saturday, spanning between about 10z and 15z with conditions being more restricted at VQQ. Winds will be mild and variable overnight and then build from out of the southeast after 13z to 15z.

MARINE

High pressure positioned near Bermuda will maintain a prevailing southeasterly wind flow across our local waters through the weekend. Meanwhile, a surge of tropical moisture overspreading our local waters will result in waves of showers and thunderstorms moving from south to north through the weekend. Outside of thunderstorm activity, winds and seas are expected to remain below Caution levels through at least Monday afternoon. Otherwise, a cold front entering the southeastern states on Saturday will slow its forward progress, moving across the Georgia waters on Monday and then stalling over the northeast Florida waters by Tuesday. Strong high pressure building over the Great Lakes and Mid Atlantic region in the wake of this front will wedge down the southeastern seaboard, providing a prolonged surge of northeasterly winds and building seas across our local waters. Small Craft Advisory conditions are likely by Tuesday, with the potential for wind gusts near Gale force through Thursday.

Rip Currents: Persistent onshore winds and 2 to 3 foot breakers will maintain a higher end moderate risk at all area beaches through Monday. Dangerous surf conditions are expected to develop on Tuesday as northeasterly winds strengthen, with the likelihood for very rough surf and deadly rip currents from Tuesday through the end of next week, with breakers potentially building to 8-10 feet at the northeast FL beaches and 6-8 feet at the southeast GA beaches by midweek.

FIRE WEATHER

- AREAS OF LOW DAYTIME DISPERSIONS OVER THE WEEKEND INTO EARLY NEXT WEEK

Waves of rain with embedded thunderstorms are expected over the next week, due to an inverted trough over the Gulf, and its associated frontal boundary which will gradually sink south across the area. An area of low pressure is expected to develop just to the northeast Tuesday, then slowly track away to the the east northeast through Thursday. The proximity of this low will result in elevated winds, especially at the coast.

Fog Potential...Significant fog is not expected Tonight. Gusty and erratic winds in and near thunderstorms. Locally heavy rainfall with localized flooding possible each day this period.

EQUIPMENT

The KVAX Doppler Radar in Valdosta GA near Moody AFB remains out of service until further notice. Please utilize KTLH (Tallahassee), KJGX (Robins AFB), or KJAX (Jacksonville) during the outage period.

PRELIMINARY POINT TEMPS/POPS

AMG 72 84 72 83 / 50 60 50 80 SSI 75 83 75 84 / 50 50 40 80 JAX 73 84 73 86 / 50 60 40 80 SGJ 75 85 75 87 / 70 50 40 70 GNV 72 86 72 88 / 60 60 50 70 OCF 74 88 74 90 / 70 70 50 70

JAX WATCHES/WARNINGS/ADVISORIES

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