Bill and Justin worked three isolated storms in the BIS area, issuing a SVR warning on one of them.  The basis for the SVR ground relative velocities, mainly a wind threat, perhaps 60-65 mph and 1″ hail.  The actual WFO issued a Tornado Warning on the storm, but the EWP team felt that the circulation was too shallow to warrant a TOR.  Our 3DVAR data feed was out until about 0040 UTC, and wasn’t used much for the warning.  By then, the storms were below severe limits.  While watching the 3DVAR on Jidong’s website prior to restoring the AWIPS feed, there was decent vorticity at 3km, perhaps at the time of the official NWS TOR warning.  Here are some images:

Fig. 1.  KBIS reflectivity and EWP SVR warning.

Fig 2.  MESH and 120-min MESH Swath, and EWP SVR warning.

Fig 3.  30-min 3DVAR Vorticity Track.

Here’s an image at 0004 UTC at the time of the NWS TOR issuance.  I’ve placed a marker where the supposed strong rotation couplet is observed.  Note on the reflectivity image that this position is well out ahead of the “hook” in the clear air ahead of the storm core.  Looks like side lobe contamination rather than a vortex couplet.  There is no continuity upstairs either.

Fig 4.  KBIS images from 0004 UTC 8 June 2011 from GR2AE.

We’ve wrapped up fpr the night, and the forecasters are filling out their surveys.

Greg Stumpf, EWP2011 Week4 Coordinator