|NWS: Wilson in a drought|
|Wednesday, June 27, 2012|
By JENNIFER HORTON
It is official: Wilson County is in a drought.
And by Thursday when the U.S. Drought Monitor is updated, Wilson and much of Middle Tennessee may well be in a severe, if not moderate drought.
That was the word Tuesday afternoon from Bobby Boyd, meteorologist with the National Weather Service Office in Old Hickory.
“We are,” he said, answering whether this area was officially in a drought. “When it updates, I think it’s going to put us in a severe drought, certainly moderate, if not severe.”
That drought conditions exist should surprise no one, especially if you’ve noticed the color of your lawn is no longer green but tending toward the brownish or if your garden is gone.Rainfall from Jan. 1 through June 25 (although this will likely be the case through the end of the month) stands at 18.18 inches which is 6.63 inches below normal, Boyd said, adding that for the same time period in 2011 we were above normal with 27.26 inches of precipitation. Normal amount for Jan. 1 through June 30 is 24.81 inches of precipitation.
So far, through June 25, Boyd said .26 of an inch of rain has fallen, officially, at the Nashville International Airport. He added that his home, which is in West Wilson County, he, like others, has had more rain and measured 1.79 inches so far in his rain gauge. Most of that, 1.21 inches, fell on June 12.
As if the lack of rainfall was not enough to worry about, temperatures in the triple digits the next few days will mean those who have to be out and about should drink plenty of water and take other precautions to guard against heat-related illnesses.
“Hot, hot weather to continue right on through the rest of the month,” is how Boyd described the forecast for the rest of this week.
The high Friday and Saturday should reach 102 degrees and 100 degrees on Sunday. The high temperature will drop slightly on Monday to 97 and to 95 on Tuesday.
“We’re looking at some real hot weather to continue,” he said, adding that lows at night and into the early morning hours the next few days will be in the low to mid 70s.
“I wish we could get some of the rain that’s down in Florida, but there’s no way we’re going to get it,” Boyd said, referring to Tropical Storm Debbie that continues to soak the, er, “Sunshine” State.
The cause of our very hot and very dry weather is a warm upper level anticyclone that extends some 40,000 feet up into the troposphere. A strong high pressure aloft is drying out the air as it is falling down. Boyd said that when air falls down, it warms. He compared it to using a bicycle pump to put air in a tire. As you continue to push the pump handle which forces air into the tire, the bottom of the pump becomes hot. In other words, when air is compressed, it gets warm.
There is no significant chance of rain in the forecast although on Sunday “there could be something isolated around. The key word is isolated,” he noted.
Monday and Tuesday of next week might also have an isolated storm somewhere, but “I wouldn’t count on it.”
Looking ahead to the July 4 holiday next Wednesday, he said rain chances will continue to be “isolated at best,” but “computer models after July 4 try to bring a disturbance down into Tennessee on Friday, July 6.”
Even so, he added, there is not much of a chance of significant rainfall for the beginning of July.
Part of the problem with the rain, or to be more exact, the lack of it, and the high temperatures is how fast what moisture is present is evaporating.
Boyd noted he has installed an Atmometer at his home in West Wilson, a gauge, if you will, that measures evapotranspiration, which dictionary.com said is the “process of transferring moisture from the earth to the atmosphere by evaporation of water and transpiration from plants.”
He said the Atmometer has shown that he is losing one-fourth to three-tenths of an inch of moisture every day from the grass and trees in his yard. It is essentially the reverse measurement of rainfall.
“My garden’s gone. I’ve just given up on it,” the meteorologist said, adding he knows the dry conditions are a concern for farmers, too. “Corn has got to be an issue.”
The outlook for July shows above normal temperatures and below normal precipitation, and the extended outlook is pretty much the same for August and September.
As hot as it has been in the past few days, Boyd said so far temperatures have been 0.4 (four-tenths) of 1 degree above normal for the first half of June.
“We’ve made up for it in the last half.”
The high temperature, so far, this month was 98 degrees on June 24 and 25, and the low temperature was 48 degrees on June 2.
There have been no record high temperatures this month, or at least, not yet. The all-time record high for the month was 106 degrees which occurred on June 30, 1952, he said.
There was a six-day stretch of 100-degree temperatures on June 21-26, 1988. “That’s a long run of consecutive days with triple-digit temperatures.”
The longest stretch, however, of triple-digit temperatures was eight days in 1952 and occurred June 23-30, he added.
The earliest recording of 100 degrees or greater was June 15, 1952 while the latest was Sept. 11, 1983.
And, Boyd noted, this June is the eighth consecutive month with above normal temperatures, a stretch that began in November 2011.
The longest such run with above normal temperatures was 12 months and ran from May 1881 to May 1882. Second was 11 months from May 2007 to March 2008, and third was 10 months from May 1998 to February 1999.
“That’s not done very often,” he said, “in 141 years of data.” Records at the NWS at Old Hickory go back that many years. Only 11 times in the past 141 years have there been eight or more months with above normal temperatures.