PITTSBURGH (KDKA) — If you’re looking for a white Christmas, the large-scale weather pattern may not end up being in Pittsburgh’s favor this year. 

The early part of this week featured a brief thaw after a short-lived cold snap last week. Colder air will make a return to the Ohio Valley and Great Lakes region this upcoming weekend. A large trough or dip in the jet stream will result in a surge of Arctic air to push south toward our region. 

It will not be extremely or dangerously cold as the air mass will modify or lose its original potency as it loses latitude with southward progression. Still we expect high temperatures to be 5 to 15 degrees below average on Saturday, Sunday and Monday next week.

Warm-up arrives for Christmas

Just in time for Christmas Eve and Christmas Day, the large-scale weather pattern is projected to shift across the entire country. The general consensus among model guidance is for the deep trough of cold air to lift out of the Great Lakes, Ohio Valley and Northeast and be replaced with a more zonal or west to east flow from the Plains and Pacific West Coast. 

This will result in a substantial and likely long-lasting warming trend that will carry us from Christmas onwards. The Climate Prediction Center has shaded virtually all of the Contiguous U.S. in a moderate to high probability of warmer than normal temperatures in their Dec. 24 to Dec. 30 outlook. 

While we are likely going to be shifting into a pattern with above average temperatures around Christmas, that doesn’t necessarily mean it will be sunny either. Surges of warm air often come with moisture in this part of the world, so we could be looking at more clouds and possibly some rain chances around Christmas. Perhaps if you’re fortunate enough to have elevation or latitude working in your favor, you may be able to squeeze out some snow in Western Pennsylvania, but as of now, things aren’t looking too great.

What are the odds of a white Christmas in Pittsburgh? 

Statistically, the probability of Pittsburgh seeing a white Christmas is around 25%, so the odds are often in favor of no white Christmas— especially from Pittsburgh south and west. Odds increase farther north toward Lake Erie where lake-enhanced snows help raise this potential and in the Laurel Highlands which usually are the first to receive wintry precipitation because of their higher elevation and more frequent time spent above the freezing level.

Here’s how the odds are shaping up for this year. 

PITTSBURGH (KDKA) — It’s going to be a clear day in the Pittsburgh area with rain chances moving back into the forecast tomorrow.

We’ve technically already reached today’s high temperature (57 degrees) just after the midnight hour or so. Cooler—but not cold—air is moving in behind this morning’s cold front and will result in slightly cooler afternoon temperatures, although with mostly sunny skies, it should still be an overall comfortable day with afternoon temperatures peaking in the lower 50s to upper 40s. 

Overnight into Wednesday morning, temperatures will drop to the low 30s for most and at the present moment, temperatures may stay around or just above freezing in Pittsburgh thanks to a light southeast wind and clouds that will move in to the region toward daybreak. 

Clouds will increase through the morning Wednesday with another round of rain showers by afternoon and evening as another trough of low pressure passes through the region. This system will not get much stronger until it passes east of us and the precipitation will end before the coldest air settles in, so wintry precipitation is not a major factor for Wednesday night into Thursday outside of a brief period of some snow north of Rt. 422 toward I-80 for an hour or two on the back end of the rain by early evening Wednesday. 

Most spots will receive around 0.25″ with a few locations possibly near 0.5″, especially closer to I-70 and I-68. Models may be overdoing the precipitation quantity with this system given how fast it is moving and how little time it will have to draw up moisture from the southwest. 

Expect temperatures to continue to drop each day this week, ultimately reaching below average levels by the end of the upcoming week. Another trough of low pressure will swing in from the northwest on Friday bringing another chance for a few snow showers along with another surge of cold air. As the cold air continues to flow over Lake Erie, that could keep lake effect snow showers and flurries through Saturday before the coldest of the air settles in with high pressure by Sunday. Although Sunday will be the coldest day of the week, models have backed off a few degrees on the lowest of the low temperatures. 

This cold air will likely stick around until early next week before a warmer pattern sets in around and especially after Christmas, so for anyone looking for a big snow—your probability is trending lower and lower.

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