Midwest Overview - January, 2003

January 2003 was surprising in several ways in the Midwest. El Niño did not bring its warming influences as far east as usual; some media described January as a "throwback" to old-fashioned cold winters. However, this cooler than normal month for the Midwest (32nd coldest on record) was actually much better characterized by its dryness, ranking 8th driest for the past 109 years. Precipitation amounted to less than an inch on average over six of the nine states in the Midwest region (Figure 1), with the vast majority of the region receiving less than 50% of normal (Figure 2). The precipitation deficit in the northern half of the Midwest meant that little snow fell in areas dependent on it as the basis for a thriving winter recreation industry worth $3.4B annually in Wisconsin alone (Figure 3). In addition to Wisconsin, Minnesota and Lower Michigan were also subject to the "snow drought", with Minnesota receiving less than 50% of normal snow fall over most of its extent (Figure 4). It was only in the last 10 days of the month that snow started accumulating in the northern Midwest, especially in the lake effect belts. The snow cover arrived and contributed to the strongest cold outbreak since January 2000 in many places, and even back to the winter of 1997 in other places. The warmth of the western ridge was still evident in the January temperature departures that were positive in parts of Minnesota and Iowa, but a large portion of the eastern Midwest was 3-6°F below normal for the month (Figure 5).

While the thin snow cover protects the ground from further dessication in the northern Midwest, the status of drought in the central Midwest substantially intensified over the course of the month (Figure 6, National Drought Mitigation Center). Furthermore, there is a potential in El Niño years for the spring to be somewhat drier than normal in the Great Lakes/Ohio Valley area, leading the Climate Prediction Center to forecast continued drought in the region (Figure 7, Climate Prediction Center). However, in a statistical sense, the broader likelihood in all years with a dry winter in the Midwest is for spring to tend towards normal or wetter than normal conditions. Given an October to January precipitation total for the region that is in the lowest third of observed precipitation totals, as it was this season, the chances of remaining in the lowest third of precipitation totals for the February to April period is only 14%. There is a 42% chance of being in the normal precipitation range, and a 44% chance of receiving precipitation totaling in the upper third of the distribution.