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

- Light Freeze and Widespread Frost Early this Morning. Hazard Areas: Southeast Georgia, the Suwannee Valley and Portions of Inland Northeast Florida.

- Low Wind Chills Sunday Night and Monday Morning. Cold Weather Advisory Conditions [Wind Chills: 15-25F]: Southeast Georgia, the Suwannee Valley and Portions of Inland Northeast Florida.

- Hard Freezes Possible For Inland Southeast Georgia Early Next Week. Light Freezes Likely for the Suwannee Valley and Portions of Inland Northeast Florida.

- Gale Warnings Possible on Sunday Night & Monday Morning

- Severe to Extreme Drought Continues for for Southeast Georgia and the Suwannee Valley.

AVIATION /12Z FRIDAY THROUGH 12Z SATURDAY/

VFR conditions will prevail at the regional terminals through at least 05Z Saturday. Fog and low stratus ceilings will likely develop at VQQ after 05Z Saturday, with IFR to LIFR conditions possible through the early morning hours. Fog could also develop near the GNV terminal after 08Z Saturday, but confidence was only high enough to indicate MVFR visibilities at this time. Light northwest to northerly surface winds will develop at the regional terminals by 15Z, followed by surface winds shifting to southwesterly at 5-10 knots at the inland terminals by 18Z. The Atlantic sea breeze boundary will develop along the Atlantic coast and will shift slowly inland this afternoon, shifting winds to easterly at SGJ and southerly at SSI. Surface winds will then diminish towards sunset.

NEAR TERM /THROUGH TONIGHT/

Current obs show temperatures beginning to reach into the mid 30s across SE GA and to winds beginning to become calm/near calm area wide. With clear skies and light winds, temperatures are expected to continue to drop with light freezing conditions across SE GA and the Suwannee Valley region, and widespread frost for locations bordering these locations during the predawn hours.

High pressure over the area begins to shift towards the Atlantic Today. Light southwesterly winds develop by the afternoon, bringing in warmer air into the area. Daytime highs in the 60s across SE GA and towards Gainesville, warmer temperatures in the lower 70s across north central FL. Overnight Lows will span in the 40s area wide, warmer temperatures across the coast and north central Florida. Could have some patchy fog develop during the early hours on Saturday morning along the Suwannee Valley Region and north towards far interior SE GA .

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Troughing aloft positioned over the Upper Midwest and the Great Lakes region on Saturday will sharpen as it digs southeastward across the Ohio Valley, Mid-Atlantic states, and New England on Sunday. This potent trough will drive an Arctic cold front into the southeastern states by late Saturday night and Sunday morning. Downstream of this Arctic cold front, deep layer flow will become southwesterly, but a dry air mass will linger through at least Saturday evening across our region. Warm air advection will promote overnight and early morning fog and low stratus development on both Saturday and Sunday, mainly at inland locations. Once fog and low stratus clouds erode on Saturday morning, plenty of sunshine will boost highs to the 70-75 degree range at most locations, except upper 70s for portions of north central FL. As surface ridging pushes offshore, a weak low pressure pattern will allow the Atlantic sea breeze to develop early in the afternoon, and cool shelf waters will keep highs in the upper 60s across southeast GA, and temperatures will fall slowly through the 60s for coastal locations in northeast FL during the mid to the late afternoon hours.

A narrow ribbon of moisture will pool just ahead of the approaching Arctic cold front on Saturday night across the Deep South, where PWATs will climb to around 1.25 inches after midnight on Saturday night and early Sunday morning. Strong forcing just ahead of the Arctic cold front and these slightly higher moisture levels will likely allow for a few showers to develop and approach the Altamaha / Ocmulgee River basins towards sunrise on Sunday. Otherwise, winds will decouple early in the evening downstream of the front over our area, allowing lows to fall to the upper 40s and lower 50s, with temperatures likely climbing a few degrees after midnight as warm air advection strengthens slightly.

