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

- Increasing Heavy Downpour Coverage. Flood Watch In Effect through Monday Evening for Locations Along & North of I-10. Waves of Downpours & Embedded TStorms will Increase the Flood Threat this Week

- Moderate Rip Current Risk all Area Beaches Today

- Coastal and Marine Hazards Tuesday through Friday. Strong & Gusty Northeast Winds Arrive Tuesday Morning. Gale Watch for the Waters from St. Augustine Northward. Small Craft Advisory Conditions for the Waters from St. Augustine Southward. Deadly Rip Currents, Rough Surf & Substantial Beach Erosion Likely. Minor to Locally Moderate Tidal Flooding Risk Tuesday through Thursday along the

- Atlantic Coast, ICWW & Tidal Tributaries of the St. Johns & St. Marys River Basins

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Flood Watch extended for the same area (I-10 and areas north) through 8 PM

- Scattered strong thunderstorms, capable of heavy rainfall and potential flooding, this afternoon across north central FL

Rainy conditions will be in place through today and tonight, along with a potential for scattered thunderstorms developing ahead of the advancing frontal boundary pressing down from out of the north. Moist southwesterly flow will bring in training bouts of precipitation resulting in localized flooding over areas already affected by heavy amounts of precipitation from the previous weekend, potentially bringing upwards of 2 to 3 inches of rainfall for some areas within the areas of the Flood Watch- along and north of the I-10 corridor. The cold front is expected to slow its advance tonight with rains continuing through the overnight hours and into Tuesday, with a potential for another 2 to 3 inches of rainfall for some areas. High temperatures this afternoon will be in the mid to upper 70s for southeast Georgia and ranging between the upper 70s and mid 80s over northeast Florida, with higher temps expected for north central Florida. Overnight low temperatures will drop down into the mid 60s for southeast Georgia and in the upper 60s and lower 70s for northeast Florida and for areas along the coastline.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Main Highlights This Period:

- Potential for rounds of heavy rainfall continues Tuesday across NE FL and the coast, then shifting to the NE FL coast on Wednesday

- Strong northeast flow pattern through midweek with potential for dangerous Surf Zone conditions, coastal flooding, and gusty winds

A moderately strong local noreaster will develop Tuesday as low pressure forms along the stalled frontal boundary and shifts east of the Atlantic coast. Strong northeast flow will become established as high pressure builds to the north, producing increasingly gusty winds, periods of heavy rain, hazardous surf, and rising tidal levels. Rainfall from the previous weekend and today will leave soils increasingly saturated ahead of the noreaster, heightening the overall flood threat.

Tuesday, rainfall will become increasingly concentrated across northeast Florida and coastal areas as convergent bands of showers develop within the strong northeast flow. Embedded thunderstorms remain possible south of Interstate 10, where sufficient instability could enhance rainfall rates. Rainfall Tuesday through Wednesday is expected to total 2 to 5 inches across the broader impacted area, with locally higher amounts possible. When combined with rainfall occurring today, the 72 hour rainfall total from today through Wednesday is forecast to be 2 to 5 inches, with isolated totals up to around 8 to 10 inches possible. Heavy rainfall occurring near high tide cycles could further exacerbate coastal and poor drainage flooding.

Northeast winds will increase Tuesday to 15 to 20 mph with gusts of 30 to 35 mph along the coast from Mayport and Jacksonville Beaches northward into southeast Georgia. Inland winds will range from 10 to 20 mph with gusts of 25 to 30 mph. Winds may strengthen Tuesday afternoon, with sustained winds of 15 to 25 mph and peak gusts of 35 to 45 mph possible along the northeast Florida coast and portions of the St. Johns River basin. Gale conditions are possible over coastal waters Tuesday night into Wednesday, with dangerous surf, strong rip currents, and beach erosion becoming increasing concerns.

Wednesday, the noreaster will persist as surface high pressure shifts northeast and an inverted trough remains offshore. Persistent northeast flow will maintain coastal convergence and periods of heavy rain, with the highest rainfall chances along the northeast Florida coast and decreasing coverage farther inland. Additional rainfall of 0.5 to 1 inch is expected Wednesday, with localized amounts of 1.5 to 2 inches possible. Highs will remain in the upper 70s to around 80 degrees.

