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 Saturday Night. High Risk for Rip Currents, Rough Surf, Elevated Tides and Beach Erosion. Minor Tidal Flooding Continues for the St Johns River

- Hurricane Isaias tracking northward toward northern Gulf coast. Reinvigorated onshore Winds and Additional Periods of Heavy Rain Today and Isolated Severe Thunderstorms/Tornadoes Possible Tonight through Saturday

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Flood Watch in effect for Northeast FL through This Evening and for Southeast Georgia this Afternoon through Saturday Evening.

- Coastal and Marine Impacts Continue, Including Coastal Flood Advisory for the St. Johns River. High Risk of rip currents and increasing easterly winds for area coastal waters today.

- Potential for Isolated Severe T'storms Late Tonight with a Threat for a few brief Tornadoes

Early this morning, increasing low level easterly flow across NE FL and SE GA north of a warm front and increasing SW flow in the mid and upper levels downstream of Hurricane Isaias over the north central Gulf waters is increasing mousier, lift and instability back over the area. Scattered light to moderate showers currently over SE GA and the Suwannee Valley will fill in gradually through sunrise along the NE FL coast and then shift into inland NE FL to I-10 and the warm front lifts from north central FL into NE FL by early this afternoon. A few strong T'storms are possible this afternoon over inland NE FL.

The heaviest showers and embedded isolated to scattered T'storms will shift into SE GA this afternoon into evening as Hurricane Isaias approaches the central Gulf coast, but remains to the west of the area. The warm front will lift into SE GA by this evening with a trailing band of showers and isolated T'storms across the Suwannee Valley near and west of the Suwannee River and into areas along and west to US-221/441 in SE GA. There is a risk of isolated severe T'storms along and south of the warm front over western portions of the area as the trailing band of showers and T'storms will be in a supportive environment for an isolated tornados and gusty winds 40- 60 mph as wind fields and shear increase after Isaias moves inland to the west and northwest of our area overnight.

The gradient between High pressure building north of the region and the Tropical system moving to our west will increase the local pressure gradient across the area. Very breezy conditions will develop with winds 15-25 mph at the coast with gust to 30-35 mph decreasing to 10-20 mph gusting to 25 mph over inland areas. A Flood Watch has been continued for all of NE FL this morning through this evening for 1-3 inches of rainfall over areas that have received 4-8 inches of rain over the course of this week and additional rainfall could lead to flash flooding. A Flood Watch will go into effect this afternoon across all of SE GA where waves of heavy showers will bring widespread 1-3 inches of rain with locally higher amounts of 5 inches through Saturday as the warm front lifts northward and tropical moisture with Isaias shifts NE across Georgia.

Highs will be near to below normal for most of the area except north central FL where more breaks in the clouds will provide for warming into the upper 80s over Marion/Putnam/Flagler counties while reaching the low 80s over I-10 and the SE GA coast and the mid to upper 70s over inland SE GA and the Suwannee Valley. Lows tonight will be above normal around 70 over SE GA and the low to mid 70s over NE FL.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Main Highlights This Period: Saturday through Sunday night

- Potential for strong to severe storms increasing through Saturday, along with flooding chances

- Strong onshore winds renew the surf zone risk and continue tidal flooding within the St Johns River and along the Atlantic coast.

Widespread showers and storms will build across the forecast area on Saturday as warm and moist air advects into the region. Prevailing flow will shift to become more out of the southwest as a cold front trailing after the remains of the tropical system presses over the region from out of the west, leading to a drop off in convection by the afternoon and evening hours on Sunday. Potential for strong to severe storms this weekend, with higher likelihoods occurring over southeast Georgia and into the Suwannee Valley area, along with a slight to marginal risk for excessive rainfall during this period. Daily high temperatures will rise into the lower to mid 80s for southeast Georgia and in the mid to upper 80s for northeast Florida. Overnight low temperatures will drop down from out of the lower to mid 70s on Saturday night down into the dropping down into the lower to mid 60s on Sunday.

