March 8-14, 2010
Midwest Weekly Highlights - March 8-14, 2010
Warmth Spreads to Rest of the Midwest
Below normal temperatures across the southern half of the Midwest the first week of March gave way to much above normal temperatures the second week of the month. Temperature departures from normal ranged from 1°F to 2°F above normal in the western periphery of the region to 10°F to 17°F across the northeastern half of the Midwest (Figure 1). There were numerous high maximum and high minimum temperature records set on March 10 and March 11, additional records on March 13-14. On March 8 temperatures reached into the 50’s over parts of southwestern Iowa, including a high of 59°F at Shenandoah. This was the first official reading of 50°F or higher anywhere in Iowa since December 17, 2009 when Fort Madison and Keokuk reached 50°F and 51°F. This streak of 80 consecutive days below 50°F statewide was the fourth longest such statewide streak since 1891.
This was also a very wet week in much of the region, with a series of systems bringing large amounts of rain. Precipitation was two to three times normal from central Missouri northward, reaching four to five times normal in parts of Minnesota (Figure 2). Precipitation was less than 50 percent of normal across the Michigan Upper Peninsula, and less than 75 percent of normal in southwestern Missouri and in central Kentucky. The March 9 U.S. Drought Monitor depicted dry areas in northern Minnesota, Wisconsin, and Michigan, and in southwestern Kentucky (Figure 3).
Warm Weather Has Its Consequences
The warm-up this week, along with the frequent rain, resulted in a rapid reduction in the snow cover across the Midwest. By the end of this week the southern extent of the snow had retreated north and west, leaving significant snow depths confined to northwestern Iowa and much of Minnesota (Figure 4). The water from melting snow and precipitation ran off saturated ground into rivers and streams. At the end of the week stream flows in the northern half of the Midwest were much above normal (Figure 5), and moderate to major flooding was in progress along the Red River in Minnesota, sections of the Mississippi River as far south as St. Louis, and along portions of the Illinois River. Flooding in Minnesota, in particular, was expected to get worse as four to eight inches of snow still remains on the ground in western Minnesota. That snow was holding two to as much as five inches of water (Figure 6).
A Stormy Week
A series of low pressure systems moving into the Midwest the first half of the week produced heavy rain across the upper Midwest, spring like warmth in the southern Midwest, and some severe storms (Figure 7). Strong southerly winds on March 10 brought 70°F readings as far north as central Illinois (Figure 8), and for many areas this was the warmest day since early November. The cold front associated with the low pressure system triggered severe thunderstorms from Missouri southward into Arkansas. There were a number of reports of golf ball size hail in Missouri, and some power lines down due to thunderstorm winds.
By March 12 a large closed upper level low was parked over the center of the country, and the week finished out with widespread cloudiness and rain from the Mississippi River eastward. By the morning of March 14 the center of both the upper level and surface lows had moved to the mid-Atlantic coast, but most of the Midwest still remained under the influence of the circulation of the storm which reached as far west as western Missouri.
-SDH-