• Event summary
• Snowfall map (graphic)
• Snowfall amounts (text)
• Forecast history
• Excerpts from Area Forecast Discussions issued by WFO Norman:

Event summary

An early-winter storm dumped up to a foot of snow on parts of northern and western Oklahoma on Monday, 23 December, into early Tuesday, Christmas Eve. Precipitation - mostly in the form of rain, with scattered thunderstorms - first developed late Sunday night across much of northern Texas and southern Oklahoma. Snow - accompanied by thunder at times - first overspread western Oklahoma early Monday morning, and spread north and northeast into northern Oklahoma by early Monday afternoon. The rain/snow line hovered across southwestern and central Oklahoma for much of the day Monday. Most of the heavy snow fell during the day on Monday, but light snow continued in many areas into the early morning hours of Christmas Eve.

The snowfall gave parts of the southern Plains a rare white Christmas. In Oklahoma City, two inches of snow fell and provided the city with it's first white Christmas since 1975. Heavy snow (defined in Oklahoma and western north Texas as four inches or more in 12 hours) fell across much of Oklahoma north of Interstate 40. Snowfall was greatest in a broad area from near Hinton, in western Oklahoma, northeastward to near Enid and Blackwell in north-central Oklahoma (see snowfall amounts). Accumulations of 7 to 10 inches were common in these areas, with a maximum of 12 inches reported in Enid. Precipitation fell mostly as rain over much of central and southern Oklahoma, but areas from the southwest corner of Oklahoma northeastward to Oklahoma City experienced a mixture of rain and snow, with several inches of accumulation.

This winter storm continued east and northeastward, eventually leaving a continuous band of heavy snow from southern Colorado all the way to New England. It was the same storm that produced record Christmas-Day snows over much of the northeastern United States, including storm totals over three feet in parts of upstate New York.

Forecast history

Area Forecast Discussions (or AFDs) are issued routinely by NWS forecasters to share their forecast reasoning with other offices, emergency managers, the media, and various other users. The history of the forecast process at WFO Norman during the week prior to the heavy snow event can be found in these AFD excerpts from WFO Norman. The discussions are somewhat technical at times, but show that, despite conflicting computer forecast data, the WFO recognized the potential for a Monday-Tuesday storm a week in advance, and recognized the potential for heavy snow a full four days before the storm occurred.

Computer forecast "models" picked up on a storm system over the northern Pacific Ocean more than a week before the snow event in Oklahoma. The models forecast the system to intensify over the southwestern United States before moving toward the southern Plains sometime between Sunday and Tuesday (22-24 December). But as typically happens when forecasting weather systems four to seven days in advance, forecasters had to struggle to resolve differences among the various computer models (which are referred to in the discussions as "GFS," "AVN," "MRF," "ECMWF," "Canadian," "Eta," etc.) Model differences in track, speed, and intensity of the storm system, as well as the amount of cold air that would be available, led to considerable uncertainty regarding when the storm would arrive, how much rain or snow would fall, where any heavy snow might fall, and even if precipitation would fall as snow at all. The AFDs clearly show the extent to which forecasters had to struggle with these model differences.

Despite the conflicting data, forecasters at WFO Norman issued an initial winter storm outlook on Thursday morning, 19 December - four days before the storm. The outlook highlighted the potential for heavy snow in the southern Plains Monday into Christmas Eve. Winter storm outlooks were updated regularly through the following Saturday. The first winter storm watch, highlighting the possibility of a significant winter storm beginning late Sunday night into Monday, was issued early Sunday morning, 22 December for most of western north Texas and all of western, central, and north central Oklahoma. On Sunday evening, the watch was upgraded to a winter storm warning for most of northern, central, and southwestern Oklahoma, indicating that significant winter storm conditions were imminent in these areas on Monday.

Both the winter storm watch and the winter storm warning covered virtually all of the areas that received heavy snow in western and northern Oklahoma. Only eight of the 29 counties in the winter storm warning did not receive heavy snow, but all eight received measurable snowfall of one to three inches somewhere in the county. Lead times of the winter storm watch (time between issuance of the watch and the verified occurrence of four or more inches of snow at a given location) were roughly 30 to 36 hours. Lead times for the warning were roughly 15 to 21 hours.