Cool spring keeps severe weather at bay
Posted May 8, 2013
Raleigh, N.C. — The overall weather pattern that has kept temperatures below normal across North Carolina this spring has also moderated the number of severe weather outbreaks, WRAL Chief Meteorologist Greg Fishel said.
In 2011, North Carolina recorded 66 tornadoes, including the outbreak April 16, 2011, which claimed dozens of lives and did millions of dollars in damage. That was an especially damaging spring nationwide. The National Weather Service counted 1,691 tornadoes in the season. April 2011 tornadoes
Since then, there has been a huge trend downward in tornadic activity, Fishel said.
The primary difference is the location of a trough of cool air. In 2011, that trough set up across the middle of the United States. "East of the axis of the trough is where rising motion, clouds and precipitation can lead to thunderstorms and tornadoes," Fishel said.
This spring, the trough is along the East Coast, keeping North Carolina considerably cooler and the rising motion offshore over the Atlantic Ocean.
"That pattern may be breaking down a little bit," Fishel said. "That means slowly but surely in the coming weeks we may see a greater chance for severe thunderstorms as summer arrives."
An area of low pressure that has capped clouds and kept temperatures below normal through the early part of this week is expected to clear out overnight, with much warmer temperatures in the forecast for Thursday, Fishel said. The moisture in the atmosphere also brings the possibility of patchy fog overnight and into Thursday morning.
Thursday will be the first day in about two weeks that temperatures will actually be above the seasonal norm.
"A weak ridge of high pressure is moving in aloft, which will help keep us mainly dry and warm for a couple of days. It could get quite toasty here on Friday before the next cold front arrives Saturday," he said.