2012-02-20 FCST: OK / KS / NE

[Jeff Snyder]

A strong shortwave trough is currently located in the central Plains, with a ~1001 mb surface low located in southcentral NE and northcentral KS. This is a pretty normal winter severe weather setup in the Plains, with very strong wind profiles and very marginal (perhaps sub-marginal) low-level moisture (42-46 F Tds) available across the warm sector. Current GOES precipitable water indicates <30 mm PWs from northern TX northward towards the surface low. Very cold temperatures aloft (e.g. mid -20s @ 500 mb) are accompanying the shortwave trough aloft, which is probably the only reason that anyone is showing any interest in this event. The dryline, currently W of I35 in OK and KS, is currently supporting some TCu and shower development per vis sat and radar, but the limited low-level moisture is really limiting the degree of potential instability that is able to develop despite some insolation. The current showers are also occurring in an environment of veered sfc winds and very low dewpoints (38-40 F). The 12z NAM and various RUCs support what is largely 200-500 j/kg SBCAPE by later this afternoon. This is typically "good enough" in cold-core setups, but I've never had much luck with such low Tds and CAPE in the typical "warm sector" environment along and east of a dryline. For what it's worth, vis sat also indicates very stable low levels with a couple counties of the dryline (low-level cloud streets, etc.), and the narrow instability axis along with fast storm motions (40-50 kts S of I70) will limit the amount of time any particular storm may spend in >250 j/kg SBCAPE environment.

The cold temps aloft may support some severe hail, and the strong winds not far off the surface may be transported downward by convective downdrafts to support severe winds at the surface. I'm not convinced on the tornado threat, given the very limited CAPE, but we'll see... I'm currently at my residence in central Oklahoma, but I may head out to northern OK should something look particularly interesting.

 

[Mike Johnston]

Looks like this event is actually materializing despite the meager surface dewpoints. Within an axis of 500 j/kg of SB CAPE over north central OK and central KS, several strong cells have developed. Very low-topped, as expected, but pretty decent shape profiles on radar. The cell north of Anthony, KS had a TVS signature for a couple of scans. Currently, the strongest cell looks to be just northeast of Enid, OK. Not a bad February opportunity for those in the vicinity that can get out and chase on this holiday.