It may yet be meteorological fall but we know better in Minnesota than to always wait until December 1, let alone to wait until the winter solstice on December 21! After a ridiculously warm first 10 days of November we’re in the throws of a ‘temperature correction’ that could very well push November to being slightly cooler than the 1991-2020 average.
Just as encouraging as the cold temperatures (from a climate perspective I celebrate any cold weather as it becomes increasingly less frequent) is the fact that we’ve had a wet week and month. We’ve had 1.59 inches of precipitation this month (0.36 inches of that has fallen as snow in liquid equivalent). That’s ABOVE the normal precipitation, month to date of 0.95 inches.
We know what’s happened so far this month, so what about the start of winter and beyond? Well, the models are in.
Is this wet November a sign of things to come for winter snowfall? The models largely say no, at least in December. Most of the models are forecasting near normal or below normal precipitation for the first third of winter. November is wetter than our winter months because our temperatures are warmer (warmer air holds more water content) and we’re closer to bigger storm tracks.
Here’s where we have to distinguish between the longer range models that forecast several months (or more out), which are updated at the start of every month and then the medium long range models which go out 4 to 6 weeks and are updated more regularly. The models that ran November 1 in and go out several months were forecasting a slight favorability toward above normal precipitation/snowfall:
The problem with this initial forecast is that they were not quite picking up on the mid to late month cold snap for November either. Most of them were thinking November would pull out above normal, but it looks increasingly like November will end up average or even slightly colder than average.
A colder than average November or March favors more snow if the precipitation is abundant but not so in the middle of winter when colder air means less moisture. Here’s a look at what the ‘big three’ models forecast for November temperatures:
You can see the European and Canadian models were likely too warm. If we plug in forecast temperatures for the remainder of this month, November comes up below normal by about -1.6 degrees (F). The CFS forecasted a cold month, but by too much and it has a well known ‘cold bias’ anyway so it likely wasn’t picking up on anything. In fact, we can see it totally botched the cold weather in western Canada that the European and Canadian models caught but didn’t forecast far enough eastward:
November 2022 temperature anomalies so far a very La Nina set up…
All in all, the European model seems to have done better with November but was too warm for most of Minnesota slightly. This isn’t surprising though given just how warm it was in those first 10 days of the month.
The long range models appear to be ‘a wash’ for December, January, February (D-J-F). We can make out the clear La Nina signal however of cold in western Canada stretching toward Minnesota.
As a reminder, here’s what a typical La Nina winter pattern looks like across North America:
The Canadian model’s long range appears the most reasonable to me given the La Nina set up and what we’re now experiencing in November (and in the medium range ahead). The North American Multi-Model Ensemble (NMME) that NOAA relies heavily on really does seem to be the most reasonable forecast for winter temperatures this year:
This places cold into Minnesota but not totally encompassing it. It also favors wetter (snowier) conditions just to our east and southeast, consistent with La Nina:
So how about the 4-6 week range in the models that are updated more regularly and in theory take into account better the pattern changes? What do they show for the start of winter in December? There’s a clear cold signal in most of the models.
The North American Multi-Model Ensemble (NMME) also catches this La Nina signature of cold in western Canada but not quite reaching Minnesota. In fact, it has above normal temperatures reaching into southern Minnesota for December.
All the models agree on no strong signal as far as December precipitation or snowfall.
NMME model for December precipitation anomalies.
The biggest thing to standout is that this December may buck the overall trend of warm Decembers that start our winters. In the recent decades (and especially since 2010) winters have gotten a later start but sometimes make up for it in February (or even April!). This year may end up a more typical winter. That’s my overall conclusion. Remember that climate change is making truly colder than normal winters more rare.
The fascinating thing about this winter is the rare triple dip La Nina: three La Nina winters in a row which has only happened three other times since record keeping began (since ~1950). As I’ve discussed before and the above La Nina pattern map shows: Minnesota isn’t a slam dunk for colder conditions, we’re on the edge of this likelihood. The winter of 2020-2021 was slightly above normal, last winter (2021-2022) was colder than normal. This winter would statistically favor a wash, of average for eastern Minnesota (but perhaps cold in northwest Minnesota).
I think the conclusion for the Twin Cities is probably an average winter for temperatures and precipitation and snowfall. We’ll have our cold snaps and mild spells but it will likely all average out to the 1991-2020 average, which of course is much warmer than the winter averages of a century ago.
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