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

- Cold Weather Advisory Late Tonight & Monday Morning. Wind Chills: 12-25F for Southeast GA, Suwannee Valley & Portions of Inland Northeast FL. Wind Advisory for Coastal Northeast FL from Early this Evening through Early Monday Morning.

- Freeze Warning for Southeast GA, the Suwannee Valley and Portions of Inland Northeast FL Tonight & Monday Morning. Freeze Watches Issued for Monday Night and Early Tuesday Morning. Hard Freezes Likely Across Inland Southeast GA Early on Monday & Tuesday Mornings. Light Freezes for the Suwannee Valley & Portions of Inland Northeast FL.

- Gale Warning for the Local Atlantic Coastal Waters from Late this Afternoon through Early Monday Morning. High Surf Advisory for Coastal St. Johns and Flagler Counties from Late Tonight through Early Monday Evening.

AVIATION /12Z SUNDAY THROUGH 12Z MONDAY/

IFR to LIFR conditions at VQQ will continue through around 13Z. Periods of MVFR visibilities will be possible through around 13Z at CRG. Otherwise, VFR conditions will prevail at the regional terminals through around 15Z. MVFR ceilings from 2,000-3,000 feet along an Arctic cold front will move over the SSI terminal from around 16Z-19Z, with these ceilings shifting southward across the Duval County terminals from 18Z-21Z and then impacting GNV and SGJ from 19Z-22Z. VFR conditions will then prevail at the regional terminals by 23Z. Southerly surface winds sustained at 5-10 knots will prevail overnight at SSI, with light southwesterly winds developing at the northeast FL terminals after 09Z. Surface winds will shift to westerly and will increase to 5-10 knots by 15Z, followed by winds shifting to northwesterly and steadily increasing to 15-20 knots with higher gusts after 17Z. Surface winds will then shift to north northeasterly after 00Z, with sustained speeds increasing to 15-25 knots with higher gusts at SGJ and SSI by 03Z, while speeds at the inland terminals remain sustained in the 10-15 knot range with occasional higher gusts.

NEAR TERM /THROUGH TONIGHT/

Overnight surface analysis depicts Arctic high pressure (1042 millibars) building over the Plains states and the Upper Midwest, which was pushing a strong cold front across the lower Mississippi Valley, the southern Appalachians, and the Mid-Atlantic states. Aloft...troughing pivoting across the Great Lakes was sharpening as it digs southeastward. Meanwhile, a shortwave trough embedded within southwesterly flow downstream of the digging longwave trough was spreading rainfall and embedded convection across south FL and the Bahamas. Latest GOES-East derived Total Precipitable Water imagery indicates that PWATs generally remain between 0.75 - 1 inch across our region, with values above 1 inch located south of Interstate 4 in the FL peninsula and also north of the Altamaha / Ocmulgee Rivers in southeast GA. A narrow ribbon of deeper moisture located along the Arctic cold front was fostering a line of moderate to briefly heavy showers that were moving southeastward across west central GA and south central portions of AL. Mid- level cloud cover was migrating across the skies for locations north of Waycross in southeast GA, while a few pockets of mostly high altitude cloudiness were moving across northeast and north central FL. Temperatures and dewpoints at 08Z generally ranged from the mid 40s to the mid 50s, except around 60 for coastal southeast GA, where a southerly breeze prevailed.

Troughing will continue to sharpen today as it pivots across the Ohio Valley and Mid-Atlantic states, with this trough taking on a more negative tilt as it swings across New England and offshore of the Mid-Atlantic states tonight. This potent trough will drive an Arctic cold front across southeast GA this morning, and then through the rest of our region during the early to mid afternoon hours. Shower activity along this front over west central GA and south central AL will likely wane in coverage as it approaches the Altamaha / Ocmulgee Rivers after sunrise, with a ribbon of low to mid level cloud cover accompanying the frontal passage at it shifts across our region. The Arctic dome of high pressure will continue to build as it shifts southeastward across the Upper Midwest, with this feature then expanding and gradually weakening overnight over the Tennessee and lower Mississippi Valleys.

Ahead of this approaching Arctic cold front, west-southwesterly flow may increase low level moisture values enough to advect low stratus clouds and areas of locally dense fog across northeast and north central FL during the predawn and early morning hours. Meanwhile, surface winds will shift to west-northwesterly as the front moves across the Altamaha / Ocmulgee Rivers during the early to mid morning hours, with a few sprinkles possible beneath a deck of thick stratocumulus clouds across inland southeast GA this morning. Measurable rainfall appears to be unlikely, with chances around or less than 10 percent. Cold air advection will then overspread southeast GA this afternoon, with morning temperatures in the 60s then falling through the 50s as winds shift to northwesterly and become breezy by early afternoon. Temperatures will then fall into the upper 40s for locations north of Waycross towards sunset.

