My grandparents’ farm. 1930 or so The farm NW of Sac City near Nemaha.

my grandparents’ farm

1930 or so

The farmThe farm

NW of Sac Citynear Nemaha

Their in-town house at Early (Sac county)

Bullseye

Early, Sac City, Nemaha

• 0158 2 E SCHALLER SAC IA4250 9526 LARGE WEDGE TORNADO JUST NORTH OF THE INTERSECTION OF HIGHWAYS 20 AND 71. (DMX)

• 0203 7 NW SAC CITY SAC IA 4249 9509 TRAINED SPOTTER REPORTS LARGE WEDGE TORNADO ON THE GROUND. (DMX) The farm

• 0209 4 N NEMAHA BUENA VISTA IA4257 9509 LARGE WEDGE TORNADO (DMX)

• 0246 7 W STORM LAKE BUENA VISTA IA4264 9534 TWO TORNADOES REPORTED BY CHASERS 7W OF STORM LAKE RELAYED BY MEDIA (FSD)

0346 EARLY SAC IA 4246 9515 MULTIPLE ROOFS RIPPED OFF HOMES ... EXTENSIVE HOUSE DAMAGE ... AND LARGE TREES DOWN (DMX) Town

Aftermath• From cousin Dave

– First encounter - Driveway in the morning– http://www.youtube.com/user/dtcoyote4#p/u/27/r54n7yNHBvA– remove tree across driveway– http://www.youtube.com/user/dtcoyote4#p/u/13/AnKo5uylPRE– morning, before much work– http://www.youtube.com/user/dtcoyote4#p/u/24/Av-fnD3eH5I– backing tractor out of shed before knockdown– http://www.youtube.com/user/dtcoyote4#p/u/23/8q65DGikiAE– piling up big back machine shed– http://www.youtube.com/watch?v=vllERczPyYk&NR=1– burying and burning– http://www.youtube.com/watch?v=_41G7HSRIB8&feature=related– Front yard view after lunch or so– http://www.youtube.com/watch?v=FQ18zvoz_VI&feature=related– Old coops and big claw– http://www.youtube.com/user/dtcoyote4#p/u/4/VxvbLPyOhcY– afternoon - by house and road– http://www.youtube.com/watch?v=1Q47vjsbsLk&feature=related– garage teardown– http://www.youtube.com/user/dtcoyote4#p/u/6/3CoKeXZB6s4– barn teardown– http://www.youtube.com/watch?v=f3cJGFCmY-E&feature=related– smoldering hole shed was buried in– http://www.youtube.com/watch?v=K85kJ94uVDg– sunset -- all gone but the house– http://www.youtube.com/watch?v=80JXYRULxbQ&feature=related

Good forecast

Good forecast

• Significant Tornado Parameter (fixed layer)

• A multiple ingredient, composite index that includes 0-6 km bulk wind difference (6BWD), 0-1 km storm-relative helicity (SRH1), surface parcel CAPE (sbCAPE), surface parcel CIN (sbCIN), and surface parcel LCL height (sbLCL). This version of STP uses fixed layer calculations of vertical shear, and the surface lifted parcels, as an alternative to the "effective layer" version of STP.

• The index is formulated as follows:

• STP = (sbCAPE/1500 J kg-1) * ((2000-sbLCL)/1500 m) * (SRH1/100 m2 s-2) * (6BWD/20 m s-1) * ((200+sbCIN)/150 J kg-1)

• When the sbLCL is less than 1000 m AGL, the sbLCL term is set to one, and when the sbCIN is greater than -50 J kg-1, the sbCIN term is set to one. Lastly, the 6BWD term is capped at a value of 1.5, and set to zero when 6BWD is less than 12.5 m s-1. A majority of significant tornadoes (F2 or greater damage) have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with values less than 1 in a large sample of RUC analysis proximity soundings.

moist tongue from south hitting warm front

moist = unstable

Well forecast

separate band to N• MESOSCALE DISCUSSION 0389 • NWS STORM PREDICTION CENTER NORMAN OK • 0657 PM CDT SAT APR 09 2011 • VALID 092357Z - 100100Z

• LOW LEVEL WARM ADVECTION IS STRENGTHENING ACROSS SERN SD AND SRN MN AS LLJ IMPINGES ON WARM FRONT. LATEST RUC GUIDANCE SUGGESTS THIS PROCESS WILL ONLY INCREASE DURING THE EVENING HOURS FORCING MOISTURE ATOP COOLER BOUNDARY LAYER. WITH STEEP LAPSE RATES IN PLACE SIGNIFICANT ELEVATED INSTABILITY WILL DEVELOP ACROSS THIS REGION SUCH THAT LARGE HAIL SHOULD BE COMMON WITH ANY SUPERCELL STRUCTURES. SEVERE THUNDERSTORM WATCH WILL BE WARRANTED ACROSS THIS REGION SOON. ..DARROW.. 04/09/2011