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Posted at 10:45 AM ET, 01/ 7/2009

InaugurationCast: T-Minus Two Weeks

By Capital Weather Gang

Testing the limits of long-range forecasts

* Rain Tapers This Afternoon: Full Forecast | Later: Snow Poems *

What's better than one Inauguration forecast? How 'bout two? Through Jan. 13, CWG's chief and lead meteorologists -- Jason Samenow and Dan Stillman, respectively -- will provide dueling forecasts for Jan. 20, Inauguration Day. Starting Jan. 14, we'll shift to a single CWG team forecast, in hopes of more confidently honing in on the forecast details. Check back daily for our latest thinking, a look at past inaugural weather, and a sampling of what you, our readers, are predicting.

So here we are, just under two weeks from the big day -- nowhere close to having confidence in what the day's weather will be. But we might as well have some fun guessing. Keep reading for Jason and Dan's latest forecasts, two new reader predictions, and more inauguration weather history...


Previous forecast

I'm sticking with my previous forecast for the time being.

The real question is whether the ridge in the jet stream in the West forecast by long-range models to develop will hold. If it holds, we'll have a dip in the jet stream over the East that will likely bring us colder than average weather. If it breaks down, we'll have more moderate conditions with Pacific rather than Canadian air. I'm betting on the colder scenario -- but it's a close call.

Storminess remains nearly impossible to predict this far out, but my gut feeling suggests there will be some storminess within a day or so of the inauguration that will add a wrinkle to the forecast.

The Bottom Line...
* Morning low: 28-33
* Swearing In (noon): 32-37
* Daytime high: 36-41
* Weather: Cloudy
* Confidence: Low

Previous forecast

The extended range indicators are leaning toward temperatures slightly below normal around Inauguration Day. I'm not ready to go full force in that direction, but am bumping my forecast down a couple degrees.

Also, I don't see anything in the data to justify changing my initial stab of a 30% chance of rain, with frozen precipitation staying north and west of D.C.

As I expected, the atmospheric index known as the NAO is forecast to be in the positive range, which as Jason recently explained tends to limit snow. So, I'll stick with my call against a big winter storm.

The Bottom Line...
* Morning low: 29-34
* Swearing In (noon): 38-43
* Daytime high: 43-48
* Weather: 30% chance of rain.
* Confidence: Low


Posted by stinkerflat1

Partly Cloudy with a risk for afternoon and evening showers possible ending as a brief mix. Morning Temps: 38-44 degrees. Afternoon High: 52-55 degrees.

Posted by spa1

Morning Temps-40s and 50s. Swearing in-a whopping 65 degrees amidst Sunshine and Blue skies!!!! Afternoon High-a Toasty 70 degrees-the record high from 1951 for Jan. 20.

Note: If you want your Inauguration forecast featured here in one of the coming days, summarize your prediction in a comment below.


Eisenhower, 1953: Noon Temp: 49F. Cloudy skies.

Eisenhower, 1957: Noon Temp: 44F. Jan. 21: Light snow in the early morning. Cloudy skies with a few flurries in the mid afternoon.

- National Weather Service

By Capital Weather Gang  | January 7, 2009; 10:45 AM ET
Categories:  Inauguration, Inauguration Forecasts  | Tags:  dc weather inauguration, inaugural weather, inauguration forecast, inauguration weather, inauguration weather forecast, weather inauguration  
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I can't make an educated forecast, but I am praying for 12 degrees and ice. Lots of ice.

Posted by: skywatcher1 | January 7, 2009 1:32 PM | Report abuse

skywatcher1: I guess that would mean hell will freeze over?

Works for me...!

Posted by: DoubleUO | January 7, 2009 3:47 PM | Report abuse

Here's my Inaugural forecast, 1 week and 6 days out:

Leftover flurries from the modest snow ( occuring the day before and during the night) ending during the early morning. Quickly becoming mostly sunny, with the bright sunshine boosting temperatures from 29-33 in the morning to 41-45 around noon- swearing in. Clear, deep blue skies during the afternoon.
Afternoon high: 43-47.

Melting snow and bright sunshine will cause a lot of glare on the streets, further worsening the traffic situation.

Posted by: Sterlingva | January 7, 2009 10:15 PM | Report abuse

Jason and Dan rightly recognize the import of the NAO in regard to chances for snow. But, can we have any faith in forecasts of the NAO, such as linked to by Dan (" forecast to be in the positive range")?

The figures themselves provide the answer - a resounding NO!

Dan and Jason are well aware and to their credit readily acknowledge that forecasts beyond about a week ahead have little, if any, reliable degree of accuracy. But, after all this is just a guessing game for the fun of it.

For the (not overly rigorous) geeks amongst us, the following provides one aspect of the rationale for having little confidence on the predictions for over a week ahead:

The correlation between forecast and observed over the period of record is shown on the upper right of each panel. From a statistical point of view any value less than .71 (50% of explained variance) suggests little, if any, reliable correspondence between the forecast NAO and that observed at the verification time.

As can be seen, the correlation falls below the .71 critical value between the 7 and 10 day forecast range. By 14 days, the value drops to .21

There are other considerations beyond the scope of this discussion, but for the current sake of argument - case closed

Posted by: SteveT-CapitalWeatherGang | January 7, 2009 10:23 PM | Report abuse

Rain, turning to freezing rain, and then snow. Major roadways will be covered with at least 1/4 inch of ice and driving conditions will be trecherous in most areas. Temperatures will drop into the low teens after nightfall with increasing winds. Increasing winds will cause dangerous wind chill conditions as road surfaces freeze. Make progress every day.

Posted by: blasmaic | January 8, 2009 10:34 PM | Report abuse

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