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Univ. of Alabama-Huntsville: "Tornadic storms associated with shear lines within mesoscale convective systems"

Final Report


The general objective of this proposed collaboration was to further understand the mesoscale to storm-scale structure of tornadic storms particularly those events that are part of convective (squall) lines. Originally we proposed to examine the 27 November 1994 squall line system over central Alabama, but the focus was shifted slightly to an analysis of the 27 March 1994 Palm Sunday outbreak, which was a case selected for detailed analysis by the Southeast Consortium on Severe Storms and Tornadoes. Our interests were to document the variability of storm structure and relate that variability to the local mesoscale setting. The project participants included Dr. Kevin Knupp of UAH, Mr. Robert Clymer of UAH and Mr. Kevin Pence of NWS/BHM. Other collaborators included Dr. Eugene McCaul (Universities Space Research Association) and Dennis Buechler (UAH).


Dr. Knupp presented a seminar at the BHM WSO on characteristics of, and some recent research on, tornadic convective lines.


Knupp, K., R. Clymer, E. McCaul and K. Pence, 1996: Structure and Evolution of the 1994 Palm Sunday tornadic storms and their near mesoscale environment. Preprints, 18th Conf. Severe Local Storms, San Francisco, AMS.

Clymer, R., K. Knupp and K. Pence, 1996: An examination of tornadogenesis within convective lines: The 28 November 1994 case study. Preprints, 18th Conf. Severe Local Storms, San Francisco, AMS.

Knupp, K.R., D. Buechler, K. Pence, and E.W. McCaul, 1997: Mesoscale Organization And Storm Properties of the 1994 Palm Sunday Tornadic Storms. Manuscript in preparation, to be submitted to Mon. Wea. Rev.


4.1 University's perspective

This project initiated research interactions between UAH and the BHM WSO, which should continue indefinitely. Kevin Pence has been extremely helpful in facilitating data requests on projects not directly related to this COMET activity. BHM is on our mailing list for seminars at the Global Hydrology and Climate Center, and some of these (e.g., a seminar on convective lines by Ron Przbylinski) are attended by BHM personnel. This interaction was also beneficial to students in a Radar Meteorology class taught by Dr. Knupp at UAH. The class made a field trip to the BHM WSO to get a briefing on the WSR-88D radar.

The only difficulty encountered was the distance between UAH and BHM (130 miles). This limits direct interaction (and use of the PUP for analysis), although e-mail has alleviated this to some extent.

4.2 NWS perspective

This project helped open more channels of communication between UAH and NWSFO BHM. Unfortunately, the case of the 27 November 1994 squall line was a difficult case to investigate. There were not many clues to be uncovered in the radar data pertaining to the one tornadic thunderstorm within the squall line. We did gain further insight into the convective mesoscale organization of the 1994 Palm Sunday tornado outbreak.

Dr. Knupp stressed the importance of the lowest 2km of shear in determining the orientation of squall lines. That information has been passed onto the staff here at NWSFO BHM.

Our staff has had interactions with several of Dr. Knupp's students/colleagues since we collaborated on the Partners Project. Eugene McCaul has spent a couple of weekends at our office, using one of our WSR-88D PUPs, to investigate tornadoes associated with tropical cyclones over the southeastern states.