Posted: Saturday, August 31st 2013 at 11:00am
Revisiting the long, cool (and wet) summer
By Ken Stanford Staff
Just two years removed from its hottest summer on record, Georgia has just experienced one of it coolest and wettest ever.
State climatologist Bill Murphey said there were many meteorological factors involved in "setting us up in this type of pattern."
Murphey said one of the "main ones" was that the Southeast has been under the influence of an upper level trough for much of the summer.
"We were also positioned on the western flank of the Bermuda/Azores High pressure system, which allowed ample return flow from the Gulf and the Atlantic through much of the summer," he added. "This trough pattern has kept temperatures cooler than normal and has allowed several waves of energy to move across the Southeastern states thanks to an active subtropical jet."
This, he said, has kept mainly moist and unstable conditions in place across a large portion of the Southeast. And, that, coupled with light winds aloft, means storm cells at times didn’t move much, so flash flooding was a problem in some places. Flowery Branch was especially hard hit by flooding on May 19 and there was flooding elsewhere across Georgia and the Southeast.
Murphey says this has been the third-wettest and 16th-coldest summer on record in Georgia. He says rainfall between May and July was 7.53 inches above normal - and it was the wettest May-July period since 2003. (August figures were not available from Murphey in time for this story but in some places, Gainesville included, it was much wetter-than-normal.)
Temperatures between May and July were 1.4 degrees below average in Georgia.
Murphey says the period June 1-Aug. 26 was the wettest on record for Gainesville, going back to 1898, with 28.45 inches of rain. It was the 8th-coolest, with an average of 73.8 degrees. The coolest on record for that period, again going back to 1898, was 71.3 degrees in 1967.
Data recorded at Lee Gilmer Memorial Airport show there were only five days during the past three months that the high temperature reached 90 or more - three of them in June and one each in August. The highest of the five was 92 on June 12. In addition, August brought with it two of the coldest highs on record in Gainesville for the month - 66 of the 16th and 65 on the 17th. The situation was the same elsewhere in north Georgia those two days.
At the Gainesville airport, temperatures were below normal on 17 of 30 days in June, 29 of 31 in July and 24 of 31 in August.
Rainfall in Gainesville totaled 27.98 inches for the three months ending August 31. That is well-above normal for the period and brings to 59.14 inches the amount of rain that has fallen at the airport since Jan. 1. That is 22.89 inches above normal for the first eight months of the year. It rained on 19 of 30 days in June, 24 of 31 days in July and 16 days in August.
In July there was one stretch when it rained 15 straight days - including all of the week including July 4. It also rained on all or parts of four of five weekends in June, three of four in July and three of four in August. Friday, by the way, was the seventh straight day of no measurable rainfall in Gainesville and you have to go back to the end of May to find the last time there was no measurable rain for seven consecutive days.
IMPACT ON LAKES AND STREAMS
The summer rains have resulted in full reservoirs and high water tables.
"Stream flows in the Chattahoochee are above to well above normal with well above normal inflow into Lake Lanier. Ground water has responded with shallow wells and aquifers showing above to well above normal values. However, some (several hundred feet) deep wells will require more time to respond to the recent rainfall.'
As of Saturday morning, the level of Lake Lanier was 1972.53, which is 1.53 feet above summertime full pool (1071).
IMPACT ON AGRICULTURE AND WHAT'S AHEAD
The rainfall has been a mixed blessing for agriculture in Georgia, according to Murphey.
"Irrigation costs were reduced but fungal pathogens (which damage roots and crops) are more prevalent. Corn, cotton, and peanuts have done fairly well. Watermelons and blueberries, a little less so. A delayed wheat harvest will cause some losses and a subsequent reduction in soybean planting. The state’s peach crop has done well overall."
Murphey says the latest three-month outlooks call for equal chances of above, below, or normal precipitation and temperatures for Georgia.
"These...outlooks are for September, October, and November. Keep in mind that longer range outlooks carry more uncertainty. Also keep in mind that we are approaching the active part of the tropical season with the peak occurring around September 10. So far we’ve had six named storms this year in the Atlantic Basin, but there are some signs in the far eastern Atlantic Basin that activity may be starting to heat up a little."
Murphey notes, however, that fall is "typically on the dry side in Georgia."
Link: 2011 ranked as Ga.'s hottest summer
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