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 10 AM Friday for eastern areas. Widespread Dense fog with mile or less visibilities can be expected. Dense Sea Fog continues into Early Friday Afternoon for the Coastal Waters. Areas of Dense Fog Possible Late Tonight and Friday Morning Further Inland

- Record Warmth Forecast on Friday and Saturday

- Inland Light Freezes on Sunday and Monday Nights. Widespread Frost potential Monday night and early Tuesday Morning Inland

- Small Craft Advisories Likely Sunday Evening through Mon Morning

UPDATE

Primary impacts tonight will continue to be extent of dense fog, which has been ongoing over most coastal waters this evening and near the immediate coast. Dense Fog Advisory has begun for coastal counties, and will begin at 8 PM EST for inland areas in the eastern portion of the region and continue through mid morning Friday. Otherwise, generally mild tonight with lows in the mid 50s to low 60s.

NEAR TERM /THROUGH FRIDAY/

Afternoon surface analysis depicts strengthening high pressure (1026 millibars) centered near the Delmarva peninsula, with this feature extending its axis down the southeastern seaboard. Aloft...ridging extending from the southern Gulf through the northwestern Caribbean Sea was deflecting a potent shortwave trough north-northeastward across the Plains states. Deep westerly flow on the northern periphery of the ridge positioned to the south of our region continues to push a veil of high cloud cover eastward across our area, with this cloud cover masking stubborn low stratus and dense sea fog that is persisting along the Atlantic coastal communities, generally from St. Augustine Beach northward. Low stratus ceilings have also persisted at locations north of Waycross in interior portions of southeast GA early this afternoon. Temperatures and dewpoints at these locations were in the low to mid 60s as of 19Z. Warm air advection was otherwise developing a cumulus field beneath the thinner high cloud cover in place across the rest of our area, with temperatures rising through the 70s and touching 80 degrees across portions of north central FL.

High pressure will strengthen as it pushes offshore of the Mid- Atlantic coast this evening, migrating northeastward towards the Gulf Stream waters adjacent to New England by early Friday morning. Meanwhile, ridging aloft over the southern Gulf and northwest Caribbean will shift northward towards the FL peninsula later tonight and Friday morning, with this feature continuing to deflect a potent shortwave trough northeastward from the Southern Plains states towards the Great Lakes region by early Friday, while another potent shortwave trough digs across the Desert Southwest. Low level flow will become more southeasterly as the surface ridge strengthens well to the north of our region tonight and Friday.

Dense sea fog blanketing some of our Atlantic coastal communities this afternoon will likely be pushed slowly inland this evening as southeasterly low level flow develops. Dense fog will likely continue its inland trek this evening, with fog likely advecting across the I-95 early this evening and then spreading inland to the U.S. Highway 301 corridor towards midnight. Confidence in this scenario was high enough Radiation fog will also be possible further inland towards the I-75 corridor during the predawn and early morning hours on Friday. Lows will only fall to the upper 50s inland and around 60 at coastal locations.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/

Friday, ridging aloft will be over the region as a trough remains to the west. This will allow surface high pressure ridge axis to extend WSW across our area from the Atlantic waters with southerly winds 5- 10 mph with a weak Atlantic seabreeze turning winds SE at the beaches in the afternoon. Partly cloudy conditions prevail after morning dense fog with patchy fog persisting along the SE GA coast. This will allow enough sunshine to bring highs to near record levels (see climate section) inland with low 80s west of I-95 while staying in the low/mid 70s along the SE GA coast and the mid/upper 70s over the NE FL coast.

Friday night, cooling temperatures after sunset will allow for patchy fog to shift inland to the St Johns river basin. Lows will be near 60F with very light southerly winds.

Saturday, a stronger shortwave shifting SE over the upper Midwest will deepen the trough across the MS river valley while ridging shifts east into the Atlantic waters. Deep southwest flow and mostly sunny skies will support near record highs again into the low 80s and into the upper 70s at the beaches.

Clouds will increase Saturday night as a cold front approaches from the northwest. Lows will be in the mid to upper 50s with southwest winds becoming westerly over SE GA by sunrise.

LONG TERM /SUNDAY THROUGH THURSDAY/

Sunday, a deep trough extending from the eastern Great Lakes will swing eastward across the central and southern Appalachians. This will bring a cold front through the area with a brief round of showers ahead of it moving over SE GA in the morning and into NE FL in the afternoon. Thunderstorm potential is very low with this system due to stronger forcing staying north of the region. Behind the cold front, winds will shift northwesterly with a colder and drier airmass filtering in from strong high pressure over the central/southern plains.

