Sunday, April 21, 2013

An Elusive Spring

The far western and southeastern third of the U.S. have enjoyed a warmer than average April so far, but warm spring weather has been a hit or miss (mostly miss) proposition for the central U.S.

Temperatures from the Dakotas through central Texas have been below normal this month. Temperatures have been 10 degrees below normal across the Dakotas and Minnesota, with with departures of more than 15 degrees below normal in North Dakota. The cold is one thing, but these areas have also received 5 to 6 times normal April snowfall.

Deep snow cover over Canada has maintained the supply of cold air this spring and there is still 30 cm (12 inches) or more on the ground across the Prairie provinces.  A persistent upper level trough pattern over over the central U.S. has deflected the storm track farther south this spring and allowed the cold air to spill farther south than normal.

Snow depth over Canada and the northern U.S. as of April 20.
In the past two days more than 600 record lows and 560 record low maximum temperatures have been recorded from the Dakotas to the southern tip of Texas.

Record low temperature records set or tied on April 19, 2013.
Maps from the National Climatic Data Center
Record low temperature records set or tied on April 20, 2013.
Maps from the National Climatic Data Center

Yesterday morning lows were in the single digits in the Dakotas and Minnesota and in the 30s as far south as the Big Bend area of Texas.

Minimum temperatures for the morning of April 20, 2013

Is there light at the end of the tunnel?  There's a light, but it might be another freight train, at least in the short term. An upper level system is moving into the Pacific Northwest today and will drop into the central Rockies by Tuesday. The surface low will organize in the Central Plains and bring another round of snow to an area from Wyoming and Colorado to Minnesota. Another surge of cold air will follow this system.

Probability for 4 or more inches of snow between 7:00 a.m. CDT Monday, April 22 and 7:00 a.m. Tuesday, April 22

Forecast high temperatures on Friday, April 26.
However, a warmup is in the cards by next weekend, and there are indications that spring may finally take hold as we wrap up the month of April.    

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