Casebook 18 August 2003: Difference between revisions

Revision as of 06:47, 24 December 2007

CSU-CHILL Casebook: 18 August, 2003

A thunderstorm briefly became severe near the foothills west-southwest of Loveland Colorado during the afternoon of 18 August 2003. The CSU-CHILL radar made an RHI scan through the core of this storm at 2010:32 UTC. (See VCHILL example below.) The $Z_{dr}$ field contains a bright band in the low reflectivity elevated echo layer near the 20 km range point. In the high reflectivity thunderstorm core, the transition from positive to near 0 dB $Z_{dr}$ values at the surface at a range of 58 km indicates an increasing hail fraction in the precipitation. Finally, a three-body scattering signature (distinctly negative $Z_{dr}$ at low elevations changing to large positive values at higher elevation angles) can be seen at the far range end of the thunderstorm. (Note: Thresholding should be selected OFF under the VCHILL Filters tab to make the three body scattering pattern visible.)

example in VCHILL

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 ==CSU-CHILL Casebook: 18 August, 2003==
-A thunderstorm briefly became severe near the foothills west-southwest of Loveland Colorado during the afternoon of 18 August 2003.  The CSU-CHILL radar made an RHI scan through the core of this storm at 2010:32 UTC.  (See VCHILL example below.) The ZDR field contains a bright band in the low reflectivity elevated echo layer near the 20 km range point.  In the high reflectivity thunderstorm core, the transition from positive to near 0 dB ZDR values near the surface at a range of 58 km indicates an increasing hail fraction in the precipitation.  Finally, a three-body scattering signature (distinctly negative ZDR at low elevations changing to large positive values at higher elevation angles) can be seen at the far range end of the thunderstorm.
+A thunderstorm briefly became severe near the foothills west-southwest of Loveland Colorado during the afternoon of 18 August 2003.  The CSU-CHILL radar made an RHI scan through the core of this storm at 2010:32 UTC.  (See VCHILL example below.) The <math>Z_{dr}</math> field contains a bright band in the low reflectivity elevated echo layer near the 20 km range point.  In the high reflectivity thunderstorm core, the transition from positive to near 0 dB <math>Z_{dr}</math> values at the surface at a range of 58 km indicates an increasing hail fraction in the precipitation.  Finally, a three-body scattering signature (distinctly negative <math>Z_{dr}</math> at low elevations changing to large positive values at higher elevation angles) can be seen at the far range end of the thunderstorm.  (Note: Thresholding should be selected OFF under the VCHILL Filters tab to make the three body scattering pattern visible.)
 [http://chill.colostate.edu/java/vchill.php?sweep=xlab.chill.colostate.edu:2510*/dsk/dnf/data/2003/08/18/%20DIR*CHL20030818_201032%20MPRHI1%20RHI*Sweep%2003&center=0.,0.&range=75.&plot=ZDR example in VCHILL]