Storm Chase Forecast - May 18, 2014

So much for Virtual Chases. I'm planning to head out to the plains for a few days to try chasing some marginal setups. Not sure if I'll be able to post a forecast ahead of each day, but I'll start with my first opportunity this Sunday.

Target: Northeast Wyoming

With all the frustrations of a flimsy severe weather pattern setting in for the latter half of May, it still looks like there will be isolated/conditional opportunities in the northern plains and elsewhere as a trough moves onshore this weekend and starts cutting off in the southwest early in the week.

For Sunday afternoon/evening, per guidance from NAM, I'm looking at a target in northeastern Wyoming as 40-50 kts of southwest H5 flow moves in over an area of low to mid 50 dew points advects around a consolidating surface low in that target area. A narrow, meridional zone of 1500-2000 j/kg CAPE will develop along the eastern Wyoming border with the CAP weak or open by mid to late afternoon in the northern portion of this ribbon. Today's 12Z NAM forecasts a focal point for convection in this area by 00Z with that area potentially ingesting 100-150 m2/s2 0-1km SRH. Mixed layer LCLs are in the 1500 meter range and heighten quickly the further south you go.

If this plays out well, I might hope to see an isolated, high-based supercell drifting slowly into South Dakota. I have no expectations of anything tornadic with this setup. And if today's 06Z GFS has its way, then I can expect a bust with maybe some elevated showers in South Dakota (GFS keeps surface moisture about a hundred miles further east under stronger capping). 00Z ECMWF agrees better with NAM on placement of moisture and location of precipitation, so I hope that agreement favors my focus on NAM.

This will be my first 2014 chase day during a week of very iffy conditions. I'm definitely concerned that I'm setting myself up for a series of busts, but also excited to take on the challenge.