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

- High Rip Current Continues through Sunday. Minor Tidal Flooding this weekend for the St. Johns River.

- Small Craft Advisories at Offshore Waters through Tonight

- Isolated Thunderstorm Activity Returns Mid to Late week

UPDATE

A very dry airmass and clear skies will yield excellent radiational cooling and another night with the potential for record coolness for late September. Inland areas will fall to the mid possible lower 50s tonight, while coastal areas remain in the low 60s. Despite the airmass near the ground being very dry, the potential for shallow ground fog remains a possibility early Sunday morning.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/

Main Highlights This Period (Monday through Tuesday night):

- Moderating temperatures, and slowly increasing moisture this period

A frontal zone will extend south across the southeastern US Monday through Tuesday morning, then push to the south through Tuesday night, as an area of high pressure builds to the north northeast.

Drier air will remain in place across area Monday, but moisture will begin to increase across NE FL due to flow from the southwest. Monday is forecast to be a dry with highs generally rising into the upper 80s. A few spots could get to 90. On Monday night, the dry weather will continue, with lows ranging from around 60 over inland SE GA to the mid to upper 60s over NE FL, due to position of the lingering front near the GA/FL line.

On Tuesday, the front will largely dissipates as it moves to the south, and high pressure builds to the north northeast. Moisture will begin to return as it wraps around the high. The greatest chances for precipitation Tuesday afternoon will be over inland NE FL, where the east coast, and gulf sea breezes will converge. Highs on Tuesday, will again be above average with readings around 90, away from the immediate coast fairly common.

Tuesday night will be a dry night, with the onshore flow and increased lower level moisture keeping lows closer to seasonal levels in the mid to upper 60s.

LONG TERM /TUESDAY THROUGH SATURDAY/

Main Highlights This Period (Wednesday through Saturday):

- Increasing chances for convection each day this period

Surface high pressure will be centered to the east northeast Wednesday through Friday. This will result in a warm and moist onshore flow. With this pattern, a gradual increase in precipitation chances is expected with with scattered activity across area Friday.

A low pressure area is expected to move toward the central Gulf coast Saturday, with a frontal zone extending east across the area from this feature. Due to continued moist onshore flow, and convergence associated with this feature, precipitation chances will be scattered to numerous.

Temperatures will trend above seasonal averages this period.

AVIATION /00Z SUNDAY THROUGH 00Z MONDAY/

Winds will trend calm this evening with local high pressure and predominantly VFR conditions. Shallow, patchy fog formation is possible during the pre-dawn hours. Very light winds from the west will develop after 15z Sunday, with a light sea breeze at KSGJ and KSSI during the afternoon.

MARINE

Strong low pressure off the mid-Atlantic coast will track further away to the north through the end of the weekend as high pressure builds southward from the eastern Great Lakes into the southeast U.S. As low pressure lifts away, seas will gradually diminish through this evening, ending small craft conditions. High pressure will shift over the region Sunday and Monday with prevailing west to southwest winds, turning southeasterly in the afternoon nearshore from the Atlantic seabreeze circulation. High pressure will shift east of the waters midweek with southerly winds, turning easterly in the afternoon over the nearshore waters from seabreeze circulation. Increasing moisture will bring a return of scattered showers and isolated thunderstorms over the waters by midweek.

Rip Currents: Breezy north northeasterly winds today, long period swells, and elevated surf heights up to 4 to 6 feet will continue high risk of rip currents today. Long period swells will persist through Sunday and continue a high risk of rip currents through the end of the weekend.

FIRE WEATHER

Over the weekend a dry airmass will push across the area and lower afternoon humidity to at least 25-30% for several inland districts Today, Sunday, and Monday. Surface and transport winds will shift to be more northeasterly Today, with breezy conditions persisting at coastal locations. Fair to good daytime dispersion values are forecast area-wide. Winds will become light and turn westerly on Sunday. Warming temperatures and rising humidity levels are expected through next week with winds favoring the diurnal Atlantic sea breeze regime.

Fog Potential...Significant fog formation unlikely the next several days.

TIDES/COASTAL FLOODING

Astronomical tides will continue rising through the weekend due to the upcoming Full "Harvest" Moon tonight. Breezy north to northeasterly onshore winds today will maintain reverse flow within the St Johns river with water slow to drain Sunday into early next week due to lingering high astronomical tides and light winds. Water levels peak during high tide between 1.5 - 2 feet above Mean Higher High Water (MHHW) this weekend into early next week.

CLIMATE

A second night of record Low Temperatures possible Sunday morning.

September 27

KJAX: 54/1940 KGNV: 53/1940 KCRG: 57/1982

PRELIMINARY POINT TEMPS/POPS

AMG 55 86 57 87 / 0 0 0 0 SSI 63 85 66 86 / 0 0 0 0 JAX 56 86 63 88 / 0 0 0 0 SGJ 60 84 65 87 / 0 0 0 0 GNV 56 85 63 88 / 0 0 0 0 OCF 58 86 63 89 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...High Risk for Rip Currents through Sunday evening for FLZ124-125- 138-233-333. Coastal Flood Advisory until 5 AM EDT Sunday for FLZ125-132- 137-225-325-633. GA...High Risk for Rip Currents until 2 AM EDT Sunday for GAZ154-166. MARINE...Small Craft Advisory until 11 PM EDT this evening for AMZ470. Small Craft Advisory until 4 AM EDT Sunday for AMZ472-474.