PHILADELPHIA (CBS) — It’s another week of winter with no snow in the seven-day forecast, a pattern we’ve gotten used to this year. So, are we skipping winter altogether and where is the snow?
It was only a decade ago, in 2009-2010, that Philadelphia suffered through its snowiest winter of all time with 78.7 inches falling.
This year, the talk around town has been the complete opposite.
Both January and February, so far, have featured temperatures well above average, and so far this season, snow has only accumulated on two calendar days for a total of 0.3 inches, making this season the second-slowest starting snow season on record.
The slowest was in 1972-1973, which ended up with no snow at all. If winter ended today, it would be the second-least snowy on record.
So why haven’t we seen the snow? One of the main oscillations referenced in winter forecasting is called the North Atlantic Oscillation, or NAO. When the NAO is negative, it generally leads to a colder, snowier pattern. When it’s positive, we experience warm, wet conditions.
This winter, the NAO has been in a nearly persistent positive phase since Dec. 1.
In addition, all of our cold spells have been transient, lasting no more than a couple of days.
While this winter has featured plenty of moisture, none of it has managed to coincide with those short cold snaps, meaning nearly all of our precipitation has fallen in the form of rain.
From a climate perspective, January was the warmest on record across the entire globe, a trend which has become noticeable in the past few years.
It’s important to note that climate change doesn’t necessarily mean warmer winters, but it can make the extremes more prominent — the mild winters are milder and the snowy winters are snowier.
While this winter has been a disappointment for snow lovers so far, it’s not over yet. Don’t forget, just two years ago, we endured four Nor’easters in the month of March, and there are signs that a pattern shift may usher in some cold to start the month. We may see some snow yet!
But does this mean we’ll have an extra warm summer?
There is not really a way to correlate a mild winter and a hot summer, but with all the warmth and moisture we’ve had, it could be a potent severe weather season if the mild patterns continue through April and May.