Midwest Weekly Highlights - March 11-17, 2007

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A Bit of Spring, A Bit of Winter

The second week of March was in keeping with March's reputation as a transition month between winter and spring. Warm air surged northward during the week, but by the end of the week wintry weather was again affecting portions of the Midwest.

Temperatures this week were above normal across the region except for extreme northwestern Minnesota (Figure 1). Temperature departures ranged from 7°F above normal in western Missouri to 1°F above normal in east-central Ohio, and 1°F below normal in northwestern Minnesota. The cooler pockets this week occurred where cold fronts had slowed or stalled out resulting in more persistent cloudiness.

Much of the Midwest was very dry this week, with the most significant precipitation occurring just north of the Ohio Valley (Figure 2). Precipitation in a band from southern Illinois through central Indiana and across most of Ohio and far eastern Kentucky was normal to well above normal. With the scarcity of precipitation there was almost no change in the drought status in the northern Midwest and in Kentucky this week (Figure 3). While most of the precipitation this week was rain, some snow fell across the region, with the heaviest amounts in northeastern Ohio (Figure 4).

 

A Surge of Warmth

The week started out with temperatures gradually warming across most of the region as high pressure moved to the east coast southerly winds became established across the central U.S. Records started to appear on March 11 when Sault Ste. Marie, MI reached 47°F, breaking the old record of 46°F set in 1927 and International Falls, MN reached 52°F, tying a record first set in 1995. The warmth peaked on March 13 when temperatures reached the low to mid 70s from central Iowa eastward to southern lower Michigan (Figure 5). A number of locations tied or set new record high temperatures on March 13, and a few records were set on March 14 although increasing cloudiness due to an approaching front prevented even more locations from establishing new records.

Date	Location	New Record	Old Record & Year
March 13	Duluth, MN	57°F	54°F, 1990
	Minneapolis/St. Paul , MN	66°F	64°F, 1974
	Manitowoc, WI	66°F	61°F, 1922
	Chicago, IL	73°F	72°F, 1995 & 1990
	Rockford, IL	74°F	70°F, 1995
	Peoria, IL	78°F	77°F, 1933
	Champaign-Urbana, IL	78°F	78°F, 1990
	South Bend, IN	74°F	74°F, 1995
	Fort Wayne, IN	73°F	73°F, 1933
	Indianapolis, IN	80°F	78°F, 1990
March 14	Springfield, IL	75°F	75°F, 1995
	Champaign-Urbana, IL	78°F	75°F, 1995

 

Strong Cold Front Produces Heavy Rain, A Few Severe Storms

The warm weather that spread over the Midwest the early part of the week was brought to an end by a strong but slow-moving cold front. This front helped trigger some scattered showers and thunderstorms across Missouri and Illinois on March 14, but the heaviest rain occurred from southern Illinois tough Indiana and Ohio and accounted for most of the precipitation this week in those areas (Figure 6). Severe storms were widely scattered, with reports of wind damage in Illinois and one inch hail in Kentucky. Severe storms also occurred across northern Ohio, including one small tornado which touched down near a shopping mall in Elyria (Lorain County), about 25 miles west of Cleveland, causing an estimated $750,000 in damages. Rainfall amounts totalling 2.00 to 3.00 inches occurred from west-central Indiana across northern Ohio (Figure 7), prompting flood warnings to be issued for much of Ohio and central Indiana. As cold air swept in behind the front, precipitation changed from rain to freezing rain a sleet in parts of Ohio. The wintry precipitation contributed to numerous accidents, some with injuries, in Union County northwest of Columbus.

 

Winter Lingers in Ohio, Brushes Iowa and Missouri

Eastern Ohio remained under the influence of this weather system through March 17 as low pressure first developed along the front in the southeast U.S. on March 16 and then intensified as it moved up along the Atlantic coast to Long Island by the morning of March 17 (Figure 8). Light snow fell across much of eastern Ohio during March 16, coming to end by midday on March 17, with accumulations of one to two inches across the northeastern third of Ohio. A few lake effect locations received as much as four inches. Meanwhile, a weak upper level disturbance trekking to the southeast out of the Dakotas brought a period of light to moderate snow to the western half of Iowa and central Missouri on the morning of the 17th. The heaviest snow accumulated in central Iowa south into north-central Missouri (Figure 9). Des Moines, IA, reported 3.0 inches of snow, while in Missouri Livonia received 4.8 inches, and Kirksville received 3.5 inches.

 

Flooding Threat Remains Across Much of Midwest

Ice jams, thawing soils, and heavy precipitation combined to keep the flood threat alive on many rivers and streams in the Midwest. In Minnesota, a massive ice jam on the Little Minnesota River caused it to overflow its banks, forcing the evacuation of 100 people in Browns Valley, MN (Traverse County). In eastern Minnesota, the Whitewater River left its banks and forced the closing of the Canadian Pacific Railroad tracks on the Winona, Minnesota (Winona County) side of the Mississippi River due to water, debris, and ice on the tracks. In Illinois, the Illinois River continued above flood stage at Havana. Heavy rain on March 14-15 caused minor flooding along Little Wabash River. Minor flooding was also reported along the Des Moines River in central Iowa and along some rivers in Michigan. At the end of the week the potential for river remained high over the northern Midwest due to the frozen ground and remaining snow pack.

SDH