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

- Dense Fog Advisory through 9 AM Monday for the I-10 Corridor West of Duval County, the Suwannee Valley, and Portions of Inland Southeast GA

- Scattered Thunderstorms through Wednesday. Few Strong Storms are Possible, with Wind Gusts of 35-45 mph, Frequent Lightning Strikes, and Small Hail. Localized Flooding Possible Due to Slow Storm Movement at Inland Locations

- Strengthening Onshore Winds & Increasing Marine Hazards from Thursday. High Risk for Rip Currents and Rough Surf Expected at Area Beaches. Minor Coastal Flooding Around Times of High Tide Beginning Late Thursday

NEAR TERM /THROUGH TONIGHT/

Main Highlights through Tonight:

- Areas of Locally Dense Fog Early this Morning Across the Suwannee Valley and Portions of Inland Southeast GA.

- A Few Strong Storms will be Possible this Afternoon and Evening, with Localized Flood Potential Due to Slow Storm Motion at Inland Locations.

Early morning surface analysis depicts a trough over the FL peninsula, with a weak pressure pattern in place across the southeastern states. Meanwhile, a wavy stationary frontal boundary extends from coastal New England southwestward through the Mid- Atlantic states and the Ohio and Mid-Mississippi Valleys. Otherwise, strong high pressure (1030 millibars) was building towards the Great Lakes states from southern Canada in the wake of this frontal boundary. Aloft...a Tropical Upper Tropospheric Trough (TUTT) that has been stationary just west of Tampa Bay is beginning to pivot slowly eastward, with a narrow ridge extending west of this feature across the lower Mississippi and Tennessee Valleys. A potent shortwave trough was otherwise digging over the northern and central Plains. Latest GOES-East derived Total Precipitable Water imagery indicates that deep tropical moisture remains in place area-wide, with PWAT values of 1.8 - 1.9 inches at inland locations in northeast FL and southeast GA and 2 - 2.1 inches for coastal locations and north central FL.

Showers and thunderstorms were mostly confined to the offshore Atlantic waters, but a few showers that briefly produced some in- cloud lightning strikes overnight were moving slowly southwestward across western portions of Nassau County. Otherwise, fog and low stratus ceilings were expanding across the Suwannee Valley and mainly inland portions of southeast GA, with some locally dense fog being reported in the Suwannee Valley. Temperatures and dewpoints were mostly in the low to mid 70s area-wide as of 08Z.

Fog and low stratus ceilings may continue to expand early this morning across inland portions of northeast FL and southeast GA, with dense fog possible across the Suwannee Valley. Fog and low stratus should then dissipate by the mid-morning hours at inland locations.

The aforementioned TUTT feature and its accompanying surface trough that have plagued the FL peninsula with widespread convection during the past weekend will lift northeastward across our area later today and this evening. A land breeze boundary currently over the near shore waters adjacent to coastal northeast FL and southeast GA is expected to trigger convection towards sunrise, with scattered showers and possibly a few thunderstorms likely moving onshore early this morning for locations north of St. Augustine. This activity should fade later this morning near the U.S. Highway 301 corridor, but another round of scattered convection will likely develop along the inland moving Atlantic sea breeze boundary this afternoon. Abundant tropical moisture and relatively cool temperatures aloft could cause a few storms to "pulse", with isolated stronger storms this afternoon west of the I-95 corridor potentially producing downburst winds of 35-45 mph, frequent lightning strikes, small hail, and localized flooding due to slow storm motion possible. Prevailing onshore winds and morning shower activity should keep coastal highs in the mid to upper 80s, while highs climb to the lower 90s for locations along and west of U.S. Highway 301, where heat index values will generally peak near 100.

