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Don Paul: Expect some reprieve from the cold ... until April rolls in

The last week of March will get some Western New Yorkers to crack a smile: Temperatures will actually move above average during that final week.

The warming won’t be comparable to that of March 2012, which I wrote about recently, but it’s safe to assume that some days in the 50s and upper 40s will not go unappreciated. The month so far is running 3.2 degrees below average, and we are about a foot above average for Buffalo snowfall for the month, courtesy of the 1-foot snowstorm we had earlier in the month.

It does not look like we’ll be adding much to the total snowfall for March, and that temperature deficit should shrink a little. As you’ll see, however, this warming trend is likely to be a setup … a setup for disappointment when April gets here.

This is the way an ensemble of European model runs depicts March 27. Just the coloring tells part of the story: a warm ridge of high pressure will be developing over the east. We haven’t had one of those warm ridges since the latter part of February.

As March finishes up, so does the warming trend. The European ensemble shows cold air reentering the Great Lakes, the upper Midwest, and the northeast, with that warm ridge gone — and it does not stand alone. The American/GFS ensemble shows similar cold and includes Easter Sunday. The American ensemble continues to have a cold look for the end of that first April week in the northeast, too. And the Canadian ensemble is in good agreement as well.

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These troughs and ridges in the ensembles tend to look flatter further out in time because the many individual model members of the ensemble tend to spread out with more uncertainty further out in time. However, there is fairly good agreement between these ensembles that a ridge of high pressure, sometimes over the North Atlantic and sometimes over northeast Canada, will often block the polar jet stream and force it to buckle southward from the upper Midwest through the Great Lakes and the northeast delivering cold air. This pattern would be similar to what we have now and might even spawn an early April nor’easter.

There is nothing unprecedented about April coastal storms, in case you were wondering. I have boyhood memories of a couple of Yankees home openers being snowed out. And Boston is worse.

Beyond the first week of April, the 46-day European ensemble mean made up of 51 individual runs of the European model fails to show lasting warming in April until, possibly, late in the month. However, the 46-day ensemble has not had a very reliable track record for doing well since last autumn in that extended range, so I’m only mentioning it in passing with appropriate skepticism. An American extended-range product called the CFS v2 (that will be on the blue book exam) is even colder for April than the European. However, the verification scores/statistics on the CFS v2 are less impressive than the European ensemble.

Over the decades, I’ve often attempted to jokingly refer to myself as the Prince of Pessimism, as if I were part of a meteorological conspiracy. These days I seek the safe harbor of hanging April's backsliding on models, ensembles, equations and the laws of physics.

On the other hand, I’ll be happy to take irrational credit for next week’s warmup. That’s how I roll.

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