2012-06-29 FCST: SD/NE

[Andy Jackson]

I'm thinking this Friday may be a chase opportunity in South Dakota. The 12 and 18z GFS is forecasting a surface low to develop from the Canadian border to Texas. Extreme instability with CAPE values over 5000j/kg with dewpoints in the 70's will make for an unstable atmosphere. The impressive part is the backed surface winds that allow for well curved vertical shear profiles. The flow a loft may be a little weak but it could be sufficient, I believe June 16, 2010 also had a weaker flow aloft yet still produced some nice tornadoes.

I'm pretty sure storms will fire given the precip models. The one issue that seems to be a problem is that the short range ensemble and NAM are not so generous with how far the moisture will actually return. Let me know if this looks good to you, given the time of year this may be a decent setup for SD.

 

[Jeff Duda]

Given the extremely warm temperatures in the lower atmosphere in this region this day, I'd say you could only really expect high based thunderstorms capable of producing dry microbursts. Thus all I see is a wind threat. Farther north and east where there is more moisture at the surface, things will most likely remain capped throughout the day.

 

[Andy Jackson]

I've been watching the models and it seems like there may be relatively cool temps aloft over SE SD. The one thing that has me perplexed is the NAM vs. GFS moisture solution. Even though it's an iffy setup I'm still going to keep an eye on it since it's close by.