Showers and thunderstorms along the inland moving Atlantic sea breeze boundary should push west of the Alapaha and Suwannee Rivers early this evening. A break in activity is expected through the evening and overnight hours, but a round of coastal showers could develop during the predawn hours for locations along and east of I- 95. Fog and low stratus ceilings may develop towards sunrise for inland locations along the I-75 corridor and interior southeast GA, with lows generally falling to the low and mid 70s.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Main Highlights This Period: (Tuesday through Wednesday Night)

- Scattered to Numerous Afternoon and Evening Showers and Thunderstorms, Especially on Tuesday

- Strengthening Northeasterly Conditions Wednesday and Wednesday Night

A rather major shift in the pattern starts on Tuesday, especially coming to fruition throughout Wednesday and into Wednesday Night as a backdoor frontal boundary pushes towards and across the region, with continental high pressure ridging building in its wake. The dailies:

Tuesday and Tuesday Night: Weak high pressure hangs on during this period, as well as some lingering energy aloft as a weakening upper trough lifts north and east of our area and an inverted trough develops diurnally east of the Florida Peninsula. This will persist a weak onshore flow, enhanced a bit by the sea breeze, with mainly scattered showers and some t'storms pushing inland. Similar to the previous few days, best chances for stronger storms will be generally inland west of I-95 during daytime heating in the afternoon/evening. Not a significant strong storm threat, though very high PWATs will result in heavy rain/minor flooding being the primary hazard potential in addition to some gusty downbursts and perhaps some isolated small hail. High temps will generally range from the upper 80s along and east of I-95, and the low 90s inland. Some coastal showers and perhaps an isolated t'storm are also expected again Tuesday Night, with otherwise dry and some clouds inland. Muggy lows in the low to mid 70s will be common.

Wednesday and Wednesday Night: An upper trough digs into the Ohio River Valley Wednesday and southeastern states Wednesday Night, pushing a "combined" back door and traditional front through and south of the region. Along with increasing coverage of showers and isolated t'storms streaming onshore with the frontal boundary, an initial surge of northeasterly winds will also begin to impact the region, especially near the coast and St. Johns River Basin. Breeziest conditions will mainly hold off until late week (more on that below), but still expecting a general 10-20G25 type of onshore flow to develop. This will also knock the temps down a few degrees on average, especially near the coast with the stronger marine influence. Mid to upper 80s are generally expected I-95 east, and around or just over 90 inland. A secondary surge of breezy northeasterlies develop Wednesday Night as the pressure gradient tightens with high pressure ridging building over the area. This will keep the winds up overnight but especially closer to the coast, where scattered to numerous showers and perhaps an isolated t'storm over the nearshore waters will make it towards the coast and just onshore at times. Breezier conditions will also keep morning fog potential lower inland. Lows will be most mild near the coast with mid 70s persisting, though upper 60s to low 70s will be expected inland.

LONG TERM /THURSDAY THROUGH SUNDAY/

Main Highlights This Period: (Wednesday through Sunday):

- Strengthening Northeasterly Winds will Bring Increasing Marine Hazards to Coastal Locations Thursday and Friday

- Minor Coastal Flooding Possible Around Times of High Tide Late this Week and Next Weekend

Surface high pressure will continue to extend down the eastern US states late this week, persisting breezy onshore flow for much of the area, but especially northeast FL. The strong flow will also correspond close with a full moon peaking on Saturday, and therefore will keep a close eye on expected coastal/river tide levels over the coming days as minor flooding will be possible around times of high tide.

A rather robust upper trough/low will linger northeast of the region and pump a much drier northwest continental flow aloft late week and into the upcoming weekend, which looks to cut down chances for showers and t'storms to at least a certain degree late week and into the upcoming weekend as well, depending on how south and east the base of the upper trough digs and how much drier air is introduced. Regardless of exact magnitude/position, long term guidance is overall in good agreement that cooler and drier conditions will be in store for late week and potentially into/through the upcoming weekend as well, with onshore flow weakening as high pressure settles further southward.

