Midwest Weekly Highlights - January 22-31, 2009

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More Cold, Major Storm

The last ten days of January brought more cold weather to the entries Midwest and a major winter storm to the Ohio Valley region. Heavy snow, heavy freezing rain, and heavy sleet combined to produce widespread damage and inconvenience across parts of five Midwestern states.

Temperatures this period ranged from 2°F below normal in southeastern Kentucky to as much as 10°F below normal in western Wisconsin (Figure 1). A persistent and deep snow cover across the northern half of the Midwest and several more surges of Arctic air allowed for subzero minimum temperatures for at least half the days this period.

While there was some light snow across the northwestern half of the region this period, precipitation was much below normal (Figure 2). In contrast, precipitation was two to three times normal from southern Missouri east through Kentucky and southern Ohio, largely as a result of the major storm January 27-29. Severe Drought continues to persist over northern Wisconsin as depicted on the January 27 U.S. Drought Monitor (Figure 3). While abnormally dry conditions continued over Kentucky, there will likely be further improvement from this week's rain which fell after the issuance of the Drought Monitor.

At the end of the month much of the Midwest had snow on the ground, with the exception of parts of western and north central Missouri, and far southeastern Kentucky (Figure 4). Two to more than three feet of snow covered the ground in northern portions of the Michigan Upper Peninsula.
 

Winter Storm Hammers Ohio Valley

The last ten days of the month began with a few cold but quiet days. High pressure sprawled across much of the contiguous U.S., and only some light snow occurred as weak upper level disturbances moved through the Midwest. Signs of trouble were already evident early on January 26 as a variety of winter weather-related watches, warnings, and advisories were issued from Texas to New York (Figure 5). During the night on January 26 moist air being drawn up over a frontal boundary in the southern states resulted in a wide swath of precipitation that extended from Texas to the mid-Atlantic states. By the morning of January 27 a broad trough of low pressure in the upper atmosphere was being reflected on the surface as a developing low pressure center in southwestern Texas (Figure 6). Warm air aloft combined with sub-freezing temperatures at the surface resulted in freezing rain from Texas through Arkansas, southern Missouri, southern Illinois, southern Indiana, and much of Kentucky. Along the Ohio River the precipitation started out as freezing rain and drizzle, then changed to sleet and then snow. As much as three inches of sleet accumulated from Missouri east to Indiana, and north of that, heavy snow. South of the wintry precipitation, heavy rain fell on southern Kentucky and southward, resulting in some minor river flooding. Precipitation fell throughout the day January 27 and continued into the overnight hours (Figure 7). On the morning of January 28 the center of the well-organized storm was approaching the central Appalachians but precipitation was still occurring over the eastern half of the Midwest (Figure 8).

On January 27 the snow in southern Indiana and northern Kentucky changed back to freezing rain, while heavy rain continued over southern Kentucky. Heavy snow fell from eastern Missouri across south-central Illinois into central Indiana. Six to eight inches of snow fell in the St. Louis metropolitan area, with 12.5 inches in the Indianapolis area, the sixth largest snowstorm on record. However, the higher totals were found south of Interstate 70 (Figure 9). In southeastern Illinois 12.5 inches was measured in Sumner (Lawrence County) by a NWS observer, and in Gosport, IN (Owen County) 16.3 inches was measured by a CoCoRaHS observer.

Ice accumulations from the freezing rain produced massive damage to trees and power lines. Ice accumulation from southern Illinois through south central Indiana and into central Ohio ranged from 0.25 to 0.50 inches. In extreme southern Missouri, far southern Illinois, southern Indiana and northern Kentucky and far southern Ohio the ice was more than an inch thick, with up to 1.5 inches in the Ozarks of Missouri. Total precipitation from this storm exceed three inches of much of southern Kentucky (Figure 10)
 

Impacts from the Storm

The heavy snow resulted in the usual travel-related impacts and numerous schools (including colleges and universities) and businesses were closed from Missouri eastward through Ohio. However, the most severe impacts occurred in the areas that received the heavy freezing rain. Tree and power line damage was massive from Missouri to Ohio. The ice followed by heavy snow caused roof collapses in Branson, MO (Taney County) and crushed a dock at a state park marina. Power outages were widespread from Missouri, where there were more than 100,000 homes without power, into Indiana. Ameren Illinois reported more than 7,000 customers without power at the peak of the storm in southern Illinois. The worst-hit area was western and northern Kentucky into southern Indiana. Snow and ice caused a roof collapse in Evansville, IN, and snow caused the roof of a building on the west side of Indianapolis to collapse. In southern Indiana an estimated 92,000 customers were without power. The Kentucky Public Service Commission reported that at least 607,000 homes and business were without power following the storm, the largest power outage on record for the state. This figure did not include municipal utilities or rural electric cooperatives within the Tennessee Valley Authority system, and estimates put the total number at more than 700,000 customers. The power outages affected many public water systems limiting drinking water supplies. On January 31 Kentucky Governor Steve Beshear ordered the activation of all Kentucky Army National Guard units and some Air National Guard units, bringing the total number of guardsmen responding to the storm to 4,600.

As of January 30 there were seven fatalities attributed to the storm in Kentucky (four of them from carbon monoxide poisoning), and three in Indiana (one from a traffic accident, two from heart attacks while shoveling snow).

For additional information on impacts of the storm in Kentucky, see this storm impact summary from the Kentucky Climate Center

A Break from the Cold?

The month ended with strong southwesterly winds setting up across the Midwest, pushing temperatures above normal one of the few times this month. High temperatures on January 31 reached well into the 60s in Missouri, with the mercury reaching 71°F in the Kansas City area. High temperatures rose into the mid 40s across snow-covered Minnesota, but remained in the 20s and 30s over the eastern half of the Midwest.

SDH