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Winter 2008/09 Forecast Verifications April 4, 2009

Posted by honestclimate in Discussions.
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Winter 2008/09 Forecast Verifications

Via ICECAP

By Joseph D’Aleo

The super El Nino of 1982/83 which coincided with world-wide weather extremes sparked significant research into the global atmospheric effects of this phenomenon. When strong correlations were found, a whole new era of long range climate forecasting began. Over the past decade, our understanding of ENSO and other climate factors or teleconnections has grown and extended and enabled skillful seasonal (and I might argue decadal) forecasting.

Before the winter in October, we used the sun, ENSO and QBO (among other factors) to identify analog years (circled). We picked 1961/62, 1964/64 as the best analogs with 1985/86 also within window of expected solar and ENSO conditions.

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They suggested another cold north central winter
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The actual temperatures generally were in line with those analogs, especially across the North Central. It was warmer in the southern Rockies and plains where it was dry. The cold in the northeast was concentrated in January.

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Compare that to the CPC forecast from last October which in the absence of a clear ENSO state used trends as their tool. This despite the fact they have done a lot of the good research most private forecasters use. Their forecasts have a warm bias, the politically correct position.  They were better in the southern plains but missed the northern plains cold as they did last year.

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They are at it again for next winter.

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Trends can be useful tool during the times when you are entrenched in a particular regime but can lead to bad forecasts when a new regime develops (like selling at the lows of a bear market or buying at the peak of a bull market). The trend they used was the trend during the recent warm PDO, warm AMO, active solar decades of the 1980s and 1990s.  Now with the PDO in its cold mode, the AMO turned negative and the sun in a superlong slumber, the trends should be and have been reversing both globally and regionally. Good luck CPC. You will need it.

See pdf here.

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