Walk Like a Penguin

Dew points are currently sitting in the mid teens across the Washington Area setting up a textbook Cold Air Damming (CAD) situation. As precipitation begins falling through the dry mid levels of the atmosphere, temperatures at the surface will drop into the middle 20s and hold steady through the event allowing for all precipitation to freeze on contact.

Ice accretion between a tenth and a quarter of an inch will accumulate on trees, power lines and roadways causing treacherous travel conditions. The 100 car pile up in Dallas-Ft. Worth yesterday was a result from only a tenth of an inch of ice.  

Winter Storm Warnings or Ice Storm Warnings are likely along and east of Interstate 95 with a Freezing Rain Advisory likely for locations further north and west.

The image below is from the latest North American Model (NAM) showing sleet (orange) and freezing rain (pink) impacting the DC region beginning Saturday morning and wrapping up by noon on Sunday.

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Ice Storm Will Likely Cause Treacherous Travel Monday Afternoon and Evening

Snow will develop on Monday during the early afternoon hours across the Metropolitan Area. Snow will quickly change over to either Sleet or Freezing Rain continuing through much of the evening hours. Temperature profiles will be tricky, however I suspect that with the rather cold, dry air mass in place, once precipitation begins falling, temperatures will fall to at or below freezing for most locations along and west of the interstate 95 corridor causing treacherous travel on untreated roadways.

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Tuesday Update: Major Snow Storm for Some, Major Ice Storm for Others?

This is a very low confidence forecast as the latest forecast models continue to indicate a more inland track of the low pressure system which is increasing the threat of sleet and freezing rain and drastically cutting down on snowfall accumulations! My map below includes Snow, Sleet (frozen rain drops) and Freezing Rain.

Any deviation in track of the area of low pressure further to the west or back to the east will have a drastic impact on whether we are digging out from snow or sleet (or both), or losing power from ice accretion from freezing rain.

Here’s a look at the latest forecast models and what they are showing for potential snowfall accumulations:

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