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October 15, 2018

Rippeology Winter 2018-19 Outlook: 3 Winters?


Hey. Whaddup? Scott Rippe here.

It’s been over a year since I blogged on Rippeology. Last year’s winter forecasting was done almost entirely on Facebook, and for those of you who followed along, thank you. I was very happy with the way last year’s forecasts verified.

Before we take a look into the Winter 2018-19 crystal ball, a few notes for those of you who might be new to Rippeology:

  1. I’m not a meteorologist. I’m a self-taught weather hobbyist who has geeked out over this stuff since I read my first weather book at age 7. I don’t suck at it, but I wouldn’t plan your March wedding around this forecast either.
  2. Like almost all of my weather forecasts, this one is specific to southern Wisconsin. If you live somewhere else and need some prognosticating, feel free to ask me on Facebook.
  3. In the event you find it stupid that anyone would barf up a winter outlook this early in the season, let me say this: there’s a high degree of confidence in the guidance already available. I could wait another month, but with the exception of some clearer definition around long-range patterns (LRC, for example), I don’t expect much to change. So a forecast today would be pretty similar to one I might issue closer to Thanksgiving.
  4. Finally, the impatient among you are welcome to scroll all the way down to the end of the post for the summary forecast. That, however, would make you a bit of an asshole, considering I put a lot of work into this. So if you do that, don’t tell me you did.

All that being said, let’s get to it.

First, let’s set the stage with some basic information:

  • Average snowfall in Madison is about 50″ per year.
  • Last year, Madison got about 44″ of snow. About half of that fell from mid-January to mid-February. Follow the green line:

  • Last year, we experienced a couple of pretty cold periods: from December 23rd to January 6th; from January 13th to 17th; and from February 2nd to 12th. Also unseasonably cold in early April.

Any winter outlook should start, in my opinion, with a look at ENSO trends, or El Nino Southern Oscillation. You’ve heard of El Nino (warmer than average sea surface temperatures in the eastern equatorial Pacific Ocean) and La Nina (cooler than average temps in that same region). Those temperatures impact global weather, sometimes mildly, sometimes extremely. Here’s a typical Nino winter in North America:

Generally speaking, El Nino results in a somewhat warmer and less snowy winter for us in Wisconsin. La Nina generally produces the opposite. Remember the winter of 2007-08 and our record 102″ of snow? That was a moderate Nina year.

But these are not absolute predictors.

Last winter, weak La Nina conditions were present and our snowfall was just a bit under average.  This year, the Climate Prediction Center estimates a ~70% chance of El Nino conditions developing in the Nov/Dec/Jan/Feb period.

In fact, most models predict sea surface temperatures between 0.5 and 1.5 degrees (Celsius) above normal. We can categorize that as a weak-to-moderate El Nino.

Knowing that, we can look back at Madison winters with similar moderate Nino conditions. It happened in the winters of 2002-03, 2009-10, and 2014-15.  Here’s Madison snowfall for those 3 winters:

  • 2002-03: 29″ of snow
  • 2009-10: 52″ of snow
  • 2014-15: 34″ of snow

So what the hell happened in 2009-10?  An 18″ blizzard on December 9, 2009. Video:

Take that freakish storm out of the equation, and all 3 of these weak-to-moderate Nino winters produced about 40% less snowfall than our 50″ average.

So, if ENSO modeling was all we had, we’d be looking at a better than 50/50 chance of below average snowfall for Madison this winter. But there’s more to consider.

For instance, we know that snow cover in Canada is already running way above normal right now.

Why is that important?  Because snow pack further cools the Canadian air that will continue to spill south throughout the fall. The temperatures we’ve been experiencing in October have been much below normal, due in part to the snow-cooled air that follows the cold fronts coming through southern Wisconsin. If that continues (and there’s no reason to believe it won’t), the colder air interacting with surface lows in our area is likely to produce frozen precipitation a little earlier than we might otherwise expect it.

That and the fact that El Nino won’t fully set up until mid-winter is a hint of early snow in our neck of the woods.

What else we got?  Well, we have models up the wazoo. Meteorologist Ben Noll publishes them on his website (click on “snow maps” in the upper right).

  • The ECMWF (Euro) model thinks we’ll have below average snowfall every month except, possibly, December.
  • The UKMET model thinks we’ll have above average snowfall January through March, with February being especially snowy. But the British are prone to hyperbole.
  • The MeteoFrance model agrees about a snowy February, but thinks every other month will be below normal.
  • As far as temperatures go, the CFS monthlies have us above average every month except February.

See a trend there? With the exception of the Euro, models are currently pointing to a colder, snowier February.

So which models do we trust?  All of them combined, but none of them individually.  What I really look for in these long-range models is some level of agreement.  And we have that to some degree.

Let’s get to it then.

SUMMARY FORECAST:

OMG, did you actually scroll all the way down here without reading the rest?

OK then.  Here’s where I think we are.  We get 3 phases of winter:

November and December: average snowfall (about 18-20″); average temperatures.

January to mid-February: below average snowfall; slightly below average temperatures until we start to see Nino impact.

Mid-February to early April: slightly above average snowfall; slightly above average temperatures.

All totaled, I think we finish the winter 10-25% under our average snowfall, and while there will be occasional cold spells, I don’t see a prolonged deep freeze for us.

STUFF YOU’LL ASK ME:

Snow for opening weekend of gun season?  Probably not, or at least not much.

A white Thanksgiving?  The RRWT guidance indicates a cold snap November 21-26, so a snowy Thanksgiving weekend isn’t out of the question.

A white Christmas?  Likely.

Best time to take a warm weather vacation?  Last two weeks of February.

Now, do me a favor if you would.  Go back to Facebook and share my original post linking to this blog.  The more people following Rippeology, the more fun I have doing weather for you guys.

Thanks for reading!

~Scott