textproduct: NWS Wilmington

WHAT HAS CHANGED

Confidence in additional ice accumulation across portions of Darlington, Marlboro, Dillon, and Robeson counties has increased for this evening.

KEY MESSAGES

-1) Lingering cold air damming will maintain a risk for freezing rain, drizzle, and fog into tonight for inland areas with a gradual warming trend ending the ice threat from southeast to northwest.

- 2)An extended period of very cold weather is expected all week and into the weekend. Nighttime apparent temperatures could necessitate a Cold Weather Advisory for at least part of the area Monday and Thursday night as well as Friday and Saturday night.

DISCUSSION

KEY MESSAGE 1: Lingering cold air damming will maintain a risk for freezing rain, drizzle, and fog into tonight for inland areas with a gradual warming trend ending the ice threat from southeast to northwest.

KEY MESSAGE 1 DESCRIPTION... While precipitation has mostly ended across the forecast area, lingering cold temperatures and a thinning cold wedge with strong south to southwest winds riding over it are supporting continued freezing drizzle, mist, and fog across the area away from the coast. Occasional freezing rain showers will remain possible across inland areas until a band of rain arrives from the west ahead of a cold front. Given this dense, cold airmass has been keeping temperatures colder for longer than anticipated, it is becoming increasingly likely that far northwest portions of the forecast area will not rise above freezing by the time this band of rain comes in. Thus, growing confidence exists for another round of accumulating ice in portions of Darlington, Marlboro, Dillon, and Robeson counties where temps stay below freezing through this evening. An additional tenth to two tenths of an inch of freezing rain is possible, mainly in Darlington and Marlboro county, with lesser amounts in Robeson and Dillon county.

The incoming band of rain will occur within, and will be preceded by, a surge of south to southwesterly winds aloft, and this will be the last ditch effort to erode away the cold wedge from the top down. Whether this occurs is still in question, and thus, temperatures across the area carry lower confidence due to the stubborn nature of the cold wedge. Nevertheless, temperatures should at least warm into the 40s in the coastal counties this evening, with low to mid-50s possible along the immediate coast if the cold wedge can erode away entirely. This band of rain may also bring occasional rumbles of thunder as weak elevated instability arrives. Additional rainfall of around 0.50" is expected, with higher amounts possible along the coast where rain will linger through most of tonight. Relatively warm, moist air within and behind the rainfall band will keep a risk for mist or fog in place through the rest of tonight, before breezy west winds bring in colder and drier air on Monday.

KEY MESSAGE 2...An extended period of very cold weather is expected all week and into the weekend. Nighttime apparent temperatures could necessitate a Cold Weather Advisory for at least part of the area Monday and Thursday night as well as Friday and Saturday night.

KEY MESSAGE 2 DESCRIPTION... Arctic air will be pouring into the region Monday night. Temperatures at 850mb bottom out at -10C, supportive of lows in the mid to upper teens. A few knots of northerly winds will push apparent temperatures below the Cold Weather Advisory-worthy values of 15F across all but perhaps our southernmost zones. After a very paltry recovery Wed and Wed night the next Arctic boundary arrives Thursday and another one Saturday, the latter accompanied by dynamics aloft. This system in previous guidance has been hinting at wintry accumulations in the Southeast but it now appears that the cold air will be so deeply entrenched that accumulating snow could very well remain suppressed to our south and offshore, a rarity indeed.

AVIATION /18Z SUNDAY THROUGH THURSDAY/

IFR to LIFR cigs will continue through the remainder of today as a cold air damming wedge remains firmly in place. This wedge will also maintain a risk for freezing drizzle/mist or fog at inland terminals near I-95 for at least the next few hours as warm air will be slow to work its way inland. By this evening, those inland sites should be above freezing, but IFR to LIFR cigs will continue. A band of light to moderate rain will arrive from the west this evening and continue into tonight with vis and cig restrictions continuing. A rumble of thunder cannot be ruled out as well, but this carries low confidence. Otherwise, with relatively warm/moist air still in place behind the rain, expect mist to linger through the night before clearing up after sunrise. By midday, inland sites should see VFR return with the coast potentially not seeing cigs scatter out until just beyond the end of the period.

Extended Forecast...Cig restrictions may remain at coastal terminals until the 18-00Z time period on Monday. VFR should prevail through the remainder of the extended period.

MARINE

Through Monday... Northwest winds will continue to weaken and back this afternoon, with south to southwesterly winds ramping up this evening into the 20-25 kt range as the cold wedge is eroded away over the waters ahead of a cold front. A band of rain and isolated thunder will shift over the waters ahead of the front and winds will turn westerly by late tonight as the cold front shifts through and brings an end to the rain. Winds back to northwesterly on Monday and continue at around 20 kts with gusts around 25 kts through the day. Seas will peak around 4-7 ft tonight amidst breezy southwest flow, before very gradually subsiding through Monday.

Monday night through Friday...With the series of Arctic boundaries pushing across the waters wind will not get much a chance of deviating from N to NW through the period and wind speeds will never get a chance to settle much though actual advisory conditions will be hard-pressed to develop as the largest waves remain outside of the 20nm forecast zones. Swell energy similarly remains well out to sea in the offshore fetch leaving the wind chop the dominant wave through the period.

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- 033-039-054-055-058-059. MARINE...Small Craft Advisory until 7 AM EST Tuesday for AMZ250-252-254- 256.