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Severe T-Storms Expected Today... - abc27 WHTM

Severe T-Storms Expected Today...

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May 3, 2011

It has been a while since I have written a blog...mainly due to all the crazy weather we've been having.  There were certainly lots of events to blog about, but unfortunately I have been swamped with other duties here in the weather center.  What an April!  We officially had the wettest April on record with 9.46 inches of rain.  Many homes across the Midstate can attest to that!  The other issue was all the severe weather across the country last month.  Here at home, we witnessed five confirmed tornadoes last Wednesday night into Thursday morning.  The tornadoes occurred in Huntingdon, Juniata (now upgraded to an EF1 tornado), York, and Lebanon counties.  It was quite an outbreak, especially for those in the deep south.  Now that all of that is behind us, can we expect a calmer May?  The answer to that question seems to be no...at least in the short-term.  More active weather is expected today.  Let's break everything down:

Every time a severe weather outbreak occurs, it is the result from a simple battle taking place within the atmosphere.  Rather than good vs. evil, this battle comes down to warm air versus cold air.  The greater the contrast between air masses, the greater the severe weather and the more destructive.  This spring, the cold air has been hanging a little longer than normal and has been helping create some of these events.  Don't listen to all that media hype about global warming...it's the cold air and the temperature contrast that comes into play when making these fierce outbreaks.  Temperatures were in the 20s in the upper plains this morning...and it's May!!

The surface map above does put us in the "battle zone" once again for severe weather later today.  We will be sitting right underneath the warm-soupy airmass that is perfect for fueling good thunderstorms.  As the cooler, drier air to the west tries to fight this warm, moist air off...sparks could fly.  Obviously, we need to dig deeper and look at some parameters within the upper atmosphere in order to see if the ingredients are truly there to form some feisty storms around these parts.

 The lifted index is a number I have talked about on the blog before.  Basically, the higher the negative value, the greater the risk for severe weather.  We are forecasted to have a -3 overtop the region later this afternoon and evening.  While not the highest value I've seen, this is pretty juicy and we should be on guard for severe potential later today.

This is a value I have not mentioned on the blog before.  This parameter is called the Significant Tornado Parameter and while a big fancy equation is used to calculate it, the basic premise is that values at or greater than 1 mean the risk for tornadoes is fairly significant.  Pennsylvania is encompassed by a value of 1 and this also has my guard up.  Apparently, I'm not the only one who thinks later today may get interesting.

The Storm Prediction Center in Norman, Oklahoma has put our region under a slight risk for severe weather later today.  This is a good indication that some type of severe weather will develop.  The main threats will be hail, flash flooding, and rotation thunderstorms which could produce tornadoes.  We must remain vigilant throughout the day ahead.  Rainfall amounts are expected to exceed one inch in many areas and therefore some counties are currently under a Flash Flood Watch through tomorrow morning.  The latest watches and warnings can be found at the top of our weather page.

The SPC's tornado outlook for today also has us under the 5% hashing and that is significant.  Even though you may think 5% isn't that high of a number, around here, it rarely happens.  Let this blog write-up serve as a warning to be alert the rest of the day.  We want all of you to be safe in times of trying weather and that includes today.  We had five confirmed tornadoes here last week...and while I don't see the parameters meeting the values we had here Thursday, the ingredients are there for some action.  Stay tuned and stay safe!

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