Forecast for the start of water year 2012: Dry across the U.S. southern tier including southeastern Colorado

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Click on the thumbnail graphic to the right for the November precipitation outlook from the Climate Prediction Center. Here’s a report from Chris Woodka writing for The Pueblo Chieftain. From the article:

The National Oceanic and Atmospheric Administration on Thursday released its forecast for coming months, based on new observations that show La Nina will influence weather patterns. La Niña is a cooling trend in the Pacific Ocean that sends moisture to the northern tier of the United States, often causing drought in the southern plains…

“The evolving La Nina will shape this winter,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “There is a wild card, though. The erratic Arctic oscillation can generate strong shifts in the climate patterns that could overwhelm or amplify La Nina’s typical impacts.” The oscillation could cause wide swings in temperatures and precipitation patterns over the winter months, although it is impossible to predict when or where they will occur. The Arctic oscillation is always present and fluctuates between positive and negative phases. The negative phase of the Arctic Oscillation pushes cold air into the U.S. from Canada. The Arctic oscillation went strongly negative at times the last two winters, causing outbreaks of cold and snowy conditions in the U.S. such as the “snowmaggedon” storms of 2009-10 on the East Coast. Strong episodes typically last a few weeks and are difficult to predict more than one to two weeks in advance, according to NOAA.

Here’s the Prognostic Discussion For Monthly Outlook from the Climate Prediction Center. As is often the case with La Niña, Colorado is in an area that is hard to predict. From the discussion:

ABOVE NORMAL TEMPERATURES ARE FAVORED FOR A LARGE AREA ACROSS THE SOUTHERN CENTRAL US, WITH AN EXTENSION INTO THE GREAT LAKES…

FOR REMAINING AREAS THAT ARE NOT HIGHLIGHTED, THERE ARE EQUAL CHANCES (EC) FOR BELOW, NEAR, AND ABOVE-NORMAL MEAN TEMPERATURE DURING THE PERIOD AS THERE WERE NO STRONG AND CONSISTENT CLIMATE SIGNALS AMONGST THE AVAILABLE FORECAST TOOLS IN THESE AREAS.

THE NOVEMBER MONTHLY PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES FOR BELOW-MEDIAN PRECIPITATION FOR THE SOUTHWEST AND ACROSS TEXAS INTO THE SOUTHEAST…

FOR REMAINING AREAS THAT ARE NOT HIGHLIGHTED, THERE ARE EQUAL CHANCES (EC) FOR BELOW, NEAR, AND ABOVE-MEDIAN TOTAL PRECIPITATION DURING THE PERIOD AS THERE WERE NO STRONG AND CONSISTENT CLIMATE SIGNALS AMONGST THE AVAILABLE FORECAST TOOLS IN THESE AREAS.

Click through and check out the forecast. They link to a glossary for many of the terms used in the forecast.

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