June 24, 2003 Southeastern South Dakota Tornadofest

A classic northern plains setup finally emerged this day as a deep upper/middle-tropospheric trough reached peak amplitude over the western U.S., overspreading the plains with strong southwesterly flow aloft. During the previous few days en route to this dream-like northern plains tornado outbreak setup, serious "obstacles" to big tornadoes became apparent each day; namely, localized forcing regimes sufficiently strong to overcome the omnipresent June "death cap" arose in regions far removed from most chasers' designated target areas and there never seemed to be one specific boundary or location where adequate shear, CAPE and forcing all appeared co-located. On June 24, the same strong EML and abundant CIN (convective initiation) were present; however this day the surface baroclinic zone was sharp, consolidated and a broad swath of extremely moist boundary layer air was present across the warm sector. During the day a very pronounced lower tropospheric convergence zone developed along this boundary, with a particularly focused regime of lower tropospheric moisture convergence occurring near Mitchell, SD; it is difficult to imagine examining the surface observations after 2 PM CDT and not being alarmed by the intensification of the baroclinic zone and focused moisture convergence (in the presence of mid-upper 70F dewpoints) over southeastern South Dakota. Supercell storms erupted first along the warm front and then in the warm sector to its south, each one producing multiple tornadoes. Silver Lining Tours' Tour #6 once again struck fantastic tornado riches as Tour Director Roger Hill led the dumbfounded/amazed group to two tornadic supercells; the first storm intercepted exploded west of Mitchell, producing a couple of tornadoes (first two images below). As that storm weakened, very explosive surface-based development was observed just to the group's northwest and they re-targeted to the new storm, which certainly appeared to develop at the nexus of the moist axis and warm front. Given the explosive environment, this storm rapidly evolved into an isolated, long-lived tornadic supercell that produced multiple classic and strong/violent tornadoes over the next 3 hours. This was one of those storms that the SLT participants on that trip will never forget.

Pictures:

The first South Dakota supercell produces a large tapered-cone tornado just north of I-90 west of Mitchell. View  towards the east-northeast	Same tornado (left) with new wall cloud to the south (right appendage).	Having just intercepted the second supercell (and main show of the day), a classic strong tornado is seen just west of Woonsocket, SD. This is about as good-looking a tornado as you can ever hope to see.	Close-up of the same tornado's debris fan and condensation funnel.
More of same spectacular tornado.	The tornado becomes partially front lit as the tornado occludes.	A new tornado develops from a new mesocyclone/wall cloud northeast of Woonsocket in northern Sanborn County, SD.	Classic tapered cone tornado.
	Next, the group proceeds north to Hwy 14 east of Iroquois, SD and then drove east into the western side of the bear's cage (the wrapping precip curtains west of the tornado). They emerged to find a large, yellow-tinged barrel-shaped tornado wiping out the hamlet of Manchester.	Classic elephant's trunk stage of the Manchester tornado. Again, the contrast and tornado appearance are top drawer.	Closeup of the Manchester tornado. Doing F3/F4 damage now.
Incredible elephant's trunk tornado continues rampaging across the countryside.	A new multiple vortex tornado takes shape just north of De Smet, SD.	A narrow columnar condensation funnel emerges.	Same.
The same highly contrasted stovepipe tornado continues to the northeast of De Smet. Shortly thereafter, the storm became outflow dominant and merged with other storms.