November 1-8, 2006
Midwest Weekly Highlights - November 1-8, 2006
Another Week Below Normal
There was a distinct west-to-east temperature gradient across the region this week, although nearly the entire Midwest experienced below normal temperatures. Temperatures ranged from 6°F to 8°F below normal in Ohio, Indiana, Kentucky, Illinois, and Missouri, to 1°F to 3°F below normal in Iowa, Wisconsin, and parts of Minnesota (Figure 1). The dry weather across the drought areas of the Midwest did help to moderate the cold weather, especially across Minnesota. In the Arrowhead region of the state, temperature departures were actually 0-2°F above normal, and this was also seen in the southwestern portions of the state.
Precipitation during the first week of November was largely non-existent, except for a few locations who saw some scattered light activity, which included a mix of rain and snow. Precipitation totals ranged from 0-10% of normal across the northern and western Midwest, to 100-125% of normal in very few select locations across the Ohio Valley, primarily in Kentucky (Figure 2). Snowfall was abundant in the most lake-favored regions of the Midwest, especially downwind of Lakes Michigan, Superior, and Erie, where snowfall totals were 100-150% of normal for the first week in November.
Long-term dryness remained entrenched across the northern tier states, where extreme drought remains (Figure 3) on account of very short 6-month precipitation totals. Over the past six months, precipitation totals across Minnesota, much of Iowa and Missouri (and even parts of Illinois), have been a meager 25 to 70% of normal. Meanwhile, residents north and east of the Ohio River have experienced a relative wet period, where precipitation totals have been 110 to 130% of normal across a very large area (Figure 4).
Cold Blast and Lake Effect Snow
The first few days of November featured a very cold upper level trough situated over the Midwest (Figure 5), dropping freezing levels throughout most levels of the atmosphere, and setting up breezy conditions across the region. Ottumwa, IA tied a record low temperature on the 1st of 20°F (last set in 1923), and Waterloo, IA tied a record low temperature of 13°F (last set in 1895) (Figure 6). Warm lake-surface temperatures, combined with cold middle-atmosphere temperatures allowed for the rapid development of significant lake effect snow across the northern portions of the Upper Peninsula of Michigan, where Lake Effect Snow Warnings were in place. When the snow subsided on November 2, totals across the area ranged from 5-7 inches (Figure 7). Temperatures through the period were well below normal, ranging from 10 to even 15°F below normal across Wisconsin, Indiana, Michigan, and Illinois. Temperatures dropped precipitously on the night of November 2, resulting in single-digit low temperatures across parts of the upper Midwest by the morning of November 3. Temperatures even dropped into the middle teens across the central Midwest - values more typical of late December than early November (Figure 8).
Once again, as the cold air moved east, the favorable wind regime for lake-effect snow set-up across eastern Ohio, especially across the counties of Lake and Geauga. In the city of Ashtabula, OH, over 12 inches of snow was deposited from the lake-effect snow event, and most locations received 6-8 inches of the fluffy white stuff. The snow, along with whiteout conditions, were enough to snarl traffic on westbound I-90 early on the morning of November 3rd. Over 6 different accidents were blamed on the snow, one of which was a tractor-trailer who had skidded off the road and tipped into a ditch. No major injuries were reported with any of the accidents.
Temperature Moderation?
As the first week of November came to a close, clouds and precipitation were experienced across Missouri, southern Illinois, Indiana, and Ohio, but rainfall amounts were generally light. Of greater significance was the return to near-normal, and even above normal temperatures as the cold polar airmass shifted off of the east coast, allowing southerly winds to transport warmer and moisture-rich air northward, blasting out any remains of what cold air was experienced during the first part of the week. Daytime temperatures on the 8th soared into the upper 70's °F and even lower 80's °F across portions of Iowa, while 70°F weather was common across Missouri and Minnesota (Figure 9). These temperatures were some 15-25°F above normal for this time of the year (Figure 10). Record high temperatures occurred in Mankato, MN, 82°F (previous record was 76°F set in 2001), and Webster City, IA 81°F (tied record set in 1931). In addition, record high temperatures were tied in Springfield, MO (80 °F, last set in 1980), and Joplin, MO (83°F, also set in 1980).
How long will the mild weather last? Will Mother Nature "elect" for a new regime to take hold during the second week of November? Find out in next week's edition of the Midwest Climate Watch.
Kruk