District of Columbia
Related: About this forumChristmas Eve storm threatens D.C. with gusty downpours before plunging temperatures.
The worst weather is expected Thursday afternoon and night. Some festive snow flurries are possible in the frigid air Christmas Day.
* Flash flood watch Thursday afternoon and night *
The weather in the 18 hours spanning Christmas Eve afternoon and Christmas morning will have it all: a surge of warmth, waves of rain that may produce strong winds, flooding and even a tornado, plummeting temperatures and then a chance of snow flurries.
The National Weather Service has issued a flash flood watch ahead of the Arctic cold front responsible for the turbulent weather. The watch, in effect Thursday and Thursday night, calls for up to 1.5 to 2.5 inches of rain, which may result in flash flooding of small streams and creeks and possible river flooding.
Scattered showers with locally heavy downpours could develop any time Thursday afternoon, but the most intense rainfall and the possibility of storms with strong winds is most likely to occur between 10 p.m. and 1 a.m.
As cold air spills into the region in the wake of the storm Christmas morning, some scattered snow showers and flurries are possible as temperatures plunge to near freezing with wind chills in the teens and 20s.
Discussion
The anticipated weather roller coaster centers on an approaching cold front and deepening area of low pressure moving north along the Appalachians late Thursday. An unseasonably mild and humid surge of air will get drawn over the D.C. region out ahead of these features. A secondary cold front the true Arctic front follows quickly on the heels of the main front, with a reinforcing surge of cold and dry air.
The mild air will contain a ribbon of very high moisture, as shown in the next image. This is a plume of tropical moisture, exceptionally large in humidity content for late December. Waves of heavy showers will develop periodically throughout the day tomorrow, tapping into this deep moisture.
The repeated movement of showers across the same areas has triggered a concern for flooding hence the flash flood watch posted by the Weather Service. The ground is quite soggy from melted snow and recent rain across the region, so water will probably quickly pond in areas.'>>>
https://www.washingtonpost.com/weather/2020/12/23/christmas-eve-storm-dc-md-va/?
bottomofthehill
(8,822 posts)Maybe a good night to put a fire in the fireplace and listen to Christmas music.