Friday, October 16, 2009

Extended Winter Outlook: CPC

Yesterday we talked about the late Fall-early Winter outlook for temperature and precipitation. Today, we'll look at the extended Winter outlook, also issued by the Climate Prediction Center (CPC).

(Images: NOAA)

As explained previously, these outlooks are primarily based on the El Nino-Southern Oscillation trend, which is currently in El Nino. These long-range Winter outlooks, which cover the Winter months (December into March), are related to the North American weather trends that tend to result from the equatorial Pacific waters being warmer-than-average. The warmer waters alter the tropical rain patterns, with a domino effect into the jet stream pattern over the Pacific into North America. When the jetstream shifts, that also shifts the track low-pressure systems take, making some regions drier than average, while others can expect a wetter Winter than average. With the jet hugging the southern parts of the U.S., this should bring more precipitation to that region. It will also result in cooler conditions for the Southeast into the Mid-Atlantic. This long-range outlook coincides with the three-month outlook we talked about yesterday, supporting the expected continuation of the El Nino trend. For Virginia, this could mean a wetter, cooler Winter, which would thus mean the potential for more winter weather events (translated: kids, that means maybe more snow days!). Look for Chief Meteorologist Zach Daniel's Snow Outlook to be released in early December.

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