Rumor Mill Season: models, forecasts, and what in the world can you believe these days?

October was hot.  Record hot.  The hottest weather we’ve ever had in October happened last month, but it was only for the first 11 days: 8.27ºF above average.  The rest of the month was actually near or just below average.

November brought a complete swing the other direction.  We’ve had very few above-average temperature days; instead, Huntsville’s November average temperature is 8.0ºF below the 30-year average.

There’s a saying that goes like this: “what happens in November, the winter will remember!”  I wrote about that more than a week ago here on WHNT.com.

So let’s get right down to it.  NOAA’s Climate Prediction Center (CPC) released an outlook for December on Thursday that shows a very ‘warm’ look for December:

NOAA/CPC

What you see there is a ~50% chance of above-average warmth in December.

Here’s the thing. If you’re a fan of cold weather and snow, an outlook like that is discouraging. If you’re a fan of not having those kinds of things, that outlook is less encouraging than you think it is.

Remember October? The first 11 days of the month were blazing hot. Do you remember the other 20 days being cooler than normal? You probably don’t because we tend to remember the extremes.

January 2018 is another good example of an outlook not telling you the ‘whole’ story. The month on the whole was slightly colder than average; however, there were two stretches of really cold weather lasting about a week each time.

I think that’s where we find ourselves for December. There’s a good chance – better than 50% in my opinion – that we’re going to have at least two strong pushes of Arctic air next month. The first one is already showing up in the GFS/GEFS model guidance, but I’ll caution you! These numbers look awfully specific, and they’re probably awfully wrong. They point to something that is possible instead of showing you something that is already ‘real.’

In other words, there’s more data here than skill in one single ‘operational’ model run.

The ensembles give us a better clue, and they have a similar trend; however, they will miss the ‘extreme’ highs and lows in any pattern more often than not.

So, unless something really unexpected happens, December will start out on the cold side of ‘normal.’ It could get as cold as it did in mid-November (or even colder).

But the obvious question is “what about snow!?!?!!”

That’s not one we’re able to answer right now. We are in a position that would be favorable for a few threats of wintry weather this season, but specifics, guarantees, or even wild guesses are not wise beyond a few days (and even then it’s dangerous).

The European model ensemble likes the odds of having some snow – from as little as a trace to as much as a few inches – in December. At some point. There’s not much agreement among the members that make up the ensemble, but they all think ‘something is possible at some time.’ (Feel free to laugh at that.)

ECMWF weeklies snowfall projection through late-December

So what can you believe or hang on to in a world of snow maps, social media click-bait traps, etc.?

We’ll always tell you what we really think. If it’s not on the Seven Day Forecast or written up on WHNT.com as a legitimate possibility, then don’t take it too seriously. We promise not to hype things up just to get your eyes on our station; that’s just wrong. Could we be wrong and expect it to snow and it fail to do so? Sure. Forecasting isn’t perfect, but if you do your best to discriminate between a ‘forecast’ by a person and a snow map generated by a computer, you’ll come a lot closer to knowing what’s real and what’s a la-la-land solution.

Looking for the forecast? It’s always online at WHNT.com/Weather and in the “Daily Forecast” section on Live Alert 19!

-Jason
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