Wednesday, March 23, 2016

March Storm Hammers Denver, Heads for Central U.S.

Earlier this week there was a lot of attention on the potential for snow in the Plains and upper Midwest, not really an unusual occurrence for this time in March. There was also some attention being given to the potential for severe weather today into Thursday from eastern Texas into Missouri and Illinois. Late on Tuesday, though, attention turned to the Rockies as blizzard warnings were issued for parts of Colorado, including the Denver area, Wyoming, southwestern Nebraska and northwestern Kansas.

Denver and the central Rockies enjoyed mild weather on Tuesday with highs in the 70s. Rain overnight changed to snow early this morning as a storm intensified over the central Rockies.

Surface weather map at 12:00 noon MDT March 23, 2016

By 7:00 a.m. observers in Fort Collins were reporting 7 to 10 inches of wet snow, while further south in Boulder snowfall ranged from 6 to 7 inches in Boulder to more than 18 inches in higher elevations west of the city.

Snowfall as of 6:00 a.m. MDT March 23, 2016

Traffic cam photo from the morning of March 23 on I-70
outside of Denver
By midday snow totaled more than 20 inches in some locations. The snow was whipped around by winds up to 50 miles per hour reducing visibility to near zero. The heavy wet snow quickly snarled highway traffic. By early afternoon Denver International Airport threw in the towel and closed until conditions could improve. All Interstates in and out of Denver were closed, and most other highways were closed as well. Chris Spears, a meteorologist with KCNC-TV, the CBS affiliate in Denver and a CoCoRaHS observer, stated that the storm in Denver was "the worst weather I've ever personally witnessed in 38 years of living!!"

The heavy, wet snow (snow-to-water ratios as low as 7 to 1) coated trees and power lines, and with winds regularly gusting in excess of 45 mph it didn't take long before power outages began to develop. More than 135,000 customers were without power by late Wednesday morning in the Denver area.

Denver endured nine consecutive hours of blizzard conditions by mid-afternoon. Thundersnow was reported from Denver into Kansas and Nebraska. At 6:00 p.m. MDT the U.S Cooperative station in Boulder reported 16.8 inches of snow with 2.40 inches of water equivalent. By this time snow was tapering off and breaks were appearing in the clouds.

In the warm sector SE of the low center conditions were ripe for thunderstorms this afternoon. A tornado watch was issued for southeastern Nebraska, southwestern Iowa and northeastern MO until 10:00 p.m. tonight. The severe weather outlook indicated an area of Slight Risk of severe storms from northeast Texas to southern Iowa.

The strong winds circulating around the strong low pressure system complicated efforts to control a huge wildfire along the Kansas-Oklahoma border.  The fire covered 75 square miles, and the plume of smoke from the fire was clearly visible on radar and satellite today.

The smoke plume from a wildfire in Kansas is visible on the Dodge City radar

The plume from the wildfire is clearly visible on this satellite image taken at 3:00 p.m. CDT

Early this evening Winter Storm Warnings were in effect from southeast Wyoming eastward across southern Minnesota, northern Iowa, central Wisconsin, and the northern half of lower Michigan. Nine to 13 inches of snow are expected along the path of this storm along with high winds. Seven counties surrounding Green Bay, WI are in a Blizzard Warning from late tonight through early tomorrow afternoon as strong NE winds off of Lake Michigan combine with the snow to lower visibility.

Watches, warnings, and advisories in effect as of 8:55 p.m. CDT March 23.
The severe weather threat will shift east into the Ohio Valley and southeastern U.S. on Thursday, while colder air spills into the central U.S. behind the low pressure system as uit lifts northeast through the Great Lakes.

Convective outlook for Thursday, March 24, 2016 issued at 12:30 p.m. CDT

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