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 Noon Today Through Monday Morning Along/North of I-10. Waves of Heavy Downpours Will Increase Localized Flooding Threat into Next 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.

Wet, unsettled weather continues for the third straight day. As of early this morning, the 72 hour (3-day) rainfall across southeast GA is roughly 3 to 7 inches, whereas areas south of I-10 have been less wet, with only a half to 2 inches and locally high amounts up to 4 inches.

More rain is on the way and will be fueled by deep atmospheric moisture, similar to the last few days. There will be a lull in the rain through the remainder of the morning but another active afternoon is expected with the heaviest rainfall expected to focus along and north of I-10 again this afternoon and through the late evening.

Widespread rain and scattered embedded thunderstorms, some becoming strong, will develop as conditions destabilize this afternoon generally expanding from the Big Bend area northeastward across NE FL and into SE GA. Given a deepening southwesterly flow paralleling a weak surface trough axis, there is concern for waves of training convection with embedded pockets of very heavy rain with hourly rates up to 3-5" in areas where several inches of rainfall has already occurred over the last few days. To highlight the flash flood potential this afternoon, a Flood Watch has been issued for all of SE GA and NE FL counties along and north of the I-10 corridor. Rainfall broadly is forecast 1-2" but there is potential for rain to overachieve with locally higher amounts of 3-5", especially across SE GA this evening.

Expect the potential for heavy rainfall and the attendant flood risk to continue well into the evening and perhaps overnight as a shortwave impulse aloft dips southeastward and a corresponding wave of low pressure tracks into southeast GA.

Despite the cloud cover this morning, there should be enough heating to push temperatures in to the low/mid 80s in SE GA and the mid/upper 80s across NE FL before convection blossoms. 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 through midweek with potential for dangerous Surf Zone conditions and Gusty Coastal Conditions.

The axis of a strong trough will swing east from the eastern Great Lakes into New England with the base of the trough moving off the Mid Atlantic and Carolina coasts as strong ridging shifts into the upper Midwest. This pattern will place a frontal boundary extending WSW from the southeast US coast back into SE GA and the FL panhandle Monday morning as strong high builds into the upper MS river valley. Very high moisture content (PWATs near Daily Max Values 2.2-2.5 inches), lift from the front and trailing shortwave energy beneath the base of the aforementioned trough will bring widespread chances for rain as a wave of low pressure moves ENE along the front from the FL panhandle through our area to the coast.

Widespread rainfall amounts of 1-2 inches will be common with localized heavier totals of 2-4 as the NBM 90th percentile amounts range up to 3 to 4 inches. WPC has a marginal risk of excessive rainfall from the SE GA and NE FL coast westward into the Suwannee Valley and the FL panhandle for at least localized flash flooding threat. Abundant cloud cover will limit highs into the mid to upper 70s over SE GA, upper 70s to low 80s over NE FL and the mid 80s over north central FL.

Winds Monday from the south and SW will begin to shift around from the north and NE as the wave of low pressure moves further east in the late afternoon across inland SE GA and by the evening for the rest of the area as the front sinks southward into north central FL overnight into Tuesday morning. Lows Tuesday morning will be in the mid to upper 60s over SE GA into I-10 inland with low 70s over the coast and NE FL due to the north to NE flow. Some increase in 0-6km shear will be present near the front Monday night into Tuesday, but mostly below 25 knots, which should limit severe potential.

Tuesday, strong NE winds will develop as mid/upper level ridging across the Great Lakes and Midwest OH valley support high pressure building into the Mid Atlantic and Delmarva Peninsula through the day as the cold front sinks south into central FL as weak waves of low pressure move eastward along it. 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.

Widespread showers expected across north central FL closer to the front and along the coast as coastal convergent showers and isolated T'storms develop in the strong convergent onshore flow resulting from the pinched local pressure gradient. The heavier axis of rain will be across NE FL and the coast with 1-2 inch amounts and isolated higher totals of 2-4 inches.

Highs will be limited again Tuesday from mostly cloudy skies and and showers and isolated T'storm coverage with mid to upper 70s over much of the area and low 80s over north central FL. Lows will range from near normal in the low 60s over inland SE GA and to the low 70s along the NE FL coast.

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 silent pops north and west of US-84. Again cooler highs prevail in the upper 70s to near 80 due to the enhance onshore NE flow. Rainfall amounts be focus along and south of I-10 and the NE FL coast with 1-2 inches across north central FL.

Much drier air will settle into SE GA Wednesday night cooling lows below normal into the upper 50s to near 60 over inland SE GA with near normal lows in the mid 60s inland NE FL, but warming to above normal along the coast with upper 60s SE GA coast and the low 70s NE FL coast. Breezy winds will remain overnight into Thursday morning.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

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

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. Showers will increase in coverage across NE FL into 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.

Persistent elevated to breezy NE to ENE onshore flow will continue during the period. While winds will not be high enough for wind advisory conditions, the fetch of onshore winds will bring 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 due to the elevated winds. 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.

High temperatures will trend below average this period. Low temperatures will begin near to below normal inland/above normal along the coast and warm to near normal inland into Saturday.

AVIATION /12Z SUNDAY THROUGH 12Z MONDAY/

A dry stretch is expected through the rest of this morning before convection develops again after 18z. Through 13z, localized fog and areas of low stratus are possible, mainly at GNV, SSI and VQQ, otherwise, VFR will prevail. Thunderstorms will push from west to east through the afternoon and likely off the Atlantic coast around 22z-00z with light trailing stratiform rain through the evening hours. Increasing probability that low MVFR and IFR ceilings will develop around midnight once the stratiform rain tapers off. Outside of convective influence, light and variable winds are expected inland while a mild Atlantic sea breeze pushes inland around 19z.

MARINE

Southeasterly wind continues today with showers and thunderstorms pushing eastward toward the Atlantic coast and into the waters late this afternoon. 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 are likely by Tuesday, with the potential for wind gusts near Gale force through Thursday. 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 are expected today and continuing into early 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 to develop Today into Monday for the entire forecast area, and low dispersion continues for portions of northeast Florida Tuesday and north central FL on Wednesday. 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 will develop early this morning with localized patchy dense fog over areas that received locally heavy rainfall Saturday, lifting after sunrise. 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.

This week, a local nor'east and high astronomical tides will combine and result in minor and potential 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.

EQUIPMENT

The KVAX Doppler Radar in Valdosta GA near Moody AFB remains out of service until further notice. Please utilize KJGX (Robins AFB) or KJAX (Jacksonville) during the outage period.

PRELIMINARY POINT TEMPS/POPS

AMG 84 70 76 66 / 80 90 90 50 SSI 85 71 80 70 / 60 90 80 90 JAX 87 71 79 69 / 70 80 80 90 SGJ 87 73 82 71 / 60 70 80 90 GNV 88 71 81 70 / 50 60 90 80 OCF 90 73 84 72 / 50 60 80 70

JAX WATCHES/WARNINGS/ADVISORIES

FL...Flood Watch from noon EDT today through Monday morning for FLZ023-024-120-124-125-220-225-322-325-425. GA...Flood Watch from noon EDT today through Monday morning for GAZ132>136-149-151>154-162-163-165-166-250-264-350-364. MARINE...None.