Missouri 2013 Growing Season Climate Summary

Pat Guinan
State Climatologist
Commercial Agriculture/University of Missouri Extension

November 5, 2013

The 2013 growing season was dominated by anomalous weather conditions for much of the spring and summer, and made it another challenging year for Missouri farmers. Agricultural conditions only began to improve toward the end of the growing season with favorable harvesting opportunities, and some rain that initiated forage growth. Drought, however, was still impacting the northern half of state during October, and despite a widespread significant rain event at the end of the month, more rain was needed to recharge water supplies above and below the ground. The most notable anomaly for this year's growing season in Missouri was incredible precipitation disparities that occurred - from historic flooding in southern sections to severe drought in the north.

Temperatures started off cool in March and persisted throughout the spring. Data from Missouri indicated April temperatures averaged nearly 3 degrees below normal for the state. It was a continuation of a cool weather pattern, contrary to the recent trend, where March and April combined to be the coldest start to meteorological spring in 17 years, or since 1996.

The clash of air masses contributed to an unsettled weather pattern during April with numerous periods of showers and thunderstorms impacting the region, including an unusual snow event during the last week of the month. Data indicated a statewide average monthly rainfall of 6.30 inches, making it the fourth consecutive month with above normal precipitation. Total statewide precipitation for the first quarter of the year was 16.43 inches, nearly 5 inches above normal, and the 7th wettest January through April on record, or since 1895. It was the wettest January through April period since 2008.

The cool, wet weather during April delayed spring tillage and planting opportunities across the state. According to the Missouri Agricultural Statistics Service, spring tillage near the end of the month was 38% complete compared to the 5-year average of 56%. Only 15% of the corn crop had been planted and was more than 2 weeks behind normal

May weather in Missouri was erratic and unusual. Temperature data indicate the monthly statewide average temperature was slightly less than 1 degree below normal, making it the third consecutive month below normal and the 7th coolest spring (Mar-Apr-May) on record. It was the coolest spring in nearly 30 years, or since 1984.

A potent and cold upper level storm system moved over the state on May 3 and prevented high temperatures from climbing out of the 30's over parts of the state - an unprecedented occurrence for May. The same storm system brought a historic and rare snow event to parts of Missouri. A north-south band of heavy, wet snow fell on May 3rd, with 2-7 inches reported along a 100-mile wide corridor extending from north central, through west central and southwestern Missouri. The last time a May snowstorm of this magnitude impacted Missouri was on May 2, 1929, when 3-6 inches of snow blanketed portions of the Ozarks, northeastward to St. Louis.

Precipitation averaged above normal for May with a statewide average of 6.87 inches, more than two inches above normal and the wettest May since 2002. It was the wettest first five months of the year since 2008, and the 7th wettest January through May period on record. The extended wet period eliminated all residual drought conditions from the historic 2012 drought. By the end of the May, surface water and subsoil moisture supplies were at capacity and concerns shifted to excessive water issues, including major flooding along the Mississippi River.

The cool spring weather began transitioning toward a more seasonable summer-like pattern during June, with below normal temperatures at the beginning of the month climbing to near to above normal conditions for much of the rest of the month. Temperature data for the state indicate a statewide average June temperature of 72.9°F, or 0.1° below the long-term average.

June precipitation was variable across Missouri, but the statewide average was 4.92 inches, or 0.25 inches above the long-term average. Due to the localized nature of convective activity, precipitation disparities were profound across the state. Most locations across the northern half of the state received 2-4 inches, whereas the southern half reported 4-6 inches. There were notable exceptions, however.

According to the Missouri Agricultural Statistics Service, by the end of June crop conditions had improved with warmer weather and scattered showers. Fifty-nine percent of the corn and soybean crop were reported to be in good to excellent condition. More than 90% of the topsoil and subsoil moisture conditions were reported to be in adequate to surplus condition and 76% of the pastures were in good to excellent condition. Hay and stock water supplies were sufficient where 86% and 99%, respectively, were in adequate to surplus condition.

Progressive and unusual weather patterns impacted Missouri during July with overall statewide conditions trending toward a cooler and drier month than normal, but with large precipitation disparities from north (drier) to south (wetter). Data indicate a statewide average temperature of 74.7°F, or just under 3 degrees below normal. It was the first cooler than normal July since 2009. The last week of the month was notably cool with Missouri sandwiched between a ridge of high pressure over the southwestern U.S., and trough of low pressure over the upper Great Lakes.

Widespread significant precipitation events were confined to the last 10 days of July with southern Missouri being the primary benefactor. Overall, statewide rainfall averaged just over 3 inches, or 0.75 inches below normal. It was the first below normal precipitation month for the year. Precipitation was highly variable, but generally ranged from 1-3 inches across the northern half of the state to 3-6 inches over the southern half of Missouri. Heaviest pockets of precipitation occurred over southwestern sections where a few counties reported 7-10 inches.

The lowest July rainfall totals were confined to parts of north central and west central Missouri where several locations reported less than 1-inch for the month. The Drought Monitor map began to show these emerging dry conditions across parts of Missouri as the month progressed. By the end of the month, abnormally dry conditions to moderate drought were impacting much of the northern half of the state. Crop stress was beginning to emerge in the driest areas, with some firing and leaf curling reported, especially in upland or higher claypan or sandy soils. Unseasonably cool July temperatures, in combination with below normal evapotranspiration rates, were mitigating full drought stress potential.

Incredible precipitation disparities impacted Missouri during August, ranging from historic flooding to severe drought. Some communities in north central and northeastern Missouri reported no measurable rainfall, and their driest August on record, whereas counties in south central Missouri received more than 15 inches of rain and witnessed their wettest August on record. In regard to departures from normal, these were some of the largest precipitation disparities in the country.

