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 Daily Thunderstorm and Heavy Downpour Coverage. Flood Watch In Effect Through Monday Morning Along/North of I-10. Waves of Heavy Downpours Will Increase Flooding Threat Through This Week

- Moderate Rip Current Risk all Area Beaches through Monday

- Coastal and Marine Hazards Increase This Week. Strong & Gusty Northeast Winds Arrive Monday Night. Small Craft Advisory Conditions Likely for the Atlantic Waters Tuesday through Wednesday with occasional Gusts to Gale Force. Deadly Rip Currents, Rough Surf & Substantial Beach Erosion Likely. Minor to 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 due to the potential for another period of heavy rain today; highest flood risk will be along and north of I-10 this afternoon and evening.

- Isolated strong thunderstorms will be possible during the late afternoon and early evening hours.

The wet and unsettled pattern continues with a juicy airmass parked over the area as a cold front remains draped across central GA. The KJAX 12Z sounding measured a daily record breaking PWAT of 2.4 inches this morning. A deepening southwesterly flow will funnel in rounds of upper impulses moving across the region triggering convection this afternoon into tonight with embedded pockets of very heavy rain. Heaviest rainfall today appears to focus along the I- 95/HWY 301 corridors where impulses will interact with the Atlantic sea breeze. A few strong storms will be possible as the airmass destabilizes mainly over NE FL this afternoon into evening. A Flood Watch remains in effect for all of SE GA and NE FL counties along and north of the I-10 corridor due to the ample amount of rainfall these locations received yesterday. Rainfall broadly is forecast for 1-2" but there is potential for rain to overachieve with locally higher amounts of 3-5", especially across SE GA into this evening. Activity becomes more stratiform in nature later this evening. Rounds of light rain will move across SE GA into early Monday morning as impulses aloft continue moving across the region. Patchy fog may develop in the pre-dawn hours for areas that received rainfall. Wet and overcast conditions tonight will bring temperatures down into the low 70s.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

Main Highlights This Period:

- Potential for rounds of heavy rainfall, and a few strong thunderstorms can not be ruled out

- Strong northeast flow pattern begins Monday night with potential for dangerous surf and marine zones, coastal flooding, and gusty winds.

High precipitation chances continue Monday and Tuesday across the area, including during the overnight hours as a front approaches and passing through and westerly flow brings tropical moisture into the region. Drier air slowly begins to drift into southeast Georgia Tuesday night, lowering precipitation chances there. Highest rainfall totals will generally be across northeast Florida Monday and Tuesday, where deeper moisture (PWATs 2-2.5") is expected closer to where the front is. While flooding is the main concern with a 'Marginal' risk of excessive rainfall for almost all of the area both days, we can't rule out a few stronger storms with gusty winds as well. NBM guidance is showing a medium to high chance for 48 rainfall totals (Monday AM through Wednesday AM) reaching 3" across the Atlantic coast and most of northeast Florida.

Strong northeasterly winds develop Tuesday following the frontal passage, bring several marine and coastal hazards including dangerous surf/rip currents, beach erosion, heavy rainfall along the coast, gusty winds, and minor to moderate tidal flooding along the Atlantic coast, ICWW, and St. Johns river basin around times of high tide. Tidal flooding in conjunction with heavy rainfall may exasperate flooding concerns for certain locations. Sustained winds from the NE 15-25 mph expected with gusts of 35-45 mph that will likely prompt wind advisory for higher gusts along the coast into the St Johns river basin.

Temperatures will be below normal Monday and Tuesday due to heavy cloud cover and precipitation coverage, highs will be in the mid 70s to low 80s.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Main Highlights This Period:

- Strong northeast flow pattern through midweek, with potential for Minor to Moderate Tidal Flooding, Deadly Surf, and Gusty Coastal Conditions.

- Increasing Rain and Thunderstorms Chances return Next Weekend

Wednesday, wind advisory conditions potential remains during the day as gusts to 30-40 mph will be common as the high to the north shifts to the NE as the front remains across the central FL peninsula. The Highest rainfall chances along the NE FL coast due to convergent showers moving onshore with less chances inland to the Suwannee river and the southeast Georgia coast. Much drier air will settle into SE GA Wednesday night cooling lows below normal, with mild lows along the northeast Florida coast as breezy onshore winds will remain overnight.

