A REVIEW OF WINTER 2020-2021

We meteorologists like tidy record keeping, which is part of the reason why we observe “meteorological” seasons. December/January/February comprises meteorological winter, so let’s dig into how the season went.

TEMPERATURES

The first 2 months of winter were pretty benign, temperature-wise. We did not have extreme warmth, no midwinter thaw. High temperatures were nothing t o write home about; we stayed below 50 during all of January. BUT, thanks partly to a very cloudy stretch, overnight LOWS were well above average during this stretch and that skews the numbers. Look at these temperature anomaly maps for January:

Temperatures (highs AND lows) compared to average

Notice the deeper reds (warmer temperatures compared to average) for the low temperatures.

February of course was a much different deal. It was a tough stretch around here but this was truly a once in a generation cold snap for the nation’s midsection.

SNOWFALL

This season has certainly been snowier than last season and it’s been pretty much “back to normal”, with seasonal totals just a few inches above average so far. While little or no snow will fall from March 2-15, it’s not wise to bet against late-season snow around here. Case in point: last year when we had accumulating snow around Mother’s Day!

HOW’D THE WINTER FORECAST DO??

We make a big deal out of winter forecasts every year in late October/early November. A lot of effort is put into these things…I typically do several versions including a video that can run 15-20 minutes. So, did it may off? Did the forecast do well?

The answer is, yeah pretty well and MUCH better than last year. Everyone busted last winter.

I often mention that, while there is skill in seasonal forecasts and they do have value…they may actually be getting harder to do, thanks to the changing climate.

Here are the temperature maps I issued during that first week of November. For the first time, I took a “probabilistic” approach this year, assigning percentages to the various outcomes.

Locally, the idea that temperatures would be above average this winter worked out. Nationally, well the forecast was not as good, thanks to the deep freeze in February. The final verdict:

A much colder looking map for the winter as a whole. The thing is, we were well on our way to a very mild winter nationwide until the polar vortex disruption occurred in January and the effects of that shifted to our side of the globe in February. Unfortunately a “sudden stratospheric warming” event, which screws with the polar vortex, is not very predictable at long lead times.

With no polar vortex shenanigans, Februarys in moderate La Nina winters (and considering a few other variables too) are very often quite toasty.

ABOUT THAT POLAR VORTEX DISRUPTION

So what happened there? A “sudden stratospheric warming” episode is a naturally-occurring thing where unusually warm air at very high altitudes infultrates the arctic circle and “disrupts” the circular vortex that spins over the pole during the winter. Instead of a tightly-spinning vortex that keep most of the big-boy cold locked up over the pole, the vortex weakens and wobbles and bubbles of very cold air start spilling south. Think of it this way: take a coffee stirrer and swirl it around in your coffee cup. You get a nice whirlpool right? Stick your finger in there and the whirlpool gets disrupted (and your finger burns I guess).

In January, much of the cold landed in Siberia and Europe. In February it sloshed to the other side of the pole. In other words, here.

Despite not seeing the February deep freeze coming, the overall “jist” of our forecast was correct; snowier than last year and not quite as mild. This graphic worked out well:

WHAT ABOUT SPRING?

Despite the chill we will have for most of the next 5-6 days, March overall should be wayyyy different than February. We’ll probably see 60+ degrees at least once or twice next week and the month overall should end up being a fair amount warmer than average. It’ll likely be on the damp side.

The overall Spring forecast looks pretty similar: we will likely have plenty of precipitation but overall a mild season compared to average.

SEVERE WEATHER SEASON

It is likely to be a pretty active severe weather season in much of the country east of the Mississippi, including around here. Does this mean we should do anything different to prepare? No. Everyone should take some time this Spring (and every Spring!) to review their plans for sheltering in the event severe weather strikes. How are you getting your warnings?

EVERYONE SHOULD HAVE MULTIPLE WAYS OF RECIEVNG SEVERE WEATHER INFORMATION. ONE SOURCE IS NOT GOOD ENOUGH.

Do not, do not, do not, rely on tornado sirens as your first line of defense. They are not designed to be heard indoors and are unreliable. Have Wireless Emergency Alerts enabled on your phone. Make sure push notifications are enabled on your apps, including the StormTracker 21 app.

And perhaps most importantly, INVEST IN A WEATHER RADIO! It’s like a smoke detector for weather alerts. It just works. It’s not dependent on cell phone signals. It can run on batteries. They are cheap and easy to find.