Severe Weather : Georgia / Alabama #Derecho Event March 18 2013

Widespread wind damage reports were reported across much of Georgia and Alabama on March 18 2013. There were also reports of Hail varying in size from small to upward of 3 inches.

While this storm system as far as I’ve seen has not been classified as a Derecho, it does qualify as one. A Derecho is classified as a long lived line of storms causing wind damage for more than 240 miles along most of it’s length. Another requirement to meet Derecho qualification is wind speeds of or greater than 57 MPH at points along the path of the storm. I don’t have data to back this up, but from following and reporting on many of the storms spawned by this system, I’d say this qualification was also met.

This system caused widespread wind damage from North Alabama where it began to take on the characteristics of a Derecho and lasting into Southeast Georgia. The distance covered is almost double the 240 mile requirement.

Here’s a Radar loop of the event …

Georgia / Alabama Derecho March 18-19 2013 photo DerechoMarch18-192013superslow.gif

Here’s a couple maps showing wind damage and hail as well as a couple tornado reports.

Storm reports March 18-19-2013

Storm reports Georgia Alabama March 18-19 2013

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Georgia / Alabama Possible Severe Storms Tuesday July 31 2012

If the NAM models holds true the local area [Columbus Georgia] may see some rough weather as early as 8 AM Tuesday Morning. At this time 5:34 AM 7/30/2012 it appears North Georgia and the Atlanta Georgia area will get the brunt of the storm at the beginning and then Central Georgia. I’m not 100% sure what may develop. That meaning / being a Mesoscale Convective System [MCS] with a Bow Segment / Squall Line capable of damaging straight line winds or just a very organized Mesoscale complex of strong to severe Thunderstorms also capable of damaging winds. The difference in the two will be the coverage area of a possible damaging wind event with the MCS being the worst more widespread of the two.

Still uncertainty in the timing, development and placement [area affected] of this storm system. Just giving a heads up. A lot can change in 24 hours.

Here’s a few of the NAM model images from the 00z run July 30 2012 showing the composite reflectivity [ Simulated Radar] beginning at 2:00 AM EDT Tuesday Morning July 31 through 5:00 PM EDT Tuesday July 31 2012. None of this is set in stone at this time.


2 AM EDT Tuesday July 31 2012


5 AM EDT Tuesday July 31 2012


8 AM EDT Tuesday July 31 2012


11 AM EDT Tuesday July 31 2012


2 PM EDT Tuesday July 31 2012


5 PM EDT Tuesday July 31 2012

AGAIN this is ‘provided’ the storm develops. At this time the Storm Prediction Center in their day 2 outlook seem to think something will happen. I’ll keep an eye on this and will post updates whether bad or good.

Here’s the wording from the Storm Prediction center at this time along with the graphics. The next update is scheduled at 1:30 PM today.

EASTERN U.S….

MODELS STILL INDICATE THE DEVELOPMENT OF MODERATE NORTHWESTERLY MID-LEVEL FLOW /ON THE ORDER OF 30+ KT AT 500 MB/ EAST OF THE MISSISSIPPI VALLEY INTO THE WESTERN SLOPES OF THE APPALACHIANS. THIS IS EXPECTED TO OCCUR AS A SERIES OF IMPULSES…WITHIN A BELT OF WESTERLIES NEAR THE CENTRAL CANADIAN/U.S. BORDER AREA…CONTINUE TO DIG AROUND THE NORTHEASTERN PERIPHERY OF THE SUBTROPICAL RIDGE INTO THE EASTERN U.S. TROUGH. AN ADDITIONAL IMPULSE…NOW EMERGING FROM THE MONSOONAL REGIME AND PROGRESSING INTO THE CENTRAL PLAINS…APPEARS LIKELY TO REACH THE TENNESSEE VALLEY/SOUTHERN APPALACHIANS REGION BY EARLY TUESDAY. THE INCREASE IN DEEP LAYER MEAN FLOW AND SHEAR IS FORECAST TO COINCIDE WITH THE EASTERN EDGE/NOSE OF HOTTER LOW-LEVEL AIR ADVECTING EASTWARD FROM BENEATH THE SUBTROPICAL HIGH. THIS PROBABLY WILL CONTRIBUTE TO A FAVORABLE ENVIRONMENT FOR ORGANIZED CONVECTIVE DEVELOPMENT CAPABLE OF GENERATING SIGNIFICANT FORWARD PROPAGATING COLD POOLS…AND ACCOMPANIED BY THE RISK FOR POTENTIALLY DAMAGING WIND GUSTS.

ONE OR TWO STORM CLUSTERS APPEARS POSSIBLE…PARTICULARLY ACROSS PARTS OF THE SOUTHERN APPALACHIANS REGION INTO THE EASTERN GULF STATES…WHERE THE RETURN OF HIGH MOISTURE CONTENT AIR…CHARACTERIZED BY 70F SURFACE DEW POINTS AND PRECIPITABLE WATER UP TO AROUND 2 INCHES…IS EXPECTED. STORMS MAY INITIATE AS EARLY AS MID DAY ACROSS PARTS OF THE CUMBERLAND PLATEAU AND SOUTHERN APPALACHIANS…BEFORE CONVECTION CONSOLIDATES AND GROWS UPSCALE…WHILE TENDING TO PROPAGATE SOUTHWARD THROUGH THE AFTERNOON AND EVENING.

Derecho June 29 2012 – Time-lapse video

Time-lapse of closest NEXRAD base reflectivity of the June 29 2012 derecho. The time-lapse moves from Davenport, Iowa to Richmond, Virginia over 14 hours.