Winter Storm Watch Friday For Snow And Freezing Rain And More Alerts Expected

Wednesday December 24: Christmas Eve Update

After this gift of a mild Christmas, the storm pattern is about to make things complicated. An active jet stream will funnel in the next piece of energy just as a large pool of cold air is attempting to slide south from Eastern Canada through New England and just barely into the Mid-Atlantic.

Winter Storm Watch

A Winter Storm Watch has been issued already for most of Pennsylvania, New Jersey, and parts of New York State. There is even an early alert in Maryland just for Extreme Western Allegany and Eastern Garrett Counties. I expect more to be added into Central Maryland.

Timing

• Starting: Friday midday to early afternoon
• Peak: Friday evening and night
• Ending: Saturday morning

It will be cold enough, and I’ve been monitoring the ground temperatures as well. There does seem to be enough time to chill the pavement, and an initial push of snow or sleet to help with the cool down and support icing.

Even if roads are OK in your area, elevated surfaces like steps, decks, and bridges can still ice easier. Also, the accumulation on trees and power lines is worth watching.

The concern will be mostly freezing rain for Central and Western Maryland to much of Pennsylvania. However, deeper into the cold air, more snow is expected to start in Eastern PA before turning to ice. Heavy snow is likely from Central New York to possibly New York City as well.

Since this is a big day post-holiday for shopping (returns), events, and travel, this is worth paying attention to. Many people may be forced to attempt to get out early or wait an extra day.

In this report, we will focus on Friday and the forecast plots from the European Model. This, in my opinion, is the best guidance for now with the general expectations for timing and totals.

The next phase will be to look at the high resolution models, which have a tendency to have difficulty with cold air blocking events like this. They can move the thaw in too early. In other words, where the cold sets up, it can last longer — and in this case, we will be looking through Friday night.

Set Up: Friday Afternoon

Jet Stream

The storm track here at 500mb is about 18,000 feet above the ground. High Pressure in Eastern Canada will be attempting to slip southwest with cold air. Note that the model trends have been to push the cold air farther south.

At the same time, the jet stream will bring in warm, moist air. The battle in between will be a large region with warm clouds and a cold surface resulting in freezing rain and sleet. The deeper cold air will be pure snow.

Surface Weather

Winter Precipitation

The complication with a layer of warm air into the clouds while cold air hugs near the ground.

The DEPTH of cold air will determine if rain can freeze to ice pellets (sleet) or remain rain and then freeze on contact with the ground (freezing rain).  Both are icy! Sleet is tiny balls of ice, freezing rain is just a layer of glaze that is smooth and more slippery.

Closer Look

Afternoon Temperatures

The cold air is forecast to keep Baltimore in the upper 20s, with the freezing line near or south of Rt 50 in Maryland. This puts Annapolis and Washington in line for a possible start as an icy mix.

Notice the 10s in the Poconos of PA and Finger Lakes to Catskills of NY. This is the prime target for the heaviest snow.

Storm Animation: 1 PM Friday to 1 PM Saturday

Snapshot: 7 PM Friday Evening

This is a 6-hour summary showing moderate freezing rain in our region. This could begin as snow or sleet briefly, then turn to mostly freezing rain.

Challenge: Where will the freezing line be? This will determine who remains icy or turns to plain cold rain. I will be looking at the wind direction for help. Turning more east will bring in warmer air from the ocean. Moving more from the north to northeast will hold the cold longer.

7 PM Evening Temperature Forecast

That freezing line will be very close to Baltimore.

4 AM Saturday

The bulk of the event will be moving away, but light precipitation may linger up to daybreak.

10 AM Saturday

This should be over and just a matter of thawing where need be.

Precipitation Totals

Total Freezing Rain

Total Sleet

Total Snow

NEXT UP

Sunday to Tuesday

After the ice event, a warm-up over the weekend will surge ahead of the next cold front.

Rain develops later Sunday and may be heavy overnight to Monday morning. This will be along a cold front with arctic air flowing in behind.

Thunder is possible with the downpours.

Jet Stream Sunday to Tuesday

Arctic air will be in place before New Year’s Eve!

7 Day Forecast

• Wednesday (Christmas Eve): Windy –  High 49°F.
• Thursday (Christmas Day): Mostly cloudy with showers possible (30%). High 52°F, Low 35°F.
• Friday: Freezing rain likely (70%). High 33°F, Low 28°F.
• Saturday: Mostly cloudy. High 40°F, Low 31°F.
• Sunday: PM rain (40%). High 45°F, Low 31°F.
• Monday: AM rain and maybe thunder. High of 45°F in the morning, then falling temps with colder winds.
• Tuesday: Cold winds. High 32°F, Low 22°F.

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Snow Report December 14  and Grade My Forecast

In case you missed it, click this image for brief summary of the final snow totals from the last event.

Snow Report December 5 to 6 and Grade My Forecast

In case you missed it, click this image for brief summary of the final snow totals from the last event.

My Winter Outlook For Above-Average Snow

Click here for the full report

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This was issued October 9, as expected: A weak and short-lived event to start winter may play a different role this winter.

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RESTATING MY MESSAGE ABOUT DYSLEXIA

I am aware there are some spelling and grammar typos and occasional other glitches. I take responsibility for my mistakes and even the computer glitches I may miss. I have made a few public statements over the years, but if you are new here, you may have missed it: I have dyslexia and found out during my second year at Cornell University. It didn’t stop me from getting my meteorology degree and being the first to get the AMS CBM in the Baltimore/Washington region. One of my professors told me that I had made it that far without knowing and to not let it be a crutch going forward. That was Mark Wysocki, and he was absolutely correct! I do miss my mistakes in my own proofreading. The autocorrect spell check on my computer sometimes does an injustice to make it worse. I can also make mistakes in forecasting. No one is perfect at predicting the future. All of the maps and information are accurate. The ‘wordy’ stuff can get sticky.  There has been no editor who can check my work while writing and to have it ready to send out in a newsworthy timeline. Barbara Werner is a member of the web team that helps me maintain this site. She has taken it upon herself to edit typos when she is available. That could be AFTER you read this. I accept this and perhaps proves what you read is really from me… It’s part of my charm. #FITF

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