Persistent onshore flow combined with high astronomical tides will drive rising water levels along the Atlantic coast, Intracoastal Waterway, tidal estuaries, and the St. Johns River. Minor tidal flooding is expected from late Tuesday through the Thursday high tide cycles, with peak water levels of approximately 1.5 to 2.5 feet above Mean Higher High Water or above ground level possible. Low end moderate tidal flooding remains possible within portions of the St. Johns River basin where heavy rainfall combines with persistent northeast winds and reverse flow conditions that restrict drainage toward the Atlantic. A Coastal Flood Watch will be issued as confidence slightly increases with the total water concept of tides and rainfall.

Wednesday night, drier air will begin filtering into southeast Georgia, allowing lows to fall into the upper 50s to near 60 degrees inland. Lows will generally be in the mid 60s across inland northeast Florida and southeast Georgia, with low 70s along the northeast Florida coast. Breezy northeast winds will continue overnight, with coastal speeds of 15 to 20 mph and gusts around 30 mph, gradually diminishing late night Wednesday or early Thursday. Coastal flooding, high surf, and beach erosion concerns will continue into Thursday as the noreaster weakens.

LONG TERM /THURSDAY THROUGH SUNDAY/

Main Highlights This Period:

- 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 Next Weekend

Thursday and Friday, broad surface high pressure will remain north of the region while the frontal boundary stalls across central Florida. Persistent northeast to east northeast onshore flow will maintain elevated coastal hazards, including minor to locally low end moderate tidal flooding, dangerous surf, strong rip currents, and beach erosion. Rain chances will be lower than earlier in the week, with highs near 80 degrees and lows in the mid to upper 60s.

By Friday, high pressure will rebuild from the Ohio Valley into the Mid Atlantic states, tightening the local pressure gradient and maintaining breezy onshore winds. The stalled boundary across central Florida will support periodic coastal showers while temperatures remain slightly below normal.

Saturday will mark the transition to a wetter pattern once again. A closed mid and upper level trough will lift into the lower and middle Mississippi Valley, supporting development of low pressure over the northwest Gulf of Mexico. The low is expected to move toward the Gulf Coast and lift the frontal boundary northward through northeast Florida Saturday and north of the area Sunday. Rainfall chances will increase Saturday, becoming more widespread with potential for locally heavy rainfall. The National Hurricane Center is monitoring the Gulf low for possible tropical depression development late this week, with a moderate chance of formation. 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.

Northeast to east northeast onshore flow will persist through Saturday before shifting southerly Sunday as the front lifts north of the region. Coastal flooding concerns, rough surf, strong rip currents, and beach erosion will remain elevated through the weekend.

Temperatures will remain below average through Saturday, with highs generally near 80 degrees. Overnight lows will range from near to slightly below normal inland to above normal along the coast, gradually warming toward seasonal averages by Saturday.

AVIATION /18Z MONDAY THROUGH 18Z TUESDAY/

A cold front tracking south across the area today will bring low ceilings, generally around MVFR, through this afternoon. A disturbance moving across the front will bring waves of stratiform rain showers with embedded heavy rain leading to degraded visibility at times. Thunderstorm potential is higher at KGNV and KSGJ this afternoon, less likely further north. Low stratus will spread inland on northeasterly winds through the evening hours leading to IFR and possibly LIFR ceilings. Additional waves of showers are expected overnight. Ceilings may occasional break during moderate to heavier rain but the prevailing conditions will be restricted. Winds will build in from out of the northeast for coastal sites overnight and will reach inland sites on Tuesday by around 14z-16z.

MARINE

A cold front will push into north to south across the waters today. As it moves through, winds will shift to the northeast and increase to Caution levels late this afternoon and through the evening hours. Conditions deteriorate Tuesday as a surge of strong northeasterly winds arrive leading to Small Craft Advisory conditions early Tuesday morning across the southeast Georgia waters and gradually spreading south into northeast Florida waters after sunrise and through the afternoon. Due to the potential for frequent gusts to gale force, a Gale Watch is in effect for Tuesday afternoon for waters north of Saint Augustine. Prolonged northeasterly winds are expected to gradually decrease through Friday and shift onshore this weekend.

