Sunday, February 13, 2011

FEB. 13, 2011 - WHERE IS THE NORTH ATLANTIC OSCILLATION HEADED?


"NEW ENGLAND & THE NORTH ATLANTIC OSCILLATION" WEEKLY INDICE REVIEW

Ensemble Mean NAO Outlook
  The NAO GFS (MRF) - Ensemble Indice Forecast from NOAA's Climate Prediction Center (CPC) is currently weakly Positive. The GFS Ensemble Indice Forecast indicates that the NAO will become neutral to weakly Negative by the third week of February. The GFS Ensemble Indice Forecast brings the NAO increasingly Negative around the last week in February (which prevailed for much of this winter so far.)
  The NAO - Operational GFS Indice Forecast from (CPC) is also currently weakly Positive. The Operational GFS Indice Forecast indicates that the NAO will become neutral by the third week in February. This indice forecast then indicates that the NAO will be neutral to very weakly Negative around the last week in February.

Ensemble Mean AO Outlook
  The Arctic Oscillation (AO) GFS (MRF) - Ensemble Indice Forecast from (CPC) like the NAO, is currently weakly Positive. The GFS Ensemble Indice Forecast indicates that the AO will become very weakly Negative by the third week of  February. This indice forecast then brings the AO increasingly Negative briefly, then weakening around the last week in February.
  The AO - Operational GFS Indice Forecast from (CPC) is currently weakly to moderately Positive. The Operational GFS Indice Forecast indicates that the AO will become neutral to very weakly Negative by the third week of  February. This indice forecast then appears to completely brake-down the pattern, with the AO becoming neutral to increasingly Positive around the last week in February.

 Ensemble Mean PNA Outlook
  The Pacific-North American Oscillation (PNA) GFS (MRF) - Ensemble Indice Forecast from (CPC) is currently moderately Negative. The GFS Ensemble Indice Forecast indicates that the PNA will significantly weaken in a Negative state by the third week of  February. This indice forecast then appears to bring the PNA increasingly Negative around the last week in February.
  The PNA - Operational GFS Indice Forecast from (CPC) is also currently moderately Negative. The Operational GFS indicates that the PNA will maintain a moderate Negative state by the third week of February. This indice forecast appears to keep the PNA in a pronounced Negative Phase around the last week in February.  
  The Eastern Pacific Oscillation (EPO) GFS (MRF) - Ensemble Indice Forecast from NOAA's Earth System Research Laboratory (Physical Sciences Division) and NCEP, is currently weakly to moderately Positive. The GFS Ensemble Indice Forecast indicates that the EPO will become neutral to weakly Negative by the third week of  February. However, this indice forecast indicates that the EPO will become neutral to very weakly Positive around the last week of  February.
   The Western Pacific Oscillation (WPO) GFS (MRF) - Ensemble Indice Forecast from NOAA's ESRL (PSD) and NCEP, is currently weakly Positive. The GFS Ensemble Indice Forecast indicates that the WPO will become neutral to very weakly Negative by the third week of February. This indice forecast later indicates that the WPO will remain neutral to very weakly Negative, during the last week of February.

Ensemble Mean AAO Outlook
  The Antarctic Oscillation (AAO) GFS (MRF) - Ensemble Indice Forecast from (CPC) is currently weakly to moderately Positive. The GFS Ensemble Indice Forecast indicates that the AAO will become neutral to very weakly Negative by the third week of February. This indice forecast then appears to keep the AAO neutral around the last week of February.


EXTENDED OUTLOOK:  I am focusing on the EPO & AO for the Extended Outlook, due to important changes that will happen with these indices. The EPO is currently moderately Positive but will become neutral to weakly Negative during the extended time frame. The AO is currently weakly to moderately Positive and will become neutral to very weakly Negative during the extended period. This means significant changes will take place over the Gulf of Alaska and eastern Pacific. As the EPO becomes neutral to weakly Negative a ridge of high pressure will rebuild over the eastern Pacific, as the ridge expands to the east a trough will be carved on it's eastern flank. This will be the steering mechanism to bring the AO back toward Negative, which in return will allow for seasonal to slightly below normal temperatures (in New England) around Feb. 20-23, as High Latitude Blocking returns.

LONG RANGE THOUGHTS: During this period signals with teleconnections spread significantly, but before that happens the NAO will become increasingly Negative due to changes with the AO (it's parent steering mechanism.) It appears that the NAO will become weakly Negative or stronger around Feb. 26 to March 5. It is important to note that because there is teleconnection support with the EPO & AO, the return of  the Negative NAO will be initially "west-based." With High Latitude Blocking returning over Greenland due to the increasingly Negative NAO, leads to a strong potential of East coast cyclogenesis or storm probability with below normal temperatures. After March 5th is when there is significant spread with teleconnections which I will discuss later.

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