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

- Flood Watch for the Atlantic Coast, I-95 Corridor & St. Johns River & St. Marys River Basins

- Coastal & Marine Hazards Continue through the Weekend. Small Craft Advisory Conditions Overspread the NE Florida Waters this Afternoon. High Risk of Rip Currents, High Surf & Substantial Beach Erosion Likely. Coastal Flood Advisory through Early Thursday Morning. Minor to Locally Moderate Tidal Flood Risk through Thursday along the Atlantic

- Coast, ICWW & Tidal Tributaries of the St. Johns & St. Marys River Basins. Gusty Onshore Winds Continue at Coastal Locations

- Monitoring the Southwest Gulf for Potential Tropical Development

UPDATE

Have extended the Flood Watch through Wednesday morning as waves of moderate to heavy rainfall will continue to move onshore into the Atlantic Coastal areas of Northeast Florida and Southeast Georgia through Wednesday morning. Additional rainfall amounts of 2 to 4 inches are expected with locally higher amounts possible. The heavy rainfall may combine with higher than normal tidal levels and may worsen flood issues in some Atlantic Coastal and St. Johns River locations. This covers the morning high tide cycle along the Atlantic Coast and into the St. Johns River Basin.

NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/

Main Highlights Today and Tonight:

- Flood Threat from Heavy Downpours Continues into this Evening for Coastal Northeast FL and Camden County, GA

- Coastal and Marine Impacts Continue to Increase Tonight as Breezy Onshore Winds Persist at Coastal Locations.

Afternoon surface analysis depicts a wavy stationary frontal boundary that stretches along the northern Gulf coast and across north central FL, with weak low pressure centers located along this front approaching Apalachee Bay and also near the Gulf Stream waters adjacent to coastal GA. Meanwhile, strengthening high pressure (1026 millibars) was building over the eastern Great Lakes and the Mid- Atlantic states in the wake of this front, with this feature wedging down the southeastern seaboard and gradually tightening our local pressure gradient along the Atlantic coast from north to south. Aloft...broad troughing continues to dig into the southeastern states, which has shifted ridging to the southern Gulf and across the Bahamas. Latest GOES-East derived Total Precipitable Water imagery indicates that a drier air mass was advecting into inland portions of southeast GA in the wake of the stalled front, with PWATs falling to the 1.5 - 1.75 inch range for locations north of Waycross. Deep tropical moisture otherwise remains in place for locations south of Waycross, with the afternoon sounding at Jacksonville registering 2.3 inches of PWAT. Mostly stratiform rainfall continues in the moist air mass that is located south of Waycross, with convergent onshore low level flow developing bands of heavier downpours along mainly the I-95 corridor, with strengthening isentropic lift also increasing rainfall rates along the I-10 corridor. Temperatures at 19Z were uniformly in the 70s, with the drier air mass advecting into inland southeast GA allowing dewpoints to fall into the mid to upper 60s.

The wave of low pressure will slide eastward along the frontal boundary across Apalachee Bay this evening, with this feature crossing the Suwannee Valley and north central FL overnight before pushing offshore into the Atlantic waters adjacent to northeast FL waters towards sunrise on Wednesday. The drier air mass advecting into southeast GA will likely sink to near the FL/GA border towards sunrise, while deeper moisture and strengthening isentropic lift associated with the approaching frontal wave expected to generate additional rounds of heavy downpours, especially for locations south of I-10 corridor and especially along the I-95 corridor and coastal locations in both southeast GA and northeast FL. Our local pressure gradient will also continue to tighten as high pressure over the Mid- Atlantic states wedges down the southeastern seaboard. Breezy conditions should overspread the I-95 corridor this afternoon and evening, and added low level convergence will keep a risk of flooding for the coastal counties and St. Johns River basin through at least sunset tonight, where slow moving downpours may "train repeatedly" over increasingly saturated ground conditions. Light to moderate rainfall associated with the frontal wave will otherwise continue for locations south of Waycross tonight, with cool air advection dropping lows into the mid 60s for locations north of Waycross, while lows elsewhere for inland locations along and north of I-10 fall to the upper 60s to around 70. Lows south of the front will remain in the lower 70s, with mid 70s for coastal northeast FL, where breezy northeasterly winds will continue overnight.

SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/

Main Highlights This Period:

- Potential for rounds of heavy rainfall for NE FL coast and North- central FL on Wednesday and Thursday

- Breezy northeast flow pattern continuing dangerous Surf Zone conditions and coastal flooding

Bouts of showers with embedded thunderstorms will progress across the forecast area along and south of the stalled frontal boundary, building primarily across northeast Florida and for areas along the coastline with more mild weather over southeast Georgia as high pressure and drier air act to inhibit convective developments. Breezy northeasterly flow and continue elevated coastal hazards, including minor to locally low end moderate tidal flooding, dangerous surf, strong rip currents, and beach erosion will affect coastal areas through Thursday. High temperatures through Thursday will be in the upper 70s and lower 80s with overnight low temperatures dropping down into the lower 60s for southeast Georgia and in the upper 60s and lower 70s for northeast Florida and for areas along the coast.

LONG TERM /FRIDAY THROUGH TUESDAY/

Main Highlights This Period: fri-mon

- Elevated northeast flow continues through the end of the week with potential for Minor to Moderate Tidal Flooding, Deadly Surf, and Gusty Coastal Winds

- Strengthening winds and increasing Rain and Thunderstorms Chances return this Weekend

Chances for widespread showers and thunderstorms will increase throughout northeast Florida and into southeast Georgia as the stalled frontal boundary recedes to the north and draws a warm front up through the region, with breezy onshore winds becoming more mild and variable by the beginning of next week as prevailing flow shifts to become more southwesterly ahead of an advancing cold front pressing in from out of the northwest. Daily high temperatures will experience a warming trend through the weekend and into the following week, with max temps rising into the lower to mid 80s by Monday. The National Hurricane Center is monitoring the Gulf low giving it a high chance of tropical development by mid-week. No direct tropical impacts are currently expected across northeast Florida and southeast Georgia, although the eventual track, size and intensity of the system will determine the magnitude and distribution of rainfall across the area.

AVIATION /00Z WEDNESDAY THROUGH 00Z THURSDAY/

Local Nor'Easter remains intact through tonight with mainly IFR CIGS and MVFR CIGS in on/off rain showers. Lowest VSBYS and highest NE wind gusts to 15-25 knots will impact the Atlantic Coastal TAF sites, while NE winds less than 10 knots are expected inland. These lower conditions will continue into Wednesday morning before the impacts from the Nor'Easter lessen Wednesday afternoon with more predominant MVFR CIGS are expected at NE FL terminals with rain chances lessening closer to VCSH by the end of the period. Even some VFR conds are expected to develop at SSI after 18Z Wed. Northeast winds will generally remain in the 10-12G18 knot range for Wednesday at local terminals.

MARINE

Small Craft Advisory conditions will overspread the northeast Florida waters this evening as a northeasterly wind surge expands southward. Occasional gusts to gale force will be possible through tonight, especially for the waters from St. Augustine northward. Prolonged onshore winds continue as weak low pressure develops offshore of the east central Florida coast and moves slowly eastward on Wednesday and Thursday. Onshore winds may briefly decrease to Caution speeds on Thursday before strengthening back to Small Craft Advisory levels by late Friday as high pressure builds over the Mid- Atlantic states and wedges down the southeastern seaboard. The National Hurricane Center is monitoring the potential development of a tropical cyclone in the Gulf. This system is expected to move northward towards the central Gulf coast region on Saturday. Showers and thunderstorms will increase in coverage throughout our local waters during the weekend as tropical moisture surges northward on the eastern periphery of this potential tropical cyclone.

