PITTSBURGH —
Pittsburgh’s Action Weather is forecasting a milder winter for Pittsburgh, with less snow expected due to the influence of a strong El Niño.
From Chief Meteorologist Mike Harvey:
You have probably heard something about the ‘Super El Niño’ we will be experiencing this winter. El Niño is an important factor and the first building block in determining winter conditions in western Pennsylvania. It influences Pittsburgh’s winter mainly by shifting the large-scale jet-stream pattern and changing where storms travel across the United States.
How El Niño shapes Pittsburgh’s winter
El Niño develops when surface waters in the tropical Pacific Ocean become warmer than normal, and this year’s event is particularly strong, with Pacific temperatures at record highs.
We do not have any historical data that is exactly similar to what is happening in the Pacific Ocean right now. However, we can reference the closest historical years during strong El Niño winters to get an idea of what we can expect.
In El Niño years, the predominant jet stream typically shifts south and pushes eastward.
This brings cooler air to the southern portions of the United States. For us, these winter seasons tend to bring warmer air to northern portions of the United States. NOAA’s winter outlook favors warmer-than-average conditions across much of the northern United States.
Why less snow is expected
The southern jet stream often creates a more active storm corridor across the southern United States, which can reduce the frequency of weather systems reaching southwestern Pennsylvania.
The result can be fewer storms passing directly through southwestern Pennsylvania in the winter. This all points to less snow this winter.
Less snow doesn’t mean no big storms
Historically, strong El Niño winters have brought less snow to Pittsburgh.
Six of the last seven El Niño winters have produced less than normal seasonal snowfall, but that’s not always the case, much like 2010’s Snowmageddon.
A warmer winter can still deliver a memorable blizzard, and one big storm can make a big difference to the season’s final total.
It’s important to monitor the nor’easters, which could still bring significant snowfall to the region.
The odds are that a major snowstorm will not happen, but we will need to keep a close eye on all nor’easters over the winter to make sure they do not travel this far inland and deliver a historical dump of snow.
The type of precipitation Pittsburgh sees this winter will depend on the nature of incoming storms.
The big question: Rain, mix or snow?
The big question this winter won’t just be how many storms arrive. It’ll be whether those storms bring rain, a wintry mix, or the kind of cold, fluffy snow that transforms the Steel City overnight.
Strong El Niño seasons have generally resulted in less seasonal snow for Pittsburgh. Since 1950, the city has averaged about 33 inches of snowfall during strong El Niño winters, compared to the normal average of 44 inches.
Monthly snowfall predictions for Pittsburgh:
November:
December:
6 inches (slightly below the normal 7.7 inches)
January:
11 inches (2 inches below normal)
February:
9 inches (3.5 inches below normal)
March:
For the season, Pittsburgh is expected to receive around 31 inches of snow, with Allegheny County totals ranging from 28 to 34 inches.
Thirty-one inches for Pittsburgh comes in around a little more than a foot of snow below normal for the season.
What could change the forecast?
While we anticipate a milder, less snowy season, keep in mind that lake-effect snow will still be a factor as the Great Lakes may remain unfrozen, allowing lake-effect snow episodes through the winter.
Initial snowstorms may arrive later than usual.
Typically, we see a late onset of initial snowstorms in strong El Niño years.