2014-06-18 FCST: NE/SD/MN/IA/ND

[Royce Sheibal]

Another day, another forecast, another possible moderate!

Yesterday the cap ended up breaking in NE and NW Nebraska, both making some serious multivortex producers. The RAP and HRRR failed yesterday on the NE NEB area, and will so again today. NAM and GFS agree on NE Neb (same as the last two days) being the hot spot. LI's are good, Cape is good, Shear is great again. Probably going to see day #3 of wedge tornadoes. Sadly I'm working again..so unless they pop closer to Omaha it's not happening. My target today would otherwise be Pender, NE to Sioux Falls.

Update: Northern SD filling in with typical upslope meso's. RAP is showing area in SE SD still the most prime for shear...but look downstream! Towers starting to form in W Kansas? Will the cap break along the dry line? I'm in Omaha looking at mid level cloud debris coming in from the southwest. The last two days there was notable non-Q low-mid clouds shooting north around noon-3pm from N KS into Central Neb and pointing toward our tornado cells. Anyone a cloud expert perhaps with some incite?

 

[Jeff House]

Strongly agree today will go. Hi-res guidance has been poor because it is designed for classic heart of tornado season classic supercells. While these have been classic sups, June climo probably hampers models. This week requires fundamental meteorology, and the original poster above has done well all week.

Starting downstairs, surface turning along the boundary will be excellent. OFB might lift north, esp west, but appears fairly well anchored east this am. LLJ up to 850 looks adequate; it should become locally good near supercells. Turning from surface to 500 mb is robust. At 300/200 little additional turning is noted; but, I don't see the veer back issue anymore. Speed at jet stream will become adequate for June by chase time.

Probably a good day for a 15% TOR. Not looking to debate the need; just making my forecast. One might take care to monitor/nowcast east and west of high-res radar forecasts, just in case. Good luck; chase safely; and, keep people impacted in our prayers. All in all I'm looking forward to more good pictures tonight.

 

[George Grant]

If you're chasing in southeast South Dakota, and have to get across the Big Sioux River into northwest Iowa, you're going to encounter many closed roads. The area has been inundated with upwards of seven inches of rain since this past weekend. My wife's hometown of Rock Rapids has seen the Rock River climb to ten feet above flood stage (13') and might go as high as 28 feet today or tomorrow and perhaps surpass the record 1993 flood stage. The sheriff of Lyon county has told people to stay out of the county (unless you're a volunteer) as there are very few roads and bridges that are unaffected by the high water. Even knowing the area somewhat, I'm not sure I'd chase across the South Dakota/Iowa border as there's the chance of getting backed into a precarious situation.