Rip Currents: A northeasterly wind will surge south along the Georgia and northeast FL coast through today leading to strong rip currents and high, rough surf. High Risk for Rip Currents and a High Surf Advisory will go into effect today and last through at least Thursday morning. There's a high likelihood that onshore winds continue into the weekend resulting in high rip current risk and elevated or possibly high surf.

FIRE WEATHER

- Areas Of Low Daytime Dispersions Inland Ne Fl Today

Frontal boundary over northeast Florida will gradually sink into central Florida by midweek. Periods of rain and isolated embedded thunderstorms will move across the area with the bulk of the rain focusing in northeast Florida through mid-week. Extensive cloud cover, showers, and thunderstorms will suppress daytime mixing heights, resulting in poor dispersion across much of the area and continued low dispersions across portions of northeast Florida today. An area of low pressure begins to develop off the local Atlantic coast later today producing breezy northeast winds particularly across coastal northeast Florida and southeast Georgia, through at least Thursday. These elevated winds will likely lead to high overnight dispersions along the coast.

Fog Potential: Patchy inland fog is possible the next few mornings, particularly in areas that received heavier rainfall, with localized visibility reductions possible. Gusty and erratic winds will occur near thunderstorms. Heavy rainfall combined with saturated soils will likely produce localized flash flooding through mid-week, with another potential period of heavy rainfall returning this weekend.

HYDROLOGY

A Flood Watch is in effect for coastal northeast FL counties, the St Johns River zones, and Camden County in southeast Georgia. Additional rainfall amounts of 1 to 3 inches with localized amounts up to 5 inches will heighten the flood risk in the aforementioned areas, especially in urban areas today early evening.

Portions of the St Marys, Satilla, Santa Fe and Alapaha Rivers have begun to rise in response to widespread 4 to 8 inch rainfall over the last several days. Most locations are not expected to rise into flood over the next several days due to the dry conditions and low water levels prior to this recent bout of heavy rain. However, portions of the Satilla and St Marys have reached Minor Flood stage but are generally beginning to peak. With a break in the heavy rain over the next few days, river levels are expected to gradually lower below flood.

TIDES/COASTAL FLOODING

Coastal Flood Advisories remain in effect through Wednesday night. A local "nor'easter" and high astronomical tides will combine and result in minor to moderate coastal flooding during times of high tide along the Atlantic coast and ICWW, beginning this evening and likely continuing through Thursday during each high tide cycle. Recent heavy rainfall and elevated tides combined with reverse flow will lead to Minor to potentially moderate flooding within the St. Johns River basin beginning Wednesday morning and continuing through this weekend around times of high tide.

PRELIMINARY POINT TEMPS/POPS

AMG 65 82 61 81 / 10 10 0 0 SSI 72 80 70 81 / 70 50 10 20 JAX 70 81 69 81 / 100 70 20 40 SGJ 72 81 73 81 / 100 90 50 60 GNV 70 80 70 80 / 100 70 30 60 OCF 70 80 70 80 / 100 90 40 70

JAX WATCHES/WARNINGS/ADVISORIES

FL...Flood Watch through Wednesday morning for FLZ024-038-124-125- 132-137-138-225-233-325-333-425-433-533-633. Coastal Flood Advisory until 5 AM EDT Thursday for FLZ124-125- 132-137-138-225-233-325-333-633. High Risk for Rip Currents through late Wednesday night for FLZ124- 125-138-233-333. High Surf Advisory until 5 AM EDT Thursday for FLZ124-125-138- 233-333. GA...Flood Watch through Wednesday morning for GAZ165-166. Coastal Flood Advisory until 5 AM EDT Thursday for GAZ154-166. High Risk for Rip Currents through late Wednesday night for GAZ154- 166. High Surf Advisory until 5 AM EDT Thursday for GAZ154-166. MARINE...Small Craft Advisory until 5 AM EDT Thursday for AMZ450-452- 454-470-472-474.