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

- Extended Duration of Coastal & Marine Hazards Begins Saturday. Coastal Flood Watch - Moderate to Potentially Major Tidal and Coastal Flooding Around Times. Gale Watches for the Atlantic Waters from Saturday Afternoon through Monday. Wind Advisory Conditions for Coast & St. Johns River Saturday Afternoon through Monday. High Rip Current Risk through much of next week. Major Beach Erosion near High Tides this Weekend & Next Week. Locally Heavy Rainfall Possible for Coastal Northeast FL late Saturday

NEAR TERM /THROUGH TONIGHT/

Main Highlights: Through Tonight

- High Risk for Rip Currents - Coastal flooding potential

For Today, high pressure to the north will strengthen as an inverted trough begins to develop to the east southeast of the area. The high to the north will continue to strengthen to the north Tonight, with the inverted trough also strengthening. Between the high and trough, an elevated northeast flow is expected. Winds will begin to pick up Today, and continue through Tonight, being most noticeable at the coast.

Coastal hazards will increase this period due to the strengthening onshore flow.

Temperatures will be below normal Today, despite sunshine. With the onshore flow, there will be a wide range of temperatures Tonight, as the coast will have lows in the mid 60s, with upper 40s over interior SE GA.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Main Highlights This Period:

- Coastal and Marine Hazards Increase on Saturday, with Coastal Flood Watches Issued Along the Atlantic Coast, Intracoastal Waterway and St. Johns River Basin. Moderate to Possibly Major Tidal Flooding is Expected Around Times of High Tide.

- Wind Advisory Likely for the Atlantic Coastal Counties this Weekend.

- Gale Watches for the Atlantic Waters from Saturday Afternoon through Monday.

- Dangerous and High Surf Conditions Develop on Saturday , with a High Risk for Deadly Rip Currents and Significant Beach Erosion at Area Beaches this Weekend.

- Locally Heavy Rainfall Possible Along Coastal Northeast FL on Saturday Afternoon and Night.

A highly amplified pattern will prevail aloft this weekend across the country, with deep troughing along the U.S. eastern seaboard, ridging extending from the lower Mississippi Valley northward to the Great Lakes states, while another deep trough progresses across the Desert Southwest and the Rockies. Strong surface high pressure building over New England will wedge down the southeastern seaboard beginning on Saturday, with this weather pattern also allowing for coastal troughing to develop and sharpen over our near shore waters. Our local pressure gradient will steadily tighten as the day progresses on Saturday, creating strengthening northeasterly winds during the early morning hours at coastal locations, with breezy conditions then developing inland during the mid to late morning hours. Speeds will likely reach Wind Advisory criteria for locations along and east of I-95 by the early to mid afternoon hours on Saturday, where sustained speeds of 25-30 mph will frequently gust to 40-45 mph.

The sharpening coastal trough will provide strengthening low level convergence, likely driving a band of moderate showers that will be oriented from northeast to southwest towards coastal northeast FL during the morning hours, with this band then shifting inland across I-95 towards portions of the St. Johns River basin and the Ocala National Forest during the afternoon hours. A few training bands of showers that could contain heavier downpours may set up along the northeast FL coast during the afternoon and evening hours, which could create some flood concerns during the evening high tide on Saturday. Low stratus cloud cover will overspread most of northeast and north central FL during the morning hours, with this cloud cover then expanding towards the Suwannee Valley and portions of inland southeast GA during the mid to late afternoon. Highs on Saturday will generally reach the low to mid 70s across our region.

Strengthening high pressure will settle towards the Mid-Atlantic coast on Saturday night and Sunday, with sharp coastal troughing remaining in place over our local Atlantic waters. This weather pattern will keep a tight pressure gradient in place across our area, with windy conditions prevailing for locations along and east of I-95 and breezy northeasterly winds continuing elsewhere. Waves of showers will continue to impact the I-95 and U.S. Highway 17 corridors in northeast and north central FL, with isolated coastal showers possible across coastal southeast GA. The threat for heavier downpours along the northeast FL coast may diminish by Sunday as a drier air mass advects into inland southeast GA, shifting deeper moisture values southward over the FL peninsula. Lows will fall to the mid and upper 50s for inland southeast GA and the northern Suwannee Valley, ranging to the 60s elsewhere, except around 70 for locations from St. Augustine southward along the northeast FL coast. Highs on Sunday will again mostly remain in the low to mid 70s, except upper 70s for inland north central FL and the Suwannee Valley.

