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

- Freeze Warnings and Cold Weather Advisories Continue through 9 AM this morning. This morning: Freeze Warning Area-Wide, Hard Freezes for Inland Locations West of I-95. Cold Weather Advisory this morning for Northeast & North Central FL. - Long Durations of Critically Low Humidity Values Nearly Area-Wide this Afternoon.

- Widespread Frost Inland Tonight with Patchy Frost at Coastal Locations.

- Warming Trend Commences on Wednesday Afternoon.

- Beneficial Rainfall and Isolated Thunderstorms Thursday Night through Friday Night.

NEAR TERM /THROUGH TONIGHT/

WEATHER CONCERNS THIS PERIOD: - Widespread freeze early this morning, with a hard freeze possible for locations west of Interstate 95. Freeze Warnings effect through 9 AM Tuesday area-wide.

- Cold Weather Advisory overnight through early Tuesday morning for northeast and north central FL.

- Long periods of critically low relative humidity values this afternoon nearly area-wide.

- Frost Advisory for much of our area late tonight through early Wednesday morning.

Overnight surface analysis depicts gradually weakening Arctic high pressure (1031 millibars) stretching across the Tennessee and lower Mississippi Valleys, with this feature building southeastward. Meanwhile, intense and occluded low pressure (972 millibars) was migrating north-northeastward across coastal Nova Scotia. Aloft...deep and dry northwesterly flow prevails across the southeastern U.S. in the wake of this intense storm system. Our local pressure gradient was gradually loosening, with breezy northwesterly winds now confined to portions of coastal northeast FL and decoupling beginning for portions of inland southeast GA and the Suwannee Valley. Clear skies prevail area- wide, with temperatures at 06Z falling through the 30s at inland locations, ranging to around 40 for coastal northeast FL. A very dry air mass persists across our region, with dewpoints ranging from the upper teens to the mid 20s.

Deep and dry northwesterly flow will prevail across our area through this evening, followed by a more zonal flow pattern taking shape towards sunrise on Wednesday. Meanwhile, Arctic high pressure building into the southeastern states overnight will become centered over the FL panhandle on Tuesday morning and will continue to weaken as it pushes southeastward across Apalachee Bay and the southeast Gulf this afternoon, becoming centered over central and south FL tonight.

A persistent northwesterly breeze will likely drive wind chill values down to the 20-25 degree range during the predawn and early morning hours today for much of northeast and north central FL, prompting cold weather advisories through 9 AM. Hard Freeze conditions will be possible for locations west of Interstate 95, with a light freeze possibly extending to around the Intracoastal waterway, while temperatures likely remain just above freezing for area beaches. The dry air mass and persistent light breeze should preclude widespread frost formation, with patchy frost possible across our area early this morning.

Plenty of sunshine, a very dry air mass, and a loosening local pressure gradient will allow highs to climb to the 55-60 degree range at most locations today. A weak Atlantic sea breeze will develop during the mid-afternoon and will push slowly inland towards the I-95 corridor late this afternoon. Otherwise, dewpoints remaining in the teens and 20s will result in long periods of critically low humidity values all the way to coastal locations through the mid-afternoon hours before some recovery occurs behind the late afternoon.

Radiational cooling is expected this evening at most locations, with low level southwesterly flow then developing after midnight. Thin cirrus cloud cover will also begin to overspread our region from northwest to southeast during the predawn and early morning hours on Wednesday. Given that some weak warm air advection is likely towards sunrise, we opted for a Frost Advisory overnight for most of our area. A light freeze is possible across areas that will be closer to the decaying Arctic high pressure center in north central FL, and an upgrade to a Freeze Warning will be possible this afternoon depending on trends in short-term, high resolution guidance. Widespread frost formation is otherwise likely for inland northeast and north central FL and for most of southeast GA, except for locations west of Waycross and Baxley, where warm air advection should keep lows in the mid to upper 30s.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Main Highlights During the Period: - Warming Trend Begins on Wednesday and Thursday

Temperatures will finally warm up Wednesday, with highs in the low 70s inland and upper 60s for the Atlantic coast as southwest winds increase moisture across the area. Highs will climb above normal Thursday into the 70s areawide as a cold front approaches from the northwest, with winds becoming breezy in the afternoon. Showers will enter southeast Georgia and the Suwannee valley area Thursday, with thunderstorm potential starting up Thursday night primarily over southeast GA. Low temperatures both Wednesday and Thursday nights will be well above freezing in the mid 40s to near 60 degrees.

LONG TERM /FRIDAY THROUGH MONDAY/

Main Highlights During the Long Term Period: - Beneficial Showers and Possibly a Few Storms Late in the Week through the Upcoming Weekend

Showers and thunderstorms will continue throughout the day Friday as the cold front makes way through the area. PWATs will rise near 1.5 inches Friday after several days of southwest flow and moisture ahead of the frontal passage, leaving high precipitation chances in the 60-80% range. There may be a window of daytime heating creating enough instability for strong storm development Friday afternoon. High temperatures will be in the 70s for most of the area, with north central FL and eastern portions south of Jacksonville reaching 80.

