Saturday, March 29, 2008

Chase Day - Sunday March 30th

Looks like a decent setup tomorrow but still some questions. In the upper levels, 500mb SW flow around 40kts will spread over much of the southern plains with main trough/vorticity maxima centered further north. 250mb jet streak will likely be entering west TX and TX panhandle late Sunday afternoon. At the surface, warm moist air will begin its return from the gulf today and continue overnight and into tomorrow morning. Further north, sfc cold front slides south throughout the day eventually stalling across northern OK into southern KS and possibly drifting back to the north a little Sunday night. A dryline will mix east across the TX panhandle and likely intersect the stalled front in the far eastern TX panhandle where strengthening sfc low seems to setup in the afternoon/evening. 850mb winds seem to remain out of the south-southwest throughout much of the day on Sunday contributing to warm layer overspreading much of the warm sector resulting in stout cap and delayed initiation. Without the upper support from 500mb wave, sfc features will have to overcome the warm layer to provide initiation in the late afternoon. This remains the biggest question with this setup. With this being said, models seem to back 850mb winds to a southerly direction and really kick-in as evening approaches and LLJ cranks to around +40kts. QPF fields are very reluctant to fire any convection due to capping as well. However, I'll be out chasing this event. My hopes are that one or two storms fire along stationary front near sfc low/dry line intersection during the evening before it gets dark. If this could happen, storms would likely have a nice environment to thrive in. Dewpoints into the mid 60's and CAPE values ~2000j/kg will provide nice instability to any storm that goes. 0-6km shear will be ample so any storms along or south of front will likely be supercells. Along the previously mentioned stationary front, sfc winds may have an easterly component and when coupled with strong LLJ, there may be favorable low-level winds to sustain mesocyclones and tornadoes into the evening hours. If cap holds strong then the majority of this chase may occur into Sunday evening. Good Luck to those heading out. Stay tuned for updates...

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