Wednesday, December 2, 2015

A Wintry End to a Warm, Wet November

This November was warmer than normal in the eastern two-thirds of the nation, and cooler than normal in the west. Drought was erased throughout much of the central U.S., with only a few parts of the country on the dry side including the Northeast, the far Northern Plains, and northern and southern California. This is in sharp contrast to last November which was cold and snowy, culminating in a historic lake-effect snow in Buffalo in mid-November.

Rain in Texas was measured in inches several times, and November rain pushed annual rainfall totals record levels in several locations. Both Dallas and Waco had their wettest falls on record with almost 22 inches of rain. November rainfall helped Dallas shatter its annual rainfall record of 53.54 inches set in 1991. As of November 30 the total for the year so far is 58.78 inches. The new record is likely to end up more than 60 inches before the end of the year.

Southern and central Florida experienced one of its warmest Novembers on record. In southern Florida Ft. Lauderdale and Naples notched their warmest November on record, and Miami and West Palm Beach had their second warmest November. More information on the warm November in southern Florida can be found here. In central Florida, Daytona and Vero Beach set a new November temperature record, and Melbourne tied the record. Orlando had it's second warmest November on record. More information on November weather in central Florida can be found here.

 The entire menu of winter weather - snow, sleet, and freezing rain - made an appearance and impact the last 10 days of the month. From November 20-22 a snow storm laid down a blanket of snow from the Colorado Rockies and Dakotas eastward across Iowa, southern Wisconsin and the northern halves of Illinois and Indiana, and Michigan. As much as 18 inches of snow was reported at locations in South Dakota and northern Illinois.

Warm weather returned in the days after the storm, and by November 26 most of that snow had melted away.

Even as that system moved to the east, another strong upper low was coming ashore along the west coast. This closed low moved inland and began to intensify and slow down.

500 millibar map for 7:00 a.m. EST November 30, 2015

The large extent of the upper level low is clearly seen in this satellite water vapor image at 5:45 a.m.Tuesday, December 1.

On the surface, cold air spilling south produced heavy freezing rain over central Oklahoma and across eastern Kansas on Friday and Saturday, bringing down trees and power lines. Some icing extended into Iowa and Minnesota as well.

A glaze of ice coats Cleveland County, OK.
Photo by CoCoRaHS observer David Demko
An ice-encased rain gauge greeted CoCoRaHS observer Brenda Culbertson in northeast Kansas on three mornings over the weekend
The low continued to deepen and by Monday was spinning over the central and northern Rockies, reflected on the surface by a low over Nebraska.

Surface map for 9:00 p.m. CST Monday, November 30.

This low began to deepen and move slowly north, and a broad area of snow blossomed across the Dakotas, Minnesota, and northwestern Iowa. By the time this low moved through the Great Lakes into Canada, another 4 to 15 inches of snow was on the ground.

As of this morning 37.4 percent of the U.S. was covered by snow with an average depth of 1.5 inch. Last year at this time most of the November snow had melted and only 22.5 percent of the country was covered, with an average depth of one inch.

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