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Thunderstorms in the Central Plains; Below Average Temperatures in the East

Storms capable of producing large hail and a few strong wind gusts will be possible from central Nebraska into northern Kansas. Below normal temperatures are expected east of the Rockies, while the western third of the country warms up. Read More >

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Ice glaze 4 miles W of Gotebo, OK.
Photo taken by Charles Kuster.

NWS Norman Operations Area during the winter storm.

Another in a series of major winter storms impacted much of Oklahoma and parts of north Texas from the morning of January 28th through the evening of January 29th, 2010. While the storm produced a variety of wintry precipitation, its most significant impacts came with an extended period of freezing rain across southern Oklahoma. Significant icing on trees and power lines resulted in damage to trees and power lines. More details on the storm's impacts can be found through the Oklahoma Emergency Management event page.

The day before the winter storm was unusually warm for a January day in Oklahoma and western North Texas.  On January 27th, the high temperature at Oklahoma City was 65 degrees, which was 17 degrees above normal.  Similarly, Wichita Falls had a high of 67, which was 14 degrees above normal.  Just stepping outside, it did not feel like a major winter storm was on the way.

However, that same day, a strong cold front was sweeping south down the Plains. By Noon, the cold front had pushed into southern Kansas, bringing gusty north winds and a rapid decrease in temperature. Behind the front, temperatures were falling back into the 30s and 40s, and the freezing line at the surface was very near the Kansas-Nebraska border.

Overnight, and into the morning of January 28th, the cold front pushed through most of Oklahoma and all of western North Texas.  By the morning rush hour, surface temperatures had fallen below freezing (32F) generally along and north of a line from Hollis, to Clinton, to the north side of Oklahoma City, to Chandler.  The cold front had stalled to the south in northern Texas leaving a shallow cold air mass in place across much of the area to the north of the front.  As an upper level low became better organized in the southwestern United States, it helped draw warm, moist air north from the Gulf of Mexico.  This warm air, being less dense than the air near the surface, essentially was lifted over the dome of cold air and contributed to the development of widespread precipitation during the morning across much of Texas and Oklahoma.

The changing temperature structure placed a broad swath of southwest Oklahoma and central Oklahoma under-the-gun for a major icing event.  As ice crystals from aloft fell into the layer of warm air being lifted into the area, they would melt, producing liquid water droplets.  Once these liquid water droplets fell to the surface, they would then re-freeze because the surface temperatures were below freezing.  (Learn more about precipitation types at the NWS JetStream online weather school)

During the afternoon, the precipitation increased in intensity particularly over southwest Oklahoma.  To the south, a squall line was producing severe straight-line wind gusts across north Texas, just outside of the National Weather Service Norman county warning area.  The northern end of this squall line may have had some sort of mesoscale circulation associated with it that helped increase the vertical motion and thus precipitation rates across southwest Oklahoma. Therefore, there was a period of fairly heavy icing that set in across much of that area during the afternoon hours.  The radar image to the right is from 1 PM CST.  You can view an animation of the radar from 6 AM to 6 PM here.

As you will see in the loop, a pocket of drier air in the middle of the atmosphere swept in behind the precipitation and started clearing it out of Oklahoma in the late afternoon. At the same time, enough cooling was starting to occur in the warm layer of air aloft to change the precipitation over to sleet across parts of the area, including much of the Oklahoma City metropolitan area.  Had the warm layer stayed more pronounced, it's likely that several more hours of moderate to heavy freezing rain would have occurred ahead of the drier air, and icing could have been much more substantial in central Oklahoma.

During the evening hours, snow gradually tapered off across far northern Oklahoma, while much of the remainder of the area saw periodic freezing drizzle. Overnight, and into the morning of the 29th, a surface low pressure developed along an existing front in southeast Texas and began to move northeast towards western Louisiana.  Behind this low, in the colder air over central Texas, precipitation began to redevelop. This was associated with moisture returning in the middle part of the atmosphere, and with vertical motion in that same layer.  The area of precipitation pivoted through central Oklahoma during the daytime hours in the form of snow.  Localized heavier bands of snow produced reduced visibilities and substantial accumulations.  One notable band set up from southeast Cleveland County, through northern Pottawatomie County, and into southwest Lincoln County.  Several snowfall reports of 8 to 9 inches were received in this very localized area.

When the storm had finally exited on the evening of January 29th, much of the National Weather Service Norman county warning area had received significant accumulations of ice, snow, sleet, or some combination of the three.  Damaging ice accumulations were especially prominent in southwest Oklahoma, particularly over Harmon, Greer, Kiowa, Jackson, Comanche, and Caddo Counties.  At least several people in those areas remarked that it was one of the worst ice storms that they could recollect, at least in the past several decades.