Another Day, Another Record......A Look Back At Forecast

Today's official high temperature at Lovell Field was 104 degrees which surpassed the old record of 101 set back in 1954. It was the second straight day of record breaking temperatures. The last time Chattanooga recorded a high of 104 was on July 29, 1993. Today was not far from the all time record of 106 set in late July of 1952. The Exceptional Drought that we are experiencing has everything to do with the fact that temperatures are extremely high. A lack of soil moisture results in lower air humidity values and hotter temperatures. It's a pattern that is often seen in the southwestern US and not here in the southeastern US. If you have been a regular reader of my blog you might recall my Summer outlook from May 10th which told of the possibility that the drought could lead to extreme heat. Here is an excerpt from that column:

(From May 10th Blog Entry): The Drought Monitor closely studies the entire country and determines the severity of dry spells. These drought conditions leading into the summer, could cause a warmer than normal summer.

A normal rain pattern would have led to an ample ground supply of water. Moisture in the top layer of the soil can serve to keep temperatures in check through evaporation. Granted, the added moisture in the air provides a muggy feeling, the evaporation and evapotranspiration process will keep air temperatures near seasonal levels. A parched, dry soil layer will absorb and retain the heat, therefore warming the air and leading to above normal temperatures. Again, on the flip side, it is not as humid, but very hot. The 2 week temperature trend keeps us in the above normal category. So, unless a wetter than normal pattern begins to take hold in June, we could be in for a hot summer.

Tropical Update: Dean is now a hurricane and should become a major one as it races through the Caribbean Sea. It "could" affect Jamaica and the Cayman Islands over the weekend and potentially Cancun by Monday. The forecast cone is close to the consensus of computer model guidance which indicates a west-northwest movement. At the current time, the western Gulf looks to be the region of highest risk from Dean next week. If this occurs, the Tennessee Valley should have no impacts at all and the heat will continue.