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

- Winter Weather Advisory through Early this Afternoon for Portions of Inland Southeast GA. Snow Accumulation of Less than 1 Inch Possible on Grassy & Elevated Surfaces. Counties Potentially Impacted: Coffee, Jeff Davis, Appling, Atkinson, and Bacon. Rain May End as a Period of Snow Flurries for the Rest of Inland Southeast GA Early this Afternoon.

- Small Craft Advisory through Tonight for our Local Atlantic Waters.

- Widespread Nightly Freezes from Tonight through Early Wednesday Morning. Hard Freeze Likely Late Tonight for Inland Southeast GA and the I-10 Corridor. Light Freezes Extend to Coastal Locations Early on Monday Morning. Low Wind Chill Values of 20-25 Degrees Early on Monday and Tuesday Mornings.

NEAR TERM /THROUGH TONIGHT/

Overnight surface analysis depicts a strong cold front moving southeastward across the Deep South, with Arctic high pressure (1031 millibars) building over the Southern Plains in the wake of this front. Aloft...a potent shortwave trough that was pivoting across the Ohio Valley was sharpening a longwave trough that was diving through the Tennessee and lower Mississippi Valleys. A powerful jet streak in excess of 150 knots at 250 millibars (around 35,000 feet) was positioned downstream of this troughing and was oriented from the southern Appalachians northeastward to coastal New England. The entrance region of this jet streak was resulting in an expanding light to moderate rain shield in the wake of the cold frontal passage from coastal Louisiana eastward to the FL panhandle and Big Bend region. Light showers and low stratus cloud cover was overspreading inland portions of southeast GA and northern portions of the Suwannee Valley along the frontal boundary, while thickening mid and high altitude cloudiness was located ahead of the approaching front across coastal southeast GA and the rest of northeast and north central FL. Temperatures and dewpoints were slowly falling to the 45-50 degree range for locations northwest of Waycross at 08Z, with values elsewhere mostly in the 50s.

Significant changes were not made to the forecast today, with precipitation perhaps lingering deeper into the afternoon hours than forecast in prior forecast cycles as a frontal wave developing over the northeast Gulf traverses north central FL this morning and then accelerates northeastward while organizing into a low pressure center off the Carolina coast early this afternoon. Temperatures will continue to gradually fall through the 40s during the predawn hours for inland southeast GA, falling to the mid and upper 30s by the mid to late morning hours as cold air advection strengthens. Model soundings indicate a brief window of time from around 9 AM - 1 PM for enough cold air throughout the atmospheric column to support light snow mixing with rainfall. The aforementioned jet entrance region should support intensification of rainfall rates along the western edge of the rain shield for locations along the Ocmulgee / upper Altamaha / Alapaha Rivers in southeast GA during the mid to late morning hours. Higher rain rates will allow for wet bulbing to cool to the atmospheric column enough to change rain to snow by the noon hour for locations west and north of Alma, with some light accumulation possible through early this afternoon at the conclusion of the precipitation event. Snowfall accumulations for these locations west and north of Alma will likely remain around or below one half inch, mainly on grassy and elevated surfaces. Rainfall amounts of one half to one inch preceding this changeover should keep roads mainly wet, with a few slick spots possible for bridges and overpasses for locations within the Winter Weather Advisory area late this morning and early this afternoon, as temperatures and dewpoints continue to fall to the low and mid 30s. Rain may end as a few snow flurries early this afternoon across the rest of interior southeast GA, mainly for locations from Waycross north and westward.

The shield of light to moderate rainfall will shift offshore by late this afternoon, with some partial clearing expected before sunset across inland portions of southeast GA, which will warm temperatures back up to near 40 degrees, melting any snowfall that manages to accumulate. Cold air advection will also rapidly drop dewpoints into the 20s this afternoon, likely drying out roadways across our area before temperatures tumble below freezing later this evening. Beneficial rainfall amounts around one quarter to one half inch are possible this morning and afternoon for locations south of I-10, with half inch to one inch amounts forecast for areas north of I-10. A 40-50 knot low level westerly jet at 850 millibars (around 5,000 feet) will traverse our region this afternoon as rainfall ends and cold air advection strengthens. Northwesterly surface winds will steadily strengthen this morning, especially across northeast and north central FL, with occasional gusts of 30-35 mph likely from late this morning through late afternoon, mainly south of I-10. Temperatures in the 50s around sunrise this morning for coastal southeast GA and most of northeast and north central FL will tumble through the 40s this afternoon, with increasing northwesterly winds dropping wind chill values to the 20s for inland southeast GA and the 30s along the I-10 corridor late this morning.

