Since New Years Day, I've had plenty of questions regarding the severe
weather season ahead. Whats it going to be like? Will we have a lot of
storms? Will they be bad? Whos going to get hit the hardest?
Well, Im going to do a little "hindcasting" here. I could say, "Yes,
sir, 2008 is going to be a rough year for severe storms." And, based on
what happened just in January and February, Id be right. Those two
months alone featured preliminary counts of 368 tornadoes—more than six
times the average in the past three years!
Blame La Niña. What happened to rile up Mother Nature so much? We can
put a fair share of the blame on La Niña. This feature occurs when the
Pacific Ocean is cooler than average and reaches its most intense phase
during the winter season.
La Niña is associated with a more stormy weather pattern during winter,
especially over the southern United States. This past winters storm
track played out very well in that regard. Another feature associated
with La Niña. also helped give a booster shot to the stormy scene: a cold
temperature trend over the Midwest through the central and northern
Plains.
Temperatures during December through February ran anywhere from 1 to 3
degrees below average. Air masses with notable contrasts in temperature
comprise one of the necessary ingredients for severe weather. Last
winter there was certainly no lack of cold air to provide a built-in and
consistent temperature contrast to fire up the supercells.
What about hurricanes? The 2007 hurricane season was about average
overall, with 14 named storms developing and six of those reaching
hurricane status in the Atlantic Basin.
Last year was actually the "quietest" hurricane season in the Atlantic
and the Gulf of Mexico since 2002. Still, there was one notable feature:
two Category 5 hurricanes (Dean and Felix)—the highest velocity
category—made landfall for the first time since 1851. As for this years
hurricane season from June through September, I think we are again in
store for an average season.
Looking ahead. The big question we have now is what can we expect moving
into the rest of the spring and the first part of summer? If we've
started out so stormy already, how can the transition of the
seasons—with their attendant pattern of stormy weather—not help but
continue this blustery trend?
While storm dodging is common during this time of year, I do not expect
this rash of stormy weather to continue at such a red-hot pace.
We are noting a warming trend in the eastern Pacific Ocean, which is a
sign the muscle of La Niña is starting to ebb. As this cool-temperature
pattern eases off, I look for a more west-to-east jet stream setup to
cover much of the continental U.S.
Well still see our share of storms, but systems of the type that
pummeled us during the winter season will back off sharply the farther
into spring we go.
Bryce Anderson has devoted his meteorology career to forecasting,
covering and dodging severe weather, blizzards and droughts across the
United States. He's also a fan of nice weather—specially during
gardening, barbecue and football seasons. He and his wife live in Omaha
and have three grown children. Bryce can be reached at
bryce.anderson@dtn.com.