The Ames Tornado of 12 November 2005 “I thought we had a pretty good mascot. But when we showed up at Iowa State and they had a real tornado, that’s the real deal!” - CU Buffalo coach Gary Barnett

A very interesting event…. Unusually late in the year (but have had 23 tornadoes in November in past 54 years; majority in 2 outbreaks)

A very interesting event…. Unusually late in the year (but have had 23 tornadoes in November in past 54 years; majority in 2 outbreaks) Almost the feared “worst case scenario” with 10,000s of fans arriving at stadium for ISU – Colorado football game

A very interesting event…. Unusually late in the year (but have had 23 tornadoes in November in past 54 years; majority in 2 outbreaks) Almost the feared “worst case scenario” with 10,000s of fans arriving at stadium for ISU – Colorado football game Missed the stadium by just over 3 miles (to NW), hitting roughly minutes before kickoff

A very interesting event…. Unusually late in the year (but have had 23 tornadoes in November in past 54 years; majority in 2 outbreaks) Almost the feared “worst case scenario” with 10,000s of fans arriving at stadium for ISU – Colorado football game Missed the stadium by just over 3 miles (to NW), hitting roughly minutes before kickoff Well-forecasted (5 days of model runs indicating severe threat)

A very interesting event…. Unusually late in the year (but have had 23 tornadoes in November in past 54 years; majority in 2 outbreaks) Almost the feared “worst case scenario” with 10,000s of fans arriving at stadium for ISU – Colorado football game Missed the stadium by just over 3 miles (to NW), hitting roughly minutes before kickoff Well-forecasted (5 days of model runs indicating severe threat) Emergency meeting of police, fire, ISU, hospital, and city officials at 9 am Saturday – indoor practice facility designated as triage site, mass casualties expected primarily from hail and lightning (tornado was considered a small risk)

A very interesting event…. Unusually late in the year (but have had 23 tornadoes in November in past 54 years; majority in 2 outbreaks) Almost the feared “worst case scenario” with 10,000s of fans arriving at stadium for ISU – Colorado football game Missed the stadium by just over 3 miles (to NW), hitting roughly minutes before kickoff Well-forecasted (5 days of model runs indicating severe threat) Emergency meeting of police, fire, ISU, hospital, and city officials at 9 am Saturday – indoor practice facility designated as triage site, mass casualties expected primarily from hail and lightning (tornado was considered a small risk) Planning for disaster about as good as could be expected, but many WHAT IFs.

Even with lots of moisture to mix down from above, the cap looks strong – substantial lift would be needed to remove the cap via cooling

500 mb maps from the 2 other “big” November events showed a very similar pattern of a strong short wave swinging into W IA around the time of the tornado events – however, in those events, the tornadoes occurred in SE – EC Iowa November 9, 1975November 15, 1988

In the other November events, the 850 mb low was further to the south, but general pattern was similar to the 2005 event

Surface low (approximated here by 925 mb low) and dew points in prior events also showed best conditions further southeast than 2005 event. Lifted Index and SRH maps (not shown) were typical of cold season tornado outbreaks – with very large SRH and only modest instability event was noteworthy in how far NW tornado-favorable conditions developed, and how unstable conditions became (LIs of -6 or so versus -1 or -2 in prior events)

Saturday…. 4pm….2 hrs to kickoff SPC still talking mostly squall line Tornado warnings in effect in W IA since 3:19 pm (watch since 2 pm) but with no reported touch downs ISU in frequent communication with NWS- DMX Based on storm upstream, ISU prepares to open gates to stadium 10 minutes early (4:20 instead of 4:30)

22:24 22:32

Just before 4:30, the first tornadoes touched down – one near Boxholm in NW Boone county and another SW of Woodward in Dallas county Woodward tornado seen via live web- cam from Madrid (15 miles SW of Ames)

Near Woodward, IA around 4:30 CST (R. Pfannkuch)

22:41 22:49

At 4:45, tornado reported near Luther (8 miles SW of Ames). Unclear if ISU authorities knew this – but based on sudden wind shift, change in storm track, and call to NWS (expressing uncertainty in what would happen), officers begin evacuation at stadium, urging people to seek shelter in cars (for hail/lightning threat – scenario 1 in morning plan)

22:58 23:06

At 4:50, based on tornado reports and knowledge of 53 mph movement, evacuations expanded and switched to scenario 2 at stadium (tornado threat) – CU players ordered off field, people told to go to concourses, restrooms, nearby buildings, ditches Tornado touchdown near west edge of Ames at 5:00 near Lincoln Way

Initial touchdown in West Ames

Near N. Dakota crossing

Near Deer Run damage

Entrance to NorthRidge Heights – looking NW

View looking south along G.W.Carver toward Ames

Twin vortices

Apparent “weak” stage of tornado pulls large tree high into the air

Looking SSW between Gilbert & Ames

View looking N from Ames Country Club (between Ames & Gilbert)

View southward of widest part of path – just east of Gilbert (note new Middle School on right)

Summary November tornado event was classic cold season situation Compared to prior IA November events, tornadic conditions extended further NW, and instability was greater More evidence of enhanced risk when dry line reaches Iowa Differential diabatic heating may have led to enhanced backing in C IA which contributed to tornadogenesis – importance of sfc boundaries and backed winds previously shown in many studies

What IF? Tornado hitting stadium (track 3 miles SE) would also have hit Mary Greeley Hospital Tornado would have hit stadium by 5:05 pm, 15 minutes after tornado evacuation began. Is that enough time? People in concourses would likely have been blown right out, and restrooms were overcrowded Metal roofing on nearby buildings would have likely caused serious problems to the thousands still outside Stadium area not equipped for sheltering 50,000 people Track only.5 – 1 mile NW would have destroyed most of town of Gilbert, hitting all 3 schools in the district

Acknowledgments Daryl Herzmann, John MacLaughlin – IEM/photos/helicopter surveys (thanks to those who took the photos and videos and contributed them, including ISU students) Jim Bishop – (video)