2013-05-01

Winter is coming . . . back, that is.

A sharp cold front is ushering in some of the coldest temperatures on record for the month of May in the southern Plains and into Texas, with temperatures plummeting from the mid-90s on Tuesday in Amarillo, Texas, to the upper 20s on Wednesday night. Houston may be in line to set a record for the coldest May day on record if the low temperature on Friday or Saturday morning falls to 43°F.

These before and after images showing the profound temperature change as the cold air sags south, toward the Gulf of Mexico. Thee images come from computer-model projections:



Surface temperatures on Wednesday afternoon.

Credit: Weatherbell.com.



Forecast surface temperatures on Friday morning for the same region.

Credit: Weatherbell.com.

As an example of the cold front's strength, consider that as of 1 p.m. Central time on Wednesday, it was snowing and in the mid-30s in northwestern Iowa, while in southeast Iowa, on the warm side of the front, it was partly cloudy and near 80°F.

According to Houston Chronicle science reporter Eric Berger, Houston has only had one May day in recorded history with a temperature below 45°F.

The cold front may even be accompanied by light snow and sleet in parts of Oklahoma and the Texas Panhandle. Here's how the National Weather Service forecasters in Tulsa, Okla,. described the cold front in an online discussion (the all-caps format is NWS style): "AN ALMOST UNBELIEVABLY STRONG COLD FRONT FOR EARLY MAY WILL BLAST THROUGH THE AREA WED NIGHT AND VERY EARLY THURSDAY MORNING . . . AS FAR AS I KNOW . . . SNOW HAS NOT FALLEN IN MAY IN OUR FORECAST AREA IN THE PERIOD OF RECORD SO WE ARE TALKING ABOUT AN UNPRECEDENTED EVENT."

Heavier snows were falling Wednesday across the Denver metro region, where 6 inches or more of snow may fall, with more than 2 feet likely in the Rocky Mountains. Colorado residents are no doubt tired of the cold and snow after the snowiest April on record in some spots, and low temperatures that frequently dipped into the teens to single digits. A major plus to the snow, though, is that it is lessening the drought and at least temporarily dampening the wildfire risk across much of the Rocky Mountain State.

Computer-model projections show that a narrow strip of accumulating snow may extend across parts of Nebraska, Minnesota and northwest Wisconsin through Friday. Minneapolis may break its record for the biggest May snowstorm, which is 3 inches, recorded in 1946.



The snowy scene in Boulder, Colo. on Wednesday morning.

Credit: Claudia Tebaldi, Climate Central.

According to Paul Douglas of WeatherNation TV, since 1891 there have only been five 2-inch-or-greater snowfalls in the Minneapolis-St.Paul.

“Numbing air over central Canada, displaced unusually far south, is responsible for this March-like time warp — enough cold air in the lowest mile of the atmosphere for an historic slush-storm,” Douglas wrote on his blog. “The ground is warm (it was 81°F Sunday) so any snow will melt on contact this afternoon but we may still wake up to a slushy 2-5" by Thursday AM. A plowable 3-7" snow may fall on some suburbs. Unreal.”

The cold and snow is the result of a persistent dip in the jet stream across the Midwest and parts of the West, which has allowed cold, Canadian air masses to move southward into those regions. The weather pattern has been largely stuck during the past month, courtesy of a "blocking high" over Greenland that is acting like a stoplight, preventing storm systems from progressing from west to east across the country.

More than 1,100 snowfall records and 3,400 cold records were set during April, and May is likely to average out to be cooler than average across the South Central states, according to the most recent climate outlooks from the National Oceanic and Atmospheric Administration.

Related Content
Wild Weather Swings May Be a Sign of Climate Change
Spring Blizzard to Dump Heavy Snow, Spawn Severe Storms
Spring Blizzard Aids Drought-Stricken States
From Heat Wave to Snowstorms, March Goes to Extremes
Boost to Colorado Snowpack May Lessen Wildfire Risk

Show more