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Freezing Rain Details: Expanded Winter Weather Advisory

Winter Weather

Warnings

Justin Berk

Jan 4, 2022

9:16 pm

Tuesday Evening Update

All of Delmarva is now included in the Winter Weather Advisory, with the exception of the beaches. This event will hit interior Delaware and Maryland’s Eastern Shore the hardest. But in general most of the places that had heavy snow east of I-95 get in on something in the morning.

There are three things I want to highlight in this report:

Temperatures are already well below freezing! There is sufficient time in the dark hours for the pavement to get very cold.
Even if there is some warming at cloud level or near the surface, the ground itself will remain cold long enough for rain to freeze on contact.
The back edge of freezing drizzle may be within a few miles of I-95. That region will get light precipitation/drizzle that might not show on radar, but be enough for a glaze for form. That can be dangerous because it can catch drivers without notice.

Winter Weather Advisory

This is the updated map, and the temps below will explain why the southern areas are involved.

This is a time it is safe to say if the decision has not been made yet, schools in Southern Maryland and Delmarva will at least be delayed (or more ) again.

Evening Temperature Observations

A clear sky and snowpack has allowed temps to tank!

Check out the pocket of lower 20s and teens for some from central Delaware to Salisbury.

Annapolis and Baltimore are in the Middle 20s, with temps near freezing in souther Maryland.

While clouds will fill in and temps may bump up a little overnight, there has been plenty of dark hours to allow the pavement to get very cold.

Temperatures Forecast

4 AM- When the precipitation should be arriving.

Even if there is a rise to or above 32ºF, the ground will remain cold to support rain freezing on contact. Also, if ice already forms it will take a while for that to thaw.

8 AM – After Sunrise and when a thaw will try to develop.

Models often try to warm up faster than can occur if there is snow or ice on the ground. So it will likely be a few more hours to thaw.

Freezing Rain and Drizzle

It is important to note that the models DO NOT tend to perform well with light precipitation. So this product can be deceiving. That is why I want to show a few plots for contrast.

Canadian GEM Model

This covers the entire event. Simply a suggestion for the impact region:

I’ve included the back edge for the ‘Freezing Drizzle’ near Baltimore and Washington. That will be spotty, but anything light can catch drivers off guard.

Chances will increase near Annapolis then to the south.

The Eastern Shore and Delmarva will be in the main target for this event.