Isolated showers developing just ahead of the Arctic cold front across inland southeast GA on Sunday morning will likely dissipate before reaching coastal locations, and dry weather is likely to prevail on Sunday afternoon across northeast and north central FL. The frontal passage will likely be accompanied by a band of mid- level cloudiness that will progress southward during the afternoon hours across northeast and then north central FL. A cooler and drier air mass will begin to advect into our region on Sunday afternoon, with dewpoints falling below freezing for locations north of Waycross in southeast GA during the late afternoon hours. Breezy northwesterly winds will overspread our region on Sunday afternoon, and cold air advection will counter increasing sunshine across southeast GA, keeping early afternoon highs in the 60s, with temperatures falling through the 50s during the mid to late afternoon. Highs will climb into the 70s early in the afternoon across northeast and north central FL, with temperatures then falling back through the 60s during the late afternoon.

An Arctic dome of high pressure (around 1045 millibars) will build over the northern Plains on Saturday night, with this surface ridge only slowly weakening as it slides southeastward on Sunday and Sunday night, reaching the Ohio and Tennessee Valleys by early Monday morning. Our local pressure gradient will continue to tighten as this surface ridge wedges down the southeastern seaboard, likely creating Gale Conditions over our local Atlantic waters by the early evening hours. Low level flow will quickly veer to northerly towards sunset and then northeasterly by sunrise on Monday. Strong cold air advection will drive an extremely dry air mass into southeast GA and inland portions of northeast and north central FL, with dewpoints falling into the single digits across inland southeast GA after midnight, with teens extending into the Suwannee Valley and coastal southeast GA and 20s for inland northeast and north central FL. A hard advective freeze is likely across inland southeast GA, where lows will fall to the low and mid 20s, with a light northeasterly breeze dropping wind chill values to mid teens. A light advective freeze will extend to coastal portions of southeast GA, the Suwannee Valley and inland northeast FL, and possibly for portions of coastal northeast FL, where breezy northeasterly winds will drive wind chills down to the upper teens and lower 20s. Cold Weather Advisories and Freeze Watches will likely be issued this weekend in advance of this Arctic plunge for these locations. Breezy onshore winds will likely keep lows in the 30s to around 40 for inland north central FL and the lower 40s for coastal St. Johns and Flagler Counties, where gusty northeasterly winds will drive wind chill values down to the low and mid 30s by sunrise on Monday.

LONG TERM /MONDAY THROUGH THURSDAY/

The base of deep troughing over the eastern third of the nation will pivot across our region on Sunday night, with dry northwesterly flow then prevailing locally through Tuesday before a more zonal flow pattern develops towards midweek. Arctic high pressure will continue to steadily weaken as it builds over the southeastern states on Monday, allowing the local pressure gradient to loosen over southeast GA during the afternoon hours. Despite plenty of sunshine, the Arctic air mass will keep highs in the 40s for locations north of Interstate 10. A tighter local pressure gradient will continue for locations south of I-10, keeping breezy northeasterly winds in place, where highs will generally remain in the low to mid 50s, except upper 50s to around 60 for inland north central FL.

Coastal troughing will begin to take shape over our near shore waters adjacent to northeast FL on Monday night, likely driving a deck of marine stratocumulus onshore along the I-95 corridor. Lows will likely remain above freezing for locations east of I-95, with low to mid 40s forecast along the northeast FL coast. Fair skies and decoupling winds elsewhere will allow for radiational cooling, with another hard freeze likely across inland southeast GA, with a light freeze expected for the Suwannee Valley. Light winds will allow for widespread frost formation, with frosty conditions likely extending into inland portions of north central FL, where lows will fall to the mid and upper 30s.

Our local pressure gradient will continue to loosen on Tuesday as coastal troughing persists over our local Atlantic waters. Cold air advection will shut off as high pressure weakens along the southeastern seaboard, allowing highs to rebound to the upper 50s across southeast GA to the 60s across northeast and north central FL. One more night of radiational cooling is expected on Tuesday night, but model blends keep lows above freezing across our area. Widespread frost formation is still likely for inland southeast GA, where lows will fall to the low and mid 30s. Lows elsewhere will likely remain in the upper 30s and 40s inland, ranging to around 50 along the northeast FL coast, where marine stratocumulus may continue to move onshore along the I-95 corridor.

