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

- Coastal & Marine Hazards Continue through the Weekend. Small Craft Advisory through Tonight. High Risk for Rip Currents, Rough Surf, Elevated Tides and Beach Erosion. Minor Tidal Flooding Continues for the St Johns River

- Weakening Tropical Storm Isaias will track northward to the TN Valley northwest of the area. Reinvigorated onshore Winds and Additional Periods of Heavy Rain Today. Flood Watch in effect over SE Georgia and into the Suwannee Valley Area. Isolated Severe Thunderstorms/Tornadoes Possible Today

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Flood Watch in effect for The Suwannee Valley and Southeast Georgia through Early This Evening.

- Coastal and Marine Impacts Continue, Including Coastal Flood Advisory for the St. Johns River. High Risk of rip currents and breezy east to southeast winds and rough seas for area coastal waters through tonight and lingers on Saturday.

- Potential for Isolated Severe T'storms Late Today with a Threat for a few brief Tornadoes for the Suwannee Valley and inland Southeast Georgia inland areas.

A lull in shower activity now after heavier showers and T'storms moved through the Jacksonville vicinity late overnight which brought locally up to 3-5 inches of rain into portions of the NE FL coast, but has now shifted NNE off the SE GA coast as frontal boundary along I-10 northward into SE GA through sunrise. Easterly winds 5-10 mph inland and 10-15 mph along the coast will trend southeasterly south of the warm front. Multi layered cloud cover will continue as tropical moisture from weakening Tropical Cyclone Isaias moves northwest of the region across the deep south. Muggy and dewpoints remained in the mid 70s.

As the weakening remnants Isaias shift northward across northern AL, strong high pressure will be NNE of the region with a pinched local pressure gradient. Breezy southerly winds will resume as more peaks of sunshine will prevail, especially over NE FL and coastal SE GA, bringing winds 15-20 mph gusting to 30-35 mph over the western half of the area and 10-15 mph gusting to 25 mph along the coast. Bands of showers trailing TC Isaias to the NW will move in from the SSW to NNE across our area. The combination of high moisture content and mid 70s dewpoints in the wake of the warm front lifting north and stronger heating will make for increased low level instability with CAPE values over 1,500 J/Kg. This instability along with low level 850 mb winds of 30-35 knots and veering flow aloft will support strong dynamics will favor potential for isolated severe T'storms with a threat for a few tornadoes across the Suwannee Valley and inland SE GA and brief wind gusts up to 50-60 mph. The Storm Predication Center has a Slight risk (level 2 out of 5) of Severe Thunderstorms for these areas mentioned with a marginal risk across the rest of NE FL to the coast. The best timing will be midday to early afternoon further inland and early to mid afternoon closer to the coast. In addition, A flood Watch remains in effect through early this evening for all of SE GA and the Suwannee Valley of NE FL where bands of heavier showers and thunderstorms will bring another 1-3 inches of rain with locally higher amounts. HREF shows Probability Match Mean percentages of up to 50 percent of one inch of rain over 3 hours over these areas with higher end amounts in the 6 hour Max values peaking 3-4 inches this afternoon, another signal for heavy rainfall potential. The Weather Prediction Center has a Slight risk of excessive rainfall (level 2 of 4) for the areas in the Flood Watch. Another lull in rain and T'storm activity is expected tonight after sunset with elevated southerly winds continuing 8-12 mph with gusts to 15-20 mph. A cold front will begin to move into western portions of the area towards sunrise. Lows will fall into the upper 60s over far inland SE GA, but remain the low to mid 70s across NE FL and eastern areas of SE GA under thinning high level clouds and winds turning southwesterly just ahead of the front.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

Main Highlights This Period: Saturday through Sunday night

- Convection will clear out by end of Sunday

- Dry weather conditions following the frontal passage, on Monday

Showers and storms associated with the frontal passage, primarily over northeast Florida, will move offshore and disperse over the course of the day on Sunday, with the dry stable air mass settling over the region by Monday bringing dry weather, clearing skies, and northwesterly winds. Temperatures will begin to undergo a brief warming trend going into the beginning of next week with daily high temps rising from out of the lower to mid 80s on Sunday up into the mid to upper 80s on Monday. Overnight low temperatures will drop down into the lower 60s over inland areas and in the mid to upper 60s for coastal areas and along the St Johns River.

