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

- Minor tidal flooding within the St Johns River continues with decreasing high tide levels through the end of the week.

- High risk of rip currents continues at northeast FL beaches today.

- Isolated storms possible near the I-75 corridor late this afternoon

- Localized dense fog possible tonight/Thursday morning and again Friday morning

NEAR TERM /THROUGH TONIGHT/

Main Highlights:

- Minor Tidal Flooding Continues Within the St. Johns River Basin.

- Rough surf and Dangerous Rip Currents Continue at the Northeast FL Beaches.

- Isolated Thunderstorms Possible Late this Afternoon, Mainly for Locations West of I-75.

High pressure off the coast of the eastern seaboard will retreat further into the Atlantic as a cold front slowly moves through the SE US. Breezy SE flow in the morning and early afternoon will pin the Gulf coast sea breeze to along or just west of I-75 today. Potential sea breeze collisions, warm and humid conditions with an axis of deeper moisture (PWATs 1.6-1.8") across inland SE GA/NE FL will foster enough instability for scattered showers and isolated thunderstorms to develop this afternoon into evening mainly near the I-75 corridor. Convection wanes this evening with the loss of daytime heating. With a relaxing local pressure gradient, winds will be allowed to decouple tonight. Lighter winds combined with lingering boundary layer moisture will result in the potential for fog development for much of the area early Thursday morning. Above seasonable temperatures continue with highs warming into the upper 70s along the coast to the low-mid 80s further inland and overnight lows in the 60s.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

Main Highlights This Period:

- Dense Fog Possible Thursday and Friday morning. Warm and unseasonably humid conditions will persist through the end of the week. An upstream cold front will stall well to the west, leading to warm and a marginally unstable airmass Thursday afternoon. Generally light low level flow will be in place with diurnal winds driven by the Gulf and Atlantic sea breeze. While the airmass will be somewhat unstable, dry air aloft should generally mitigate any deep convection from developing; however, widely scattered low-top showers will be possible during the afternoon.

By Friday, the stalled front will regain momentum as an upper trough pivots into the deep south. Progressive trough will sweep across the region through Friday night pushing the prefrontal trough and trailing cold front southeastward through the region. This appears to be a dry frontal passage with moisture being limited along it but cannot rule out a couple of showers across SE GA during the afternoon and over NE FL overnight Friday night into early Saturday morning.

Before the front pushes through, there will be favorable conditions for early morning fog and low stratus both Thursday and Friday mornings, which could be locally dense each day.

Unseasonable warmth will continue with highs in the mid 80s to close out the week and overnight lows in the mid to upper 60s.

LONG TERM /SATURDAY THROUGH TUESDAY/

Main Highlights This Period:

- Cooler and Drier Conditions Expected this Weekend.

Drier west-northwestelry flow will usher in drier and noticeably cooler air this weekend. Though there is some uncertainty in the upper level pattern evolution, the consensus is dry conditions with bouts of high clouds Sunday into early next week as trailing shortwave energy passes over the deep south. Temperatures will fall below normal behind the front with highs dropping into the low 70s by Sunday while lows fall into the mid/upper 40s in SE GA and Suwannee Valley and into the low 50s for NE FL.

AVIATION /06Z WEDNESDAY THROUGH 06Z THURSDAY/

MVFR conditions are expected to develop at VQQ and GNV as low stratus and patchy fog develop in the predawn and early morning hours. All sites lift to VFR by 13Z. Rain chances will be limited to GNV this afternoon but chances are too low to include with this set. Easterly winds will be less than 10 kts overnight and then southeasterly winds around 10 kts prevail after 14Z.

MARINE

High pressure shifts further eastward into the western Atlantic as a cold front moves into the southeastern states today into tonight. Coastal troughing over the area weakens with winds and seas subsiding to caution levels for the offshore waters today. The cold front slows its progress allowing winds to shift to southeasterly on Thursday then southwesterly on Friday. The cold front moves through the area late Friday into Saturday with winds shifting to northwesterly then northerly in its wake this weekend. A reinforcing cold front will then cross our local waters on Sunday night and Monday morning, with high pressure building into the southeastern states providing a surge of breezy northerly winds in the wake of this frontal passage.

Rip Currents / High Surf:

A high risk of rip currents continues for NE FL beaches today with a higher end moderate risk at SE GA. Winds continue to weaken and shift to offshore for the end of the week. A lingering easterly ocean swell will still yield a moderate risk at all area beaches on Thursday and Friday.

FIRE WEATHER

Winds will continue to decrease through the end of the week as a cold front approaches. Today, easterly to southeasterly winds are expected with the Atlantic sea breeze developing this afternoon. As winds ease up Thursday, dispersions will fall to poor or low levels, especially at the coast. A weak and mostly dry cold front will push across Friday night, ushering in a drier and cooler airmass over the weekend and into early next week.

FOG POTENTIAL AND OTHER WEATHER REMARKS: Patchy to areas of fog formation are possible for inland locations along and north of the I- 10 corridor this morning. Areas to widespread fog will be possible during the predawn and early morning hours on Thursday and Friday across the area.

TIDES/COASTAL FLOODING

Tidal levels along the St Johns river continue to reach minor flood stage at high tide mainly from downtown Jacksonville southward. Easterly winds decrease today and shift to southeasterly on Thursday allowing for water to gradually drain into the Atlantic. A Coastal Flood Advisory remains in effect for the entire middle and lower St Johns River zones. Despite the flow shifting to offshore Friday into the weekend, recent heavy rainfall over central FL may allow elevated water levels to linger in the St Johns river basin as the floodwater drain northward.

PRELIMINARY POINT TEMPS/POPS

JAX WATCHES / WARNINGS / ADVISORIES

FL...Coastal Flood Advisory until 4 AM EST Friday for FLZ038-125- 132-137-325-633. High Risk for Rip Currents through late tonight for FLZ124-125-138- 233-333. GA...None. MARINE...None.