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

- Seasonably hot today. Peak Heat Index in the 102-106 degrees.

- Limited Thunderstorm Potential Until Higher Chances Return this Weekend

- Moderate Rip Current Risk through Wednesday, lower risk Thursday

NEAR TERM /THROUGH TONIGHT/

Main Highlights for Today:

- Mostly dry conditions with seasonably hot conditions

A Saharan Air Layer has delivered a substantial amount of dry air into the mid levels tonight. This will mostly stay intact and erode lingering moisture through sunrise and limit shower development through today.

The lack of rain and dry airmass will allow for temperatures to soar into the mid and upper 90s inland this afternoon. Southerly flow will efficiently mix down dry air aloft, lowering dewpoints to the upper 60s for inland areas this afternoon, keeping heat index in the 100-106 degree range (below Heat Advisory levels). Though Atlantic moisture will be brought inland with the sea breeze, it will be offset by the cooling effect of the onshore breeze and also keep heat index from pushing to Heat Advisory levels.

While largely rain-free conditions are expected, there is a chance that sufficient moisture will reach Marion and Putnam counties by the late afternoon and that may be enough for a few showers or an isolated t'storm to develop as the Gulf and Atlantic sea breezes merge. Very isolated showers may continue to pop up through 10 PM but subside by midnight, setting up tranquil conditions and a cooler night compared to the last few as winds trend calm allowing lows to reach the low 70s inland and mid/upper 70s at the coast.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

Main Highlights This Period:

- Isolated to Widely Scattered Thunderstorms return Thursday Afternoon and Evening at Inland Locations.

- Seasonably Hot and Humid Weather Inland, Near Heat Advisory Along coastal counties

Thursday, ridging aloft extending ESE from the southern plains will create weak low to mid level flow over the area. Weak surface ridging will be over the NE Gulf and extend over the northern half of the FL peninsula with very light winds in the morning and midday hours before mostly sunny skies and the weak pressure pattern allows the seabreeze circulation to bring the Atlantic and Gulf seabreezes onshore, eventually merging near highway 301. Moisture levels will be closer to near normal with a cold front slowly sinking south of the TN valley into northern GA and expecting isolated to widely scattered thunderstorms to form from the merging seabreezes.

Highs will extend into the mid to upper 90s with low 90s at the coast and Suwannee Valley behind the Advancing seabreezes. Dewpoints mixing out to the upper 60s to around 70 north of I-10 and low 70s over inland NE FL will limit heat index values below heat advisory levels, but higher dewpoints in the mid to upper 70s behind the Atlantic seabreeze will elevate heat indices to 105-110 along the coast and I-95 corridor.

Friday, ridging aloft will persist from the west as troughing over the Mid Atlantic remains north of the region. This will keep the frontal boundary stalled north of the area across central GA and the Carolinas with weak ENE flow becoming more westerly late in the day. Seabreezes pushing inland will lead to widely isolated storms along highway 301 due to subsidence and a slight decrease in moisture levels compared to Thursday (PWATS near 1.40-1.60) a little below normal for late July. Light and variable winds will turn ESE behind the Atlantic seabreeze 10-15 mph. Highs will match Thursday's values with similar expectation for near heat advisory values at the coast and just below inland.

LONG TERM /SATURDAY THROUGH TUESDAY/

Main Highlights This Period:

- Increasing Chances for Afternoon and Evening Thunderstorms Late this Weekend and Early Next Week

- Potential Heat Advisory Conditions Late Week & Weekend

This weekend, a ribbon of shortwave energy between strong western ridging centered near the 4 corners region and a trough over the Mid Atlantic and NE states will dive ESE across southern Appalachians to the Carolina coast. This will deepen the trough over the east coast as the western ridge shifts eastward into the southern plains, and will allow the previously stalled cold front to move south into SE GA Saturday and then sink into NE FL Sunday. The front will stall across the northern FL peninsula Monday and dissipate as it sinks into central FL on Tuesday.

Increasing chances of showers and Thunderstorms are expected due to increasing moisture this weekend and lift along the front Sunday into Tuesday as it moves slowly across the area. Light west to WSW flow will become a bit breezier late this weekend as a low develops along the front near or offshore the NC coast Sunday and lifts away to the NE on Monday.

Highs during the period will be above normal in the mid to upper 90s this weekend into early next week with mid 90s even to the beaches due to West to SW low level flow. Heat index values will rise to heat advisory levels this weekend 106-110 along the coast and near heat advisory levels 104-108 inland due to dewpoints staying in the mid to upper 70s each afternoon.

AVIATION /06Z WEDNESDAY THROUGH 06Z THURSDAY/

While there could be spotty showers late in the day at KGNV and/or KSGJ, chances are too low to include any mentions at this time due to overwhelming dry air aloft.

VFR conditions are expected through the period with high clouds and diurnal cumulus today. Winds will be southerly around 10 knots ahead of the sea breeze which will push in from the Gulf and Atlantic this afternoon. For terminals along the I-95 and along the coast, an east- southeasterly wind shift is expected between 16z-22z with the Atlantic sea breeze while KGNV will turn southwesterly with the Gulf sea breeze around 20z.

MARINE

Southerly breezes will continue at Exercise Caution levels through the afternoon before easing overnight tonight as consolidated and stacked high pressure builds over the region. With light flow in place Thursday and Friday, the wind regime will be driven by the sea breeze development. A weak cold front will approach from the north this weekend and turn winds offshore with afternoon sea breeze development likely for the nearshore waters. Offshore flow and the nearby front will encourage scattered afternoon thunderstorm chances.

Rip Currents:

Longshore currents will persist through this afternoon but surf will diminish to around 2-3 feet today. As sea breeze develops, Rip Current Risk will increase to a Moderate Level this afternoon. Surf heights continue to lower another foot by Thursday, leading to low- end Moderate risk of rip current with the afternoon sea breeze.

FIRE WEATHER

- High Daytime Dispersion Values Inland Today

Tropical Storm Bertha will exit away from the region today across the northern Gulf waters with breezy southerly winds 10-15 mph gusting 20-25 mph. Atlantic seabreeze will move onshore and press to US-17 through the mid afternoon as the Gulf seabreeze progresses to highway 301 late this afternoon. Winds will shift southeasterly behind the Atlantic seabreeze and southwesterly behind the Gulf seabreeze. Dry conditions will prevail with only exception over the Ocala National Forest where widely scattered thunderstorms will develop along merging Gulf/Atlantic seabreezes. Dry air may enhance a few downdrafts with any storms leading to gusty and erratic winds. A frontal boundary will approach on Thursday with widely scattered thunderstorms in the afternoon hours and again Friday afternoon. Increasing thunderstorm chances expected this weekend as the front sinks slowly into the area.

Breezy surface and transport winds today along with high mixing heights will create areas of high dispersions inland across the area each day.

Fog Potential and Other Remarks: Significant fog development is not expected for the next several nights. No significant impacts expected from Tropical Storm Bertha.

PRELIMINARY POINT TEMPS/POPS

AMG 95 74 95 75 / 0 0 10 10 SSI 93 80 93 80 / 0 0 0 0 JAX 96 76 96 76 / 0 10 10 0 SGJ 95 76 93 76 / 0 0 0 0 GNV 95 74 95 74 / 0 0 20 10 OCF 95 74 95 74 / 10 10 20 10

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...Small Craft Advisory until 5 AM EDT early this morning for AMZ450-452-454-470-472-474.