Rip Currents: A moderate risk at all area beaches Today. Dangerous high surf conditions are expected to develop on Tuesday as northeasterly winds strengthen, resulting in battering surf up to 10 feet and deadly rip currents from Tuesday through the end of next week.

FIRE WEATHER

- Areas Of Low Daytime Dispersions Through Tuesday

- High Minimum Dispersions Tuesday Night And Wednesday Night

Periods of rain and isolated embedded thunderstorms will persist this week as waves of low pressure move along a frontal boundary settling southward across the region. Extensive cloud cover, showers, and thunderstorms will suppress daytime mixing heights, resulting in poor dispersion across much of the area and continued low dispersion across portions of northeast Florida Tuesday. These conditions will limit smoke ventilation and could contribute to localized air quality concerns near prescribed burns or ongoing fires.

Low pressure developing near the Atlantic coast Tuesday, combined with high pressure building to the north, will tighten the local pressure gradient and produce elevated northeast winds, particularly across coastal northeast Florida and southeast Georgia, through Wednesday. Gusty winds may contribute to rapid changes in fire behavior where fuels remain receptive, although widespread wetting rainfall will generally mitigate overall fire danger.

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 through Wednesday may produce localized flooding, with another potential period of heavy rainfall returning this weekend.

HYDROLOGY

A tropical-like airmass will remain over the area today. Sea breeze driven thunderstorms this afternoon and then a passing wave of low pressure this evening and overnight may lead to periods of heavy rainfall across areas that have already received 3 to 7 inches over the last three days, mainly locations along and north of I-10. Additional rainfall amounts of 1 to 3 inches with localized amounts of 4 to 5 inches may result in flash flooding, especially in urban areas today and tonight. A Flood Watch is in effect through Monday morning for Southeast GA and portions of Northeast FL along the I-10 corridor.

Next week, a local nor'easter and high astronomical tides will combine and result in minor and potentially moderate coastal flooding during times of high tide along the Atlantic coast, beginning with the late evening high tide on Tuesday and likely continuing through Thursday during each high tide. Minor to moderate flooding may also become possible within the St. Johns River basin from Wednesday morning through next weekend around times of high tide.

TIDES/COASTAL FLOODING

Astronomical higher than normal tides will continue into this evening with Minor Flooding occurring during times of high tide within the St. Johns River Basin and possibly along the NE FL Atlantic coast/ICWW. Recent water levels today (e.g., Dames Point) have peaked at around 1.6 feet above Mean Higher High Water (MHHW). This may continue into the evening for the St Johns River Basin.

PRELIMINARY POINT TEMPS/POPS

AMG 74 64 75 63 / 100 50 50 20 SSI 79 70 79 71 / 90 90 90 80 JAX 79 69 76 69 / 80 80 100 80 SGJ 82 71 78 71 / 80 80 100 90 GNV 82 69 76 68 / 80 80 100 70 OCF 85 72 79 70 / 80 60 90 70

JAX WATCHES/WARNINGS/ADVISORIES

FL...Flood Watch until 8 PM EDT this evening for FLZ023-024-120-124- 125-220-225-322-325-425. Coastal Flood Advisory from noon Tuesday to 5 AM EDT Thursday for FLZ124-125-132-137-138-233-325-333-633. High Risk for Rip Currents from Tuesday afternoon through late Wednesday night for FLZ124-125-138-233-333. GA...Flood Watch until 8 PM EDT this evening for GAZ132>136-149- 151>154-162-163-165-166-250-264-350-364. Coastal Flood Advisory from 8 AM Tuesday to 5 AM EDT Thursday for GAZ154-166. High Risk for Rip Currents from Tuesday morning through late Wednesday night for GAZ154-166. MARINE...Small Craft Advisory from 2 AM to 5 PM EDT Tuesday for AMZ450- 470. Gale Watch from Tuesday afternoon through late Wednesday night for AMZ450-452-470-472. Small Craft Advisory from 8 AM to 5 PM EDT Tuesday for AMZ452- 472. Small Craft Advisory from 5 PM Tuesday to 5 AM EDT Thursday for AMZ454-474.