By Saturday afternoon, the front will be over north central Florida, with rain chances lingering through the day. Thunder chances are generally low, but some rumbles are possible mainly near the Georgia coast in the morning. It'll be a little bit cooler Saturday as an onshore breeze develops behind the front, highs staying in the 60s for the southeast GA coast. Rainfall totals are generally in the 0.5- 1.0" range for Thursday through Saturday.

Mostly sunny skies and onshore winds will allow warmer temperatures inland Sunday, with coastal showers and heavier cloud cover near the coast keeping temperatures there in the upper 60s/low 70s. Onshore winds, warm temperatures, and coastal showers continue into Monday and Tuesday.

AVIATION /06Z TUESDAY THROUGH 06Z WEDNESDAY/

VFR conditions will prevail at the regional terminals. Northwesterly surface winds of 5-10 knots will prevail through around 16Z. The Atlantic sea breeze boundary will develop after 17Z and will push across the SSI and SGJ coastal terminals after 18Z, resulting in surface winds becoming onshore. This boundary should reach CRG after 21Z. Light southerly surface winds will diminish to less than 5 knots after 00Z Wednesday at the regional terminals.

MARINE

Arctic high pressure building into the southeastern states overnight will shift over the Florida panhandle on Tuesday morning. Winds and seas will fall below Small Craft Advisory levels towards sunrise throughout our local waters. This high pressure center will continue to gradually weaken as it becomes centered over the Florida peninsula on Tuesday night, allowing for breezy southwesterly winds to develop offshore. High pressure will then shift offshore of the Florida peninsula by Wednesday afternoon, with breezy south- southwesterly winds continuing offshore and then expanding to the near shore waters on Thursday, well ahead of a frontal boundary that will be entering the southeastern states on Thursday night. Showers and embedded thunderstorms will gradually increase in coverage ahead across our local waters from late Thursday night through Friday night. The frontal boundary slow its forward progress as it crosses our area on Friday night and will then stall over the Florida peninsula on Saturday, with a weak wave of low pressure developing south of our local waters keeping scattered showers in the forecast through the upcoming weekend.

Rip Currents: Prevailing offshore winds through mid-afternoon and diminishing surf heights should yield a low risk at area beaches today. A developing northeasterly ocean swell on Wednesday should increase the threat to lower-end moderate at all area beaches, with this swell expected to persist into Thursday before diminishing later this week.

FIRE WEATHER

- Min RH Values Below 30 Percent Tuesday - Areas Of High Dispersions Wednesday And Thursday

Critically low relative humidity values continue on Tuesday, although lighter winds will keep conditions below Red Flag Warning nor Elevated Fire Danger criteria. Prolonged southwest winds will begin to bring in more moisture Wednesday, improving minimum relative humidity values through the weekend. Winds will be breezy in the afternoons, creating areas of high daytime dispersion Wednesday and Thursday. An approaching cold front will bring showers and storms Thursday through Saturday, with winds shifting to northeasterly Saturday behind the front.

FOG POTENTIAL AND OTHER REMARKS: Significant fog is not expected Tonight. Frost is forecast this morning and again Tuesday night. Thunderstorms are the forecast for Thursday night through Saturday night.

CLIMATE

Record Low Temperatures today at our designated climate sites:

Tues, February 24: KJAX: 27/1989 KCRG: 27/1989 KGNV: 25/1989 KAMG: 24/1964

PRELIMINARY POINT TEMPS/POPS

AMG 56 34 70 52 / 0 0 0 10 SSI 56 38 66 53 / 0 0 0 10 JAX 58 34 71 49 / 0 0 0 0 SGJ 58 37 71 47 / 0 0 0 0 GNV 59 33 71 46 / 0 0 0 0 OCF 60 31 70 45 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Freeze Warning until 9 AM EST this morning for FLZ021-023-024- 030-031-035-038-120-124-125-132-136>138-140-220-225-232- 233-236-237-240-322-325-333-340-422-425-433-522-533-633. Cold Weather Advisory until 9 AM EST this morning for FLZ021- 023-024-030-031-035-038-120-124-125-132-136>138-140-220- 225-232-233-236-237-240-322-325-333-340-422-425-433-522- 533-633. Frost Advisory from 2 AM to 8 AM EST Wednesday for FLZ021-023- 024-030-031-035-038-120-132-136-137-140-220-232-236-237- 240-322-340-422-425-522-533-633. GA...Freeze Warning until 9 AM EST this morning for GAZ132>136-149- 151>154-162-163-165-166-250-264-350-364. Frost Advisory from 2 AM to 8 AM EST Wednesday for GAZ134>136- 151>154-162-163-165-166-250-264-350-364. MARINE...Small Craft Advisory until 7 AM EST this morning for AMZ450- 452-454-470-472-474.