May 23, 2009

5/23/09: Denver Cyclone Reprise

The morning's surface weather maps shows, basically, a reprise of yesterday's pattern. A subsynoptic low is centered northeast of Denver, and, for this portion of the Plains, a rich supply of moisture is evident (basically, dew points in the mid 50s at 4000-5000 feet corresponds to dewpoints in the low 60s at sea level).

For Thom's last "chase" day, we will be playing the Palmer Divide, east of Denver. This is the sort of pattern in which strong, early updrafts can spawn a non-supercell tornado (called, popularly, "landspouts"). Here's a picture of the two of us at Mt. Rushmore.

This has been an uneventful trip so far (and likely to end so for me too). However, our frustration is tempered by the successful trips we had in 2004 and earlier years. This year's pattern is particularly frustrating for the participants of the VORTEX2 experiment.

This huge operation, involving over 40 vehicles stationed at three locations over the Great Plains, and deployed to observe the microscale meteorology around tornadic storms, has been deployed exactly once since the operation started on May 10. That was this past Tuesday, when we saw a few supercells in the Nebraska Panhandle. However, these were not close to being tornadic.

Thunderstorms are likely to occur over this region (as they have occurred the last few days) over the next weeks or so, but projected shear patterns do not indicate that they will be tornadic. Hence, many chasers are making the decision to abandon their quests this year...the mission is not to find thunderstorms (which is an easy thing to do) but to find rotating thunderstorms (which is a much more challenging proposition).