Friday, October 5, 2007

MET Office - NAO Prediction


From the UK Met Office...
"The figure below shows that the predicted winter NAO index for 2007/8 is weakly negative at -0.05 with a standard error of ±1.0. The near zero amplitude of the predicted index relative to the error bar means that the NAO prediction provides little signal for below- or above-normal European winter temperatures or precipitation. However, the prediction is consistent with a cooler, drier winter over northern Europe as a whole than experienced in winter 2006/7, when the observed index was +1.1."


The model does an OK job forecasting inter-annual variations...but not so much for an upcoming season. Its correlation coefficient (R) is an anemic 0.45. Enough to demonstrate some skill but not high enough to hint at which way it/s heading next.

Here/s the model/s loading pattern. The anomaly tri-pole along NOAM/S EC and the Saragossa Sea dipole are associated with anomalies @ 500 mb and a positive NAO.


Here/s the model/s SSTAs for this year. A strong signal NAO won/t be strong positive.


Forecasts for the previous two years/s have been good for sign and magnitude...however...past performance does not guarantee future rate of return. The error bars suggest 1) NAO won/t be stronger than last year and 2) the index has a 50/50 chance of going either way relative to zero.

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