textproduct: NWS Wilmington

WHAT HAS CHANGED

12Z TAF Aviation discussion updated.

Previous from 341am Sun...Placed Georgetown County within a Winter Weather Advisory. Temps continue around 30 with pcpn being reported in the area. The pcpn that falls will either be in the form of freezing rain or freezing drizzle and will result in atleast a light glaze or even a few one hundreths of an inch possible.

Previous from 250am Sun... Have held onto the freezing temperatures a bit longer than the previous update. This based on the latest sfc obs trends and high res model data. Have temps climbing above 32 by daybreak at the coast, reaching along and west of the I-95 corridor by early to mid afternoon. This will extend the freezing rain potential across the area but with pcpn being light and patchy in nature, have basically kept the same forecast icing accumulation values, thus no change with any of the winter weather headlines.

KEY MESSAGES

1) Freezing rain and associated ice accumulations will remain the primary winter weather hazard associated with this winter storm through this morning at the coast and extending into the afternoon well inland. Winter weather headlines remain unchanged. The milder temps, above 32 degrees, will be a bit slower to manifest, spreading from the coast and inland today and then remaining above freezing across the entire ILM CWA thru tonight. Remote possibility of thunderstorms tonight.

2) Extended period of unseasonably cold temperatures expected through next week with dangerously low wind chill temperatures at times, especially Monday and Thursday nights.

DISCUSSION

KEY MESSAGE 1: Freezing rain and associated ice accumulations will remain the primary winter weather hazard associated with this winter storm through this morning at the coast and extending into the afternoon well inland. Winter weather headlines remain unchanged. The milder temps, above 32 degrees, will be a bit slower to manifest, spreading from the coast and inland today and then remaining above to well above freezing across the entire ILM CWA thru tonight. Remote possibility of thunderstorms tonight.

Ongoing CAD continues in full tilt. Shallow Arctic airmass holding tough across the FA, with 30-32 degree readings even at the coast. Models having difficult time with severity of this CAD event as well as the colder temps having held on longer than expected. This will result in an extended period of freezing rain and ice accumulation all the way to the coast, with coastal Georgetown County the exception, but that may need to be re- visited given latest pcpn trends and the dense shallow Arctic air still in place. High res models still want to decay the Arctic airmass from top/down and also from east to west as mild flow aloft increases across the FA. Latest sat imagery depicting the low/mid levels also confirms this trend. Timing is the problem child here, with regard to the milder temps raising the the temps above 32, and thus ending the threat for freezing rain/drizzle. As mentioned prior, have extended the occurrence of the freezing pcpn and the 32 degree or less readings. Will continue to advertise the ice accumulation range from a trace to less than one tenth of an inch at the coast to one tenth to two tenths from the coast to I-95 and up to one quarter of an inch along and west of I-95.

Once the CAD ceases, temps will climb into the 40s inland and 50s at the coast later this afternoon and likely continue thru the night ahead of the approaching cold front. This should give ample time for melting to occur across the entire ILM CWA, with obviously the areas along and west of I-95 taking longer to melt. The pcpn extending ahead of the approaching cold front to push across the FA later this evening and overnight. Elevated instability and dynamics from the passage of a 5h s/w trof (that was once a closed 5H low in the Pacific) will result in the possibility of an embedded tstorm.

KEY MESSAGE 2: Extended period of unseasonably cold temperatures expected through this week with dangerously low wind chill temperatures at times, especially Monday and Thursday nights.

Temps will hold in the 40s for highs most days this week as deep mid to upper trough lingers across the eastern CONUS with arctic air flowing into the Carolinas. The 850 temps dip to -10 C Mon night and Thurs night and possibly down to -15 C next weekend. The overnight lows will be in single digits Mon night and Thurs night with stiff northerly winds making it feel even colder. Should not see overnight lows above freezing until at least a week from Mon. These dangerously cold temps Mon night and Thurs night should lead to a Cold Weather Advisory.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

IFR ceilings to dominate across all terminals nearly the entire 12Z Forecast Issuance Period. Air mass has finally moistened up enough for low level stratiform clouds to dominate with ceilings generally in the 300 to 700 ft range. CAD holding on tough and as a result, temps have only steadied overnight. With light and patchy pcpn continuing across the area via 88D returns and high res model data, have kept the freezing rain and drizzle ongoing into the mid daytime morning hrs for the coastal terminals...and thru mid afternoon hrs for the inland terminals. Reduced vsby in fog has been a mainstay at the coastal terminals and see no reason to cease from advertising it thruout much of the day. Have continued to illustrate a PROB30 threat for thunder generally in the 22Z thru 08Z time frame as pcpn ahead of the cold front pushes across. An embedded northeast moving 5H s/w trof will provide dynamics combined with elevated instability to produce a tstorm. NNE winds 10 kt will diminish to around NW 5 kt as the CAD breaks down across the ILM CWA during today. SW winds increase to 10-15 kt g20 kt later this evening ahead of the approaching cold front along with mild temps as wintry pcpn no longer an issue.

Extended Forecast...Flight restrictions expected up until moisture is scoured out behind a cold frontal passage Mon. VFR should return by Mon afternoon and prevail through the remainder of the fcst period. Next CFP, albeit dry, slated for Wed night with gusty NW winds as the next Arctic high settles in.

MARINE

Through Tonight...CAD breaking down and the sfc pg to relax- some, resulting NE winds at initially 15 to 25 kt diminishing to nearly a variable in direction at 15 kt or less during today as the coastal trof gets pulled just inland and onshore. Tonight, the coastal front actually lifts north of the area waters altogether with S-SW winds becoming dominant and increasing to 15 to 25 kt with a few gusts up to 30 kt. An elongated area of showers with possible thunder, will align ahead of an approaching cold front tonight, pushing across the waters and just offshore around daybreak Mon. With cold SSTs, may be difficult for those stronger mild temp winds aloft to mix down to the ocean sfc. Seas generally in the 4 to 8 ft realm this period with short period wind waves, relatively speaking, dominating given the changes in wind directions.

Monday through Thursday...A Small Craft Advisory will be ongoing with seas running 5 to 7 ft through Mon and winds NW at 20 to 25 kts with higher gusts. Heading into Tues, winds and seas will drop below SCA thresholds with northerly winds down to 15 to 20 kts. Winds and seas will drop off through Tues and into Wed as high pressure migrates across the Southeast, but will increase once again ahead of next cold front Wed night into Thurs.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Ice Storm Warning until 1 AM EST Monday for NCZ087. Winter Weather Advisory until 7 PM EST this evening for NCZ096- 099-105>110. SC...Ice Storm Warning until 1 AM EST Monday for SCZ017-023-024. Winter Weather Advisory until 7 PM EST this evening for SCZ032- 033-039-054>056-058-059. MARINE...Small Craft Advisory until 7 AM EST Tuesday for AMZ250-252-254- 256.