Friday, February 25, 2011


I have talked about intense amplification with the longwave pattern briefly around Feb. 28 to March 5, due to Teleconnection support for an increasingly Negative NAO during this time-frame. I also stated that around March 6-8 temperatures would moderate to seasonal levels, as the pattern de-amplifies and the NAO becomes neutral to weakly Positive. If you have been following the WEEKLY INDICE REVIEW - last updated on Sunday Feb. 20, you are aware that a major pattern change will take place by March 8-10. But, will this change truly mark the end of the Winter Season 2010/11? To answer this question I would like to look at the Western Pacific Oscillation (WPO) Ensemble Indice Forecast from NOAA's Earth System Research Laboratory (Physical Sciences Division), which indicates that the WPO will become neutral to very weakly Positive around the beginning of March. However, what also is note worthy is that the indice is then forecasted to become increasingly Negative around the second week of March. When the WPO is Negative, High pressure builds through the west-central Pacific. This in-return serves as a steering mechanism for the Eastern Pacific Oscillation, (EPO) due to the eastward expanding High pressure ridge. Which would strongly influence an increasingly Negative EPO, blocking the jet-stream from driving across the Pacific. Even though we may have Spring like conditions with an increasingly Positive AO & NAO around March 8-13, the strengthening Negative WPO may be giving us a hint that the March pattern could possibly be changing again - for the second half of the month. I will be following-up on this Later.           

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