Area Forecast Discussion

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 and Marine Hazards Continue into the Upcoming Weekend, includes: Coastal Flood Warning for localized Moderate Flooding along the middle St. Johns River and a Coastal Flood Advisory along the Atlantic Coast and lower St Johns River.

- High Rip Current Risk and High Surf at all Area Beaches through Sunday.

- Heavy Rainfall and Localized Flooding Possible Sunday Afternoon through Monday Evening, especially along the coast where focused rain bands may develop.

NEAR TERM /THROUGH TONIGHT/

Main Highlights:

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

- Rough surf and dangerous rip currents continue

Backdoor cold front is currently situated over North Carolina will continue making a southern push into the area through this morning, stalling and weakening almost directly across the area this evening and tonight. A "fresh" high pressure ridge will build down the southeastern seaboard in its wake throughout the day today, tightening the pressure gradient a bit and therefore enhancing the onshore flow once again. Ahead of the front, a diffuse band of showers currently streaming onshore the northeast FL coast is expected to pivot northward this morning, taking advantage of better lift and moisture ahead of the front. This will shift rain chances more so towards coastal I-10 corridor and northward, though a few showers will be possible across much of northeast FL overall with the continued onshore flow and the weakening frontal boundary stalling near northeast FL.

Breezier overall over inland areas today, though only a few mph breezier on average for the coast and St. Johns River where the onshore flow has been persistent. This will keep up/reinforce coastal and beach hazards today and through Sunday, as a high risk for rip currents, elevated surf, and coastal flooding will persist. The good news is astronomical influence continues to subside this weekend, and therefore not expecting a significant increase in tidal flooding potential. Mostly minor flooding is forecast (around 1.5- 2ft above normal dry ground) at times of high tide, with moderate flooding (around or just over 2ft above dry ground) expected in portions of the St. Johns River near Putnam County.

Tonight, scattered showers will persist at times, especially over north FL where the weak boundary settles. Lows will range from the low to mid 60s north to the low 70s south and east, after high temps in the mid 70s to low 80s for most this afternoon.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

Main Highlights This Period:

- Coastal flooding and surf hazards continue.

- Heavy rain and localized flooding possible, especially along the coast Sunday night into Monday

Despite the persistent onshore flow in place and coastal hazards continuing through Sunday and early next week, there will be wetter conditions during this period. The primary features will be a diffuse stationary front draped across central FL while an upper shortwave gradually lifts out of the eastern Gulf. Though the trough is trending slightly slower, compared to 24 hours ago, the associated with it is likely to induce a surface wave of low pressure along the stalled frontal zone. Taking the strong ascent, deeper moisture (PWATs up to 1.75"), and enhanced convergence, it's likely that several bouts of heavy rain and coastal banding will develop through the late afternoon Sunday and continuing through the overnight hours into Monday, especially for the NE FL zones. While isolated thunderstorms may develop during the afternoon, especially toward the I-75 corridor, available buoyancy is expected to be marginal and be more conducive to heavy rain showers.

Spread among guidance in terms of how much rain remains a bit wide, but reasonable expectations are around 2-3" with locally higher amounts. As of right now, WPC has an areawide "Marginal Risk" of excessive rainfall and focused "Slight Risk", highlight the heavy rain/flood potential Sunday into Monday. Heavier rainfall may continue along the coast throughout Monday as an inverted coastal trough develops in the wake of the passing wave of low pressure.

Damp and overcast conditions will keep temperature readings in the upper 70s during the days with mild conditions in the 60s overnight.

LONG TERM /TUESDAY THROUGH FRIDAY/

Main Highlights This Period:

- Thunderstorm potential returns Thursday.

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

Moist, local nor'easter conditions being to relent during the first half of next week as trough digs across the southern tier of the CONUS. As the system pushes toward the region steering flow will veer to the southeast helping to alleviate the tidal flooding with the St Johns River. There remains fair agreement among clustered ensembles, deterministic and AI models that the amplified upper trough will push a cold front in from the west around Thursday next week. Trends over the last 24 hours suggest the front may slow or stall across the southeast as the parent trough ejects to the northeast. While the potential for severe thunderstorms appears low, it can't be ruled out entirely. Temperatures will initially warm amid the southeasterly flow but should cool slightly to seasonable readings with the front Friday and into the weekend.

AVIATION /06Z SATURDAY THROUGH 06Z SUNDAY/

MVFR and IFR ceilings remain stubborn across the region early this morning. This trend is expected to continue through the morning hours except at SSI. Ceilings are expected to improve late morning and into the afternoon as winds also pick up with another surge of northeasterly winds. The good news is VFR is expected to prevail at this time later today and through this evening while this surge occurs. The other main factor through tonight and the rest of today will be SHRA potential, especially with a weakening front dropping southward today. At this time, only confident enough to include VCSH with the coverage expected, though TEMPO groups may be necessary for higher impacts overnight and through today, especially closer to the coast.

MARINE

A strong high pressure ridge will build southward across area waters today behind a weakening cold front. This ridging will then wedge down the southeastern seaboard this weekend and early next week. A slight surge in northeasterly winds today will return hazards across the coastal waters once again for the weekend. A wavy stationary frontal boundary lifting slowly northward across the Florida peninsula late this weekend will return more numerous showers and a few embedded thunderstorms on Sunday and Monday across our local waters. High pressure will then build more northeast of the region towards mid week before another cold front approaches from the northwest.

Rip Currents / High Surf: High rip current risk continues at all area beaches through this weekend as another surge of onshore flow arrives today. This will also return surf heights of up to 5 to 7 feet by this evening, and hence a High Surf Advisory will begin once again this evening.

FIRE WEATHER

A cold front will lead to strengthening northeasterly winds through the weekend, especially at the coast with gusts up to 30 mph. Isolated afternoon thunderstorms possible Sunday, primarily along the I-75 corridor with a passing wave of low pressure. Rain chances stick around through early next week, favoring the coast and I-95 corridor. Winds will begin to shift easterly next week then southerly by midweek as speeds diminish. Otherwise, mild and humid conditions continue.

FOG POTENTIAL AND OTHER WEATHER REMARKS: Significant fog formation is not expected through Monday. Locally heavy rain is possible across NE FL Sunday afternoon through Monday.

TIDES/COASTAL FLOODING

Relatively lower astronomical tides will allow for mostly minor coastal flooding along the coast, ICW and portions of the St Johns River through the weekend. Coastal Flood Warning only continues for eastern Putnam County at this time for areas along the St Johns River where localized peaks into moderate flood stage are still anticipated the next couple of high tide cycles. ENE winds increase again today, maintaining reverse flow/trapped tides in the St Johns river and continuing beach erosion along the Atlantic coast. Flood levels may rise back into moderate Sunday into early next week along the St Johns river.

PRELIMINARY POINT TEMPS/POPS

JAX WATCHES / WARNINGS / ADVISORIES

FL...Coastal Flood Advisory until 5 AM EDT Sunday for FLZ038-124- 125-132-138-225-233-325-333-633. High Risk for Rip Currents through Sunday evening for FLZ124-125- 138-233-333. Coastal Flood Warning until 5 AM EDT Sunday for FLZ137. GA...High Risk for Rip Currents through Sunday evening for GAZ154-166. MARINE...Small Craft Advisory from 2 PM this afternoon to 7 PM EDT Sunday for AMZ450-452-454. Small Craft Advisory until 7 PM EDT Sunday for AMZ470-472-474.