Monthly Overview - August 2019

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Wet to the South, Dry to the North

Wetter and drier areas across the Midwest evened out to lead to near-normal precipitation for the month of August (Figure 1).  Monthly precipitation was 3.70 inches which was 0.04 inches above normal.  Moderate to heavy rainfall occurred mostly across Missouri and southern Illinois, where 150-200 percent of normal fell (Figure 2).  Missouri statewide precipitation was among the ten wettest on record for August (1895-2019).  More than 250 daily precipitation records were broken across the region (Figure 3). Meanwhile, significantly drier conditions were common across Michigan.  Parts of northern lower Michigan received less than half the normal amount for the month.
 

Slightly Cooler

Cooler temperatures were common across the western Midwest in August and near-normal for the eastern half of the region (Figure 4).  The average temperature for the region was 70.3°F which was 0.6°F below normal.  Maximum temperatures were even cooler across the western half of the Midwest (Figure 5).  More than 100 daily low maximum temperatures were broken during the month (Figure 6), with most occurring in Missouri and western Iowa.
 

Widespread Severe Weather

Severe storms led to strong winds across the Midwest in August, with nearly 1,000 reports of strong winds, hail and tornadoes (Figure 7).  More than 800 of these reports were for strong winds.  More than 200 reports of strong winds were recorded on August 20 alone.  Injuries were reported in Ohio, Michigan and Indiana during the month from thunderstorm wind damage and debris.  Large hail impacted the Minneapolis/St. Paul, MN area on August 5, where hailstones 2-4 inches (5-10 cm) in diameter were reported.  Of the tornadoes reported during the month, most were weak land spouts or rated EF-0 or EF-1.
 

Drought Forms for the First Time in 2019

Drought formed in the Midwest for the first time in 2019 in the August 13 U.S. Drought Monitor (Figure 8).  This broke a stretch of 32 consecutive weeks without drought in the region, the longest in the history of the U.S. Drought Monitor (2000-2019).  Continued dry weather in early August after drier weather to end July in eastern Iowa and northwestern Illinois contributed to the addition of drought.  Drought also formed in northern Michigan during the month (Figure 9).  Rainfall later in the month also eliminated drought that formed in Kentucky in mid-August.  Impacts on crops were felt, especially in areas where a wet spring led to soil compaction and poorer root structures.
 

Stormy Summer

Thunderstorms led to wetter conditions across the Midwest with widespread severe thunderstorm winds in each month from June-August. Regionwide, 12.81 inches (32.54 cm) fell which was 0.85 inches (2.16 cm) above normal (Figure 10).  Heavier precipitation in June decreased to near-normal precipitation regionwide in July and August.  Missouri and the Ohio River Valley received the heaviest precipitation for the June-August period.  Both Kentucky and Missouri ranked among the wettest 10 percent of June-August periods on record (1895-2019).  Overall, 1,000 daily precipitation records were broken in the region from July-August. Severe weather was also widespread, leading to more than 1,700 reports in June (Figure 11), 1,050 reports in July (Figure 12) and 950 reports in August (Figure 13) of thunderstorm wind damage or large hail.

Meanwhile, June-August temperatures were near normal across the Midwest at 70.8°F (Figure 14).  Ohio was slightly warmer than other states in the region.  Maximum temperatures in the region were slightly cooler (Figure 15) while minimum temperatures were slightly warmer (Figure 16) for the region, which evened out in the average.  Cooler June temperatures gave way to hotter July temperatures before moderating in August. Hundreds of low maximum records in June (Figure 17) and high minimum records in July (Figure 18) were recorded regionwide.
 

-BJP-