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

- Improving Coastal & Marine Hazards through Monday. Moderate Rip Current Risk Today at All Area Beaches.

- Minor Tidal Flooding Continues through Monday for Portions of the St. Johns River Basin.

- Isolated Thunderstorms Possible on Friday and Friday Night.

NEAR TERM /THROUGH TONIGHT/

Main Highlights through Tonight:

Drier, becoming mostly clear with cooler overnight lows trailing today's cold front passage. Breezy WNW winds will funnel across the area, with clearing skies and no rain chances in the forecast until later this week (Friday time frame).

With abundant ground moisture across the area, the chance of inland fog will progressively increase this week. Tonight, boundary layer winds will remain elevated to keep fog minimal across most areas, but we could have some form across portions of inland north-central FL, generally near and south of the Interstate 10 corridor where winds will be weaker.

Seasonably cool overnight lows are forecast tonight, with low 60s to even a few upper 50s well inland to mid 60s toward the St. Johns River basin and coast under offshore westerly winds.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

Main Highlights This Period:

- Dry Air Mass Prevails Across Our Area.

- Patchy to Areas of Fog Possible Inland Late on Tuesday Night.

Troughing associated with the remnants of Isaias will progress offshore of the Mid-Atlantic coast by Monday afternoon, allowing ridging to develop over the western Gulf and then expand towards the lower Mississippi Valley and the Ozarks by Monday night. Meanwhile, surface high pressure centered along the northern Gulf coast will build eastward towards our region while gradually weakening, with a dry northwesterly flow advecting a seasonably dry air mass into our area, with PWATs remaining below 1 inch area-wide through at least Tuesday evening. Cool air advection will continue on Monday morning on the heels of a northwesterly breeze, followed by our local pressure gradient gradually loosening as high pressure builds eastward towards our area. Plenty of sunshine and a relatively dry air mass should allow highs to uniformly climb to mid 80s, which is slightly above mid-October climatology. Fair skies and light northerly winds on Monday night will result in lows generally falling to the 60-65 degree range, with a few inland locations possibly falling to the upper 50s. These values are close to mid-October climatology.

Ridging aloft will continue to build over the lower Mississippi Valley on Tuesday, with this feature expanding towards the Tennessee Valley and the rest of the southeastern states by Tuesday night. Surface high pressure will continue to gradually weaken while relocating to the southern Appalachians by Tuesday night, resulting in our low level flow veering to northerly early on Tuesday and then northeasterly by Tuesday afternoon. Rising heights aloft, sunshine and a lingering dry air mass will allow highs to nudge upwards at inland locations, where upper 80s are forecast, while an onshore breeze during the afternoon will keep coastal highs in the low to mid 80s. The lingering dry air mass will result in dewpoints falling to the upper 50s and lower 60s during the afternoon at most inland locations, keeping heat index values close to actual temperatures. Radiational cooling at inland locations on Tuesday night will result in lows falling to the upper 50s and lower 60s, except mid 60s for north central FL. Patchy to possibly areas of fog may develop during the predawn and early morning hours on Wednesday given the saturated ground conditions and excellent radiational cooling. Otherwise, a light northerly breeze will keep coastal lows in the 65-70 degree range.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Main Highlights This Period:

- Warm Weather Continues through Friday.

- Patchy to Areas of Fog Possible Each Morning through Friday.

- Increased Chances for Showers and a Few Thunderstorms on Friday and Saturday.

- Gusty Onshore Winds Develop at Coastal Locations on Saturday Night, with Cooler Temperatures Funneling into Interior Southeast GA.

Deep-layered ridging will continue to expand across the southeastern states on Wednesday, keeping a dry and subsident air mass in place across most of our area. Low level east- northeasterly winds on the southern periphery of this ridge may moisten the low levels enough to advect a few showers onshore from the Atlantic waters for the northeast FL coastal counties through Thursday night as PWATs slowly climb back above 1 inch, but model blends currently keep measurable rain chances below 10 percent at this time. Highs will continue to climb to the upper 80s inland and the low to mid 80s at coastal locations. Winds should continue to decouple at inland locations on both Wednesday and Thursday evenings, allowing lows to fall to the 60-65 degree range, while a light onshore breeze keeps coastal lows in the upper 60s to around 70. Patchy to areas of fog formation

Deep-layered ridging will shift offshore of the southeastern states on Thursday night, allowing for low level flow to veer locally downstream of a progressive trough that will be digging southeastward from the Canadian prairies across the Upper Midwest and Great Lakes region. This trough will drive a strong cold front into the southeastern states by Friday afternoon and evening, with long term guidance currently indicating PWATs climbing above 1.5 inches ahead of this front for locations along and south of the Interstate 10 corridor from late Thursday night through Saturday morning. Widely scattered showers and possibly a few thunderstorms will be possible for these areas, with the front otherwise passing through mostly dry for southeast GA and the Suwannee Valley. Warm air advection ahead of this front will result in highs again climbing to the mid and upper 80s on Friday despite increasing cloud cover. Lows on Friday night will generally remain in the 65-70 degree range across our region.

