April 5, 2009 Storm - Paducah Wind Event

April 5, 2009: McCracken County Wind Storm

Type of event: Microburst (area residents reported debris was seen blowing high up into the sky - several reported a funnel cloud, as well)
Wind estimated between 70-80 mph.
Path length: 3 miles - from interstate to Southland Baptist Church
Injuries: 12 injured in a bus wreck caused by a car being blown into a truck. The truck then hit a charter bus with more than 50 people on-board.
Time of incident: Approximately 20:33 Zulu
Storm survey link - n/a

Approximate Path:

Radar review: By Beau Dodson - radar time stamps are on the right side of the page (Zulu)

At 20:29 Zulu time the storm was not yet producing damaging winds. A few minutes later the next scan was taken from radar.

Note the bright green area (word Downburst is below the area of concern) over Old Mayfield Road/Lone/Hendron - this was the beginning of the downburst. It showed up in one scan/frame of the radar image. This was right before the winds hit the church (estimated at 70+ mph) and while the storm was striking the I24 area (winds of 40-55 mph) where the 12 people were injured on the bus.

In the next scan the area of highest winds is no longer showing. Some wind shear is noted in the southeast portion of the county. The damage is over at this point.

Some more image scans of this severe thunderstorm.

The severe thunderstorm is approaching McCracken County from Graves county. At this point there was high reflectivity levels well up into the storm. An indication
that the storm had some potential to become severe and produce hail and high winds.

Note the dramatic increase in storm reflectivity on this image - compare to the one above. The storm had obviously strengthened within a a short time period.

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Let's walk through the images frame by frame as the storm developed over McCracken County.

20:24 Zulu

20:29 Zulu time

20:33 Zulu time

20:41 Zulu time - dramatic increase in the size of the storm

20:46 - storm had increased quite dramatically and was producing an estimated 70-80 mph winds ahead of it in the Marshall County area.

Here is the reflectivity and SRV (wind) radar grab from the time the damage was occurring. You can see the bright green area near Old Mayfield Road. Winds in this area were likely greater than 50-60 mph and would peak around 70+ mph.

Looking at the higher tilts - looking higher up inside the storm with my radar program - there was strong reflectivity at higher levels. This should have been an indicator that the storm was going to strengthen and produce hail and possibly high winds. 20:33 Zulu time stamp.

At 20:37 Zulu - the storm was still showing strong reflectivity at higher levels.

The Storm Prediction Center had placed our area in a tornado watch:

No warnings were issued for the McCracken County thunderstorm. A warning was
issued after the cell left the county. Sometimes that happens - anytime there is a tornado
watch we have the threat for severe weather - warnings or not.

Tornado Watch Text:

URGENT - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH NUMBER 117
   NWS STORM PREDICTION CENTER NORMAN OK
   1145 AM CDT SUN APR 5 2009
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   TORNADO WATCH FOR PORTIONS OF 
   
          PARTS OF SOUTHERN ILLINOIS
          MUCH OF SOUTHERN INDIANA
          MUCH OF WESTERN AND CENTRAL KENTUCKY
          SMALL PART OF SOUTHEAST MISSOURI
          PARTS OF NORTHWEST TENNESSEE
   
   EFFECTIVE THIS SUNDAY MORNING AND EVENING FROM 1145 AM UNTIL 600
   PM CDT.
   
   TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
   GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
   AREAS.
   
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
   MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH NORTHEAST OF
   BLOOMINGTON INDIANA TO 60 MILES SOUTHWEST OF CLARKSVILLE
   TENNESSEE.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).
   
   REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
   TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS.
   
   DISCUSSION...STRONG S/WV TROUGH AND ASSOCIATED 100KT MID LEVEL JET
   MAX WILL BE TRACKING INTO LOWER OH VALLEY THIS AFTERNOON. DEEPENING
   SURFACE LOW MOVES ACROSS CENTRAL IL INTO IND WITH COLD FRONT
   EXTENDING SSWWD INTO CENTRAL AR ATTM.  LOW LEVEL MOISTURE INCREASING
   IN WARM SECTOR ALONG WITH SURFACE HEATING WILL RAISE MLCAPES TO NEAR
   1000 J/KG.  SEVERE THUNDERSTORMS INCLUDING SUPERCELLS WILL DEVELOP
   AHEAD OF SURFACE LOW AND COLD FRONT AND TRACK RAPIDLY ENEWD ACROSS
   THE WATCH.  IN ADDITION TO DAMAGING WINDS/HAIL...TORNADOES WILL BE
   POSSIBLE...PARTICULARLY WITH ANY SUPERCELL THAT IS ABLE TO DEVELOP
   IN WARM SECTOR.
   
   AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
   SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
   WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
   500. MEAN STORM MOTION VECTOR 24050.
   
   
   ...HALES