AVIATION /12Z MONDAY THROUGH 12Z TUESDAY/

Some low flight conditions around VQQ, SSI, and possibly GNV early this morning before 13z, but otherwise increased moisture will lead to some MVFR cigs at other TAFs. Scattered coastal showers expected to increase through the morning hours also leading to chances of MVFR vsby and cigs for JAX, SGJ, CRG, and SSI and possibly VQQ. Afternoon sea breeze and outflow boundaries will lead to more showers and storms by about noon to 1 PM, and advance inland to around VQQ and then GNV. Heavy rainfall may lead to some TEMPO IFR vsby as well. After about 20z, most of the showers and any storms probably will be past the coastal terminals, and so still affecting GNV into the evening hours. This convection should end for GNV terminal by at least 01z. VFR should be prevalent in the evening hours, but then potential for coastal showers again and possibly a storm overnight (near or after 06z) that could affect SGJ, CRG, and SSI so will probably show VCSH or VCTS.

MARINE

Surface troughing and a disturbance aloft located just west of Tampa Bay will lift northeastward across our local waters on Monday night and Tuesday morning. Scattered showers and thunderstorms are forecast to continue through Tuesday. East-northeasterly winds will prevail, with afternoon sea breeze shifting winds to easterly for the nearshore waters through midweek. Strong high pressure building over New England on Wednesday will wedge down the southeastern seaboard on Wednesday night, driving a frontal boundary southward across our area that will be accompanied by widespread showers and embedded thunderstorms. A surge of north-northeasterly winds will then overspread our local waters in the wake of this frontal passage on Wednesday night, with Small Craft Advisory conditions expected across our local waters from late Wednesday night through Friday. Winds may occasionally gust to Gale Force on Thursday afternoon and evening. Breezy northeasterly winds and elevated seas may continue into Saturday before subsiding on Saturday night and Sunday.

Rip Currents: Persistent onshore winds will keep a lower-end moderate risk in place through Tuesday at all area beaches. Northeasterly winds will gradually strengthen on Wednesday afternoon, creating a higher end moderate risk at area beaches. A surge of north-northeasterly winds and building surf will arrive at area beaches on Wednesday evening, with a high risk of deadly rip currents at all area beaches from Thursday through at least Saturday. A period of high surf conditions will be possible from Thursday afternoon through Friday at the northeast FL beaches, where breakers may build to the 6-7 foot range before gradually subsiding during the upcoming weekend.

FIRE WEATHER

Weak high pressure will remain in place across the area today, combined with a disturbance aloft will result in scattered to numerous showers and thunderstorms during the afternoon and evening. Flow will be onshore again, with highest chances for storms being west of I-95. More stable onshore flow will keep dispersions only in the fair range at best, more favorable the further inland you go. Onshore flow and poor to fair dispersions hang on with a similar regime Tuesday before a cool front moves through on Wednesday, bringing a much stronger northeasterly wind surge and moderate to high range changes Wednesday through the rest of the week.

Fog Potential...Patchy inland fog will be possible through Wednesday Morning.

TIDES/COASTAL FLOODING

Astronomical tides will be on the rise later this week due to the upcoming Full "Harvest" Moon, and minor coastal flooding during times of high tide appears to be likely along the Atlantic coast, beginning with the evening high tide on Thursday and likely continuing during high tide cycles through at least Saturday. Minor flooding may also become possible within the St. Johns River basin from Friday through the upcoming weekend around times of high tide.

PRELIMINARY POINT TEMPS/POPS

AMG 91 70 91 72 / 30 10 20 10 SSI 88 74 87 76 / 30 30 30 30 JAX 89 70 89 72 / 40 20 40 10 SGJ 88 75 87 74 / 30 20 30 20 GNV 89 71 90 72 / 40 20 40 10 OCF 90 72 91 73 / 40 10 40 10

JAX WATCHES/WARNINGS/ADVISORIES

FL...Dense Fog Advisory until 9 AM EDT this morning for FLZ021-023- 030-035-120-220-322-422-522. GA...Dense Fog Advisory until 9 AM EDT this morning for GAZ162. MARINE...None.