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Jan 6-7, 2017 Winter Weather Event Decision Support Briefing # 2

Wilmington, NC Weather Forecast Office weather.gov/ilm | @NWSWilmingtonNC

Steven Pfaff, WCM Steven.Pfaff@noaa.gov

National Weather Service Wilmington NC 8 AM EST Thursday January 5, 2017

Assessment for northeast South Carolina & southeast North Carolina

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Potentially a slower transition to wintry weather from late Friday night into early Saturday morning.

Temperatures lowered with the arctic air-mass Sunday into Monday.

Could see more sleet which would limit snowfall accumulations in some areas, also there may be more freezing rain in some locations than previously thought.

New Information

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None Elevated Moderate High Extreme

None Elevated Moderate High Extreme

None Elevated Moderate High Extreme

None Elevated Moderate High Extreme

None Elevated Moderate High Extreme

Impact Summary Greatest expected impacts

Snow/Sleet

Surge/ Inundation

Wind

Ice

Marine

*These impacts do not apply to all areas of southeast NC or northeast SC, check the following slides for details on where impacts will be greatest.

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Hazard Overview, Timing & Confidence Confidence

• Low confidence with snow amounts at this time given model differences & impacts from sleet

• Low confidence with freezing rain/icing location, higher confidence that ice accumulations will remain below one tenth of an inch.

• High confidence with cold temperatures early Sunday through Monday

Potential Impacts • Hazardous driving conditions, especially

bridges, overpasses, & elevated road surfaces early Sat morning through Saturday afternoon, especially across inland areas

• Black ice possible on roadways Saturday night into Sunday morning

• Isolated power outages possible Sat

• Dangerously cold weather Sun - Mon

Approximate Timing

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Expected Storm/Sleet Total Snowfall

Highest snow accumulations are expected to occur north of a Florence, SC to Elizabethtown, NC to Wallace, NC line.

Relatively warm ground temperatures and sleet will limit the amount of accumulations.

Some icing from a period of freezing rain is also possible Saturday morning and early afternoon.

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Probability of Snow Accumulating ≥ 1”

WPC Probability of Snowfall Accumulating ≥ 1” valid 7 PM EST Friday through 7 PM EST Saturday

Probabilities remain highest from near Greenville, SC to Fayetteville, Raleigh and Rocky Mount/Greenville, NC. However some scenarios still bring accumulating snowfall to the coast as noted by the lower probabilities depicted along the coast on the map. As a result, coastal areas could still be impacted but the best chances for accumulating snowfall appear to be farther inland and this has been a consistent trend in recent model runs.

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Probability of Freezing Rain Accumulating ≥ 0.01”

WPC Probability of Freezing Rain Accumulating ≥ 0.01” valid 7 PM EST Friday through 7 PM EST Saturday

The highest probabilities for some freezing rain accumulations have shifted slightly farther south and east compared to yesterday’s information. The best chances based on the probabilities shown is from near Columbia, SC to Lumberton to near New Bern, NC.

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Wind Chill

Period of Coldest Wind Chill • Wind Chill Advisory is possible Sunday night into Monday

morning with more of the area with wind chill values <5F

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Arctic Temperatures

Arctic air-mass in place through Monday • Coldest temperatures Monday morning, these will be the coldest

temperatures the area has received since Feb of 2015

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After a start as rain late Friday afternoon/evening a transition to a wintry mix is expected early Saturday morning (inland areas, later in the day along the coast), primarily causing travel hazards through the day.

Single digit wind chill values (combination of wind and temperature) are expected Sunday morning and, especially Monday morning.

Highest snowfall accumulations are expected farther inland given the track of the low and later arrival of arctic air.

NEXT PDF BRIEFING: 4 PM EST - Thursday January 5, 2017

Key Points

Very cold low temperatures are expected early Sunday morning with even colder temperatures early Monday morning with a strong arctic air-mass building into the Carolinas.