Thursday, March 17, 2011

U.S. Spring 2011 Flood Risk

From NOAA: March 17, 2011
Spring Flooding Underway, Expected to Worsen through April

U.S. Spring Flood Risk Map for 2011.

(Image Credit: NOAA)
With spring flooding already underway over portions of the U.S., NOAA forecasters are warning the worst is yet to come. Almost half the country – from the North Central U.S. through the Midwest and the Northeast – has an above-average risk of flooding over the next few weeks, according to the annual spring outlook released today by NOAA’s National Weather Service. This week is also national Flood Safety Awareness Week, and NOAA has partnered with FEMA to encourage residents to prepare for this imminent threat.

The highest spring flood risk areas include the Red River of the North, which forms the state line between eastern North Dakota and northwest Minnesota, the Milk River in eastern Montana, the James and Big Sioux Rivers in South Dakota, the Minnesota River, the upper Mississippi River basin from Minneapolis southward to St. Louis, and a portion of lower New York, eastern Pennsylvania and northern New Jersey. Many metropolitan areas have a greater than 95 percent chance of major flooding, including Fargo, Grand Forks, St. Paul, Davenport, Rock Island, Sioux Falls and Huron. Devils Lake in North Dakota has an 80 percent chance of reaching two feet above last year’s record of 1452.1 feet.

“For the third consecutive year, the stage is set for potential widespread, record flooding in the North Central United States,” said Jack Hayes, Ph.D., director of NOAA’s National Weather Service. “We’ve been coordinating with federal and state partners and high risk communities since December to raise awareness and help them prepare. All the ingredients are in place for major flooding so this situation should be taken very seriously. We’re asking citizens to stay informed and be prepared.”

Warm temperatures in the forecast this week could cause much of the snowpack to melt across South Dakota and southern Minnesota, setting off moderate to major flooding in eastern South Dakota next week. Minor flooding could begin this week on the Mississippi River and its tributaries over southeastern Minnesota and southwestern Wisconsin, leading to moderate to major flooding by early April.

In addition, a series of storm systems are forecast to move across the region during the next two weeks, which could bring additional snow or rain on top of the remaining snowpack. These systems may cause substantial runoff and the beginning of minor flooding in the southern headwater portion of the Red River of the North, eventually leading to major flooding sometime from the last week of March through early April.

Monday, March 7, 2011

February 2011 Arctic Ice Cover

Overview of conditions

Sea ice extent averaged over the month of February 2011 was 14.36 million square kilometers (5.54 million square miles). This was a tie with the previous record low for the month, set in 2005. February ice extent remained below normal in both the Atlantic and Pacific sectors, particularly in the Labrador Sea and the Gulf of St. Lawrence.

While ice extent has declined less in winter months than in summer, the downward winter trend is clear. The 1979 to 2000 average is 15.64 million square kilometers (6.04 million square miles). From 1979 through 2003, the February extent averaged 15.60 million square kilometers (6.02 million square miles). Every year since 2004 has had a mean February extent below 15 million square kilometers (5.79 million square miles).

Tuesday, March 1, 2011

Climatological Winter 2010-11

Climatological Winter ended on February 28. Although most people use the astronomical seasons with Winter starting around December 21 on the Winter Solstice and ending on the Spring Equinox. The problem with this is that the exact starting date for the Solstice and the Equinox varies by several days from year to year.

Meteorologists and Climatologists instead use calendar months for the seasons with December 1 though the end of February defining Winter.

Therefore, as of March 1, 2011, the Climatological Winter of 2010-11 has ended.
The attached map shows the departure from normal for the Winter 2010-11 temperatures for the conterminous 48 states. The areas in green and blue experienced a colder than normal Winter and the areas in yellow and orange experienced a warmer than normal Winter. It was a "tale of two winters" with the high Plains and the area to the east of the Missouri-Mississippi Rivers experiencing a colder than normal Winter. The exception to this was the state of Maine which had a warmer than normal Winter.