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

- Widely Scattered Showers and Thunderstorms Today. Localized Flooding Possible Due to Slow Storm Movement at Inland Locations

- Scattered to Numerous Showers and Thunderstorms on Wednesday. Locally Heavy Downpours Possible at Coastal Locations Wed through Thurs

- Strengthening Onshore Winds & Increasing Marine Hazards Thurs - Sat. High Risk for Rip Currents and Rough Surf Expected at Area Beaches. Frequent Wind Gusts of 30-40 mph Possible at Coastal Locations on Thursday. Minor Coastal Flooding Around Times of High Tide Beginning Thursday Evening

NEAR TERM /THROUGH TONIGHT/

Main Highlights through Tonight:

- Isolated to Widely Scattered Thunderstorms expected this Afternoon and Evening

- Localized Flood Potential Due to Slow Storm Motion Inland

- Locally Dense Fog This Morning and Late Tonight

Overall a similar or slightly less active day is expected today as compared to Monday, as weak surface troughing and high pressure ridging remain across the region. Northeasterly winds will bring a few isolated showers onshore once again this morning, with coverage expanding inward through the day as daytime heating ramps up. Isolated to widely scattered storms will be possible primarily in the afternoon and evening hours, especially for central and western portions of the area as the sea breeze moves inland. Once again, not a significant strong storm threat like Monday, as the weak upper troughing moves out of the area and overall instability lessens to a certain extent. Very high PWATs will result in mainly heavy rain/minor flooding being the primary hazard potential in addition to some gusty downbursts. Above average temperatures in the low 90s inland will continue, with coastal highs in the mid to upper 80s.

Northeasterly winds start to gradually surge overnight tonight as a frontal boundary approaches from the west, and low pressure starts to develop south of Cape Hatteras along the boundary, tightening the pressure gradient a bit. More significant impacts do not arrive until later on Wednesday, though overnight coastal shower potential increases from the northeast accordingly, especially for coastal GA. Lows will be mild and muggy again before the arrival of the front, mainly in the low to mid 70s. Less confident overall in the fog potential Wednesday Morning given more of a transition period, though at least some patchy fog will be possible inland once again, especially over interior north/central FL.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Main Highlights This Period:

- Scattered to Numerous Showers and Thunderstorms Area-Wide on Wednesday.

- Strengthening North-Northeasterly Winds at Coastal Locations on Wednesday Night and Thursday, with Locally Heavy Downpours Possible Along the Northeast FL Coast.

- Increasing Marine and Coastal Impacts Expected on Thursday and Thursday Night.

Troughing aloft will dig and sharpen over the eastern third of the nation as ridging amplifies over Texas, the Southern Plains, and the lower Mississippi Valley. Meanwhile, strong high pressure building over southeastern Canada and New England will push a "backdoor" cold front down the southeastern seaboard on Tuesday night and Wednesday, with this front crossing southeast GA on Wednesday and then slowing its southward progress over northeast and then north central FL on Wednesday night and Thursday. Deep tropical moisture will pool ahead of this "backdoor" cold front along the I-95 corridor and north central FL on Wednesday, with a drier air mass slowly filtering into interior southeast GA and the Suwannee Valley during the late afternoon and evening hours. Our local pressure gradient will tighten as the day progresses from north to south as high pressure wedges down the southeastern seaboard in the wake of the frontal boundary, while low pressure begins to deepen off the Mid-Atlantic coast. Convergent northeasterly low level flow and plenty of available moisture should develop numerous showers and a few embedded thunderstorms by the late morning hours across coastal southeast GA, with activity then expanding southwestward across much of northeast and north central FL during the early to mid afternoon hours. Locally heavy downpours will be possible, especially along the I-95 corridor in northeast FL, and breezy conditions at coastal locations will keep highs generally in the mid 80s. Inland highs should still climb to the upper 80s to around 90 before showers and thunderstorms increase in coverage.

