Then the skies opened up, making a bad day even worse for the Golden Eagles.
McNutt had 140 yards receiving for the Hawkeyes, who won their 11th straight home opener despite an 84-minute delay because of lightning.
''If you're not going to win a game like this, it's fantastic to come and play a team that does it the right way,'' Tennessee Tech coach Watson Brown said. ''They're not very complicated. They just don't make mistakes.''
Iowa overwhelmed the Golden Eagles of the FCS with 24 points in the second quarter. McNutt took a Vandenberg pass 88 yards for a touchdown, and Shaun Prater returned an interception 89 yards for a TD late in the first half to put the Hawkeyes ahead 27-0.
Vandenberg's 19-yard TD pass to McNutt gave Iowa a 34-0 lead with 6:19 left in the third quarter. The game was delayed shortly thereafter and the stadium was cleared.
Dontey Gay rushed for 108 yards for Tennessee Tech, including a 1-yard TD run with 5:02 left.
The game kicked off in a driving rain, which led to three first-quarter fumbles.
The clouds parted to start the second, allowing the Hawkeyes to impose their will on the overmatched Golden Eagles.
Wide receiver Keenan Davis, who the Hawkeyes are counting on to take pressure off of McNutt, leapt over Tennessee Tech's Richmond Tooley, tipped the ball and caught it at the 1-yard line. Vandenberg's plunge put Iowa up 10-0 early in the second quarter.
Vandenberg then floated a pass to McNutt in coverage, and McNutt sprinted past the Golden Eagles' secondary for the sixth-longest TD reception in school history, making it 17-0 just over three minutes later.
Tech quarterback Tre Lamb, whose interception to Iowa linebacker James Morris set up Mike Meyer's 20-yard field goal, tried to force the ball to the sidelines late in the first half. Prater, an All-Big Ten pick in 2010, was waiting for it, and he saw little resistance on an 89-yard TD return that gave the Hawkeyes a 27-0 lead with 10 seconds left in the second quarter.
Lamb finished 14-of-24 passing for 128 yards and those two costly picks.
''The second one was a beautiful play by their corner,'' Brown said. ''Tre laid it up there thinking our guy could get it.''
Vandenberg, a junior in his first start since taking over for Ricky Stanzi, was 13-of-21 passing, including a few drops from his receivers.
The rain returned right around the time Vandenberg and McNutt hooked up for their second touchdown. It brought some hail and the threat of lightning with it, and Kinnick Stadium was cleared as officials and players waited out the weather.
''We hadn't had one drop of rain in preseason, and I just dumb enough to never work with a wet football. Well, we don't have to worry about it the rest of the year. We got plenty of wet football work (Saturday),'' Brown said.
About the only hiccup for Iowa besides the conditions came from its running backs - a source of considerable consternation for the Hawkeyes of late.
Coker, last seen ripping apart Missouri's defense for 219 yards and two TDs in the Insight Bowl, fumbled the ball away on Iowa's opening possession. He put it on the ground again in the first quarter and was subbed out for freshman Mika'il McCall - whose debut was impressive but brief.
McCall, the son of former heavyweight boxing champion Oliver McCall, rushed for a team-high 61 yards on nine carries before breaking his ankle late in the first quarter. Iowa coach Kirk Ferentz said after the game that McCall will miss the rest of the season.
Coker finished with 41 yards on 11 carries.
The Hawkeyes, who play at Iowa State next week, are coming off one of their most disappointing seasons in recent memory. Picked by many to contend for the Big Ten title in 2010, Iowa stumbled to an 8-5 finish and just 4-4 in league play.
The Hawkeyes have just 10 starters back on offense and defense. But that didn't matter against the Golden Eagles, who simply couldn't match up with them.
''Based on what we saw on tape and saw last year, they're going to go and have a good year,'' Ferentz said of Tennessee Tech.