Drought Intensifies in 2007

Since January 2005, the Tennessee Valley has been slowly descending into drier and drier conditions. In early 2005, drought was prevalent over the mountain west and there was not a sign of how bad things would get here in the Tennessee valley.

Dry springtime conditions really intensified in May 2005, and abnormally dry (D0) conditions were first placed in north Alabama by the U.S. drought monitor on May 24, 2005, and continued off and on through the rest of the year.

The first intensification of the drought began in June 2006 during a very dry summer. Moderate drought (D1) conditions were assigned to areas south of the Tennessee River on Independence Day 2006. By the end of July, the rest of north Alabama was included in the moderate drought. By August 8th, moderate drought covered southern middle Tennessee, and much of north Alabama was downgraded to severe drought (D2) conditions.

Near-normal rainfall resumed by September 2006, which helped conditions abate somewhat. Still, rain was below normal. But, even the abnormally dry conditions were removed from the area for most of the end of 2006.

By early 2007, however, the rainfall faucet turned off once again. January 2007 was the 19th driest month in Huntsville and 33rd driest in Muscle Shoals. It was even drier in February, the 6th driest in the shoals and 19th driest again in Huntsville. By the end of February, moderate drought conditions (D1) returned to extreme northeast Alabama.

March was one of the driest march months ever on record, 4th driest in the Shoals and 3rd driest in Huntsville. On an area wide basis, March 2007 was probably the heart of the drought development. As a result of the incredible dryness, conditions rapidly deteriorated, with extreme drought (D3) conditions developing in the Huntsville metro area by the end of the month, with the rest of the area in severe drought (D2).

April was a bit wetter, but May turned very dry again, spreading the extreme drought (D3) conditions across the entire Tennessee Valley.

For the first time since 2000, a large portion of the Tennessee Valley was placed in exceptional drought (D4) conditions on June 5th. Exceptional drought is the worst of the five-category system used by the U.S. drought monitor, and usually indicates at least a 50-year drought. D4 conditions have stuck around in some portion of our area ever since.

Rainfall did improve slightly during the second half of the year. Of the 28.86 inch deficit at Huntsville during 2007, 18.98 inches of the deficit accumulated in the first six months of the year. Only 3.59 inches of the deficit accumulated in July through October.

The last above normal rainfall month in Huntsville was in October 2006. The last month with at least an inch above normal rainfall was December 2004.

Statistics and Records

2007 went down in the record books as the driest year ever recorded in Huntsville.

The rainfall total at Huntsville International Airport for 2007 was 28.65 inches. This is an incredible 28.86 inches below the normal for a year, which is 57.51 inches.

The previous verifiable driest calendar year ever recorded is 37.18 inches, which occurred in 1925. 2007 broke the old record by a staggering 8.53 inches.

There is published weather data from 1840 in Huntsville that indicates a rainfall total of 29.08 inches that year. This data is not part of the official Huntsville climatological record. Even if it was, the 2007 total in Huntsville was 0.43 inches less than the 1840 total.

In addition, the January through December 2007 total sets a record for the driest twelve-calendar-month period ever recorded. The previous record was 29.09 inches, which occurred from 1 October 1924 through 30 September 1925. The 2007 total was 0.44 inches less than this.

Other records that also fell include:

• Driest May through April on record, 36.88 inches (May 2006 through April 2007)
• Driest November through October on record, 32.45 inches (November 2006 through October 2007)
• Driest December through November on record, 30.83 inches (December 2006 through November 2007)

It is also worth remembering that in Huntsville, 2006 was the 13th driest year ever recorded and 2005 was the 6th driest. So this is a long-term situation that was at its worst in 2007.

The deficit at Huntsville since the beginning of this drought in January 2005 is now approaching 62 inches, or more than five feet.

Elsewhere in the central Tennessee Valley, Muscle Shoals ended with its third driest year on record with a total of 38.25 inches, but nowhere close to the driest year of 30.92 inches set in 1943.