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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