The cold front will then quickly cross our region on Saturday morning, with strong high pressure building over the Upper Midwest in the wake of this front shifting eastward across the Ohio Valley on Saturday night, arriving over the southern Appalachians by next Sunday morning. Northerly winds will become breezy across our area in the wake of this frontal passage on Saturday, with cool air advection keeping highs in the mid to upper 70s for most locations. High pressure will then wedge down the southeastern seaboard beginning on Saturday night, with gusty onshore winds potentially advecting scattered showers onshore from the Atlantic waters towards the northeast FL coast. These breezy onshore winds will keep lows in the 60s at coastal locations, while lows potentially fall to the 50- 55 degree range for inland southeast GA, ranging to the lower 60s for north central FL.

AVIATION /18Z SUNDAY THROUGH 18Z MONDAY/

VFR conditions will prevail at the regional terminals through 12z tomorrow, except for MVFR due to BR advertised at VQQ after 07z tonight. Drier air and progressively clearing skies into tonight trailing a cold front passage. Winds will continue to veer from WSW to more WNW at times through 00z with gusts of 15-20 kts.

MARINE

Showers and isolated storms will move across the waters south of St. Augustine this afternoon, with Caution conditions expected along and just behind a cold front. Dry weather and subsiding winds and seas are expected tonight. High pressure builds west of the region Monday then north to northeast of the region mid to late week. Winds and seas are expected to remain below Caution criteria.

Rip Currents: Rip current risk improves slightly to moderate today as flow shifts to west-southwesterly, but some lingering longer period swells will keep risk from dropping significantly. This moderate risk is likely to continue into the start of the work week as well.

FIRE WEATHER

Dry weather is expected through at least Thursday. Westerly transport winds overnight will shift to northwesterly towards sunrise on Monday, with breezy surface and transport speeds through the early to mid afternoon hours creating good daytime dispersion values area-wide. Surface and transport winds will shift to northerly on Monday evening and then northeasterly towards sunrise on Tuesday, with breezy surface speeds expected along the northeast Florida coast on Tuesday afternoon. Lighter transport speeds across southeast Georgia will yield generally fair daytime dispersion values on Tuesday, while good values continue for inland locations in northeast and north central Florida. Surface and transport winds will shift slightly to east-northeasterly by Wednesday, with fair to good daytime dispersion values continuing at inland locations, while poor values are expected for coastal southeast Georgia.

FOG POTENTIAL AND OTHER WEATHER REMARKS: Patchy fog formation is possible at inland locations during the predawn and early morning hours on Monday and Wednesday.

HYDROLOGY

River flood warnings continues for the Satilla at Atkinson which is cresting in lower-end Minor flood stage today and the St. Marys River at Macclenny which is hovering just above Minor flood stage. The Satilla at Waycross is forecast to crest below Minor flood stage early this week.

Some tributaries of the St. Johns will remain high as heavy rainfall from last week's rainfall drains. Locations include Julington Creek, Thomas Creek, and Pottsburg Creek.

TIDES/COASTAL FLOODING

Adjusted the coastal flood advisory to focus between downtown JAX southward to Welaka and Crescent Lake areas where Minor tidal flooding is expected to continue through tomorrow. Peak high tides will gradually dampen with lowering peak amplitudes. Northerly winds return Monday and become more northeast to east toward the end of the week, with the higher water level departures continuing for locations generally south of the Shands bridge with an extended duration of Minor flooding possible for some locations.

PRELIMINARY POINT TEMPS/POPS

AMG 62 84 60 87 / 0 0 0 0 SSI 64 84 63 85 / 0 0 0 0 JAX 63 85 63 87 / 0 0 0 0 SGJ 66 85 66 84 / 0 0 0 0 GNV 62 85 63 87 / 0 0 0 0 OCF 63 85 63 87 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Coastal Flood Advisory until 8 AM EDT Monday for FLZ038-132- 137-325-633. GA...None. MARINE...None.