Today we enjoyed temperatures in the upper 60s and lower 70s, giving the area a taste of spring. Temperatures are expected to crash overnight, dropping to/around the freezing mark mid-morning Thursday morning. Highs tomorrow will likely be around 35 degrees with temperatures hovering around freezing again Thursday night when the precipitation begins and go back up to about 35 degrees in the morning. Right now, temperatures don’t support much ice, but it’s still possible things are a little cooler than expected.
The most recent map from the National Weather Service, seen in our featured photo, shows almost all of MoCo getting a trace of ice with a sprinkle of northern areas getting up to a tenth of an inch.
Though temperatures could reach or even go below freezing, the ground will struggle to get cold enough to support much ice. Significant icing has a better chance of occurring the further north you go, but we’ll continue to monitor and have an update tomorrow morning.
Per the National Weather Service:
Arctic high pressure will allow for much colder air to build in ahead of the disturbance tomorrow but there continues to be a battle thermally for how p-types are going to be realized. For now, the most likely scenario as of the latest guidance would be for an initial period of rain/snow/sleet mix when temperatures are hovering at or just slightly below freezing. With the CAD wedge in place, it will be difficult to pinpoint the gradient of 0C and colder temps for the day on Thursday and into Friday.
Temperatures off the surface and further up are expected to warm up a bit during the day and will therefore start to introduce freezing rain potential for portions of the area, particularly north-west of the DC metro area. Guidance continues to be in a bit of disagreement with respect to temperatures and freezing rain accumulations. NAM/NAMnest/HRW suite are all much colder than other guidance and have been showing a cold bias this winter so inclination at this time is to gear towards a bit warmer solution with respect to this event. Canadian/GFS/ECMWF have a more climatological approach to the colder temperatures and the ice accumulation.
It will be interesting to see how temperatures and dew points react tonight and into Thursday morning to account for the potential shift in higher ice accumulation potential. For now, overall ice accumulations looks to be most significant across eastern Garrett, western Allegany and western Mineral counties. Ice accumulations of a quarter of an inch to three tenths of an inch are possible for those areas, yielding a Winter Storm Watch.
Elsewhere, accumulations of less than a quarter of an inch are expected north and west of DC, with higher amounts particularly in and around the Mason-Dixon line. Guidance has continued to have a northern shift in the higher amounts in terms of QPF and ice accumulation well into PA. Conditions should begin to improve by late Thursday night (southwestern areas) to late Friday morning (NE MD). Continue to visit weather.gov/lwx/winter for the latest winter forecast. Behind the disturbance, gusty winds will build in on Friday. These gusty northwest winds may be strong enough to yield a Wind Advisory but confidence is low at this time. Upslope snow may be possible for the Allegheny Front Friday night into Saturday morning with lingering low-level moisture coupled with a colder airmass.