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Published byMartha Wells Modified over 9 years ago
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A Review of the March 28, 2007 Tornado Event Teresa Keck NWS North Platte, Nebraska Courtesy of Mike Hollingshead
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Introduction March 28, 2007 in review Forecasts leading up to event Vorticity Generation Parameter (VGP) emphasis in the warning process VGP application for future events
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In Review
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Progression of Day 1 Outlook
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Day 1 Tornado Outlook
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Highlights Dryline retrograded west by early afternoon shifting focus westward. The VGP forecast and analysis graphics helped refocus the forecast team to the potential for tornadoes in a storm environment where radar signatures were not clear cut. Storms moved from 34 to 52 knots while moving through the eastern panhandle and slowed to around 26 knots as storms intensified prior to tornado development. The 0.5 degree elevation slice was over 10 KFT off the ground. Twelve tornadoes occurred in a 2 hour and 8 minute period. The largest tornado was rated an EF 2 that tracked 17 miles across Perkins county.
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NAM 500MB Height & Wind Speed
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Surface Analysis 29/0000Z
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Visible Image
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NAM12 CAPE and CIN 29/0000Z
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LAPS CAPE and CIN 28/2300Z
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LAPS CAPE and CIN 29/0000Z
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LAPS CAPE and CIN 29/0100Z
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LAPS Compared to RUC Wind Profile
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Vorticity Generation Parameter - Resource Rasmussen and Blanchard 1998 study Box and whisker plot of VGP showing the 10 th to 90 th percentile Estimates the rate of tilting and stretching of horizontal vorticity by a thunderstorm updraft Levels 0 – 3 km on average with values of 0.2 or greater suggesting an increasing possibility of tornadic storms. Model data and LAPS analysis
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NAM12 VGP 29/0000Z
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RUC VGP 28/2100Z - 29/0000Z
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Composite Radar 29/0000Z
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Radar Reflectivity 29/0001Z
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LAPS 0-3km VGP 28/2300Z
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Composite 28/2300Z
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LAPS 0-3km VGP 29/0000Z
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Composite 29/0000Z
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LAPS 0-3km VGP 29/0100Z
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Composite 29/0100Z
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LAPS 0-3km VGP 29/0200Z
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Composite 29/0200Z
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LAPS 0-3km VGP 29/0300Z
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Composite 290300Z
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Future use of VGP Review other events to look for similarities and influence of gradients Correlations in VGP for ranges created when CAPE and wind shear environments vary (low CAPE to high shear verses high CAPE to low wind shear) Storm types
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Questions…
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