The high will sink south and east across the Ozarks plateau on Sunday night into Monday with a light advective freeze over inland areas north of I-10. High level clouds will remain over the area Monday with the high sinking into the deep south and lower MS valley turning winds north to northeasterly. Another inland freeze expected across SE GA and decreasing winds will allow for frost potential early Tuesday morning.

The high will weaken over the area Tuesday and then shift away to the ENE as a an upper trough begins to deepen again over the eastern half of the U.S. Ahead of the trough, a southern stream shortwave will move across the Gulf and spur a developing low over the eastern Gulf waters with scattered showers spreading north and east across the FL peninsula into SE GA. Some timing and placement will need to be refined between Global models for more precise rainfall totals, but the system may bring a wetting rainfall Wednesday into Wednesday night. Temperatures will be below normal during the period.

AVIATION /00Z FRIDAY THROUGH 00Z SATURDAY/

Fog and low stratus will continue to be the main operational impact through the next 12+ hours, as expecting dense fog nearing coastal terminals to spread inland over the next several hours. Expecting all airfields to reach LIFR restrictions, with the greatest uncertainty being at GNV depending on how far inland the fog penetrates. Conditions are expected to improve from about 15Z onward, though SSI and SGJ will have the highest chances for periods of fog/low clouds to linger longer as expecting sea fog to also linger into early Friday afternoon. No other significant concerns otherwise as winds are expected to remain below 10kts during peak daylight Friday. Fog will be possible again after sunset Friday, though confidence is lower for this event at this time.

MARINE

Dense sea fog will continue across the near shore waters and also for portions of the offshore waters through early this afternoon, with dense fog possibly persisting or likely redeveloping this evening. Otherwise, Atlantic high pressure will extend its axis across the Florida peninsula through Saturday. This weather pattern will create a prevailing south to southwesterly wind flow across our local waters, likely supporting another round of dense sea fog this evening through Friday morning, with visibilities less than 1 nautical mile likely. High pressure will then move further offshore on Saturday as a cold front enters the southeastern states. The cold front will move across our local waters on Sunday, accompanied by scattered showers. Northwest winds will strengthen following this frontal passage on Sunday evening, followed by winds shifting to northerly overnight as high pressure builds into the southeastern states. Small Craft Advisory conditions will be likely on Sunday night and Monday morning.

Rip Currents: Moderate Risk continues through Friday at all area beaches.

FIRE WEATHER

- Areas of low dispersions Today - Areas of high dispersions Saturday and Sunday - MinRH levels below 30 percent over inland SE GA Monday afternoon

High pressure over the area today will keep very light winds from the south inland 3-5 mph and 5-10 mph at the immediate coast as weak Atlantic seabreeze develops easterly winds at the coast turning more southeasterly inland late this afternoon. Weak transport winds will keep dispersions in the poor range. Calm winds tonight will support another night of widespread dense fog. High pressure remains Friday with fog lingering in the morning and southerly winds 5-10 mph becoming southeasterly at the coast.

The high will shift east northeast on Saturday with breezy south to southwest winds and warm conditions ahead of a front approaching from the northwest. Widely scattered showers arrive Sunday with winds turning northwesterly in the afternoon behind the front. Increasing winds this weekend will create high daytime dispersions Saturday and Sunday. High pressure will build in from the northwest early next week with a colder and drier airmass to start next week with minRH values nearing critical values.

FOG POTENTIAL AND OTHER REMARKS: Widespread dense fog returns this evening into Friday morning. Patchy fog will develop Friday evening along the coast and into the St Johns river basin. Inland Freeze potentially Sunday night with an inland freeze and frost potentially inland Monday night.

PRELIMINARY POINT TEMPS/POPS

AMG 57 81 58 83 / 0 0 0 10 SSI 59 72 58 76 / 0 0 10 0 JAX 57 81 59 83 / 0 0 0 0 SGJ 60 79 60 80 / 0 0 0 0 GNV 59 83 59 84 / 0 0 0 0 OCF 59 83 58 83 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Dense Fog Advisory until 10 AM EST Friday for FLZ024-038-132- 137-225-232-237-325-425-433-533-633. Dense Fog Advisory until 1 PM EST Friday for FLZ124-125-138- 233-333. GA...Dense Fog Advisory until 10 AM EST Friday for GAZ134>136- 151>153-165-264. Dense Fog Advisory until 1 PM EST Friday for GAZ154-166. MARINE...Dense Fog Advisory until 1 PM EST Friday for AMZ450-452-454- 470.