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Latest entries from the Weather Journal blog
About Kevin
Kevin Myatt grew up in Arkansas to the tune of tornado sirens and the rhythm of hailstones, aspiring to be a meteorologist before his studies and career were turned to journalism instead. Though he often chases storms, he prefers living in the cooler, more tranquil weather of the Blue Ridge. He moved to Roanoke in 1999 to take a job on the copy desk of The Roanoke Times; writing headlines and editing copy is his principal work for the newspaper today.
Each May, Kevin assists Pulaski County High School / Virginia Tech meteorology instructor Dave Carroll in leading college and high school students to the Plains to observe severe weather firsthand. The accounts of many of his storm chases can be found here on the storm chasing page of his weather blog on roanoke.com.
Kevin was an editor for "Hurricanes and the Middle Atlantic States," a book written by D.C.-area weather enthusiast Rick Schwartz and published by Blue Diamond Books that documents hurricanes striking the mid-Atlantic states since colonial times.
The Weather Journal column began in 2003 and appears on Friday's Virginia section front in The Roanoke Times. The Weather Journal blog began in 2006 and follows weather day-by-day between the larger columns.
La Nina may hang South out to dry
By Kevin Myatt
The Roanoke Times
Never mind the groundhog. The "little girl" is screaming.
La Nina, which in Spanish means "the little girl," has entered its strong phase, according to the last two weekly updates from the Climate Prediction Center.
That could have major implications on the rest of this winter that would be quite opposite from Punxsutawney Phil's forecast of six more wintry weeks.
La Nina refers to the occasional deep cooling of central Pacific sea surface temperatures.
Over time, La Nina conditions correlate fairly well to mild and dry weather over much of the United States.
That is not good news for regions of the Southeast running two or three feet behind normal in rainfall over the past few years. That region tends to be the driest of all during a strong La Nina, according to Climate Prediction Center data.
La Nina conditions in the central Pacific tend to lead to a weakening of the subtropical branch of the jet stream, the flow of air high in the atmosphere that would bring wet Pacific storms across the southern United States.
La Nina also tends to be connected to an increase in high pressure off the Southeast coast of the U.S. Such a high, which has been present almost all of this winter in varying strengths, tends to deflect cold air masses and strong low-pressure systems away from the eastern U.S.
Nothing is ever as simple as 1-2-3 in weather or climate. La Nina does not act in a vacuum independent of other variables.
But one of the other major variables has been even less conducive for long-term wintry weather this season.
This season, there has never been a solid case of high pressure in the North Atlantic near Greenland blocking the northern branch of the jet stream and forcing it southward, leading to a prolonged outbreak of Arctic air. Even the cold air we have gotten has been transient, moving on after a couple of days.
There is no real sign that blocking high pressure near Greenland will be established anytime soon.
Though Tuesday's balmy April-like temperatures might suggest an early spring has arrived already, I would stop well short of saying "winter is over."
La Nina winters, while mild and dry overall, often are interspersed by short, sharp outbreaks of cold. We've certainly seen those this winter, and probably will see at least a couple more, maybe as early as next week.
If a wet storm system moves on the right path during one of those cold intermissions from the overall pattern, there can be a winter storm, even a severe one.
And there is always the chance that the pattern just won't act the way it's expected to.
Last winter's El Nino was supposed to deliver copious rains to the Southeast. Instead, those wet storms hit the central U.S., freeing that region from long-term drought while sending the Southeast into an unprecedented dry period.
Besides, as the groundhog reminds us, there are still at least six weeks left in what we typically think of as winter.
That's a lot of time for a lot of weather to happen.
But the little girl is screaming loudly that the groundhog is wrong, and I believe her.
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