Thursday, March 20, 2008

Happy Spring!

Happy March 20th, the official first day of Spring! While doing a little blog spring cleaning, I happened upon this interesting piece of weather forecasting from last year. It’s NOAA’s forecast for winter, 2007-2008, released on October 9, 2007 and updated on November 15th.

Did they do any better than a guy with a bone in his nose reading pig entrails? You be the judge:
CPC forecasters remain confident in predicting above average temperatures for much of the country – including southern sections of the Northeast
Let’s see what they say now about the actual winter we just experienced:
The average temperature across both the contiguous U.S. and the globe during climatological winter (December 2007-February 2008) was the coolest since 2001
Well, okay, but since 2001 the world’s been heating up like spandex between Al Gore’s thighs. What about putting it historically?
In the contiguous United States, the average winter temperature was 33.2°F (0.6°C), which was 0.2°F (0.1°C) above the 20th century average – yet still ranks as the coolest since 2001. It was the 54th coolest winter since national records began in 1895.
113 winters, and this one ranks right around the middle. Cheers to NOAA for accurately predicting the southern sections of the Northeast would be above-average. Jeers to NOAA for predicting it would be so far above average:
For the country as a whole, NOAA's heating degree day forecast for December through February projects a 4.0 percent warmer winter than the 30-year normal, which is very similar to last winter.
So what did we get? A winter that was 0.6% warmer than normal, and much cooler than last winter. When other scientists are this accurate, things blow up and people get sued.

Did these latter-day shamans accurately predict rainfall? Well, here’s what they expected:
As for precipitation, it will be drier than average across the Southwest and the Southeast, the National Oceanic and Atmospheric Administration projected in its winter forecast.
The Ohio and Tennessee Valleys, northern Rockies and Hawaii will be wetter than normal this winter, the agency predicted.
Let’s see what the actual precipitation was this last winter:
Winter precipitation was much above average from the Midwest to parts of the West, notably Kansas, Colorado and Utah. Although moderate-to-strong La Niña conditions were present in the equatorial Pacific the winter was unique for the above average rain and snowfall in the Southwest, where La Niña typically brings drier-than-average conditions.
Mountain snowpack exceeded 150 percent of average in large parts of Colorado, New Mexico, Arizona, and Oregon at the end of February. Spring run-off from the above average snowpack in the West is expected to be beneficial in drought plagued areas.
While some areas of the Southeast were wetter than average during the winter, overall precipitation for the region was near average. At the end of February, two-thirds of the Southeast remained in some stage of drought, with more than 25 percent in extreme-to- exceptional drought.
Good call on precipitation in the northern Rockies. But in the Southwest it was much wetter than average, and in the Southeast it was an average winter for precipitation. Not so good call there.

To a casual observer, it seems as if there’s something about rainfall and climate that we don’t understand which is destroying our ability to accurately forecast the weather. But that just couldn’t be, could it?

At least Texas took the NOAA predictions seriously:
Winter temperatures were warmer than average from Texas to the Southeast and along the Eastern Seaboard, while cooler-than-average temperatures stretched from much of the upper Midwest to the West Coast.
Drought conditions intensified in Texas with areas experiencing drought almost doubling from 25 percent at the end of January to 45 percent at the end of February.
And environmentalists hate Texas? They should put the whole state on climate change posters like they do with bleak-eyed children to get you to donate to Oxfam.

The bottom line is this: climate experts like to portray themselves as Cassandras, crying out a terrible truth that nobody will believe. But they’re really much more like the little boy who cried wolf.

If you can’t accurately predict next winter from its doorstep, don’t try to sell me a disaster story for what’s coming in ten or twenty or thirty years.

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