After a dead quiet 2020, last winter finally brought us some snow! Most of the snow fell in Mid-December and February, with no snow in March for the first time since 2012.
Last year, we were in a weak to moderate La Nina winter, which is when water temperatures in the central pacific are cooler than normal. The same pattern will persist this winter…so does that mean a similar winter to last year? In some ways, yes! A big part of our winter outlook is looking at previous years with similar conditions in the fall. We call that analog forecasting. These are the years we ended up with when accounting for trends with La Nina, water temperatures over the northern and eastern pacific, and polar vortex strength. In most of these years, snowfall was actually pretty close to normal, along with overall precipitation. None of these years featured a historic snowstorm, and temperatures in most years averaged slightly above normal, a good sign for those not exactly wanting a blockbuster winter.
Get daily news, weather, breaking news and alerts straight to your inbox! Sign up for the abc27 newsletters here
But the late-November chill now will have some staying power as we head into the holidays. The biggest question mark this winter…when does the mild air return? History suggests February, but if we see an unexpected polar vortex disruption like early last-winter, some of the more active weather could bleed from January into early February.
I do believe this will be one of those winters that is likely going to be front loaded when it comes to the cold and some of the more active weather. Notice the pattern as we head into the early part of winter. The cold air stays nearby and there’s just enough of an active storm path to keep our weather interesting.
The cold air remains locked in place, but as we move into the second half of winter, that cold air is displaced more north and west…allowing more mild air to come up with a new storm track. This will limit snowfall chances. This is a typical progression that we see in these weak to moderate La Nina years.
So let’s break it down. When it comes to temperature, overall we are expecting another warmer than average winter, albeit slightly because we are going to see those cold shots of air in December and January.
Everything should begin to flip around in February with more of a milder pattern again lowering that snowfall potential. We’ll see perhaps one more cooler shot of air in March.
When it comes to snowfall, our normal snow each season is around thirty inches, so kind of like last year, this year could be a pretty typical season when it comes to snowfall, with snowfall expected to be within 10 inches of normal.
Perhaps a few small snow storms here and there, perhaps not the big one everyone looks for. But what’s exciting is that this year could provide elevated chances for a White Christmas, something Harrisburg has not experienced since 2012!
-The abc27 Weather Team