Low stratus clouds and areas of locally dense fog across northeast and north central FL early this morning will quickly dissipate by mid-morning as a west-northwesterly breeze develops. Highs will climb to the 70-75 range across most of northeast and north central FL during the early to mid afternoon hours, except mid/upper 60s for northern portions of the Suwannee Valley, where the Arctic front will move through around the noon hour. Temperatures will then tumble through the 60s this afternoon as winds shift to northwesterly and become breezy in the wake of the Arctic frontal passage, with 50s expected across northern portions of the Suwannee Valley before sunset this evening.

Arctic high pressure will shove the cold front southward across the FL peninsula tonight, with our local pressure gradient continuing to tighten this evening in the wake of this frontal passage. Winds will shift to northerly around sunset and then north-northeasterly overnight as the Arctic dome of high pressure wedges down the southeastern seaboard. Wind speeds will continue to increase tonight for locations east of I-95, and a Wind Advisory has been issued for coastal northeast FL, where sustained speeds of 20-25 mph will frequently gust to 40-45 mph through around sunrise on Monday. These strong onshore winds will keep lows in the 40s along the northeast FL coast tonight. Winds speeds at inland locations will remain sustained in the 10-15 mph range, which will create a wind chill hazard during the predawn and early morning hours on Monday as strong cold air advection results in temperatures plummeting overnight. A hard advective freeze is likely across inland southeast GA, where lows will fall to the low and mid 20s. Wind chill values will fall to around 15 degrees during the predawn and early morning hours on Monday for these locations, prompting a Cold Weather Advisory.

A light advective freeze is forecast for coastal southeast GA, the Suwannee Valley, and portions of inland northeast FL by the predawn and early morning hours on Monday, where lows will fall to the upper 20s and lower 30s. Wind chill values will fall to the 20-25 degree range towards sunrise on Monday, prompting a Cold Weather Advisory. Lows elsewhere for inland north central FL will generally fall to the 35-40 degree range, with wind chill values dropping to around 30 towards sunrise on Monday.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

High pressure will continue to build south and eastward throughout the day on Monday, settling in possibly the coldest and driest airmass of the winter season so far. Winds will turn more northeasterly throughout the day as the high pressure ridge builds southward, and be quite breezy through the morning hours and into the early afternoon before rather quickly subsiding during the evening and after sunset. Winds will range from the 10-15G20 range over inland GA to around 15-20G30 closer to the coast and over much of northeast FL, and combined with highs in the 40s and 50s will make the air feel up to 5-10 degrees colder. Weak troughing along the coastal waters will result in scattered cloud cover over eastern counties, with mostly sunny skies expected inland.

Monday night, the high will settle over southern GA, with weak troughing remaining over the coastal waters and keeping a light north to northeasterly breeze around 5-10 mph overnight closer to the coast and St. Johns River Basin. Across much of the interior, radiational cooling conditions will be much more favorable closer to the high pressure center, and therefore a rather wide range in low temperatures is expected Monday Night. Lows in the low to mid 20s will be common over inland SE GA, upper 20s to mid 30s are forecast north and west of the St. Johns River Basin and Upper Suwannee River Valley in northeast FL, and upper 30s to mid 40s will be expected for the NE FL coast/areas furthest south and east. With the prime radiational cooling conditions the further north and west you go, a Freeze Watch has been posted for much of the interior Monday Night, where areas/widespread frost is also likely.

High pressure slowly shifts eastward into the Atlantic throughout the day Tuesday and through Tuesday Night, gradually shifting the light north to northeast winds towards towards the east-northeast to east. This will help to moderate our temperatures rather quickly on Tuesday, though still trending a bit below normal with highs ranging from the upper 50s to low 60s north to the mid to upper 60s south. The coastal trough, albeit weaker on Tuesday, will keep a few low clouds around closer to the coast with plenty of sunshine elsewhere. Though the airmass will be moderated somewhat, conditions will still be rather favorable for radiational cooling Tuesday Night, with lows in the 30s likely across inland GA with 40s expected elsewhere. The only limiting factor will be some increasing mid and high clouds across the area Tuesday Night.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

The area will remain on the western periphery of the above mentioned high pressure ridge Wednesday before shifting further offshore Thursday ahead of the next frontal system taking shape over the Plains. The next frontal system will move through the area around Friday and Friday Night, though it does not look to be as strong as the system from earlier in the week. Rain chances also look limited with this system at this time, with drought conditions expected to continue through the long term. Temperatures will be near normal Wednesday, trending above normal for Thursday and Friday before likely falling closer to normal into the start of the weekend after the frontal system moves through.