A drier air mass will advect into our region on Wednesday evening from north to south, with PWATs falling below 1.5 inches across southeast GA before sunrise on Thursday. Meanwhile, our local pressure gradient will continue to tighten, and breezy north- northeasterly winds will prevail for locations along and east of I- 95 throughout the night. Convergent low level flow will continue to develop showers and a few embedded thunderstorms over the Atlantic waters overnight that will occasionally move onshore and impact areas along and east of I-95, with the drier air mass then shifting activity to coastal northeast FL by Thursday morning. Cool air advection will be countered by low stratus cloud cover in the wake of the frontal boundary, with lows falling to the upper 60s for inland southeast GA, with lower 70s elsewhere inland and mid to upper 70s for coastal northeast FL.

North-northeasterly winds will peak on Thursday at coastal locations, where sustained speeds of 20-25 mph will frequently gust to 35-40 mph. A Wind Advisory may be required for coastal locations on Thursday and Thursday evening. Bands of showers and isolated embedded thunderstorms developing near and just behind the southward moving frontal boundary could bring waves of downpours to coastal northeast FL and possibly north central FL, especially during the morning hours before the drier air mass over southeast GA and the Suwannee Valley overspreads the rest of our area by late Thursday afternoon and evening. Otherwise, plenty of low and mid level cloud cover and strengthening cool air advection will keep highs in the low to mid 80s, with upper 80s possible across north central FL, where the frontal passage may not occur until the afternoon hours.

A cooler and drier air mass will continue to funnel into our area on Thursday night as low level flow backs to a more northerly direction. Breezy to windy conditions will continue along the I-95 corridor and points eastward overnight, and a few coastal showers will remain possible, mainly for locations from around St. Augustine southward. Clearing skies and a light northerly breeze will drop lows to the lower 60s for most of inland southeast GA, and coastal locations in southeast GA will likely fall to the mid and upper 60s despite breezy conditions prevailing. Lows will drop to the mid 60s for the Suwannee Valley and I-10 corridor, while breezy to windy conditions keep lows in the low to mid 70s along the northeast FL coast.

LONG TERM /FRIDAY THROUGH MONDAY/

Main Highlights This Period:

- Marine and Coastal Impacts Continue on Friday and Saturday as Gusty Northeasterly Winds Prevail at Coastal Locations.

- Minor Coastal Flooding Likely Around Times of High Tide Along the Atlantic Coast from Thursday Evening through the Weekend. Tidal Flooding Possible within the St. Johns River Basin from Friday through the Weekend.

- Onshore Winds Gradually Diminish on Saturday Night and Sunday, with an Unseasonably Dry Air Mass Overspreading Our Area this Weekend and Early Next Week.

Troughing will continue to deepen along the U.S. Eastern seaboard on Friday and Saturday, allowing for low pressure to rapidly deepen off the Mid-Atlantic and New England coasts. This feature will likely retrograde towards these coasts on Saturday night and Sunday, with a deep and dry north-northwesterly flow in the wake of this strong coastal storm funneling an unseasonably dry air mass into our area this weekend and early next week.

Our local pressure gradient will remain tight on Friday, with breezy to windy conditions expected at coastal locations, where isolated showers will be possible on Friday morning for locations south of St. Augustine. Marine stratocumulus and cool air advection should keep coastal highs in the upper 70s to around 80. Breezy north- northeasterly winds will otherwise advect an unseasonably dry air mass into our area, allowing skies to clear from northwest to southeast and dewpoints to fall into the 50s across inland southeast GA by Friday afternoon, with values slowly falling through the 60s elsewhere. Highs at inland locations will generally reach the low to mid 80s, except upper 80s for locations south of Gainesville. Winds will then decouple on Friday evening at inland locations, allowing for radiational cooling overnight, possibly dropping lows to the mid to upper 50s for inland southeast GA, with low and mid 60s elsewhere inland and upper 60s to lower 70s at coastal locations, where breezy northerly winds will continue overnight.

