Winter 2010–2011 Forecast Summary

Over the past few weeks a variety of winter forecasts were released to the public, all of which are hinting at another season of extremes for the United States.

While the extremes of last winter will likely not be felt in the same regions, with this coming winter a new round of crazy weather could be in store for areas far removed from the 2010 blizzard-plagued mid-Atlantic and northeast.

To make it easier for you, here's a regional summary of pretty much every forecast released:

Pacific Northwest: Colder and wetter than average. La Niña often brings lower than average temperatures and increased mountain snow to the Pacific Northwest and western Montana during the winter months, which is good for the replenishment of water resources and winter recreation but can also lead to greater flooding and avalanche concerns.

Southwest: Warmer and drier than average. This will likely exacerbate drought conditions in these areas. All southern states are at risk of having above normal wildfire conditions starting this winter and lasting into the spring.

Northern Plains: Colder and wetter than average. Likely to see increased storminess and flooding.

Southern Plains, Gulf Coast States & Southeast: Warmer and drier than average. This will likely exacerbate drought conditions in these areas. All southern states are at risk of having above normal wildfire conditions starting this winter and lasting into the spring.

Florida: Drier than average, with an equal chance for above-, near-, or below-normal temperatures. Above normal wildfire conditions.

Ohio and Tennessee Valleys: Warmer and wetter than average. Likely to see increased storminess and flooding.

Northeast and Mid-Atlantic: Equal chances for above-, near-, or below-normal temperatures and precipitation. Winter weather for these regions is often driven not by La Niña but by weather patterns over the northern Atlantic Ocean and Arctic. These are often more short-term, and are generally predictable only a week or so in advance. If enough cold air and moisture are in place, areas north of the Ohio Valley and into the Northeast could see above-average snow.

Central U.S.: Equal chances of above-near-or below normal temperatures and precipitation.

Hawaii: Drier than normal through November, then wetter than normal December through February. Statewide, the current drought is expected to continue through the winter, with several locations remaining on track to become the driest year on record. Drought recovery is more likely on the smaller islands of Kauai and Molokai, and over the windward slopes of the Big Island and Maui.

Alaska: Odds favor colder than average temperatures with equal chances of above or below normal precipitation. The interior and southern portions of the state are currently drier than normal. A dry winter may set Alaska up for a greater chance of above normal wildfire conditions in the spring.

Courtesy NWS

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Long-Lasting La Niña Poised to Control Weather

Earlier this month the Climate Prediction Center (CPC) announced that we officially moved into a La Niña pattern, and recent images from NASA's Jason-2 oceanography satellite verify. The opposite of El Niño, La Niña is the cooling of the equatorial Pacific Ocean.

Both El Niño and La Niña play a major role in global weather. During a La Niña, trade winds in the western equatorial Pacific Ocean are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central regions. La Niñas are associated with less moisture in the air, resulting in less rain along the coasts of North and South America. They also tend to increase the formation of tropical storms in the Atlantic.

So what exactly does that mean for the United States? What impact can we expect?

• An increase in the number of tropical storms as a result of La Niña boosts the chances that a storm (or hurricane) will enter the Gulf of Mexico, home to about 30 percent of U.S. oil and 12 percent of U.S. natural gas production, as well as the anomaly of an oil slick this year.
  
  
• La Niña's cooling pattern often brings dryer, warmer weather to the southern half of the United States, thus increasing the wildfire threat in Florida and California.
  
  
• During La Niña, the northern third of the United States often has colder winters.
  
  
• Increased rainfall in the Pacific Northwest is also common during La Niña.
  

Experts expect the central equatorial Pacific Ocean to stay colder than normal throughout the summer and beyond, so the risk for long-lasting La Niña-type weather conditions to affect North America in coming months is quite likely.

Looks like next winter could be VERY different from last, which was largely controlled by El Niño!

Weakening El Niño's Last Punch

Recent ocean satellite imagery continues to indicate a weakening El Niño, but one last punch by the warm Pacific-driven weather phenomenon is likely to impact our weather in coming weeks and months.

According to sea-level height and temperature data, another strong, eastward-moving wave of warm water, known as a Kelvin wave, is heading towards the United States west coast.

Now in the central and eastern equatorial Pacific, this Kelvin wave is not expected to impact global weather events as the full-fledged El Niño has for the better part of the past year, but this could be the last hurrah before El Niño's dry sibling, La Niña, takes over.