LONG TERM /MONDAY THROUGH THURSDAY/

Main Highlights This Period: Monday through Thursday

- Dry and warm weather next week

Dry weather conditions will be in place for the beginning of next week as the frontal boundary progresses south of the Florida peninsula bringing dry weather, clearing skies, and mild winds through midweek. High temperatures for next week will rise to be above the seasonal average with max temps reaching into the mid to upper 80s.

AVIATION /06Z FRIDAY THROUGH 06Z SATURDAY/

For the 00Z TAF period, MVFR or near MVFR conditions will persist through early morning from moist onshore flow and redevelopment of coastal convergent showers at the coastal and duval TAF sites through 10Z. Have TEMPO groups for showers bringing MVFR VSBY/CLNGs at SSI for next few hours into 08Z. More showers will redevelop over the Northeast FL waters and move to the Northeast FL coastal sites after 08Z with heavier showers after 13Z arriving. Tempo groups follow heavier showers moving from SGJ late this morning and midday to the duval TAF sites mid to early afternoon, then shifting north and west to GNV and SSI through 21Z. Isolated to scattered embedded Thunderstorms will enhance downpours with IFR VSBY and MVFR CLNGs. SHowers will continue through sunset with decreasing coverage of showers and thunderstorms across Northeast FL terminals after 04Z but continuing through the end of the period at SSI.

Winds pick up during today as the gradient between onshore flow and Hurricane Isaias over the Gulf strengthens with sustained 15-20 near the coast and gusts 25-30 knots while decreasing to 15 knots gusting to 20-25 knots inland at GNV and VQQ. Winds will decrease slowly after 00Z at most sites except SSI to 10-15 knots with gusts near 20 knots and MVFR ceilings persisting.

MARINE

A front will lift northward through the waters starting tonight with another high pressure center building in north of the region Friday and to the north northeast on Saturday. Small Craft Advisory conditions will return to the Southeast Georgia Waters due to elevated easterly winds and seas early this morning through Saturday night.

The National Hurricane Center is monitoring Hurricane Isaias in the central Gulf. This system is expected to move northward towards the central Gulf coast region Friday into Saturday. Showers and thunderstorms will increase in coverage throughout our local waters during the weekend as tropical moisture surges northward on the eastern periphery of this tropical system.

Rip Currents: Strengthening easterly onshore winds today becoming southeasterly on Saturday will support dangerous rip currents and rough surf. High Risk for Rip Currents will likely continue through this weekend with continued breezy/windy onshore flow.

FIRE WEATHER

- Patchy High Dispersions Sunday And Monday

The warm front stretching east across central Florida today will lift north of the area by later tonight as Hurricane Isaias makes landfall over the northern Gulf coast. A cold front will move southeast across the area Sunday into Sunday night. Above average precipitation chances through Sunday, with potential for strong to severe thunderstorms. The greatest chance for severe storms will occur on Saturday. In addition, flooding potential will continue through Sunday.

High pressure will provide mainly dry weather for next week.

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 while decreasing below minor flood stage along the Atlantic coast Today into Saturday, so the Coastal Flood Advisory will remain 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 75 70 82 71 / 90 100 100 60 SSI 82 74 85 75 / 90 90 70 50 JAX 83 73 88 73 / 90 70 70 40 SGJ 84 76 88 75 / 90 60 70 40 GNV 85 73 88 73 / 70 70 70 40 OCF 87 75 89 75 / 70 50 80 40

JAX WATCHES/WARNINGS/ADVISORIES

FL...Flood Watch through late tonight for FLZ021-023-024-030-031- 035-038-120-124-125-132-136>138-140-220-225-232-233-236- 237-240-322-325-333-340-422-425-433-522-533-633. High Risk for Rip Currents through late Saturday night for FLZ124- 125-138-233-333. Coastal Flood Advisory until 2 PM EDT Saturday for FLZ125-132- 137-225-325-633. GA...High Risk for Rip Currents through late Saturday night for GAZ154- 166. Flood Watch from 2 PM EDT this afternoon through Saturday evening for GAZ132>136-149-151>154-162-163-165-166-250- 264-350-364. MARINE...Small Craft Advisory until 5 AM EDT Sunday for AMZ450-470. Small Craft Advisory until 5 AM EDT Sunday for AMZ452-454-472- 474.