Even though August precipitation totals occurred on both extremes across Missouri, the preliminary statewide average total for the month was 4 inches, which is slightly above normal. Generally, northern sections reported less than 1-inch for the month, central sections between 1-3 inches, and 4-10 inches over southern Missouri. Extreme and intense rainfall, approaching 10 inches in some locations, was reported on August 6-7 in south central Missouri and impacted Camden, Laclede, Miller, Maries, Pulaski, Texas, Phelps, and Dent counties. The Branson Airport reported 8.00 inches on August 8.

Seasonably cool and pleasant temperatures were the rule for much of the summer, but a major pattern change during the third week of August resulted in a late summer heat wave for Missouri. Temperatures during the first 3 weeks of the August averaged 5-6 degrees below normal, but those departures quickly evaporated when heat built-in during the last 10 days of the month, and high temperatures climbed well into the 90's, including some triple digit heat at the end of the month. Overall, the statewide average temperature for the month was 74.5°F, or 1.6 degrees below the long-term normal.

Dry conditions had existed across northern and central Missouri since June, but cool temperatures and an unusual amount of cloudy days this summer mitigated drought stress, in addition to below normal evaporative rates. For comparison, total estimated April- August evapotranspiration was nearly 7 inches less this year in mid-Missouri than for the same period last year.

Unfortunately, the late summer heat wave initiated "flash drought" conditions across northern Missouri and vegetative stress quickly ensued, including significant declines in row crop and pasture conditions. By the beginning of September, the northern half of Missouri was experiencing moderate to severe drought.

According to the Missouri Agricultural Statistics Service September 1, 2013 report, the north central and northeastern crop districts were reporting 67% and 76%, respectively, of their topsoil moisture in very short condition. Corn, soybean and pasture conditions had also notably declined during the latter half of August across northern and central Missouri, especially in the north central, northeastern and central districts where 49%, 41%, and 35%, respectively, of the corn was in poor to very poor condition and 52%, 38% and 36%, respectively, of the soybean crop, was in poor to very poor condition. The majority of pastures across northern Missouri were in poor to very poor condition. Hay and stock water supplies were mostly adequate across the state, though there were numerous reports of feeding hay across northern Missouri where pastures had burned up.

Summer-like temperatures prevailed for much of September in Missouri and resulted in the first warmer than normal month since February. Preliminary data indicate a statewide average temperature of 70.8°F, or 2.5 degrees above the long-term average. The abnormal warmth was especially notable during the first half of the month with high temperatures on several days reaching the 90's. A few locations across the northern half of Missouri broke records when unusual late-season triple digit heat was reported from September 7-11. There were only a handful of cooler than normal days, and no freezing temperatures were reported across the state.

Rainfall was below normal across all of Missouri during September and averaged slightly less than 2.5 inches, or about 1.6 inches below normal. There were some notable precipitation events including one on September 1 that benefited soybeans and pastures in the northwestern tip of the state, and some west central counties. Another event on the 8th of the month brought some much needed rain to a few counties in east central Missouri. Parts of extreme northern Missouri received between 0.5-1.5 inches of rain on the 11th and 12th. The northeastern community of Edina, MO went a record 43 consecutive days, Jul 31 - Sep 11, with no measureable rainfall. The streak ended when 1.23" was reported on the 12th of the month.

Cooler and wetter conditions during the latter half of September initiated vegetative growth, and slightly improved hydrological conditions, but much of the northern half of the state was still experiencing moderate to severe drought by the end of September according to the Drought Monitor map.

As of September 30th, the Missouri Agricultural Statistics Service reported 74% of the pastures in fair to good condition, and 78% of the hay supply and other roughages adequate. Cooler than normal temperatures this past summer mitigated evaporative loss and 78% of the stock water supplies remained adequate. Crop conditions across the state were mostly fair to good condition with corn at 70%, and soybean at 67%.

Unseasonably mild temperatures impacted Missouri during the first half of October but a major weather pattern change resulted in much below normal temperatures, freezing temperatures, and record lows during the latter half of the month. Temperature data indicate an average statewide temperature of 55.7°F, or 1.3° below the long-term normal for October.

October rainfall was variable across Missouri, averaging mostly above normal over western and southern sections and near to below normal for the rest of the state. Precipitation data indicate an average statewide total around 3.5 inches, which is near normal.

The biggest rain event to impact the state in months occurred during the final days of October when a tropical fetch of moisture from the Gulf of Mexico and Pacific Ocean interacted with a strong storm system and frontal boundary over the central U.S. Much of the state received 1-3 inches of rain from October 29-31.

Despite the end of the month rain event, dry conditions dominated in October and allowed numerous harvesting opportunities. Moderate to severe drought was still impacting the northern half of the state at the end of October, and more precipitation was needed to replenish soil profiles and surface water supplies. The growing season effectively ended statewide when sub-freezing temperatures impacted all of Missouri on October 25th.

As of October 27th, the Missouri Agricultural Statistics Service reported 60% of the pastures across north central Missouri in poor to very poor condition. The northeastern crop reporting district reported 50% of the pastures in poor to very poor condition. Despite these conditions, all crop reporting districts reported the majority of their hay supplies and other roughages as adequate. Stock water supplies remained mostly adequate statewide, though the east central district reported 46% in short supply. As the growing season came to a close, crop conditions across the state were mostly in fair to good condition with winter wheat at 97% and soybean at 57%. The soybean conditions were least favorable across north central (54% poor to very poor) and northeastern (50% poor to very poor) sections.