Midwest Overview - February 22-28, 2003

The last week of February was very cold in the Midwest, with the well established dry northwest - wet southeast pattern dominating. Virtually no precipitation fell in northern Minnesota, while 2-3 inches of liquid water equivalent were received in Kentucky (Figure 1). Parts of southern Missouri, and most of the Ohio Valley and Kentucky were more than 200% of normal precipitation for the period February 22-28, while most of the remainder of the Midwest received less than 50% or even 25% of normal (Figure 1a). A one-two punch brought most of the precipitation during the week, as a strong low pressure center passed to the south of the Midwest on the 22nd, and was followed closely by a clipper system on the 23rd and 24th. A substantial swath of snow was left by the storms, with 10-12 inch totals across much of southern Missouri and the southern tip of Illinois, turning to the northeast to cross Indianapolis and Detroit (Figure 2). The storm track was depressed to the south by strong and persistent high pressure that brought much colder than normal air to the region. The far western Midwest was 15-20°F below normal for the week, while the rest of the Midwest was 6-12°F below normal (Figure 3). The drought-afflicted areas of the Midwest did not receive much moisture, and so continued to deteriorate, while the Ohio Valley and southern edge of the Midwest were abundantly moist. The drought status in southwest Missouri was eased, while the situation became more severe in northern Minnesota (Figure 4, National Drought Mitigation Center).

As the major low was crossing eastern Kentucky on the 22nd, heavy snow was occurring in the cold sector to the northwest over Indianapolis (Figure 5, NWS). The 7.8 inches from this storm, in addition to 2.5 inches from the following clipper, helped to establish a new record in Indianapolis for the snowiest February with 21.7 inches. This has now become the 4th snowiest winter at Indianapolis, and many other locations in southern Missouri, Indiana, and Ohio are now approaching a top 5 winter for snow fall.

The warm sector in front of the low reached into eastern Kentucky late on the afternoon of the 22nd. Some particularly strong thunderstorms for the time of year developed ahead of the cold front (Figure 6, NWS). Near the town of Oakdale, KY, an F1 tornado imbedded in strong straight line winds descended on a trailer park, killing two and seriously injuring seven others as it destroyed six of the trailers. Numerous other severe hail and wind reports were associated with a number of storms in the area (Figure 7, Storm Prediction Center). The storms also brought heavy rain to saturated areas of Kentucky, sustaining high levels along some of the large rivers, including the flooding lower Ohio at Newburgh, IN (Figure 8, USGS).

The flow of very cold air into the region behind the low set some new record low minimum temperatures in the Midwest from Kansas City, MO, to Marquette, MI. Many location in Missouri also set records for record low maximum temperatures on the 25th. The cold air froze the surface ice pack on the Great Lakes to an extent and thickness greater than any seen in the last 6 year (Figure 9, National Ice Center). This is actually a good thing, as the warm and open water conditions earlier in the winter enhanced evaporation and caused lake levels to dip very close to record low February values in the Michigan-Huron system (Figure 10, U.S. Army Corp of Engineers). The hope of a quick recovery of lake levels is even less likely due to the extremely limited snow pack present at the end of the month in the Great Lakes basin (Figure 11). At the end of February, the Michigan-Huron level was 576.64 feet, only half a foot above the all-time February record of 576.15 feet, set in 1964.