Midwest Weekly Highlights - February 22-29, 2008

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More Cold and Snow

The last week of February was not much different than the two previous weeks, with more cold weather and several bouts of snow. In contrast to previous weeks, there was only one major storm that moved through the Midwest, but that along with several smaller events was enough to produce above normal snowfall across the central Midwest (Figure 1).

On the whole, precipitation was below normal across much of the region this week (Figure 2). The exception was a narrow band from western Iowa through northern Illinois, then southeast through Indiana and much of Ohio where precipitation was normal to as much as twice normal. The driest area was minnesota east through the northern half of lower Michigan where precipitation was only 25 to 50 percent of normal. Snow was heaviest from the Mississippi River eastward, with the greatest amounts in lake-effect areas of Michigan, Indiana, and Ohio (Figure 3). There was no change in this week's U.S. Drought Monitor for the Midwest region (Figure 4).

The entire region was colder than normal this week, with daily average temperatures in the central Midwest running 9°F to 11°F below normal (Figure 5). The warmest area was western Minnesota where temperatures were only 3°F to 4°F below normal.
 

More Snow for Eastern Midwest

Winter weather advisories and winter storm watches were in effect from southwestern Missouri to New England on February 22 (Figure 6) as an area of low pressure extending from the Gulf states into the Ohio Valley produced a broad shield of precipitation (Figure 7). This weather system, while not particularly strong, did generate a brief but heavy period of snow along its path from central Illinois into western Indiana . Snow accumulated 3 to 6 inches in this area, with snow falling at the rate of one inch per hour for two to three hours at a number of reporting locations (Figure 8). In Ohio, snow and freezing rain combined to create hazardous roads, and most schools in the Columbus and Cincinnati areas closed for the day.

Most of the region enjoyed cold but fair weather the next two days as high pressure settled in over the Midwest. However, by sunrise on February 25 another low pressure system was gathering strength over the Central Plains and promised to be stronger than the previous system. In anticipation of this winter weather warnings, watches, and advisories were in place from central Iowa/eastern Missouri eastward through New England (Figure 9). The storm intensified as it moved east into central Kentucky by the morning of February 26 (Figure 10). Ahead of the main area of snow, freezing rain coated roads in parts of Lower Michigan, dropping three to six inches of snow across the north-central Midwest, with the heaviest snow from northern Illinois into northwestern Ohio (Figure 11). Lake-effect areas of northern Michigan, Indiana, and northeastern Ohio added on to the snow as strong northwesterly winds followed the storm and produced heavy snow in the days following. The heaviest snow came during the 24 hours ending the morning of February 27 (Figure 12), with more than a foot of snow in LaPorte County, IN (Figure 13), and more than 20 inches for the three-day storm period.

SDH