It’s been a pretty typical July, weather-wise, in Missouri. The only problem is
it’s barely June, and high temperatures and lack of rain threaten damage to
crops, pastures and lawns.
A University of Missouri climatologist said May, and now June, continued a
weather trend that set records and prefaced an emerging drought most of the
state faces.
“Back to back we’ve seen top 10 records for temperature highs and
precipitation lows for Missouri, and we’re breaking various temperature records
left and right across the state with a string of some very mild months,” said
Pat Guinan, MU Extension state climatologist for the Commercial Ag
Program.
The lack of rain is reaching a dire point for drought-stricken areas. In
May, preliminary data indicated Missouri only averaged 2.30 inches of rain,
ranking it as the eighth driest on record since 1895 for what is typically the
wettest month of the year.
Temperatures brought no relief either. Running about 5 degrees above
normal, the 70-degree average will likely fall in the top five warmest May
periods on record for the state.
When climatologists look at spring – from March to May – it’s just one
record-breaking event after another.
“It was our warmest spring on record, which blew the previous record set in
1977 out of the water by 3 degrees,” Guinan said. “That’s significant because
typically you break a monthly or seasonal record by a smaller margin.”
You can see this impact in the field.
MU Extension specialists across Missouri observed uneven soybean stands and
corn fields where leaves roll from lack of moisture and heat, both signs of
drought stress. Pastures and lawns also have that characteristic “crunch” when
walked upon due to the browned, dead or dormant grass needing a drink.
Southeast Missouri began experiencing the dryness in April, but it has
since spread across the rest of the state. especially after the first week of
May.
“It’s called an Omega block, where the upper level pressure pattern takes
the shape of the Greek Omega character,” Guinan said. “If you look at a synoptic
map of the upper air patterns over the past few weeks, you see a high pressure
ridge across the center of the U.S. and trough-like areas of low pressure in the
east and west, literally looking like an Omega.
This typifies a blocking pattern, keeping clear skies and little
precipitation in the middle part of the country.
Missouri is not alone, with neighboring states starting to feel the scourge
of drought. Portions of Kansas, Nebraska, Iowa and Illinois also saw these dry
conditions emerge, with a flash drought impacting much of the middle of the
U.S.
Historically, a dry May in Missouri doesn’t promise for a good outlook for
the rest of the growing season.
“If you have a very dry May, generally the following summers tend to be
hotter and drier than normal,” Guinan said. “When you look at the top 15 driest
May months on record, only two of the subsequent summers saw precipitation
average more than 1 inch above normal.”
The accompanying heat with low humidity also means that evaporation from
soils and transpiration from plants accelerates, making the drying out process
speed up. This warm weather continues a trend that climatologists have
documented for the past year.
“Over the past 12 months there’s only been one month with below normal
temperatures, and that was September 2011,” Guinan said. “When you crunch the
numbers it’s unprecedented; we haven’t seen a warmer 12-month period, starting
last June, since 1895.”
While some rain came through parts of Missouri Monday, significant amounts
are needed to replenish water resources above and below the ground. Guinan joins
many in hoping more rain will come.
“Hopefully we will see a change and a wetter pattern that sets up soon,
because things are going to go downhill very quickly if we don’t.”
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