Jacksonville, FL 32226 Weather

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 Flooding Continues within the St Johns River through the weekend.

- High Surf Advisory for NE FL beaches and a High risk for Rip Currents continues at all beaches through the weekend.

- Small Craft Advisory for the Atlantic waters likely through the Weekend

- Isolated Thunderstorms Possible on Sunday and Sunday Night; Heavy Rainfall Possible across portions of NE FL south of I-10.

Near term

Main Highlights:

- Minor to Moderate tidal flooding continues along the St Johns River basin, Atlantic Coast, and ICW

- Rough surf and dangerous rip currents continue, especially at Northeast FL Beaches

Overall similar conditions across the area today, as high pressure to our north weakens, but starts to get replaced by another ridge building in from the north. This will keep a northeasterly onshore flow persisting, though overall a bit weaker, especially at the coast and over area waters. Coastal Flood Warning persists for the St. Johns River Basin south of downtown JAX, with advisories now in effect elsewhere. More details on this situation can be found with the Hydro discussion further below. Otherwise, occasional coastal showers will also continue at times today and into tonight, especially at the northeast FL coast. Low clouds will effect the coast and portions of northeast FL, with more higher clouds also starting to fill in from the west throughout the day as well. Highs will remain in the mid to upper 70s generally near or east of I-95, with low 80s inland.

A backdoor cold front will start to approach from the north with a fresh ridge punching down the southeastern seaboard tonight, though any changes/impacts from these features will hold off until the day on Saturday. Lows tonight will range from the 60s over southeast GA and inland FL to the low 70s closer to the St. Johns River and coast.

Short term

Main Highlights This Period:

- Coastal flooding and surf hazards continue through the weekend.

- Heavy rainfall and scattered thunderstorms for portions of NE FL on Sunday

The prolonged onshore flow will restrengthen through Saturday as a reinforcing "backdoor" front pushes in along the edge of progressive low level ridging. Though coastal flooding, maritime and surf zone conditions will diminish in intensity going into Saturday, the increasing northeasterlies will likely add more potential for beach erosion while the "reverse flow" within the St Johns River is likely to lead to Minor to Moderate flooding, especially along the section of the river between Lake George and Jacksonville.

Convergence along the frontal zone will bring a bout of scattered coastal showers that is anticipated to expand inland through the day Saturday. Not too confident in thunderstorm potential given the meager instability but inland areas that overachieve on afternoon high temps (low 80s) may be enough for an isolated storm or two.

There is some uncertainty in how far south the front will make it before it stalls. As it stalls, attention will turn towards a dynamic upper disturbance moving across the region on Sunday. A wave of surface low pressure developing beneath the shortwave along the stalled front will strengthen convergence and may lead to increased thunderstorm potential through Sunday evening and potentially some training heavy rain bands, mainly across NE FL south of I-10. Still on the early side to call for rain amounts but ensemble guidance has reasonable high-end amounts only around 2-3" Sunday into Monday.

Temperatures will stay fairly consistent through Saturday before dropping a 3-6 degrees Sunday (highs in the mid/upper 70s) due to a mix of cooler air making it into SE GA and high rain chances for NE FL.

Long term

Main Highlights This Period: Sunday through Wednesday

- Thunderstorm potential returns midweek.

- Diminishing onshore flow and improving coastal and surf zone conditions.

There's some uncertainty on the evolution of the surface trough as it pushes off the Atlantic coast on Monday in whether it hugs the coast and propagates northward or pushes eastward offshore developing into a surface low. If it does develop and strengthen along the coast heavy coastal rain bands are likely to continue to through Monday. Guidance is in decent agreement on a stronger frontal system developing east of the Rockies early in the week and pushing a cold front and potential line of thunderstorms into Florida Wednesday night or Thursday. Confidence in severe convection remains low but with a later arrival, potential may begin to increase.

Temperatures will stay fairly consistent around normal early next week with some prefrontal warming during mid week.

Aviation

Primary concern through the morning hours will be MVFR and IFR ceilings as onshore flow continues. Expecting IFR to prevail at SGJ, VQQ and GNV, with more of a cut off further north and west. This is causing some uncertainty with respect to impacts at other terminals, but opted for prevailing MVFR at JAX and CRG at this time only, with TEMPO groups for occasional IFR ceilings possible. Also expecting VFR to prevail at SSI, though brief MVFR or IFR cannot be ruled out later this morning. Onshore flow around or just over 10 knots with periods of SHRA will continue at most airfields Friday afternoon and evening, along with MVFR ceilings for portions of the coast.

Marine

Strong high pressure over area waters will shift southward while weakening slightly today. Another strong high pressure center building southeastward from the Upper Midwest today will reach the Mid-Atlantic coast by Sunday, with this feature wedging down the southeastern seaboard this weekend and early next week. Although a slight lull in winds and seas is expected through tonight, the surge is likely to strengthen hazards once again for the weekend. A wavy stationary frontal boundary lifting slowly northward across the Florida peninsula this weekend may generate numerous showers and a few embedded thunderstorms on Sunday and Monday across our local waters.

Rip Currents / High Surf: High Surf Advisories remain in effect for the northeast FL beaches through tonight, where breakers of 5 to 6 feet will prevail. Breakers of 3 to 5 feet will prevail at the southeast GA beaches today. These elevated, rough surf conditions will maintain a high risk of deadly rip currents at all area beaches through the upcoming weekend, and additional beach erosion is likely to occur around times of high tide.

Fire weather

Persistent northeasterly winds will continue through the weekend as a reinforcing front pushes into the area. Breezy winds will elevate dispersions overnight while shallow daytime mixing keeps dispersion poor near the coast. Chances for showers and thunderstorms will increase this weekend with potential for heavy rain across portions of northeast Florida. Next week the onshore winds will begin to relax as a frontal system approaches from the west during midweek.

Tides/coastal flooding

As we continue to move away from the recent peak astronomical tides earlier this week, Coastal Flood Warnings for the coast have been downgraded to Coastal Flood Advisories, as mainly minor flooding is forecast with localized marginal moderate flooding remaining possible. Water levels will generally reach 2-2.5 feet above Mean Higher High Water (MHHW) during times of high tide south of the Downtown Jacksonville, and generally 1.5-2 feet above MHHW for the Atlantic Coast. The long duration of this strong onshore wind event will produce additional beach erosion during each high tide cycle through tonight. Onshore winds pick up a bit this weekend, but impacts are expected to remain overall similar as we continue to move away from the recent full moon.

Preliminary point temps/pops

AMG 82 62 80 63 / 0 0 30 0 SSI 75 65 76 64 / 0 10 40 10 JAX 78 66 79 66 / 10 20 40 10 SGJ 77 70 79 70 / 40 30 40 20 GNV 82 68 82 68 / 10 0 10 20 OCF 83 68 83 70 / 10 0 10 20

Watches, warnings and advisories

FL: Coastal Flood Warning until 5 AM EDT Saturday for FLZ038-125- 132-137-225-325-633. Coastal Flood Advisory until 3 PM EDT Saturday for FLZ124-138- 233-333. High Risk for Rip Currents through Sunday evening for FLZ124-125- 138-233-333. High Surf Advisory until midnight EDT tonight for FLZ124-125- 138-233-333. GA: Coastal Flood Advisory until 3 PM EDT Saturday for GAZ154-166. High Risk for Rip Currents through Sunday evening for GAZ154-166. MARINE: Small Craft Advisory until noon EDT today for AMZ452-454. Small Craft Advisory until 8 AM EDT Saturday for AMZ470-472- 474.