Texas Severe Storms Association 1997 Annual Meeting

TESSA Founder and Chairman Martin Lisius welcomes the membership to the annual meeting.


The Plano City Council Chambers were filled to capacity.


Glenn Wise, TESSA Trustee, hosted the meeting.
Roger Edwards of the Storms Prediction Center spoke on severe weather watches and forecasting.
Alan Moller of the Fort Worth National Weather Service Forecast Office was the featured speaker. Al's topic was severe weather.
Al emphasized the importance of the integrated warning system and its constituent parts which include the National Weather Service, the news media, local government emergency preparedness agencies and the SKYWARN spotters.
Al pointed out the advances made and successes in severe weather forecasting and related warnings. But, Moller expressed concern that unwarranted complacency may be developing because of past successes.
Moller forcefully made the point that the system is bigger and more important than any one of the parts. Everyone involved in the system must work together as a team, each contributing their individual part to keep the system working.
Moller asked for everyone's full cooperation and support of the integrated warning system. He challenged young meteorology students to hone their skills as forecasters and cautioned them to avoid the pitfalls of relying too heavily on computer products.
Moller presented numerous slides, a few of which are included below.


  • Moisture

  • Instability

  • Lift

Wind shear profiles compared to expected thunderstorm types.
Hodograph of wind shear environment favorable for supercell thunderstorm formation.

Supercell tornado ingredients.

  • Moisture

  • Instability

  • Lift

  • Vertical wind shear/instability balance capable of producing long-lived, strong mesocyclone with a balanced circulation.

Vertical cross section of a pulse type single cell thunderstorm. This type of storm forms with minimal wind shear, such as is typical during mid-summer in the southern United States. (This and succeeding simulated radar cross section diagrams were based on a paper by Les Lemon.)
Multicell cluster storms form when wind shear is moderate.
Vertical radar cross section of a multi-cell storm showing the various stages of development of each cell in the complex.
Horizontal radar cross section of a Multicell line storm.
Horizontal cross section of the "classic" supercell thunderstorm.
Supercell thunderstorm during early stages of development.
Artists concept of a Classic Supercell Thunderstorm.
Supercell with radar cross section overlaid.
Graphic of a bow echo storm showing the weak echo channels that precede severe downburst wind events.



Doppler radar image of twin tornadic supercell thunderstorms, including the Lancaster, Texas tornadic supercell thunderstorm (on the right side of the image).
Doppler radar velocity display showing the Lancaster, Texas tornadic supercell thunderstorm mesocyclone indication at the bottom of the image (red adjacent to green).
Image of a classic supercell thunderstorm updraft base with a wall cloud and cloud to ground (CG) lightning underneath.
Same wall cloud as above after further development and the appearance of a tail cloud seen stretching to the right. Tail clouds represent cool, but very moist air being drawn in from the precip area into the updraft.

Wall cloud images copyright 1992 Alan Moller.


Artists conception of a Heavy Precipitation (HP) supercell thunderstorm showing significant precipitation behind the wall cloud.
Simulated horizontal cross section of an HP supercell.
Radar image of the June 5, 1995 Dougherty, Texas tornadic HP supercell.
The crowd thoroughly enjoyed Moller's presentation.



Martin Lisius reviewed TESSA's performance during the past year and introduced the educational production Beneath Stormy Skies.

Glenn Wise presented the TESSA award to Alan Moller for his outstanding contribution to severe weather research and education.

Alan held up his award for the crowd and photographers to see.


Crowd shots.


Texas Severe Storms Association Annual Meeting

April 12, 1997

Link to Al Moller's Storm Track article on the Pampa, Texas tornado of June 8, 1995.

Go to Sam Barricklow's STORM CHASE Home Page

If you want to learn more about Storm Spotting or experience the thrill of Storm Chasing, visit The Storm Shop - a source for excellent SKYWARN training and Storm Chase adventure videos.

My lightning, tornado and storm video is available through Storm Stock

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All images on this page, other than the reproduction of the slides presented by Alan Moller,

are copyright 1997, Samuel D. Barricklow

Last revised: March 14, 2003