LONG TERM /TUESDAY THROUGH FRIDAY/

Main Highlights This Period: Monday through Thursday

- Dry and warm weather next week

- Diurnal sea breeze winds by Friday

Predominantly benign weather will be in place through next week as the dry air mass remains in place over the forecast area bringing clear skies and warm weather through midweek. Partly cloudy skies with chances for diurnal showers will increase going into the end of the week as the remnants of Isaias crosses into towards the Atlantic up to the north and shifts the prevailing flow about to become a more onshore southeasterly direction, increasing the reach of diurnal sea breeze winds reaching inland past the St Johns River. Daily high temperatures will initially be above the seasonal average through midweek, reaching into the upper 80s, and then dropping to be nearer to the seasonal average by the end of the week.

AVIATION /06Z SATURDAY THROUGH 06Z SUNDAY/

Warm front lifting through the terminals this evening will continue TSRA chances at GNV/SGJ until 02Z, then at JAX/CRG/VQQ from 01-04Z, then SSI from 02-05Z. Gusty E-NE winds around 15G25 knots will continue through 06Z before becoming E-SE and decreasing to 10-15 knots overnight. Mostly MVFR CIGS are expected tonight with TEMPO IFR conds with TSRA activity this evening as it lifts northward through the terminals. SE winds around 10 knots and brief break in the SHRA activity will develop between 09-15Z time frame and have continued MVFR CIGS with VCSH at most terminals. Diurnal heating in S-SE flow increasing to 10-15G20-25 knots by 15-16Z will help to trigger shower activity along with TSRA chances through the end of the TAF period and have added PROB30 for gusty MVFR TSRA activity with 30 knot potential at all terminals.

MARINE

A warm front will lift north of the waters this morning as the remnants of Tropical Cyclone Isaias moves northwest of the area with elevated southerly winds and seas through tonight that will continue Small Craft Advisory conditions through late tonight evening hours. Winds will become westerly on Sunday and gradually decrease as a cold front moves through and exits east of the waters. A round of showers and thunderstorms will move through the waters today as tropical moisture moves over the region. A cold front will move through the waters Sunday with chances for showers and thunderstorms early in the day with high pressure building in from the west. High pressure will build over the waters Monday into much of next week.

Rip Currents: Elevated southeasterly winds Today will support dangerous rip currents and rough surf. High Risk for Rip Currents will likely continue through this weekend with continued breezy/winds, and lingering rough surf at times on Sunday as winds turn more southwesterly.

FIRE WEATHER

- Patchy High Dispersions Sunday

Waves of showers and storms are expected to persist through this afternoon as trailing bands from Hurricane Isaias sweep across the area. Breezy conditions also are expected through today, with occasional gusts near 30 mph. Drier weather begins to develop as a cold front begins to move into the area on Sunday, with shower and storm chances beginning to diminish by the afternoon to evening hours. Quieter weather is expected during the upcoming as high pressure builds over the region into midweek, with winds from the west to northwest.

FOG POTENTIAL AND OTHER WEATHER REMARKS: Dense fog formation is not expected for the next few days. Heavy rainfall may lead to another potential period of flash flooding today, with a potential for isolated severe thunderstorms. Gusty and erratic winds will develop near thunderstorms.

HYDROLOGY

Portions of the St Marys, Satilla, and tributaries to the St Johns River have risen into minor flood stage. Additional rainfall through the weekend may bring further increases in water levels and lead to other local river rises. Rain-free conditions next week will allow river levels to lower.

TIDES/COASTAL FLOODING

Coastal flooding will persist through the weekend within the St Johns River, so continuing the Coastal Flood Advisory only along the St Johns river. Anticipate water levels at high tide to be at least at Minor Flood level through the weekend within the St Johns.

PRELIMINARY POINT TEMPS/POPS

AMG 82 69 80 64 / 90 80 10 0 SSI 85 74 85 66 / 70 50 20 0 JAX 88 73 85 64 / 80 40 30 0 SGJ 89 75 85 65 / 80 30 40 0 GNV 87 73 84 63 / 80 70 50 0 OCF 88 75 84 63 / 70 60 60 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Flood Watch through this evening for FLZ021-023-030-035-120- 220-322-422-522. High Risk for Rip Currents through late tonight for FLZ124-125-138- 233-333. Coastal Flood Advisory until 4 PM EDT Sunday for FLZ125-132- 137-225-325-633. GA...Flood Watch through this evening for GAZ132>136-149-151>154- 162-163-165-166-250-264-350-364. High Risk for Rip Currents through late tonight for GAZ154-166. MARINE...Small Craft Advisory until 5 AM EDT Sunday for AMZ450-452-454- 470-472-474.