Case Study 04"Bow
Echo Over Paducah, Kentucky"
05 May 1996
Case Summary
Synoptic Overview
The flow was zonal at all upper levels from coast to coast over the U.S. There was an unusually strong jet max stretching from coast to coast along the northern states at this time. In mid-levels, several gentle shortwaves existed in the flow. A shortwave at 0600Z 5May may have helped to initiate the convection over east-central Colorado that later became the MCS. The evolving storm seemingly followed the shortwave and associated weak vorticity max through 1200Z 5May as it moved into Kansas.
The MCS formed near and followed an existing surface boundary, just north of a surface low in north central Oklahoma. Ahead of the boundary was warm, moist air from the south, and behind the growing storm, northerly flow. The MCS grew rapidly as it moved along the boundary, the warm, moist inflow providing fuel for development. The storm followed the upper-level pattern, moving almost due east until turning slightly north as it moved into the northeast U.S.
Storm Development
The storm to the left of the X in east central Colorado was to become the MCS that night and into the next afternoon. Three hours later, at 0515Z 5May, the storm grew, but was still not unusually large. Another 3 hours, now 0815Z, shows the storm beginning to show explosive development, as it begins to extend southward. By 1215Z, the storm is now over 1/2 the size of Kansas, and has 2 strong squall lines in east central Kansas and central Missouri. These would move together to form the enormous bow echo later in the day. The storm grew more, and was larger than Missouri, with a wide squall line oriented SW-NE by 1515Z. Here is the bow echo as it passed over Paducah, Kentucky.
There were many reports of wind gusts to 70 mph and one tornado in central Kentucky. Also, flooding was widespread, as it took the life of a boy who was swept away in a flooded creek. Property damages in central Kentucky were near $800,000. Eastern Kentucky experienced extensive flooding also, as in Pike County, flooding caused over $1,000,000 in property damages.