The growing season's bookends are dry, but farm diaries they hold spill water when opened. Rain day notations abound.
“In March, we had less than half the normal amount of rain,” says Barry Keim, Louisiana state climatologist. “April had a normal amount of rain. May, though, started a trend of rainy weeks. And the word rainy probably doesn't do that period justice.”
Louisiana averaged 9.5 inches of rain in May — almost twice the norm. A swath from Baton Rouge to Lake Charles — right along the I-10 corridor — “really got hammered,” says Keim. Much of that area received 20 inches of rain or more — most falling in eight days.
“An upper air disturbance that hung over the state produced copious rain. As soon as that disturbance moved out, a surface cold front rushed in and brought more rain.”
Louisiana dried out towards the end of May. Keim, who works at the Southern Regional Climate Center in Baton Rouge, describes June as an “incredible month” for much of the Delta and Texas. Mississippi had its wettest June on record. Louisiana (which averaged 11.5 inches — 6.5 inches over the norm) and Texas ended up with their third-wettest Junes.
Keim says it's interesting that the June rains weren't driven by a single, major storm. “We just had repeated thunderstorms. Several late-season fronts penetrated the area, rather unusual for that time of year. A number of upper air disturbances rippled through and kept the storms firing off.”
Some areas had “incredible” June runs: Alexandria had 25 days of rain, as did a New Orleans site. Several areas around the state had 23 rain days.
Normally by June, Louisiana has settled into a summer weather pattern. “Afternoon convective showers slide through. You can set your watch by them — they'll show between lunch and mid-afternoon. This year, though, the storms were coming through at all times of night and day. That's very unusual.”
The two wettest Junes on record in Louisiana occurred in 1989 and 2001. Both were driven by tropical storms named Alison.
Since this June's rain wasn't caused by a single event, “the million dollar question is what, if anything, this portends.” The climate is seldom average, so reading too much into this isn't the right thing, says Keim.
“Yes, we had a very unusual June, but we had a normal pattern in July. Now, in August, it's drying up. It seems the pendulum has swung in the other direction.
“Weather across the United States has been in an odd configuration much of the summer. The jet stream was displaced south over the Delta. The latest front that came through (in early August) is an example — it looked like a system you'd see in the winter. It was welcome, of course, because it kept temperatures down. But if the same thing had happened in January, it would have produced a deep freeze in the South.
“It's strange to see a cold front of that substance make it this far south in the summer — and we've had three or four in the last couple of months.”
Over the harvest months, the prediction is for an above normal tropical season, says Keim.
Odd weather has also been in evidence on the upper end of the Delta. July temperatures in Missouri were the coolest in 37 years. This summer could be the coolest on record.
“Across the state, July temperatures averaged 2 to 5 degrees below normal,” says Pat Guinan, Missouri Extension climatologist.
Guinan says the eastern two-thirds of the United States has remained cooler than normal. The western third has been warmer than usual.
“The heat waves have been few and far between and have lasted only a few days.”
In southeast Missouri, June temperatures were about 0.5 to 1.5 degrees below the norm. “Preliminary temperature reports indicate this June-July period rank as the eleventh coolest on record (1895 to present),” Guinan says. “July alone is the ninth coolest on record.”
In Missouri July rainfall was 5.75 inches, nearly 2 inches more than the 30-year average of 3.96 inches.
“Pretty much the entire state is nice and green throughout,” Guinan says. “It's unusual to have this weather persist.”
Editor's note: for more information check www.losc.lsu.edu.