Posted at 4:57 PM on July 31, 2012
by Bill Endersen
July is on its way out the door after being the second hottest July on record, behind 1936, for the Twin Cities. It was 6.4 degrees warmer than normal. And it was the first month ever without a single high temperature below 80 degrees. Craig Edwards spelled out more about this past month in the previous Updraft posting.
Unlike the Great Plains and areas farther south in the Midwest, we did get some rain. In fact, the Minneapolis-St. Paul International Airport got 4.9 inches of rain. The National Weather Service Office in Chanhassen got much less, just 3.34 inches. My rain gauge measured 3.83 inches. Just to our east, Eau Claire, Wisconsin, was a lot drier with a meager 1.6 inches.
Down in Tulsa, Oklahoma, it's been another scorcher. After a morning low of 88 degrees again, the afternoon high was a record 111. Tulsa has heated to at least 105 degrees the last five days.
The outlook for August temperatures from the Climate Prediction Center is calling for warmer than normal temperatures for most of the US, especially the middle of the country centered on Nebraska, Kansas, Iowa and Missouri. Here's how it looks:
The issue of whether it can be too hot for tornadoes comes up from time to time. There certainly have been very few tornadoes nationally during this hot July. When it is really hot, it is often also too hot aloft for the atmosphere to become unstable - a requirement for severe thunderstorms. A trigger such as a front or trough is also necessary but would be unlikely in the middle of a hot air mass. And to turn a severe thunderstorm into a tornado-bearing thunderstorm also requires that the wind veer, that is rotate counter-clockwise with height, to get things spinning. So yes, the short answer is that extremely hot weather can stomp out the threat of tornadoes.
Wednesday around here will be hot and humid. Minnesota high temperatures will range from the mid-80s to mid-90s. Showers and thunderstorms will be likely, and some storms could become strong as a cold front slides southeast across the state. The National Weather Service prepared a nice map showing the expected weather nationwide at 7 p.m. Central Time.
Looking farther ahead, there will be another chance of thunderstorms from Friday into Saturday. That will set the stage for some cooler, more comfortable, temperatures for Saturday and Sunday.