LONG TERM /MONDAY THROUGH THURSDAY/

Main Highlights This Period:

- Coastal and Marine Hazards Continue, with Moderate to Possibly Major Tidal Flooding Possible Around Times of High Tide Early in the Week Along the Atlantic Coast, Intracoastal Waterway, and St. Johns River Basin.

- Wind Advisory Conditions Prevail through Monday Evening at Coastal Locations.

- Gale Watches Continue through at Least Monday for Our Local Atlantic Waters.

- Dangerous and High Surf Conditions Persist, with a High Risk for Deadly Rip Currents and Significant Beach Erosion Possible at Area Beaches through Much of the Upcoming Week.

Strong high pressure over the Mid-Atlantic region early on Monday will slowly settle southward while gradually weakening through midweek. Meanwhile, deep troughing initially in place along the southeastern seaboard will likely cutoff over the Bahamas, with lowering surface pressures to the south of our region keeping a relatively tight local pressure gradient in place on Monday and Tuesday. A slightly drier air mass will continue to overspread our region, but enough low level convergence will remain in place to occasionally bring showers to coastal northeast FL and the St. Johns River basin. Northeasterly winds will remain sustained in the 25-30 mph range for coastal northeast FL on Monday, where winds will frequently gust to 40-45 mph through around sunset before a gradual decrease begins on Monday night. Otherwise, mostly sunny skies will prevail in the drier air mass for inland southeast GA and the Suwannee Valley, while partly to mostly cloudy skies continue elsewhere on Monday. Highs will again remain in the low to mid 70s, except upper 70s for north central FL and the Suwannee Valley.

A gradual loosening of our local pressure gradient on Monday night will allow for winds to decouple overnight across inland southeast GA and northern portions of the Suwannee Valley, where fair skies will allow lows to fall into the mid and upper 40s. Lows elsewhere inland and along the southeast GA coast will fall into the 50s, while breezy onshore winds keep lows in the mid to upper 60s for most of coastal northeast FL.

Cutoff troughing and lower surface pressures will likely meander around the Bahamas on Tuesday before developing zonal flow finally pushes these features northeastward and away from our region towards midweek. However, a reinforcing high pressure center building over New England could begin to wedge down the southeastern seaboard by Wednesday night or Thursday, which would keep gusty northeasterly winds in place at coastal locations for the duration of the upcoming week as coastal troughing remains situated over our local Atlantic waters. This long duration wind event will maintain significant coastal and marine impacts as high astronomical tides persist next week. Scattered coastal showers will also continue to occasionally move onshore, with highs generally remaining in the 70s for the rest of next week. Lows may again fall into the 40s for inland southeast GA and the Suwannee Valley on Tuesday night, with 50s then forecast for the rest of the week for these locations. Lows elsewhere will fall to the 50s, except 65-70 along the northeast FL coast, where gusty onshore winds will prevail.

AVIATION /12Z FRIDAY THROUGH 12Z SATURDAY/

VFR conditions are forecast throughout this 06z TAF period.

Winds will increase through the day Today, especially near the coast, as strong high pressure builds to the north and an inverted trough develops to the east southeast. The winds will remain elevated into the night Tonight near the coast, with winds increasing throughout the forecast area Saturday morning.

MARINE

A combination of strong high pressure developing to the north, and a trough of low pressure to the east southeast will result in a tight pressure gradient over area waters this weekend into early next week. This will lead to elevated conditions with gales expected by Saturday afternoon. While the high will weaken to the north into the middle part of next week, an enhanced northeast flow will continue.

Rip Currents / High Surf: Breakers of 5-6 feet at the northeast FL beaches and 3-4 feet at the southeast GA beaches will maintain a high rip current risk today. High Surf Advisories will likely be required by Saturday afternoon at the northeast FL beaches, as breakers build to the 6-7 foot range, while 4-5 foot breakers are expected at the southeast GA beaches. Surf will likely peak on Sunday and Monday, with breakers of 8-10 feet at the northeast FL beaches and 6-7 feet at the southeast GA beaches, and High Surf Advisories will likely be expanded to cover coastal southeast GA during this time frame. High surf conditions may continue through at least midweek at the northeast FL beaches, and a high risk of deadly rip currents will continue during the entire forecast period at all area beaches, where major beach erosion is likely to occur during this extended duration onshore wind event.

