- Saturday March 7, 2009 Big day in Kansas' Flint Hills! -
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FORECAST SUMMARY: Compact but potent system over the western half of the US will eject into the Plains Saturday afternoon placing a strong jet stream (150mph @ 35k feet) over a moderately moist airmass. A surface low pressure system will strengthen over western KS in response to the approaching shortwave trough. Isolated supercells and tornadoes will be possible near the surface low, dryline, and warm front intersection (triple point) west of Wichita before the cold front comes through and mashes everything into a linear mess after dark.
TECHNICAL DISCUSSION: Depending on morning analysis, I might start the day playing the warm front in northeast Kansas and northern Missouri... getting some help from isentropic lift (air being forced to rise as it is slammed into denser cold air) to help punch through the cap. If this happens and a surface based supercell fires on the warm front, projected easterly storm motions would track the storm directly over the east-west oriented warm front and the enhanced low-level turning. Even a blob of elevated, left-over convection will have a chance to become surface based throughout the morning and early afternoon if it can remain on the warm side of the boundary. The NAM and the GFS have been showing a pool of the best surface moisture (~60F) well off to the east of the triple point which will give a big boost to any updrafts that track into it on the nose of the LLJ. Definitely want to stay on the southernmost cell in this scenario.
Regardless of if the warm front idea pans out, I'll be positioning myself 25-30 miles east of the deepening surface low around late afternoon, likely around Newton or Hutchinson, Kansas. There should be a window of opportunity for tornadoes within of a couple hours around sunset when the LCL's (cloud bases) diurnally lower to a more manageable level given the marginal surface moisture. Very steep mid-level lapse rates (850mb-500mb 8C) spreading above the warm sector will promote rapid convective development with any updrafts that can penetrate the cap. Low-level convergence and locally strong surface heating will be crucial to breaking the cap before sunset. Hopefully the only convergence won't come from the advancing cold front. As the afternoon progresses, I'll be keeping a close eye on the surface obs and visible satellite imagery looking for subtle boundaries and areas that are receiving strong insolation.
STAY TUNED!
- Chad
