Tuesday, February 17, 2009

Storm chasers featured on The Weather Channel's web site

FWIW, I'm being featured currently on The Weather Channel's web site along with several other prominent storm chasers. See:


There's some photos, video, and miscellaneous information about me there. Thanks to Tony Grohovsky at TWC for setting this up.

Shawna and I just got back from the Denver Chaser Convention. It was great talking with so many chasers there, including Reed Timmer, Tim Samaras, Roger Hill, Mike Umscheid, Matt Crowther and Betsy Abrams, Jim Leonard, Tony Laubach, Brandon Ivey, Kory Hartman and Kenny Allen, and I could on and on. The presentations by experts such as Rich Thompson, Dr. Greg Forbes, Tim Marshall and others were excellent. And Shawna's talk about chaser preparedness and first response was very well received.

Here's a good recap of the convention at examiner.com:


- Jon Davies 2/17/09

Wednesday, February 11, 2009

Deadly tornado after dark in south-central Oklahoma on 2/11/09

Sadly, 2009's first "tornado disaster" has come with a tornado after dark at Lone Grove (near Ardmore) in south central Oklahoma. With news reports of at least 8 dead, one has to wonder if darkness contributed to the death toll. In 2007, 2008, and now 2009, we continue to see damaging and deadly nighttime tornadoes in the Plains, something more commonly associated with the southeastern United States.

Above, two radar reflectivity images (see white arrows) show the deadly supercell at 0000 UTC, and again at 0135 UTC, just after the time the tornado was hitting Lone Grove. With a large line of storms to the west and north, this reaffirms that discrete supercells tend to produce the strongest tornadoes, removed from immediate interference by adjacent storms. As the line to the west overtook and engulfed the supercell after 0200 UTC, tornadoes ceased.

The environment was very primed for tornadoes after dark. Strong forcing was occuring with the upper system, seen in the 500 mb NAM/WRF forecast graphic above. The RUC model was forecasting strong combinations of CAPE and low-level shear (storm-relative helicity or SRH) well in advance of this event, seen in the first part of the forecast graphic above. The second half of the same graphic suggested a very moist, surface-based environment forecast in the same area, with large low-level CAPE.

A modified RUC analysis sounding at Ardmore (also seen above) as the tornadic cell was passing to the north and west, also suggests that an excellent setting for strong or violent tornadoes was present. Instability was large for after dark at this early time of year, with MLCAPE > 2500 J/kg, while 0-1 km SRH was also very large (> 500 m2/s2) for support of low-level rotation in storms. Deep layer shear was quite strong, approaching 60 kts to intensify updrafts, and low-level MLCAPE below 3 km (> 250 J/kg!) indicated a strongly surface-based setting with essentially no inhibition (MLCIN).

Excellent tornado warnings were issued for this storm by the National Weather Service. Better awareness and action by the public in response to such warnings and settings is what will save more lives with nighttime tornadoes.

My wife Shawna will be giving a talk at the Denver Chaser Convention this weekend (Feb 14-15) about how chasers can help with severe weather education, and be better prepared to assist in first response situations. This deadly early season Oklahoma event reminds me that it's an important talk.

- Jon Davies 2/11/09