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The Jarrell, TX Tornado: May 27, 1997. Karin Swanson AOS 453 May 11, 2000. What happened?. May 27, 1997-huge tornado outbreak 24 tornadoes were sighted throughout Texas Tornadoes ranged from F0 to F5. They were just funnel clouds in some areas, and huge causes of destruction in others. - PowerPoint PPT Presentation
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The Jarrell, TX Tornado:May 27, 1997
Karin Swanson
AOS 453
May 11, 2000
What happened?
May 27, 1997-huge tornado outbreak 24 tornadoes were sighted throughout Texas Tornadoes ranged from F0 to F5. They were
just funnel clouds in some areas, and huge causes of destruction in others
Jarrell, Texas
F5 on the Fujita scale Touched down at 2:40 pm CST Vortex 1/2 mile wide Property damage $40.0 million Crop damage $100,000 27 deaths in Jarrell alone
What made the Jarrell tornado occur?
Synoptic overview Mesoscale analysis
– satellites– sounding– indices for the area
Mean Sea Level Pressure Analysis
What is needed for a tornado?
Dry area to west of tornado area Vertical wind shear Latent instability Middle level jet Moist air at surface Dry air aloft
Miller diagram
Conceptual Model
Probabilities
Helicity=56.0 m^2/s^2 (12Z)
+ CAPE=3447 J/kg
=
Good Chance for Tornado
Indices (from 12Z)
Lifted Index=-9.59C > Probable T-storm Showalter=3.77C >No chance Total Totals=43.60C >No chance K Index=21.10 >20-40% chance Sweat Index=45.50 > No chance BRN=152.20 CAP=4.8
Conclusion
Several things happened on May 27, 1997 in Texas to make tornadic activity possible. – Large CAPE coupled with a lower helicity and
a strong cap– Moist air was present at lower levels, while dry
air was present aloft – Supercell progression through Texas
Questions?