FIRE WEATHER

- Critically Low Humidity This Afternoon For Inland Southeast Ga - Marginally High Dispersion Values Inland This Afternoon ELEVATED NIGHTTIME DISPERSION VALUES AT COASTAL LOCATIONS - Tonight Expand To The I-95 Corridor On Saturday And Sunday Nights

Dry weather will continue today, with critically low humidity values forecast this afternoon across inland southeast Georgia. Showers will begin to move onshore along the northeast Florida coast after midnight tonight, followed by waves of showers throughout the weekend and into Monday along the I-95 corridor in northeast Florida, with activity occasionally extending to coastal southeast Georgia and for inland locations east of U.S. Highway 301 in northeast and north central Florida. Locally heavy downpours will be possible this weekend along the I-95 corridor in northeast Florida. Otherwise, light northerly surface and transport winds early this morning will shift to northeasterly by mid-morning, with breezy conditions expected by mid-morning at coastal locations that will spread to inland northeast and north central Florida during the afternoon hours. These breezy conditions will yield marginally high daytime dispersion values this afternoon at inland locations. Breezy northeasterly surface and transport winds will continue at coastal locations tonight, creating elevated nighttime dispersion values. Strong northeasterly surface and transport winds will then overspread the I-95 corridor on Saturday and will continue through Monday, yielding elevated nighttime dispersion values. Breezy conditions are expected inland, creating good daytime dispersion values despite mostly cloudy skies.

FOG POTENTIAL AND OTHER WEATHER REMARKS: Significant fog formation is not expected during the next several days.

HYDROLOGY

Minor flooding will continue along lower portions of the Satilla River during the weekend, with water levels forecast to fall below flood stage by Monday night or Tuesday near the gauge at Atkinson.

TIDES/COASTAL FLOODING

Tidal departures of 0.75 - 1 foot above the predicted astronomical tide continue along the Atlantic coast and within the St. Johns River basin. We expect water levels to top out near the minor flood threshold around times of high tide through tonight, and a Coastal Flood Advisory has been expanded to include all of coastal northeast FL and the entire St. Johns River basin.

Northeast winds surging on Saturday morning will combine with the upcoming full moon on Sunday/Monday Oct 25-26 and lunar perigee on October 28th to increase water levels to at least moderate flooding during times of high tide beginning on Saturday. Confidence is growing for peak water levels of 2.0-3.5 feet above MHHW by the Sunday high tide cycles, and a Coastal Flood Watch has been issued for the Atlantic coast and St. Johns River basin beginning late on Friday night. Tidal stations may approach low-end moderate flooding as early as the Saturday morning high tide, but Sunday and Monday are when the peak tidal flooding will occur.

As the astronomical tides increase this weekend, the combination of the building surf and water levels will lead to higher beach erosion potential. This potential looks higher than the prior northeast wind event around Oct 17th-18th, and the long duration of this event could produce significant erosion during each high tide cycle during the upcoming week.

PRELIMINARY POINT TEMPS/POPS

AMG 74 49 73 54 / 0 0 0 0 SSI 71 59 71 63 / 0 0 20 10 JAX 74 57 72 64 / 0 10 40 30 SGJ 75 64 74 70 / 0 30 90 90 GNV 78 56 75 64 / 0 0 10 10 OCF 78 57 76 65 / 0 0 10 10

JAX WATCHES/WARNINGS/ADVISORIES

FL...Coastal Flood Advisory until 2 AM EDT Saturday for FLZ038-125- 132-137-138-225-233-325-333-633. Coastal Flood Watch from late tonight through Monday evening for FLZ038-124-125-132-137-138-225-233-325-333-633. High Risk for Rip Currents through Monday evening for FLZ124-125- 138-233-333. GA...Coastal Flood Watch from late tonight through Monday evening for GAZ154-166. High Risk for Rip Currents through Monday evening for GAZ154-166. MARINE...Small Craft Advisory from 2 PM this afternoon to noon EDT Saturday for AMZ450. Gale Watch from Saturday afternoon through Monday evening for AMZ450-452-454-470-472-474. Small Craft Advisory until noon EDT Saturday for AMZ452-454- 470-472-474.