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Posted at 10:45 AM ET, 01/30/2009

Grading CWG's Inauguration Forecast

By Capital Weather Gang

Weather Checker

* Storm Next Week? Full Forecast | Later: Snow Lover's Crystal Ball *

Weather Checker is an outsider's analysis of CWG's forecast accuracy. See previous Weather Checker posts here.

By Jamie Yesnowitz

When I first heard that CWG was planning to start forecasting for Inauguration Day (Jan. 20) on Jan. 2 -- first with dueling forecasts from Jason Samenow and Dan Stillman, and later with a single "team" forecast -- I thought the exercise would provide a good deal of insight into how a forecast is refined over time. I also saw the potential for a really big miss.

In looking at the results, however, I'm surprised by how little adjustment was needed from the initial team forecast made a week out, and was particularly impressed with Jason's performance during the earlier duel.

Keep reading for the Weather Checker's full assessment of CWG's Inauguration Day forecast...

First, let's take a quick look back at the weather conditions recorded at Reagan National Airport (DCA) on Inauguration Day. The watchword was definitely "cold"...

* High of 30 was reached between 1-2 p.m.
* Low of 19 occurred at sunrise.
* Winds generally from the northwest ranged from around 8-9 mph in both the early-morning and late-evening hours, to midday speeds around 15-20 mph (with gusts to near 25 mph).
* Weather was variably cloudy with occasional breaks of sun, including during the Inauguration ceremony.
* No precipitation was reported at DCA, but there were anecdotal reports of flurries nearby during the afternoon.
* Interestingly, the dew point was nearly constant throughout the 24-hour period, only ranging from 9 to 10.4 degrees.

The Long-Range Duel

Both forecasters appropriately emphasized that weather predictions more than two weeks ahead of time have very little skill, and in fact the duo subtitled their forecasts, "Testing the limits of long-range predictions."

That said, Jason correctly predicted the general state of affairs in the duel's debut 18 days before Inauguration Day, calling for a ridge of high pressure in the west and cold temperatures for D.C., though he undershot by about 10 degrees the magnitude of the cold (Jason's initial forecast: Cloudy, morning low of 28-33, swearing in temp of 32-37, and high of 36-41).

Dan's prediction of above-normal temperatures clearly did not pan out -- he was about 15-20 degrees off with his initial high-temperature forecast. He was banking on a shift from a cold pattern that did briefly materialize -- but a few days too late. (Dan's initial forecast: 30% chance of rain, morning low of 31-36, swearing in temp of 39-44, and high of 46-51)

Both were fairly consistent with their precipitation forecasts -- Jason predicting a "better than average chance of storminess either just before or sometime during Inauguration Day," and Dan predicting a 30% chance of rain but no big winter storm. And both were for the most part correct: Indeed, there was no major storm around, but a period of light snow on Inauguration Eve did coat areas just north and west of D.C. with around a dusting to an inch.

The dueling meteorologists didn't change their initial predictions until Jan. 7, when Dan nudged his temps down a couple of degrees. It wasn't until Jan. 12, the final day of the long-range predictions, when Dan caved and dropped his temperature forecast to a morning low of 25-30, swearing in temp of 30-35 and high of 35-40. While Dan's revised prediction was a little closer than Jason's original guess, Jason gets credit for staying the course throughout the long-range process, and as such, clearly won the duel.

The CWG Team Forecast

On Jan. 13, CWG shifted to a team forecast, and for the most part, this forecast did an admirable job of predicting what would happen. The initial team forecast called for a morning low of 24-29 and swearing in temp of 29-34, with an uncertain sky and a 25% chance of precipitation.

Throughout the week, the forecast was refined slightly, as the temperatures were pushed down a few degrees by the 17th to a morning low of 19-23 and swearing in temp of 26-30 with partly cloudy skies and a continued slight chance of precipitation. Overall, the forecast was not so bad from the 4-7 day range, despite a little misjudgment on the severity of the cold air mass. And the Jan. 17 forecast was close to perfect.

Also of note, the snow threat for Inauguration Eve was reported with the appropriate caution.

An interesting experiment indeed, yielding a pretty good forecast. Maybe 18-day forecasts aren't so impossible after all...

About the Weather Checker...

Jamie Yesnowitz has been interested in the weather since he rooted for school-closing snowstorms while growing up in Brooklyn and East Rockaway, N.Y. After graduating from Dartmouth College with a bachelor's degree in economics and government, his focus on the accuracy of weather predictions took hold when he moved to Coral Gables, Fla., to attend the University of Miami School of Law. Class was scheduled to begin on August 24, 1992. Hurricane Andrew had other ideas, however, shutting down the school for weeks. But what stuck in Jamie's mind was the final unpredicted swerve of the eye that saved those living in Miami and points north, and completely devastated areas about 20 miles south of Miami.

Undeterred by the hurricane, Jamie ultimately served as editor-in-chief of his law school newspaper, and earned both a juris doctorate and master's degree in taxation. Following law school, Jamie practiced corporate and securities law in New York before shifting to the state and local tax consulting world. Jamie moved from New York to the Washington area in 2003, and he is presently a state and local tax senior manager at a major accounting firm. Jamie lives in Potomac with his wife, Sandra, and their two daughters, Sarah and Carly.

By Capital Weather Gang  | January 30, 2009; 10:45 AM ET
Categories:  Capital Weather Gang, Inauguration Features, Inauguration Forecasts, International Weather  
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Next: Next Week's Storm: Big Snow or Big Bust?

Comments

Nice report and summary. It sure felt colder than upper-20's to 30 on Inauguration Day.

Regarding next week's storm, it's amazing to see the changes in storm tracks from day-to-day and model-to-model. The type of storms like '93, '96, and '03, where the models could lock down the storm tracks many days in advance, seem to be quite rare. It's looking better for snow next week, but everything has to line up perfectly with the storm track and the limited cold air.

Posted by: Kevin-CapitalWeatherGang | January 30, 2009 12:28 PM | Report abuse

"Kevin said...The type of storms like '93, '96, and '03, where the models could lock down the storm tracks many days in advance, seem to be quite rare"

Ive noticed that too. It seems like with every recent storm the models track all over the place (one run and inland runner, the next run, off the coast).

Has it always been like this and maybe I have only recently noticed it?

Posted by: fishman1 | January 30, 2009 1:34 PM | Report abuse

Your discussion totally omits the most important factor in measuring forecast skill, namely climatology. For example, a forecast of no measurable precipitation in January already has a built-in 68% chance of being correct. A forecast of 36-41° has a 23% chance of being correct, and a forecast of 46-51° throws in another 15%, for a total of 38% between the 2 18-day guesses. Techniques have been available since at least the middle of the last century to take this into account (see, for example, Brier, Monthly Weather Review, 1950). A forecast which can't beat climatology adds no value, although that hasn't stopped the Old Farmers Almanac and quacks like Gordon Barnes from building quite profitable businesses from a gullible public.

Unless this "experiment" is repeated a statistically significant number of times with objective verification, it's nothing more than a cheap corporate media publicity stunt.

Posted by: CapitalClimate | January 30, 2009 4:08 PM | Report abuse

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