Midwest Overview - July 2008

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The Heavy Rain Continues

Much of the central Midwest received normal to above normal rainfall during July, but an area from central Iowa through the northeastern half of Missouri into western Illinois accumulated more than twice the normal July rainfall (Figure 1), with more than three times normal in a small portion of northeast Missouri. Clusters of thunderstorm repeatedly developed and moved over this area during the month. The week of July 11-17 was the only dry period for this region, with less than 50 percent of normal rainfall in Iowa and Missouri (Figure 2). Rainfall amounts in northern Missouri approached 20 inches for the month (Figure 3). The highest amounts reported by cooperative observer stations in Missouri are:

Long Branch Reservoir (Macon County)	18.34"
Mexico (Audrain County)	17.19"
Moberly (Randolph County)	16.23"

In addition, two CoCoRaHS observers in northern Missouri reported more than 19 inches of rain in July. The CoCoRaHS observer in Kirksville received more the 19.78" of rain. During the July 25 event the rain gauge overflowed and some of the rain that fell was not measured and accounted for in the amount reported for the month. In Macon, MO (Macon County), a CoCoRaHS observer measured 19.64 inches of rain during the month.

Based on preliminary data, July 2008 was the 8th wettest on record for Missouri and Illinois, and the 14th wettest on record for the nine-state Midwest region. In addition, January-July precipitation for Missouri, Illinois, and for the Midwest as whole was the greatest on record.

State	2008 July Rank	2008 Jan-July Rank	Jan-Jul 2008 Precipitation (in)	Record Jan-Jul Precipitation (in)
IA	8	2	30.55	33.18 (1993)
IL	8	1	32.85	old record 30.96 in 1990
IN	31	2	34.99	36.44 (1950)
KY	35	29	33.70	43.85 (1950)
MI	16	4	21.23	22.05 (1950)
MN	78	66	15.19	21.47 (1993)
MO	8	1	39.06	old record 36.10 in 1898
OH	65	3	30.97	31.43 (1913)
WI	34	7	22.88	25.32 (1999)
Midwest	14	1	28.07	old record 26.43 in 1950

Temperatures across the Midwest were cooler than normal in most areas (Figure 4). The exceptions were in northeastern Wisconsin and northwestern Minnesota, where temperatures averaged 1°F above normal, and in eastern and northeastern Ohio, where temperatures were 1°F to 2°F above normal. The coolest weather was found across the central Midwest, where clouds and thunderstorms were most prevalent. July temperatures in southeastern Iowa, western Illinois, and northeastern Missouri were 1.5°F to 2.5°F below normal. High temperatures equal to or greater than 90°F were limited to the southern and western Missouri, southern Illinois, and Kentucky. As of July 31 many locations in the central and northern Midwest had yet to record the first 90°F temperature of the season.
 

Great Lakes Levels Rebound

The wet and snowy winter combined with a wet spring has helped the Great Lakes levels to return to near normal levels. At the end of July, Lake Superior was within 4 inches of its long-term average after setting a record low level in the fall of 2007. Lake Erie is 2 inches above its July average, and Lake Ontario is 4 inches above. Lakes Michigan and Huron are up 8 inches, but still more than 12 inches below the normal for July. Lake Erie was at its normal level for July. Despite the increases in water levels, ships are still loading light because some harbors are still too shallow. On Lake Superior,the Wenonah ferry from Grand Portage, MN to Isle Royale National Park is still not running after not running at all in the summer of 2007. The water is still too shallow at Grand Portage to ensure the ferry will not bottom out in a swell.

For more information on Great Lakes water levels, visit the NOAA Great Lakes Environmental Research Laboratory web site.

For more details on weather and climate events during July 2008, click on the individual weekly report links on the upper right.

-SDH-