Skies will clear from west to east late this afternoon and early this evening as Arctic high pressure weakens as it shifts eastward along the northern Gulf coast. This weather pattern will allow for our local pressure gradient to loosen early this evening, but a light northwesterly breeze will continue through the night at most locations, adding an extra chill to the frigid air mass that will be advecting into our region. Freeze watches were upgraded to Freeze warnings tonight, with a long duration, hard advective freeze expected across inland southeast GA and for inland locations along the I-10 corridor to the west of Jacksonville, where lows will fall to the mid 20s. A light freeze is expected elsewhere and will extend to coastal locations by sunrise on Monday. The light northwesterly breeze will drop wind chill values to the 20-25 degree range across northeast and north central FL during the predawn and early morning hours on Monday, prompting a Cold Weather Advisory. Wind chill values should remain just above 20 degrees across southeast GA, where criteria for a Cold Weather Advisory is 20 degrees or below.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

High pressure conditions associated with the cold air mass will dominate the weather pattern with dry weather persisting through the period as high pressure shifts more towards the northeast, resulting in a more onshore flow over the forecast area by Tuesday. High temperatures for the beginning of the week will be in the 50s with overnight and early morning low temperatures dropping into the mid to upper 20s over inland areas with the coolest temperatures occurring over inland southeast Georgia.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

Chances for showers and storms will increase after midweek as high pressure over the region moves off to the northeast and a more moist southwesterly flow builds in over the forecast area as a frontal boundary presses down over Georgia from out of the north. Temperatures will warm through the end of the week with daily high and min temps rising to be above the seasonal average before the weekend.

AVIATION /12Z SUNDAY THROUGH 12Z MONDAY/

MVFR ceilings, accompanied by light and intermittent showers early this morning, will lower to IFR around 15Z at the regional terminals as moderate rainfall rates develop. Ceilings could briefly lower to LIFR at VQQ late this morning or early this afternoon, but confidence was too low to include in the 12Z TAFs. Rainfall will diminish in intensity towards 19Z at the regional terminals, with light rainfall ending and ceilings lifting to MVFR by 21Z, followed by VFR prevailing towards 00Z Monday. North to northwesterly surface winds will increase to 5-10 knots early this morning. Surface winds will then shift to north-northwesterly as ceilings lower and moderate rainfall develops towards 15Z, with sustained speeds increasing to around 15 knots and gusty through around 20Z. Surface winds will then shift to northwesterly by 22Z, with speeds gradually diminishing to 5-10 knots by 00Z this evening.

MARINE

An Arctic cold front will cross our local waters early this morning, accompanied by light to occasionally moderate showers. Northwesterly winds will strengthen shortly after sunrise as low pressure develops off the southeastern seaboard, with Small Craft Advisory conditions persisting into the evening or overnight hours tonight as this low pressure center strengthens while accelerating northeastward off the Mid-Atlantic and New England coasts. Occasional gusts to Gale Force will be possible this afternoon through early this evening. Arctic high pressure building along the northern Gulf coast in the wake of this cold frontal passage will remain centered to the west and northwest of our region through Tuesday, keeping breezy northwest to northerly winds and elevated seas in place. High pressure will then shift eastward towards the Carolina coast on Tuesday night, allowing winds to shift to northeasterly across our local waters. Coastal troughing will develop on Wednesday over our near shore waters, with this feature then lifting northward in advance of a weak frontal boundary that will be entering the southeastern states on Thursday. A few showers will be possible along and ahead of this approaching front from Wednesday night through early Friday morning.

Rip Currents: Southeast GA Beaches - Low Today and Monday Northeast FL Beaches - Moderate Today, Low on Monday

FIRE WEATHER

Area-wide showers and breezy northwesterly winds will occur today ahead of an advancing cold front pressing in from out of the northwest, developing across the forecast area today with a potential for snowfall occurring over deep inland southeast Georgia in the afternoon. Dry weather following the frontal passage will be in place over the region by this evening with overnight and early morning freeze conditions expected for the next few days with MinRH values dropping down into the 20s and 30s over inland areas on Monday and Tuesday.

FOG POTENTIAL AND OTHER REMARKS: Light snowfall is possible over far inland southeast GA today. Hard inland freezes are likely for inland southeast Georgia early on Monday, Tuesday, and Wednesday mornings, with a hard freeze possible early on Monday morning for inland locations along the Interstate 10 corridor. Light freezes and frost potentially may extend to coastal locations early next week.

PRELIMINARY POINT TEMPS/POPS

AMG 45 25 51 25 / 100 0 0 0 SSI 51 30 54 34 / 90 0 0 0 JAX 52 27 56 30 / 90 0 0 0 SGJ 57 33 56 37 / 90 0 0 0 GNV 54 28 57 30 / 90 0 0 0 OCF 55 28 57 30 / 90 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Freeze Warning from 9 PM this evening to 9 AM EST Monday 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 from 1 AM to 9 AM EST Monday 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. GA...Freeze Warning from 9 PM this evening to 9 AM EST Monday for GAZ132>136-149-151>154-162-163-165-166-250-264-350-364. Winter Weather Advisory from 9 AM this morning to 2 PM EST this afternoon for GAZ132>135-149. MARINE...Small Craft Advisory until 7 PM EST this evening for AMZ450. Small Craft Advisory from 9 AM this morning to 9 PM EST this evening for AMZ452-454. Small Craft Advisory until 3 AM EST Monday for AMZ470-472-474.