Friday, February 18, 2011


Blocking Strength GHGS Observations
This chart from NOAA's Climate Prediction Center (CPC) shows when and at what longitude High Latitude Blocking was most pronounced. You can clearly see the change to a Positive AO & NAO pattern as the blocking (over eastern North America) has significantly weakened and collapsed during Feb. 6-16. As present changes with the Northern Hemisphere Teleconnection Pattern take place, the EPO which is currently trending toward neutral will become Negative. I expect the EPO to become weakly Negative by Feb. 20, which will allow for falling heights to the east of the building Gulf of Alaska & eastern Pacific ridge as the AO becomes increasingly Negative. During Feb. 21-24 the pattern will amplify as the trough expands to the east with the strengthening Negative AO & NAO, temperatures will be seasonal then below normal. I believe the pattern will peak in it's overall amplification between Feb. 26 to March 3, however there will be some brief moderation before the peak in amplification. It is during this period when there is the strongest probability of below normal temperatures, and East coast cyclogenesis or storms. During March 5-10 the Negative NAO will loose Teleconnection support and weaken to "east-based," then later become neutral to increasingly Positive. By March 10-15 it appears the westerlies will become quite pronounced, with the Polar Vortex (PV) shifting north and the Negative NAO completely absorbed.  

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