March 1-10, 2007
Midwest Weekly Highlights - March 1-10, 2007
Winter Keeps Teeth In Midwest
The beginning of climatological spring was marked by snow and cold in the upper Midwest and severe weather in southern portions of the region.
Precipitation was well above normal across the upper Midwest (Figure 1), largely due to the major storm that hit the region on March 1-2. Precipitation from southern Missouri up through central Illinois and western Indiana was well below normal for the period, amounting to some light snow and light rain showers from weak frontal systems that moved through the region. Snowfall was much above normal from Iowa northward through Minnesota and east through Wisconsin and western lower Michigan (Figure 2). The plentiful snow in the upper Midwest and rain in the eastern portions of the region helped improve moisture conditions in drought-affected areas of the Midwest. There was improvement in southeastern Kentucky, where the areas of Abnormally Dry and Moderate Drought were reduced (Figure 3). In the upper Midwest, there was an improvement of one category from Severe to Moderate in the western Michigan UP and northern Wisconsin, and improvement across central Minnesota. The last two major storm brought substantial moisture to Minnesota helping reduce fire danger and providing additional flows to rivers and lakes. Recharging of soil moisture, however, will have to wait for warmer weather and spring rains as melting snow will run off due to frozen soils.
Temperatures the first ten days of March ranged from 4°F to 6°F below normal across the central third of the region to 2°F above normal in southeastern Missouri and western Kentucky (Figure 4). The largest departures below normal were found where snow cover was the most persistent during the period. Following a major storm on March 1-2 deep snow covered much of the upper Midwest (Figure 5), and significant snow remained at the end of the period (Figure 6).
Another Blizzard
At dawn on March 1st a strong and intensifying low pressure system was centered over southwestern Iowa (Figure 7). Heavy snow with blizzard conditions were occurring from Iowa through much of Minnesota and the eastern Dakotas, Further south, severe thunderstorms erupted along the cold front in Missouri. A variety of winter weather warnings and advisories were in effect for the northern half of the region, including a blizzard warning for the western half of Iowa and southwestern Minnesota (Figure 8). Flood watches were posted from Illinois eastward into Ohio. Tornado watches were in effect for southeastern Missouri and much of the Gulf States.
Iowa Clobbered Again
Iowa took a direct hit from this storm just as many areas in the state were beginning to recover from a blizzard that hit the region on February 23-25. The storm brought western Iowa to a standstill as plows were pulled off of roads because they could not keep up with the blowing and drifting. Snowfall from the first day of the storm totaled 10 to 17 inches in western Iowa and drifts were reported as high as 8 to 10 feet. The entire 150-mile length of Interstate 29 in western Iowa was closed. The Iowa National Guard teamed up with Department of Transportation snow plows and Iowa State Troopers to assist hundreds of stranded motorists. Snow, blowing snow, and wind chill temperatures near zero made for dangerous conditions. Along one 35-mile stretch of Interstate 80 between Avoca and Adair (west of Des Moines), an estimated 130 vehicles were reported to be in the ditch. The winds and heavy snow knocked out power to more than 2,000 customers in Iowa, on top of an estimated 25,000 customers still without power from the previous winter storm. An estimated 80,000 customers in Michigan had power knocked out by the storm as well. Schools throughout the upper Midwest were closed. In Minnesota, the heavy snow caused the roofs on a bowling alley in Elk River and a hardware/lumber store in Winona to collapse. Sections of Interstate 35 and Interstate 90 were closed in western and southern Minnesota, and the Minnesota Department of Transportation closed all roads in southwestern Minnesota on the afternoon of March.
South of the winter weather, strong to severe thunderstorms developed ahead of the cold front in Missouri. The thunderstorms spawned at least two tornadoes in Missouri, one of which resulted in a fatality. A 7-year-old girl was killed and a number of people were injured in Caufield, MO (Howell County) when a tornado touched down there damaging four mobile homes, two houses, and a service station. Tornadoes also touched down in Illinois and Kentucky, causing only minor damage. Storm reports also indicated large hail (>= 1 inch) at a number of locations in Missouri and Illinois, and one in Indiana.
Slow to Move Out
Many roads remained closed into Friday, March 2, as strong winds generated by the slow-moving storm continued to create blizzard conditions. On the morning of March 2 the storm center had moved only to south central Wisconsin (Figure 9) and continued to affect most of the upper Midwest. Blizzard warnings were continued in western Iowa, southwestern Minnesota, and the eastern Dakotas because of the strong winds (Figure 10). High wind warnings were posted for central Illinois through the northern two-thirds of Indiana and the western half of Ohio. Schools remained closed in Iowa, Minnesota, and Wisconsin because of the snow and blowing snow. Much of the Midwest was still being influenced by the circulation of this storm on Saturday, March 3 (Figure 11), and along with windy conditions numerous snow showers dotted the region during the day producing light amounts of additional snowfall.. The heaviest snow accumulation from this storm (March 1 to March 3) occurred from western Iowa through central Wisconsin and into western lower Michigan (Figure 12).
Signs of Spring?
Cold weather continued through the end of the first week, and a clipper system on March 7 brought some light snow to northern Minnesota and to Michigan. By March 9 the center of high pressure had moved to the east coast, and southerly winds began bringing warmer air into the Midwest. Temperatures reached the 70s well north of the Ohio River under partly sunny skies (Figure 13). A weak cold front moving through the Midwest on March 9 triggered some light showers, but by March 10 clearing skies were found across the Midwest with temperatures rising back into in the 50s and 60s in non snow-covered areas.
As the first ten days of March came to an end a number of rivers and streams in Iowa, Minnesota, Illinois, Indiana, Ohio, and Michigan were at or near flood stage due to snow melt, ice jams, and the heavy precipitation during the previous month.
SDH