Wednesday, May 20, 2009

This is a weird state

I grew up in Massachusetts where, when there was a sea breeze, you could get on the T in Newton and it would be 85 and get off downtown where it would be 55. But yesterday in Minnesota, it was crazier.

At 4:00 p.m., it was 100˚ in Granite Falls, Minnesota and 34 in Grand Marais. There was a cold front draped across the state and there was a 66 degree differential between the northeast and south. By late in the evening, temperatures were still near 100 down south and Grand Marais had dropped to 32—there were reports of freezing drizzle along the north shore.

It rather outrageous. East of the Rockies, Minnesota had both the warmest and coldest temperatures in the country. Even Death Valley wasn't much warmer.

The NWS has some sweet data including some temperature and surface analyses, as well as information about the rather bizarre event, such as the warm front actually showing up on the doppler radar. It had something to do with warm temperatures, ample sunshine across the plains, and (so I heard) the atmosphere expanding (high thickness values) allowing the air to heat. Temperatures, which had been predicted to be in the low 80s, spiked to 97 in Minneapolis by 6:00. I went for a rollerski in that and came back drenched in sweat, having guzzled a liter of water. Once I found out it was 97, I figured out why.

Along with the wicked warm conditions came a bit of a breeze from the southwest. There were three observations from this. The first two have pictures involved, a tree which fell across the bike path along River Road in Saint Paul and whitecaps, yes, whitecaps, on the Mississippi, where it runs parallel to the fetch of the wind.

The third observation was flight patterns in to the Minneapolis-Saint Paul Wold-Chamberlain International Airport. MSP has four runways, two of which are parallel (12L-30R and 12R-30L). (Runways are numbered by their magnetic bearing with two significant digits, and 36 is used for due north. For instance, an east-west runway is 9-27.) Because the runways are parallel and can allow for simultaneous use, these runways are are almost always used—if the wind has a southerly fetch, runway 12 is used, if it is northerly or westerly, they use runway 30. In addition, runway 17-35 can be used in pairing with these two, but it is shorter.

However, with winds out of the south and southwest today gusting to 40 or more miles per hour, they had to use runway 22, with is a southwest-northeast runway. This is normally used for mainly one thing—taking off 747s and other heavy aircraft (jumbo jets) for Asia, since it is 1000 feet longer than 12R-30L and these planes can use the extra distance. But with winds today, everyone was using it, and it was supposedly causing some ground delays.

Now, how do I know that it was in use? Well, normally, planes take off or land over South Minneapolis, which is very noisy. Citizens' groups, led in part by now-mayor Rybak, worked to get mitigation funds to soundproof houses in the area, but many people still live with planes constantly buzzing overhead. Today, however, their skies were quiet. Usually, the mid-afternoon departure to Tokyo flies over Mac-Groveland (if the wind is from the east) and makes a huge racket. Today, the planes were all landing on runway 22, which happens to have a flight path half a mile southeast of my house.

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