An extraordinarily dangerous blizzard may strike the high plains this weekend with total snowfall amounts perhaps as high as 40 inches, according to the European ECMWF model. A storm system just entering California today will slowly move across the southern Rocky mountains. On Friday, as a low pressure area develops over northern New Mexico a strong flow of warm humid air will flow up slope, on strong southerly winds, from the Gulf of Mexico. Two areas of high pressure, one a warm high centered over Florida and the other a cold Arctic air mass moving down over the Great Lakes will trap the moisture flow along a frontal boundary. The developing storm will turn the flow of Gulf air towards the west, up the slope of the great plains towards the Rocky mountains. The moist Gulf air will be lifted up both by the dynamics of the storm and the increase in elevation of the ground surface from the Gulf coast to the Rocky mountains (meteorologists call this isentropic lift). Moreover, the Gulf air layer will rise up over the wedge of Arctic air that will be trapped in eastern Wyoming, eastern Colorado and western Nebraska by the front range.
Wednesday morning update: The storm system is forecast to be a bit north of the Tuesday afternoon forecasts so the impacts to South Dakota may be greater than the earlier forecast indicated. This could be an extremely dangerous situation on the Pine Ridge reservation.
Blizzard conditions with sustained winds of over thirty-five miles per hour and snowfall rates of two inches per hour may produce white out conditions at the peak of the storm. Both the European ECMWF and American GFS models agree that an extremely blizzard will take place this weekend although they differ on the details of timing and where the peak snowfall will take place.
Moreover, on the warm side of the storm, in north Texas, Oklahoma and Arkansas, NOAA’s severe weather prediction center (SPC) is already forecasting severe thunderstorms this weekend. Severe thunderstorms, possibly with tornadoes, are predicted in an area centered around the state of Oklahoma.
This is one of the worst set of forecast maps I have ever seen for the high plains. Fortunately, we have the technology to warn people to prepare for it. I hope that the models are wrong, but given how the breakdown of the polar vortex around New Year’s day has affected the weather so far this winter, I think we are going to see a bad storm.