The Climate Prediction Center (CPC) has issued the latest round of seasonal climate outlooks, which include the winter 2010/2011 winter season. The winter outlook can be found here. A strong La Niña is currently ongoing in the Pacific, and this will likely have a significant impact on the weather across the northern plains. The most likely impacts include an enhanced threat for more frequent cold snaps, and an increased threat for above normal precipitation.
While the temperature signal is quite strong during La Niña winters the precipitation signal is weaker. The main factors which usually influence the seasonal climate outlook include:
1) El Niño and La Niña - which comprise El Niño/Southern Oscillation or ENSO. Impacts of these events are summarized by separating 3-month observations from 3 or more decades into El Niño, neutral, and La Niña sets, averaging each separately, and then computing anomalies.
2) Trends - approximated by the Optimal Climate Normals (OCN) tool as the difference between the most recent 10-year mean of temperature or 15-year mean of precipitation for a given location and time of year and the 30-year climatology period (currently 1971-2000).
3) The tropical 30-60 day oscillation - sometimes called Madden Julian Oscillation (MJO) - affects climate variability within seasons.
4) the North Atlantic Oscillation (NAO) and the Pacific North American (PNA) patterns - which affect the temperature anomaly pattern especially during the cold seasons. These phenomena are currently known to be predictable only over a week or so.
5) The Pacific Decadal Oscillation (PDO) - an ENSO -like pattern of climate variability affecting both the tropics and the North Pacific and North American regions, but which varies on a much longer time-scale than ENSO.
These, and other tools are called "ENSO composites", and are used to subjectively modify the forecast. Other tools include Soil Moisture anomalies, which can impact the regional climate; Statistical Forecast Tools - Canonical Correlation Analysis (CCA), Screening Multiple Linear Regression (SMLR), Constructed Analogue (CA) And Ensemble CCCA (ECCA).
Moderate-to-strong La Niña conditions continue in the tropical Pacific Ocean. Sea surface Temperatures (SSTS) in the tropical Pacific have declined to values ranging from 1 to 2.5 degrees c below long-term averages. Buoy measurements of ocean temperature from the surface to 600 meters below the surface indicate the existence of a pool of subsurface water which is from 1 to 6 centigrade degrees cooler than long term averages, between about the date line to near the coast of South America, with coldest temperatures between about 50 and 125 meters below the surface, between about 160w and 110w. This feature supports the maintenance and continuation of this La Niña event.
Below are the CPC outlooks for the December 2010 through February 2011 time period, as well as the March through May 2011 time period.
Above is the CPC temperature outlook for the December 2010 - February 2011 time period.
Above is the CPC precipitation outlook for the December 2010 - February 2011 time period.
Above is the CPC temperature outlook for the March - April 2011 time period.
Above is the CPC precipitation outlook for the March - April 2011 time period.
From a historical perspective, the winters of 1955/56, 1973/74, 1975/76, 1988/89, 1998/99 and 2007/08 were influenced by a strong La Niña event. Below is a table of the December through February and November through March total snowfall and average temepratures. Based on the information below, the temperatures during La Nina winters are most commonly colder than normal, while the snowfall totals for the seasons listed is greater than normal. These are for comparative only, and not to be used as an outlook.
|Winter Season totals and Averages Snowfall (inches)|
|Winter Season totals and Averages Temperatures (F)|
The data used in these station's record may include data from more than one, possibly incompatible, locations. It reflects the longest available record for the Fargo and Grand Forks Area. *DJF=December through February, NDJFM=November through the following March. The green (orange) shading represents seasons with above (below) normal snowfall and temperatures, respectively.
For additional information contact Mark Ewens, Climate Services Focal Point at the Grand Forks NWS at 701.795.5198 or email Mark at Mark.Ewens@noaa.gov