Spring temps forecast warmer than average
AccuWeather predicts moderate risk of severe thunderstorm activity
Spring may trend slightly warmer than average across the Lehigh Valley, according to an outlook from Empire Weather, which provides localized forecasts for The Morning Call.
Temperatures in March, April, and May are predicted to be above average from the Southwest and Southern Plains northward into the Ohio Valley and mid-Atlantic regions. But in this area temperatures could lean near normal rather than above average, the outlook said.
The forecast features a wetter than normal pattern across a large portion of the Southeast, from the Mississippi River Valley into the Tennessee Valley, Ohio Valley, and parts of the mid-Atlantic. But the Lehigh Valley is expected to see neutral or average conditions.
Multiple factors were cited, including the lingering effects of La Niña, or a climate pattern where the water in the equatorial Pacific is cooler than normal, which affects weather worldwide. Also analyzed were analogous years, or years with similar trends in temperature or precipitation.
“The goal of these is always to just try to provide a general outlook as to what is coming down the road here,” said meteorologist Ed Vallee. “As we get closer [to each month], that’s where we incorporate some of our medium-range data and tweak that forecast.”
Severe weather
There are two key pieces needed to drive severe weather during the spring — cold air from the north clashing with warm, moist air typically funneled from the Gulf of Mexico.
The spring outlook suggests a heightened likelihood of severe thunderstorms over parts of the Southeast, particularly from Arkansas into Dixie Alley (a name given to the area from Louisiana to the Carolinas that is vulnerable to strong tornadoes).
Some other outlets, including AccuWeather, say the overall outlook has some similarities to 2011, which was a very active year for severe weather. More than 800 tornadoes were reported in April 2011, which holds the record for the most tornadoes reported in a single month, including seven in Pennsylvania.
While Empire Weather does not have the mid-Atlantic region highlighted for above-average activity, AccuWeather puts our area at a moderate severe thunderstorm risk from March to May.
One of the main factors cited in AccuWeather’s outlook is the dryness in the High Plains (including parts of Colorado, Kansas, Nebraska, and the Texas Panhandle) that could push severe activity farther east and away from the area known as Tornado Alley, which stretches from Texas north to the Dakotas.
Experts say there are some similarities between our current set up this year and 2011, but there are also some important differences too. Most notably, that deep and persistent drought in the western U.S. that extends into the western Plains. Moisture availability can play a very big role in storm initiation, says Jana Houser, an Emmaus grad who specializes in the analysis of tornadoes and the supercell thunderstorms that produce them.
February tornadoes trended well below average, according to the National Weather Service’s Storm Prediction Center, with just seven reported for the month. There have been 23 tornadoes across the country so far this year, down significantly from an average of 59 by the beginning of March.