April brings volatile storms, plus sharp temperature swings
Sunday, April 9, 2017, 5:00 - Stormy weather and temperature swings are expected to dominate the weather story for the month of April, which is by no means out of character for this typically active month. After a volatile beginning, we should see the warmest temperatures relative to normal settle into the East, as some persistent cool conditions linger in parts of the West.
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March comes to an end
Before we get into the details on April, let’s take a quick look back at the month of March. March ended with an extended period of severe weather, and this year's spring tornado season got a fast start out of the gate. This was thanks in part to unseasonably warm and humid conditions centered on the Great Plains, which allowed spring-like weather systems to ramp up early this year.
As the temperature anomaly map for March shows a large part of the country saw normal to above-normal temperatures (shades of red and orange). The warmest spots in the Texas and Oklahoma panhandles were more than ten degrees above normal for the month.
Cold and stormy conditions lingered across the northern tier, particularly the Pacific Northwest and New England (shades of blue and green). Washington and Oregon saw the storm parade continue, which brought persistent cool and wet weather. Meanwhile in the Northeast winter-like conditions lingered as frequent storms brought down unseasonably cold air masses from near Hudson Bay.
Looking ahead to April, the first part of the month is likely to be volatile. Frequent storms will continue and sharp temperature contrasts will bring a period of back-and-forth temperatures from coast to coast. As the forecast guidance below shows, shots of unseasonably cool air are likely all the way into the Southeast in early April.
Later in the month we expect a more persistent pattern to develop, which will allow more widespread warmth to take hold again, particularly in the East. The image below shows how we think the month will develop, particularly the second half.
Though warm temperatures will dominate much of the East, New England may continue to lag behind seasonal averages, thanks to continued back-and-forth bouts of cooler air.
The West will see a contrasting temperature pattern through the month. As the jet stream dips southward, much of the region will see temperatures near normal, with the Pacific Northwest having the greatest chance for below normal temperatures for the month.
This jet stream pattern would also cause the storm track across North America to shift northward, compared to March. This would likely mean a period of above normal precipitation for the Midwest. Warm water temperatures should keep the Gulf Coast states well supplied with moisture as well. The rest of the country can expect near-normal precipitation in April.
It's important to keep in mind that April is a month of transition, and aside from the patterns we've described, everyone can expect a distinct warming trend through the month, based on climatology alone. And so although some may see a rockier transition, by the end the month we will be moving into the heart of spring, and well along the path to summer-like warmth across the country.