Recent Months Wettest on Record

Recent months wettest on record in Missouri, says MU Extension climatologist
COLUMBIA, Mo. – The past six months mark Missouri’s wettest December-May period on record. Precipitation across the state averaged just over 30 inches from Dec. 1 through the end of May, said a University of Missouri Extension climatologist with the Commercial Agriculture program.
Since 1896, precipitation during this period has averaged 18.72 inches, said Pat Guinan. The previous record was the six months ending in May 1973, which saw 29.21 inches of precipitation.
Prodigious rainfall has saturated soil, putting Missouri corn farmers weeks behind schedule in planting, forcing many to consider switching to soybeans or other crops.
The state has also endured more than its usual share of tornadoes. Since Jan. 1, nearly 60 tornadoes have hit Missouri, almost twice the number the state sees in a typical year. On May 10, a devastating twister killed 15 people in Newton and Barry counties, making it the deadliest single tornado to strike Missouri in almost 50 years.
The culprits behind the state’s wet and windy weather include above-normal temperatures in the southern United States and below-normal temperatures in the north. "The larger contrast in air masses provides more opportunity for unstable weather," Guinan said.
Running between these air masses is the jet stream. During most winters, this high-altitude air current travels across the southern U.S. "This year that has not been the case," he said. "It’s been a few hundred miles to the north, pretty much running from the central Rockies to the Great Lakes area. That puts Missouri in the storm track."
The jet stream changed its itinerary thanks to the La Niña phenomenon, a recurrent cooling of surface waters in the equatorial Pacific. (There is also a corresponding interval of higher-than-normal water temperatures, which climatologists call El Niño.)
La Niña has been losing strength since February. Does that mean calmer, sunnier days lie ahead? Climate scientists are confident that the answer is "maybe": The National Weather Service’s Climate Prediction Center forecasts equal chances of high, low and normal amounts of rainfall in Missouri this summer.
To add insult to injury, below-normal spring temperatures abruptly gave way to above-normal temperatures in many parts of Missouri at the end of May. High humidity has made the warm weather especially oppressive.
"It seems like an early start to summer with the hot and sticky weather that we're already feeling across a good part of the state," Guinan said.
The good news, he said, is that the Climate Prediction Center anticipates below-normal temperatures on average from June through August.