Midwest Weekly Highlights - January 11-17, 2010

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Little Precipitation

The second week of the month was relatively quiet with no strong synoptic scale systems affecting the region. The quiet weather led to another week of below normal rainfall for the Midwest. Only a sliver of southern Kentucky was above normal for the week and the vast majority of the region was below 25% of normal (Figure 1). There was no measurable precipitation across most of the western half of the region (Figure 2). The US Drought Monitor continued to note moderate to severe drought from east central Minnesota, through northwest Wisconsin, into upper Michigan (Figure 3).
 

Warming Temperatures

After a cold start to the year, temperatures warmed during the second week. High temperatures averaged above freezing in the southern half and eastern half of the region. Only the northwest quarter of the Midwest (Minnesota, Iowa, Wisconsin, and northern Illinois) averaged high temperatures below 32°F(Figure 4). Low temperatures ranged from the high single digits to the low 20s. Few temperature records were set during the week.

Temperature departures for the week were slightly below normal, 2 to 4°F, only in southeast Kentucky. Near normal temperatures, with 2°F of normal, extended from western and northern Kentucky to southern Ohio and also from southwest Iowa into northern Missouri. Above normal temperatures were found across the rest of the region with departures of 13 to 20°F in the northern half of Minnesota (Figure 5).
 

Foggy Days and Nights

Dense fog developed during the week affecting all nine states at times. The fog formed as relatively warm air moved over the cooler surface. The extensive snow cover that remained into mid-week (Figure 6) kept surface temperatures cool and caused water in the relatively warm air to condense into fog. Where the temperature was below freezing, freezing fog developed as is seen in this picture from northern Illinois (Figure 7). Dense fog, and in places freezing fog, was widespread late in the week (Figure 8).
 

-MST-