Thursday, June 13 2013 2:23 PM EDT2013-06-13 18:23:00 GMT
Security video captured a man narrowly escaping a tree falling on him during Thursday morning's storms. Cameras at DialOne Security in Madisonville caught the event. Jeff Payne, marketing director forMore >>
Security video captured a man narrowly escaping a tree falling on him during Thursday morning's storms. Click to see the video.More >>
Friday, April 11 2014 11:51 PM EDT2014-04-12 03:51:28 GMT
Heavy rains overnight Sunday and into Monday have caused flooding in some areas of the state, but even as the rain has moved out of the area, the Doppler 12 StormVision team says river flooding will beMore >>
The swollen rivers in the River Region are starting to recede. Many rivers in the WSFA 12 News viewing area flooded this week after heavy rains Sunday night and Monday morning. More >>
Tuesday, April 8 2014 7:39 PM EDT2014-04-08 23:39:18 GMT
Here are the updated river levels and forecast levels for several major river sites in our area. These are current as of 11 a.m.It is important to note a couple of thing, in many cases, we won't reachMore >>
Here are the updated river levels and forecast levels for several major river sites in our area.More >>
A derecho, pronounced day-ray-cho, is a line of severe thunderstorms that moves in a straight line. The word derecho is Spanish for 'straight'.
Derechos come in three types: Serial, progressive and hybrid. The diagram, courtesy of the NOAA's Storm Prediction Center shows both a serial derecho and a progressive derecho.
The serial derecho forms in the warm sector ahead of a cold front with a very strong, low pressure system at its north end. The warm sector supplies the soupy tropical air that drives the thunderstorms, and the low pulls it northward.
Typically, a series of 'bow echoes' forms and joins to make a long line of severe storms. The bow, like an archer's bow, indicates strong winds behind the line and the threat of straight line winds.
It is called a 'serial' derecho because bow segments form, die out and new segments develop to replace the old ones.
There is enough rotation where the bow segments meet for occasional tornadoes from a serial derecho.
A progressive derecho forms north of a stationary front or a warm front. The derecho typically heads to the east or southeast following upper level winds. The progressive derecho looks like it follows the front like a train follows railroad tracks.
The progressive derecho usually consists of a single, large bow echo that may last for hours and progresses to the east or southeast.
Straight-line winds are the main threat from the progressive derecho, but occasionally weak tornadoes may occur.
The hybrid derecho is a mix of the progressive and serial types and can take many forms.
All derechos can produce flooding rains and most have intense, frequent lightning.