After looking at the latest forecast models, confidence continues to remain low in regards to how much sleet and or freezing rain falls from the Blue Ridge and Catoctin mountains eastward toward the western suburbs of Baltimore and Washington. “The Devil is in the Details” and there will be a lot of “now-casting” going across these areas as everything will depend on temperature profiles. I’m most concerned about today’s freezing rain potential (more below).
The image below (courtesy WxBell) is the High Resolution Rapid Refresh (HRRR) model showing the future-cast precipitation type through the duration of this storm. Blue represents snow, orange represents sleet and pink represents freezing rain.
The high-resolution national blend model (image below courtesy WxBell) showing potential snowfall accumulation through the duration of this winter storm.
Snow totals in Cumberland, Hagerstown, Martinsburg, Thurmont and Winchester may be higher with locally 14 to 18″ if sleet doesn’t mix in.
The latest NAM model continues to remain bullish on sleet making it north of the Mason-Dixon line and across the interstate 81 corridor (this solution is not guaranteed but possible).
My biggest fear is if the threat of Freezing Rain materializes which would greatly increase the threat for power outages. Notice in the image below that the latest NAM model is depicting hefty ice accumulations at Dulles Airport (.58″), Leesburg (.77″), Frederick (.86″), Gaithersburg (.34″) and Westminster (.65″).
Ice accretion on trees and power lines of over a quarter of an inch (.25″) can cause scattered power outages while accumulations above a half-inch (.50″) can cause widespread power outages and damage to trees.
What a way to kick off mid December with a strong 1037 mb High pressure system anchored over eastern Canada and one of the most mucked up tracks of an area of low pressure that I have ever seen displayed on the forecast models.
It is my hope that as today wears on, the cold air holds in tougher than the forecast models are predicting and the track of this low shifts east, preserving higher snowfall totals and removing the threat of freezing rain (sleet is much easier to deal with). Stay safe out there!