Arctic blast threatens flash freeze Friday in DC and then subzero wind chills

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An extraordinary cold front that has sent temperatures tumbling as much as 60 to 70 degrees in a day across parts of the central US is on the way to the nation’s capital Friday. The cold front won’t be quite as startling here, but it will still pack a huge punch.

Friday’s highest temperatures will come before dawn. It’s the weird kind of day that temperatures start dropping on fierce winds once the sun is up and keep doing so until it goes back down. By Friday evening, dangerously cold wind chills near zero will grip the entire region.

The Arctic front will bring very powerful winds into areas. The National Weather Service has issued a wind advisory from 8 am until 2 pm Friday for potential wind gusts up to 50 mph. “Gusty winds could blow around unsecured objects. Tree limbs could be blown down. A few power outages may result,” the agency warned.

The cold front could also deliver a little bit of snow and the potential for a flash freeze as it moves by Friday morning — possibly creating areas of hazardous travel. The front will certainly bring the DC area the coldest Christmas holiday since at least 1989.

A large storm system is expected to move through the United States starting on Dec. 20, bringing heavy snow and freezing temperatures to much of the country. (Video: John Farrell/The Washington Post)

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Showers along the Arctic front will sweep across the area between roughly 6 am and noon Friday. Temperatures may cool quickly enough for some snow to fall as cold air spills westward.

The big story will be how fast temperatures fall. Here’s a timeline:

5 to 7 am: Temperatures hover near 40 as the Arctic front races this way from the west. Winds gust upwards of 40 mph while a few showers develop.

7 to 9 am: The cold front punches through western parts of the area and rapidly progresses eastward to near the District. Temperatures fall quickly through the 30s. Showers may be locally heavy as the front passes, with even a small chance of some thunder and small hail. Winds gust upward of 40 mph with isolated tree damage and power outages possible.

9 to 11 am: Front races through areas east of Interstate 95. Any lingering rain showers may turn briefly to snow as temperatures fall into the mid-20s to near 30. However, it’s uncertain how much, if any, snow will materialize. At most, a dusting could occur.

If it’s snowing as temperatures fall below 32 degrees and/or the pavement remains wet from earlier rain, slick spots could form on roads. However, if precipitation ends before temperatures fall below freezing, strong winds may help dry pavement, minimizing the flash-freeze threat. Wind chills fall through the teens, with winds gusting near 40 mph.

11 am to 1 pm: Any snow should have ended and skies trend clearer. By 1 pm, temperatures range from the teens to the 20s, northwest to southeast. Gusts are around 35-45 mph.

1 pm to 7 pm Temperatures fall off to the teens areawide by around sunset, under mainly clear skies. Wind chills could be within several degrees of zero by midafternoon, before dipping below zero areawide by nightfall. Winds are still gusting around 35 mph.

If travel is a must Friday afternoon into Friday night, prepare for the possibility of being stuck in extreme cold and high winds. Carry a winter emergency kit. Temperatures are expected to be about 35 to 40 degrees colder than 24 hours prior, and that’s without the wind chill.

“[I]t will be dangerously cold,” the National Weather Service forecast office serving the region wrote. “Even into the metros we could see wind chills into the negatives Friday evening and into Friday night.”

By Saturday, we woke up to wind chills ranging from about zero to minus-15. Wind chills of minus-40 to minus-50 are possible in high elevations of West Virginia.

The general forecast for Friday into the weekend has trended colder in the past two days. The forecast now calls for lows in the single digits and lower teens. These are near-record lows for the date across the region.

Washington’s record low of 5 in 1983 is probably safe, but a temperature of 11 or lower would be as cold as it has been in December since 2000.

Saturday’s high temperatures are more likely to threaten records. They may struggle to surpass the low 20s, close to the Dec. 24 record of 23 for the District, set in 1989. Well north and west of the city, parts of the area may stay in the teens.

Winds blowing around 10 to 20 mph, with gusts around 30 mph through Saturday, keep wind chills in the single digits to near 10 at most.

Conditions are similar but slightly milder for Christmas morning. Lows are mainly in the low and middle teens with wind chills in the single digits. Christmas Day highs should reach the mid- and upper 20s.

Both days are mostly to partly sunny, with perhaps an outside shot at a passing snow flurry.

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