UNIVERSITY PARK, Pa. — April showers supposedly bring May flowers. But what will spring bring this year, after what seemed to be an unusually wet winter?
Paul Knight, Pennsylvania state climatologist and manager of Penn State Weather Communications Group, differentiates past winters to the most recent and discusses how this may impact the spring and summer weather.
Q. Looking throughout the U.S., how would you describe this winter, compared to those in the past?
A. Let’s first define winter as the three coldest months: December, January and February. For the nation, this winter averaged cooler than normal from the Southwest to the western Great Lakes, including all of the interior West except Montana.
The region from Texas to New England was milder than average, with the warmest conditions in the Mid-Atlantic region.
Rankings for the winter were as follows: The winter ranked 54th out of 112 — very slightly above normal — and it was the coolest winter since 2000-2001.
As far as precipitation is concerned, there was a swath of wet weather from the Southwest into the Central Plains and across the Great Lakes into the Northeast.
It was also moist from the Louisiana Bayou to interior South Carolina. Very dry conditions dominated Texas and much of the northern Plains.
The nation ranked 97th, or the 15th-wettest since 1896. The season’s snowfall set new records from eastern Iowa across southern Wisconsin and central Michigan and into central and northern New England.
In Pennsylvania, only the northwest section of the state had near- to slightly above- average snowfall.
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Q. What about precipitation? Last fall Southerners were in a drought. Did last winter’s weather help them out?
A. Winter precipitation was above average in about half the drought-stricken region of Alabama, Georgia, Tennessee and North Carolina/South Carolina.
It put a dent in the drought, but it did not end it.
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Q. How far are you willing to forecast the spring and summer weather? Are you able to see any unusual weather patterns coming in the next few weeks or months?
A. The seasonal pattern is being driven in large part by La Nina, a pool of cooler-than-average water in the tropical Pacific.
The usual progression is for the warmest and driest conditions to build in the eastern Rockies and Plains during the later spring and summer, with near- to above-normal rainfall in the Ohio Valley and Northeast and near-seasonal temperatures, after a coolish spring in the Mid-Atlantic and parts of New England for the summer.
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Q. In Pennsylvania, how was this winter compared with last year’s? It seems as though it wasn’t as cold as past years, yet we had more snow.
A. This winter in Pennsylvania was almost identical temperature-wise to last winter but it was much wetter — in fact, it ranked as the third-wettest on record.
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Q. Does winter weather in any way impact spring and summer weather?
A. Wet winters are seldom followed by very hot summers and usually followed by cool springs.
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Q. Will you explain the different types of forecasting, how far in advance you can predict the weather and how accurate most weekly weather predictions may be?
A. Short-range forecasts are made using precise computer simulations of the atmosphere based on detailed observations (these have skill to about 5-7 days).
Seasonal/monthly forecasts use computer simulations of sea surface temperatures, soil moisture, snow cover and other long-term effects on monthly conditions.
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