MPR's Paul Huttner talks Target Field climatology

MPR's Paul Huttner talks Target Field climatology
Photo by Jen Boyles

With each ballgame, we learn a little more about Target Field.  Yet even considering the small sample of games played to date (18) at the Twins' new home, I think if I had a buck for each time I've heard, "Damn, that ball died in the gap," I'd own a sizeable cache of those delicious Murray's Steak Sandwiches.  But it's true:  despite the diminutive degree of foul territory (only Wrigley Field sports less), in its early stages of existence Target Field appears very much a pitcher's park.

Entering Thursday's play, only five parks in baseball have yielded fewer HR's per game than has Target Field at 1.39.  According to Hit, just two balls measured at more than 420 "true distance" feet have left the park.  Also worthy of note, Park Factors at charts Target Field as one of the top-11 Pitchers Parks for runs, hits, and, again, home runs.

But will those numbers alter with the seasons?

To help us better understand the weather conditions and related structural positioning of Target Field, we're most fortunate to be joined by Mr. Paul Huttner, Chief Meteorologist for MPR and author of the "Updraft" weather blog.  

Aside from his weather expertise, Huttner is also an astute MLB follower, along with being a former youth coach.  Like myself: Huttner is of the belief that baseball success (or lack thereof) is most aptly, above all other factors, charted by the performance of on-field personnel.  But that doesn't preclude our guest from recognizing that myriad elements of climate do in fact alter the flight of a baseball.  

"The main things that affect a ball's flight are air temperature, humidity, and wind," Huttner explains.  "In the spring in Minnesota we tend to have higher air pressures and colder temperatures.  Temperature and air pressure are inversely proportional.  One goes up, the other goes down.  As the temperature falls in colder spring weather in Minnesota, the pressure is usually higher.  So, meteorologically speaking, air is denser at higher pressures.  That creates more friction on the ball in flight.  All other things being equal: if Justin Morneau hits one good with a home run swing, that ball will fly farther in warm, less dense air.

"Air pressure depends on elevation above sea level," he continues.  "The higher you are, the lower the air pressure -- that's a constant fact in the state of the air pressure.  Higher elevation means lower air density, so as a result baseballs will travel farther.  Colorado is the highest elevation park in Major League Baseball.  Arizona is second, Atlanta is third.  At

about 840 feet, Target Field is the fourth-highest elevation above sea level stadium in MLB.  There was a study done at Middlebury College in July of 2005 that suggests that for every 500 feet you go up above sea level, you add about 10 home runs at your stadium every three years.  So if you take that theory, Target Field would have about 3 to 4 more home runs every year than you would compared with the same stadium at sea level.

"But here's the thing about Minnesota: we tend to have higher air pressures -- especially in the spring and fall -- than these other stadiums might in other parts of the country.  Our weather systems here also affect that.  We get colder air and get higher pressures than in Phoenix or Atlanta, and even in some cases Colorado.  So that tends to counteract the higher elevation a little bit."


Further affecting a ball's flight at Target Field are the average, seasonal wind conditions in Minneapolis.  Those wind directions are concurrently notable when taking into play the stadium's design elements and structural positioning.

"For the spring and fall in Minneapolis, the prevailing wind is from the northwest toward the southeast.  At Target Field, that means the wind is blowing out," Huttner says.  "So a northwest wind is going to blow from, roughly, the third base lane out toward right center field.  That's most of the time, if you average it out.  That probably holds true for April and May, and then again in September."

Yet while the winds are now blowing out, let us recall that baseballs are still fighting the friction of the cooler, denser air.  But will deep balls hit in this part of the season receive a potential advance from the stadium itself?

"What's interesting about Target Field is that the canopy covering from the first base line to

the third base line is a huge wind shield," Huttner details.  "So when the wind is blowing from the west, it is reduced a little bit by the high profile of the stadium behind home plate.  So a wind blowing out at Target Field may not help a baseball as much as it would in a more open stadium. 

"The other aspect with wind blowing out, that we don't know about yet and that I wonder about, is that when you have a strong wind blowing over an object like the canopy you can get what's called a rotor -- where the wind is forced over the top of the stadium and then spins back toward home plate.  So some balls could get hit up, caught in that rotor, and then encounter a head wind and then get knocked down a little bit."

So, considering wind direction and the increase in summer temps, should we expect more bombs to be hit come June and July?  The answer leans toward a "Yes," however there's a caveat there as well.  Huttner continues:

"In the summer the prevailing wind here comes from the southeast which is, basically blowing in from right center field.  That's pretty much for June, July and August.

"Humidity affects the flight of a ball as well.  Higher humidity air is less dense air, so as a result balls will fly farther in humid air, all other things being equal.  Water vapor is lighter than nitrogen and oxygen.  But here's the interesting thing about Target Field:  Again, the warm and humid winds are southerly, those are blowing in.  So on a warm, humid night if there is a breeze, it's generally going to be blowing into the ballpark.  So, it counteracts; it's fighting each other.  It's almost like the perfect set of circumstances for long home runs to rarely occur at Target Field.

"Bottom line as far as wind at Target Field: you don't get as much benefit of a wind blowing

out because of the high stadium profile and it's easier for the wind blowing in to get into the stadium.  And both of those factors may reduce the flight of baseballs a little bit."
Just as Huttner and I agree that ballgames are ultimately decided by ballplayers, we further concur that Target Field's rep as a pitcher's or hitter's park will take several seasons to flesh out.  But with forecasts suggesting that the stadium's most sultry temps to date are to ensue in the next week, it will be noteworthy to track how many more souvenir balls fly in the very near future.  

"I think what we've seen at Target Field in the spring is going to be pretty typical with fewer home runs," Huttner concludes.  "That may again re-appear in the fall.  But these next two series with the Brewers and Yankees will be quite interesting because next week it looks like we are going to get very warm and much more humid here.  I think that's going to help the ball fly farther.  I think we're going to see more home runs from late-May through August."

Now we just need Huttner to forecast which side will be knocking those balls through our less dense air.

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