Friday, December 21, 2012

WRF-GFS Temperature Forecast Verifies Well

The WRF-GFS forecast for temperatures overnight (see earlier post -with a correction, since I had pasted-in the wrong graphic) was very accurate. It was a much milder night, and the official forecast of a low of 33F for the airport was far off the mark - it appears that the actual low at TUS this morning will be 48F. Low here at house has been 38F (edited to add: It dropped down to 32F here at house right around sunrise) - so the Rillito cold continues to be a bit beyond the capabilities of Mike Leuthold's current version of the local WRF.

The overnight T and Td traces for the airport (above) and Atmo (below) show the truncated diurnal curve that was caused by the gusty east winds continuing through the night.

The winds at the rooftop anemometer on the Atmo building stayed strong and gusty (green trace shows gusts) after about 10 am yesterday morning, with a number of gusts above 30 mph.

A significant miss with the nighttime temperatures can have important economic impacts - particularly if the local utilities planned electricity and gas needs during the night were seriously off. A number of years ago, when I was familiar with the daily operations at SRP in Phoenix, an error in the forecast max or min temperature of 3F or greater was considered a busted forecast, worthy of a postmortem look to determine what went wrong. The forecasts I refer to were made within SRP operations, not by the NWS.

Finally, it appears that the last 10 days of 2012 will be characterized by stormy, winter weather over much of the country - will take a look at what's being predicted by the models for rest of december later today.

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