TornadoVideos.net

Posted At: April 1, 2006 @ 3:12 PM

Posted By: Reed Timmer

A very dangerous late afternoon and evening could be in store for western OK, the extreme eastern TX Panhandle, and southwest KS tomorrow, April 1, 2006. A classic springtime warm front/dryline setup will be established on Saturday, with the late afternoon/evening thermodynamic and kinematic profiles strongly supporting supercells with potentially long-track, violent tornadoes over the above areas. TV.net stormchasers Joel Taylor, Dean Schoeneck, and I (Reed Timmer) plan on departing from Norman at around 9 am, and will stop at Joel's parent's house in Elk City, OK for data. Right now, we believe the best area for large tornadoes is southwest OK and the extreme southeast TX Panhandle during the late afternoon and evening, especially after 2300 UTC. The ETA and GFS models appear to have the 0-1 helicity, 900 mb flow, and CAPE maximized in this region, with locally backed surface winds enhancing the low-level shear. Saturday is a classic case of "00-03Z magic",with a strong low-level jet developing around and after 00Z as the low-level atmosphere begins to decouple. During these events, supercells often develop in the mid to late-afternoon, and fail to produce tornadoes during the first few hours of their life-cycle. However, as the low-level jet commences and if discrete supercells can remain intact, all hell can break loose, and a supercell can become a tornado-producing machine in a matter of minutes (Example: May 12, 2004 in SW KS). As can be seen in the figure below of ETA-forecast 850 mb flow over western OK on April 1, 2006 at 00Z (left) and 03Z (right), the magnitude of the 850 mb flow increases from around 30 kts at 00Z to 45 knots at 03Z, especially over southwest OK, hence our target selection. The 0-1 km helicity increases due to the low-level jet during this time-frame, and the backed surface winds in SW OK further enhances this vital parameter.

Further supporting our initial selected target of extreme southwest Oklahoma are the higher ETA-forecast CAPE values in SW OK by 00Z as seen in the figure below at left, and this pattern has been consistent in the previous few ETA runs. The blue color represents CAPE values of greater than 3000 J/kg. The forecast hodograph at 03Z for Frederick, OK in extreme southwest OK is presented at right below, and reveals that a westerly moving supercell moving at 25-25 kts would be very likely to produce large tornadoes, given that the storm motion vector makes an approximate 90 degree angle with the large 0-1 km shear vector (based on research of John Esterheld and Don Guiliano).


Stay tuned to TornadoVideos.net for more updates concerning this dangerous situation. We hope to capture up-close, extreme tornado footage from this event, and we will display it immediately following the chase on this page and on the chase logs page as well. Interested media outlets can contact Reed Timmer via cell phone at 405-206-2307.