MARINE

An Arctic cold front will cross the Georgia waters towards noon today and will continue southward across the northeast Florida waters during the early to mid afternoon hours. Winds will shift to northwesterly and will steadily increase this afternoon through tonight. Small Craft Advisory conditions will develop early this afternoon across the Georgia waters, followed by winds shifting to northerly towards sunset and then northeasterly after midnight. Frequent Gale force wind gusts will develop late this afternoon and will continue through around sunrise on Monday throughout our local waters as strong high pressure wedges down the southeastern seaboard. Coastal troughing will then develop over our local waters on Monday and Monday night, developing scattered showers, mainly offshore. Weakening high pressure will then shift southward towards our area on Tuesday, allowing winds and seas to quickly subside. High pressure will then shift offshore on Wednesday afternoon, with scattered showers possible by Thursday and Thursday night in advance of a weakening frontal boundary that will be entering the southeastern states. This front will likely cross the Georgia waters on Friday morning and may then stall over the northeast Florida waters by Friday night.

Rip Currents: Southeast GA Moderate Today, High on Monday Northeast FL Low Today, High Monday

FIRE WEATHER

A strong cold front will move southeast across the area today and into tonight, ushering in a much drier and cooler airmass into the region. Strong high pressure will build behind this boundary through Monday. Rain chances will be very low with the front (around 5-10%), with the main impact along with drier conditions being breezy northwest to northerly winds in the 10-20G30 mph range inland and 15- 25G40 mph range near the coast. Conditions will approach elevated fire danger over interior southeast GA this afternoon and evening behind the front, though minRH values are expected to only reach about 30-35%. Dispersions will be good to borderline high area wide today. Very dry airmass will linger through monday with RH values in the 20-30% range over inland GA, though fortunately winds will subside essentially throughout the day. Weaker winds and lower dispersions will return Tuesday and into mid week as high pressure settles almost directly over the area. The next frontal boundary doesn't look to approach the region until about Friday.

FOG POTENTIAL AND OTHER REMARKS: A hard freeze and dangerous wind chills are expected for most of the area Monday morning, though winds will be too strong for frost in most areas. Widespread Frost will be likely over SE GA and inland NE FL Monday night. Areas of frost likely inland SE GA once again Tuesday night.

PRELIMINARY POINT TEMPS/POPS

AMG 63 24 44 23 / 10 0 0 0 SSI 68 32 47 36 / 0 0 0 0 JAX 70 32 51 34 / 0 0 0 0 SGJ 72 44 56 45 / 0 0 10 0 GNV 73 33 56 35 / 0 0 0 0 OCF 75 39 59 38 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Cold Weather Advisory from 1 AM to 10 AM EST Monday for FLZ021- 023-024-030-031-035-120-124-125-132-136-220-225-232-236- 322-325-422-425-522. Freeze Warning from 1 AM to 10 AM EST Monday for FLZ021-023- 024-030-031-035-120-124-136-220-225-232-236-322-422-425- 522. Freeze Watch from Monday evening through Tuesday morning for FLZ021-023-024-030-031-035-120-136-220-232-236-322-422- 425-522. Wind Advisory from 7 PM this evening to 9 AM EST Monday for FLZ124-125-138-233-333. High Surf Advisory from 1 AM to 7 PM EST Monday for FLZ138-233- 333. GA...Cold Weather Advisory from 1 AM to 10 AM EST Monday for GAZ132>136-149-151>154-162-163-165-166-250-264-350-364. Freeze Warning from 1 AM to 10 AM EST Monday for GAZ132>136- 149-151>154-162-163-165-166-250-264-350-364. Freeze Watch from Monday evening through Tuesday morning for GAZ132>136-149-151>153-162-163-165-250-264-350-364. MARINE...Small Craft Advisory from 1 PM to 4 PM EST this afternoon for AMZ450-470. Gale Warning from 4 PM this afternoon to 7 AM EST Monday for AMZ450-452-454-470-472-474.