Northeasterly winds will remain breezy on Saturday for locations along and east of I-95, but our local pressure gradient will loosen by Saturday night and Sunday, with additional nights of radiational cooling expected at inland locations. A rather pleasant early Autumn weekend is expected area-wide, with dry weather and only gradually warming temperatures expected early next week as broad troughing and a dry northwesterly flow aloft prevail across the southeastern states. Highs will generally climb to the low and mid 80s this weekend for most locations as mostly clear skies and an unseasonably dry air mass continues, with inland lows likely falling into the 50s, with upper 60s forecast at coastal locations. Temperatures may climb slightly on Monday, but dewpoints will remain in the 50s for inland southeast GA and the 60s elsewhere, keeping overall pleasant conditions in place, especially overnight.

AVIATION /12Z TUESDAY THROUGH 12Z WEDNESDAY/

Patchy fog will dissipate early this period.

Have highlighted the time period with the greatest chance for thunderstorms Today. In general, this activity is expected to start near the east coast, and work its way west through the afternoon. Coverage will be scattered. Patchy fog is expected to develop again Tonight, mainly affecting inland sites. Restrictions in fog will be possible at KGNV toward sunrise Wednesday.

MARINE

A surface trough and an upper level disturbance will lift northeastward away from our local waters today, with scattered showers and thunderstorms expected to continue through this afternoon. Meanwhile, strengthening high pressure over southeastern Canada and New England will push a backdoor cold front southward across the Georgia waters on Wednesday and the northeast Florida waters on Wednesday night, accompanied by widespread showers and embedded thunderstorms. A surge of north-northeasterly winds and building seas will arrive on Wednesday afternoon and evening, with Small Craft Advisory conditions overspreading our local waters from north to south, with potential Gale Force Wind Gusts on Thursday and Thursday night. Breezy northeasterly winds and elevated seas will maintain Small Craft Advisories through Saturday, followed by winds and seas slowly subsiding on Saturday night and Sunday as high pressure builds towards the southeastern states.

Rip Currents: Weaker onshore flow will result in a lower-end moderate risk today at all area beaches. Northeasterly winds will gradually strengthen on Wednesday afternoon, creating a higher end moderate risk at area beaches. This risk will likely become high from south to north Wednesday evening through late week as a stronger northerly wind surge arrives.

FIRE WEATHER

ELEVATED NIGHTTIME DISPERSION VALUES WILL BE POSSIBLE AT COASTAL - Locations On Wednesday Night And Area Likely On Thursday Night

Scattered showers and isolated thunderstorms are expected to develop this morning at coastal locations, with activity moving slowly inland during the afternoon hours. Scattered to numerous showers and thunderstorms are expected area-wide on Wednesday, with shower activity then shifting to coastal locations on Wednesday night and Thursday. East-northeasterly surface and transport winds will prevail today, with poor to fair daytime dispersion values forecast. Northeasterly transport winds will gradually strengthen on Wednesday, with breezy surface winds developing along the I-95 corridor during the mid to late morning hours. Increasing cloud cover and rain chances will keep dispersion values in the poor to fair range. North-northeasterly surface and transport winds will remain breezy at coastal locations on Wednesday night, possibly creating elevated nighttime dispersion values. North-northeasterly surface and transport winds will continue to strengthen on Thursday and Thursday night at coastal locations, with breezy conditions developing at inland locations on Thursday morning, creating good daytime dispersion values area-wide. Elevated nighttime dispersion values will then be likely at coastal locations on Thursday night, as breezy surface speeds continue.

Fog Potential...Areas of locally dense fog are expected during the early morning hours on Tuesday across inland portions of southeast Georgia, with patchy fog possible early this morning across the Suwannee Valley and inland portions of north central Florida.

PRELIMINARY POINT TEMPS/POPS

AMG 90 70 90 69 / 30 10 40 10 SSI 86 74 86 72 / 30 20 60 40 JAX 88 72 88 72 / 30 10 60 20 SGJ 87 75 86 75 / 30 20 50 40 GNV 90 71 90 71 / 30 10 60 0 OCF 91 73 91 73 / 30 10 60 10

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...None.