Thursday, 19 September 2013

Winter Ramblings

Couple Interesting developments with regard to the GWO phase spacing over the last few months. Notice the gradual but significant shift to positive phases since june/july. The GEFS forecast continues this trend with propagation into phases 5-8 by late sept/early oct. 
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Definitely goes to show the significant recovery from what looked to be at least a weak la nina for a time in early to mid summer. 

The latest weekly SST departures valid sept 16th:
Niño 4 0.0ºC 
Niño 3.4 0.0ºC
Niño 3 -0.2ºC
Niño 1+2 -0.4ºC

With a neutral ENSO signal we will have to turn to other factors...starting with the atlantic. Here is the ideal SST setup for a -NAO in DEC-FEB.
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If we look at our current SST setup we notice a southerly displaced warm belt, positioned off the coast of NL and NS. Cooler SST's are evident south of greenland and iceland. This doesn't bode well for a consistently negative NAO and leans more towards a +NAO pattern in the cold season with a SE ridge.
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H5 anomalies from the past month illustrate this well. Will be interesting to see where we head in the fall.
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In terms of the pacific, +QBO la nada's or la nina's favour a stronger and northerly displaces bering sea ridge. With the GOA expected to cool off, this type of pattern keeps height falls east of the west coast with a SE ridge in place and wave breaking events/troughiness across E CAN, New England and the maritimes. This would keep the mean storm track across the great lakes with above normal precip in the west as well. The Mid ATL/SE would stay warm and dry in this setup. This is how I see the mean pattern setting up for the first half of winter. We should see more enhanced blocking in JAN-FEB and may even see a SSW event with the low solar regime in place. 2001-02 is a good example of how this can happen, despite a +QBO event. 

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