textproduct: NWS Wilmington

SYNOPSIS

A powerful arctic cold front will blast through the Carolinas on Sunday. High pressure following the front will bring very cold temperatures Sunday night through Monday night. Temperatures will then gradually warm up Tuesday and Wednesday with another mainly dry cold frontal passage expected Thursday night.

NEAR TERM /THROUGH SUNDAY/

High and dry this afternoon as temperatures have soared into the middle to upper 60s along the coast with slightly cooler albeit still pleasant readings inland. Long advertised arctic front now located off to the north and west (as seen by numerous satellite images) will move across quickly Sunday mid morning. A quick area of showers with the boundary remains reasonable with high/short lived pops. Highs in the lower 50s Sunday will be realized early then falling rapidly into the 40s by mid to late afternoon.

SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/

*KEY MESSAGES/HIGHLIGHTS* *Hazards: Dangerous cold Sun night into Mon AM *Rain Chances: None *Temps: Well Below normal *Confidence: Moderate to High

Details: Arctic high pressure will bring near record cold temperatures and gusty winds causing dangerous wind chills around 5- 10 degrees Sun night into early Mon morning. We have maintained the Extreme Cold Watch for now given some lingering uncertainty regarding how low wind chills will get but confidence is high that at the very least we will reach Cold Weather Advisory criteria (6-15 degrees) for all areas. Also something to note as a very low but non- zero probability, black ice may develop on roads Sun eve as temps quickly fall below freezing (especially inland). Fortunately, the lack of significant rainfall and rapid drying/breezy conditions for several hours Sun afternoon should prevent much ice from developing.

Not much warming expected Mon as highs struggle to reach 40 degrees. Another very cold night is on tap Mon night as the high moves more overhead leading to better radiational cooling conditions. Thus, we leaned toward the lower end of model guidance for lows (~20 inland to ~30 at the immediate coast), although with much less wind the wind chills should mostly stay above our Cold Weather Advisory criteria (15 degrees). Dry weather with below normal temps will then continue through Tue night as high pressure maintains control.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

*KEY MESSAGES/HIGHLIGHTS* *Hazards: None *Rain Chances: Low to Mod Thu thru Fri w/ best chances Thu night *Temps: Near to above normal *Confidence: Moderate to High

Details: The arctic air mass over the area will continue to modify as it slides offshore late week ahead of a cold frontal passage late Thu night/early Fri. Moisture/forcing appear limited with this feature so only carrying low to moderate rain chances with not much accumulation anticipated. Temps will fall back closer to normal late week.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Low level wind shear should develop by 03z for all local airports except perhaps CRE and MYR. This is due to a southwesterly low level jet developing ahead of an approaching arctic cold front. As the front arrives Sunday morning, MVFR clouds will develop along with a few hours of shallow convective showers. Some of the high-res models show visibility dipping to 2-3 miles within these showers, but only very briefly. As the front passes through between 13-16z, winds will shift to the northwest and increase to 15 knots with gusts to 25-30 knots anticipated to continue through the afternoon hours.

Extended Outlook...Predominantly VFR through the extended period.

MARINE

Through Sunday...Gale warnings have been posted for all waters beginning late Sunday via strong sustained winds and moreso gusts associated with the arctic front currently in the Missouri Valley. While some small craft advisory conditions may be observed prior to this onset (Sunday morning) they should be brief as the main system is not wasting any time. Favorable marine conditions this afternoon and into the early evening before all of this ockers however.

Sunday night through Thursday...Moderate to high confidence this period. Hazardous marine conditions expected into early Mon due to strong cold advection behind a passing arctic front with gale force gusts up to around 40 kt a good bet thru Sun night. Conditions will improve pretty quickly Mon as high pressure moves more overhead and the pressure gradient/cold advection slacken. High pressure will then maintain control as it slowly shifts offshore with no additional marine concerns expected thru mid week.

CLIMATE

Record Low Temps for Dec 15: KILM: 17 / 2010 KLBT: 13 / 2010 KCRE: 17 / 1944 KFLO: 13 / 2010

ILM WATCHES/WARNINGS/ADVISORIES

NC...Extreme Cold Watch from Sunday evening through Monday morning for NCZ087-096-099-105>110. SC...Extreme Cold Watch from Sunday evening through Monday morning for SCZ017-023-024-032-033-039-054>056-058-059. MARINE...Gale Warning from 4 PM Sunday to 7 AM EST Monday for AMZ250- 252-254-256.