Broad surface high pressure will be to the north of the region Thursday as a frontal boundary remains across the central FL peninsula to end the week. The frontal boundary will begin to lift back northward to begin next weekend as a low develops to the west near the TX coast. Thursday will have scattered shower coverage with numerous showers and a few storms closer to the northeast Florida coast and north central Florida. Showers will increase in coverage across NE FL Friday and Saturday with widespread showers potentially advancing northward into SE GA by Saturday. Embedded T'storms will also return into most of the area as shortwave energy aloft moves downstream of a closed shortwave trough over the southern plains.

Breezy NE to ENE onshore flow will persist during this week, continuing tidal flooding concerns as the astronomical tides begin increasing with the approaching New Moon, with minor to possible low- end Moderate tidal flooding potentially into next weekend. Dangerous surf conditions, Rip Currents, and minor to moderate beach erosion will also be likely. Periods of heavy downpours with any showers or storms that develop during the period as moisture levels remain elevated across NE FL and north FL.

Temperatures continue to trend below average Wednesday through Saturday, with highs generally in the upper 70s to low 80s.

AVIATION /18Z SUNDAY THROUGH 18Z MONDAY/

Scattered showers and isolated storms have begun to develop near the TAF sites this afternoon. Convection will spread across the TAF sites bringing lower ceilings and visibilities with heavier downpours. Have TEMPOs in between 18-00Z to account for lower conditions. Outside of storms, ceilings will bounce between MVFR and VFR into this evening and winds will generally be light and variable. Light trailing stratiform rain will likely continue tonight. Increasing probability that low MVFR and IFR ceilings will develop around midnight once the stratiform rain tapers off.

MARINE

Southeasterly wind continues today with showers and thunderstorms pushing eastward toward the Atlantic coast and into the waters late this afternoon into evening. Outside of thunderstorm activity, winds and seas are expected to remain below Caution levels through at least Monday afternoon.

Deteriorating conditions are expected Tuesday as cold front enters and stalls over the area waters. Following the front, a strong high pressure building will wedge down the southeastern seaboard, initiating a prolonged surge of strong northeasterly winds and high seas across our local waters. Small Craft Advisory conditions begin in the southeast Georgia waters on Tuesday and gradually spreads southward into the northeast Florida waters by late Tuesday. A Gale Watch is in effect for Tuesday afternoon into evening for the southeast georgia waters for potential frequent gale force gusts. Northeasterly winds are expected to gradually decrease through Friday and shift onshore next weekend.

Rip Currents: Persistent onshore winds and 2 to 3 foot breakers will maintain a moderate risk at all area beaches through Monday. Dangerous surf conditions are expected to develop on Tuesday as northeasterly winds strengthen, resulting in very rough surf and deadly rip currents from Tuesday through the end of next week, with breakers potentially building to 8-10 feet.

FIRE WEATHER

- Areas Of Low Daytime Dispersions Through Tuesday

Waves of rain with embedded thunderstorms through this week as a wave of low pressure along the central Gulf coast moves east along an associated frontal boundary which will gradually sink south across the area. Lower mixing heights across much of the area due to low cloud cover, showers an thunderstorms will lead to poor dispersions Monday for the entire forecast area, and low dispersion continues for portions of northeast Florida Tuesday and north central FL on Tuesday. An area of low pressure is expected to develop just to the northeast Tuesday as high pressure builds to the north into midweek, bringing elevated northeasterly winds to the area, especially along coastal locations.

Fog Potential... Patchy fog is possible Monday morning, especially over areas that have received a lot of rain this weekend. Gusty and erratic winds will be possible in and near thunderstorms. Locally heavy rainfall with localized flooding possible each day this period.

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.

PRELIMINARY POINT TEMPS/POPS

AMG 70 76 66 75 / 90 90 50 60 SSI 71 80 70 79 / 90 80 90 90 JAX 71 79 69 78 / 80 80 90 100 SGJ 73 82 71 79 / 70 80 90 100 GNV 71 81 70 78 / 60 90 80 100 OCF 73 84 72 80 / 60 80 70 90

JAX WATCHES/WARNINGS/ADVISORIES

FL...Flood Watch through Monday morning for FLZ023-024-120-124-125- 220-225-322-325-425. GA...Flood Watch through Monday morning for GAZ132>136-149-151>154- 162-163-165-166-250-264-350-364. MARINE...Small Craft Advisory from 8 AM to 5 PM EDT Tuesday for AMZ450- 470. Gale Watch from Tuesday afternoon through late Tuesday night for AMZ450-470.