Temperatures will continue to modify during mid to late portions of next week as zonal flow aloft develops and surface ridging shifts offshore of the southeastern seaboard. Onshore low level flow on Wednesday will continue to advect marine stratocumulus onshore from the Atlantic waters across our region, but rising heights aloft will allow highs to climb into the 70s for inland locations south of I- 10, while mid to upper 60s prevail elsewhere. Lows on Wednesday night will only fall to the mid and upper 40s for inland southeast GA and northern portions of the Suwannee Valley, with 50s elsewhere. Low and mid level flow will continue to veer on Thursday, with southerly winds in the morning shifting to south-southwesterly during the afternoon, boosting highs into the 70s, except upper 60s for coastal southeast GA due to the afternoon sea breeze.

MARINE

High pressure centered over our local waters this morning will shift offshore tonight. Meanwhile, an Arctic cold front will enter the southeastern states on Saturday night, with this boundary pushing across our local waters on Sunday. Northwesterly winds will quickly strengthen in the wake of this frontal passage on Sunday afternoon, with Small Craft Advisories likely, followed by possible Gale Warnings on Sunday night as winds shift to northerly and then northeasterly due to strong high pressure wedging down the southeastern seaboard, resulting in quickly building seas. High pressure will then gradually weaken over the southeastern states early next week as coastal troughing develops over our local waters. Gale Warnings will likely continue through Monday morning, with onshore winds and seas then gradually subsiding from Monday afternoon through Tuesday. Coastal troughing may generate a few showers early next week, mainly for the offshore waters. High pressure will then shift eastward and off the southeastern seaboard by midweek.

Rip Currents: Southeast GA: Low Friday & Saturday Northeast FL: Low Friday & Saturday

FIRE WEATHER

A dry air mass will prevail at inland locations today, dropping minimum relative humidity values to the upper 20s and lower 30s, with values closer to 40 percent at coastal locations. Southwesterly transport winds will become breezy during the mid to late afternoon hours across inland portions of southeast Georgia, where fair daytime dispersion values are forecast. Lighter speeds across northeast Florida will yield poor daytime dispersion values today, except low values for coastal locations and also across north central Florida. Southwesterly transport winds will continue across southeast Georgia on Saturday, with elevated mixing heights countering lower speeds, keeping fair daytime dispersion values in the forecast. Poor values will prevail elsewhere, with marginally low values again possible at coastal locations in northeast Florida. Westerly surface and transport winds on Sunday morning will shift to northwesterly late in the morning and early in the afternoon. A few showers will be possible across inland southeast Georgia during the morning hours, with dry weather continuing elsewhere. Surface and transport winds will strengthen during the afternoon hours on Sunday area-wide, creating good daytime dispersion values at most locations. A much colder and drier air mass will then plunge into our region on Sunday night, with breezy northeasterly surface and transport winds yielding elevated nighttime dispersion values at coastal locations.

FOG POTENTIAL AND OTHER REMARKS: A light freeze and widespread frost is forecast early this morning across inland southeast Georgia, the Suwannee Valley, and portions of inland northeast and north central FL. Patchy to areas of fog formation are possible for inland areas during the predawn and early morning hours on Saturday and Sunday.

PRELIMINARY POINT TEMPS/POPS

AMG 64 42 70 48 / 0 0 0 10 SSI 64 48 68 52 / 0 0 0 0 JAX 69 43 73 49 / 0 0 0 0 SGJ 69 48 73 53 / 0 0 0 0 GNV 72 43 75 50 / 0 0 0 0 OCF 72 44 76 52 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...Freeze Warning until 8 AM EST this morning for FLZ021-023-024- 030-120-220-322-422-522. Frost Advisory until 8 AM EST this morning for FLZ031-035-124- 136-225-232-236-425. GA...Freeze Warning until 8 AM EST this morning for GAZ132>136-149- 151>153-162-163-165-250-264-350-364. Frost Advisory until 8 AM EST this morning for GAZ154-166. MARINE...None.