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Don Paul: A shot at a spring weather outlook

I decided to write this article on what will surely be the coldest day for the remainder of March. Thermally, we have nowhere to go but up, right?

In the longer term, most guidance, including the 46-day experimental European output, favors temperatures to run above seasonal average for much of the spring in the plains, the Midwest and much of the Northeast west of central and northern New England.

However, I have to hasten to add that the warm anomalies — departures from average temperatures — near the eastern Great Lakes are unimpressive.

Unimpressive warmth in both the European and the U.S. Climate Forecast System output is a problem for someone in my position. In my experience, when the anomalies are weak, confidence should be weak. When I break down that 46-day European outlook, it shows lots of ups and downs. Both the ups and downs can end up being quite significant as they draw near.

So we’ll start with this premise: I doubt we are through with measurable snow. No, I see no signs of anything like last week’s huge snowstorm looming on the horizon as of this writing. However, April is seldom a snow-free zone in Western New York, and I offer you these numbers of proof. Just take a gander at the April snowfall column on this page.

The latest European extended guidance shows some vulnerability in the Great Lakes around the week of April 5 and other cold intrusions at times later in April, as well. We may end up by April 30 with a mean monthly temperature that runs a little above average, but that would not preclude some unwelcome colder hits during the month.

(NOAA)

The National Weather Service Climate Prediction Center/CPC has somewhat higher confidence in warmth than I do, if that makes you feel better.

The CPC has a large area of a 40 percent probability of temperatures running above average in April. (I can’t show you the European output, because it is subscription-based and proprietary.) On the other hand, I’m not so certain the CPC has all that much confidence in their April outlook, made on March 16. The very next day, the CPC’s experimental three-to-four week temperature outlook shows EC for us. EC stands for “equal chances” of things going either way, because there are no clear signals upon which to hang a hat.

(NOAA)

However, as we move into mid- and late spring, signals do indeed favor a more consistent tendency toward warmer than average temperatures much of the time. So I have better agreement with the CPC’s 50 percent probability for warmer than average, if you cancel out April from their April-June outlook.

There should be more consistent presence of a warm high-pressure ridge over the southeast and eastern United States. That would favor more frequent episodes of a warm southwesterly flow over the Midwest and the Great Lakes, as well as much of the east, though I still think things could be stubbornly cooler in northern New England.

Precipitation is nearly always a tougher call than temperatures. Evidence for this is supplied in the vast portion of the lower 48 in the "EC" category in CPC’s April-June outlook:

(NOAA)

However, there are other indications to which the CPC does not wish to commit that suggest a more active severe weather season first in the Gulf states (we’ve already seen that this winter and early spring) and southern plains, gradually spreading northward in the plains and into the midwest.

This will likely be a bigger year for tornadoes than last year, though, by way of comparison, last year tornadoes were especially low in number.

Whether that severe weather threat eventually makes forays to the northeast and into the eastern Great Lakes remains to be seen, but there are at least a few early hints, in my judgment, that we may see more severe weather around here later in spring than we’ve been used to in recent quiet years. That doesn’t necessarily mean tornadoes, but it might include more frequent encounters with severe thunderstorms.

This last part of my outlook, which is admittedly low confidence, is something I hope turns out to be a bust.

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