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December 22, 2010

Storm edges into Sunday, track still uncertain

The most definite thing that can be said about the prospects for a Christmas snowstorm in Baltimore may be that the storm mostly likely won't get to the East Coast by Christmas. But nobody is sure yet whether Central Maryland should prepare for a near miss, or a serious day-after-Christmas winter storm. Cars in snow 2010

The best news is that, if you're traveling in the region on Friday or Saturday, the chances are you'll be able to make the trip without worrying about getting stranded in a ditch, or at the in-laws' house.

Forecasters say the storm - still coming ashore in California on Wednesday afternoon - looks like it will be moving slowly enough to put off any snowfall in the mid-Atlantic states until Sunday and Monday.

What happens then remains a frustrating meteorological cliffhanger - all the more so because so many millions of Americans will be traveling this weekend into the path of this cross-country storm. 

"To give you a number, an exact snow total, wouldn't be a great forecast because there is such uncertainty with the storm," said Jared Klein, a National Weather Service forecaster in Sterling, Va. "It's a very complex pattern" that is still coming together.

The complex computer models that forecasters use to predict the evolution of such storms days ahead of the actual events simply have not been able to reach agreement on this one. Some have been predicting a track that would take the bad weather off the southeast coast of the United States and out to sea. Others bring it off the Virginia Capes by Sunday, tracking up the coast with a major snowstorm for the mid-Atlantic.

"There are some models that are showing a light dusting, and there are some systems showing heavy snowfall ... six inches or more," Klein said.

It's not like last year, he said. "With the December and February storms, five or six days out we saw this coming. We didn't give amounts this far out, but there was a lot of agreement on a big storm."

That should begin to change as the Pacific element of the storm gets ashore in California, and more surface observations and analyses can be made. "Usually, when you start getting three days before the event, you start getting higher confidence," Klein said.

One issue on which there was increasing agreement Wednesday, in addition to the later arrival, was on the storm's intensity. "There is increasing confidence it is going to be a strong storm," Klein said. But "it may be out to sea, too."

As the hours went by Wednesday, the models, and forecasters, could do no better than offer a choice between two possible scenarios.

The afternoon online forecast discussion from the weather service in Sterling, said, "The first scenario is that low pressure intensifies as it tracks along the coastline, producing a significant snowstorm across the area. The second scenario is that the low remains far enough off the coast for little or no snowfall across our area."

"Latest guidance [Wednesday] has trended a bit towards the first scenario, but [computer model] AccuWeather.comguidance still remains divergent in the overall solution," forecasters said.

The forecasters at, in State College, Pa., took a similar, two-choices (map at left) approach: "The first is the storm will quickly strengthen, tracking northward along the coast and spreading heavy, accumulating snow through the I-95 mid-Atlantic and New England. Snow could extend back to the Appalachians with this track."

"The second," they continued, "is the storm will drop accumulating snow on part of Georgia and the Carolinas, but then head out to sea. However, this track could still allow the storm to hook back into New England with heavy, windswept snow."

Other meteorologists have weighed in with their own ideas about how this storm will behave four or five days out. Eric the Red, a professional forecaster from Baltimore who contributes his predictions anonymously to the Maryland Weather Blog, said, "The trend is ominous ... There is going to be a whale of a storm moving up the coast Sunday into Monday. Its final final track means everything ... but I'm starting to get that sinking feeling about Monday."

Foot's Forecast, a forecasting web site manned by high school and college students who did well with last winter's storms, was saying this on Wednesday: 

"Abundant surface and upper level cold air in place across the eastern U.S., combined with the expected influx of Pacific moisture may increase the possibility that energy from [the] northern jet stream phases with an already active subtropical jet. This scenario would produce a significant to major winter storm along the U.S. East Coast."

Posted by Frank Roylance at 4:34 PM | | Comments (11)
Categories: Forecasts, Sky Notes


"It's not like last year [ last year's storm], he said. "With the December and February storms, five or six days out we saw this coming. We didn't give amounts this far out, but there was a lot of agreement on a big storm."

Yes. They saw it coming. And did nothing. BOTH times. This time you see it coming and what are you doing... probably nothing. AGAIN. I already bought my shovel.

FR: You want they should send it away, maybe?

Hey baltobikeboi, what do you suggest they do? Maybe huff and puff and blow it away? Seriously, what do you want them to do? I'm dying to know.

FR: Maybe we missed a tongue-filled cheek?

Hey baltobikeboi, I'm not sure if you were trashing the forecasts and the forecasters or the average person in general. If you (or anyone else out there) were taking a shot at the forecasters(which people love to do), please bud, understand how complicated forecast models are. Then you'll appreciate the fact that we can get an idea of a possible storm this far out, and no longer expect meteorologists to exactly predict the future.

Weather forecast models take point data (from weather stations and weather balloons, that aren't always accurate) and spatially interpolate them to get a 3D understanding of very, very large areas. Then they use that information (which really isn't accurate itself since its spatially interpolated) to predict changes in the weather (atmosphere) using general principles of physics. Its probably the most involved mathematical calculations going on in the world at any given time. So when you think about it, its pretty crazy that we can even get forecasts as good as we do now.

I'm no professional, just a weather dork, so people, feel free to critique my statement.

I was completely spoiled by last year, and although at a point I was ready for it to be over, I am now ready for it to be back. I would love us to get at least a foot - that would extend my holiday vacation by a little bit.

Last year, had to delay a departing flight due to the storms. Now I might have to delay my return? Ahrg. Who wants to deliver a shovel to the long term lots at BWI?

This is a fun blog to read--and as this storm might be approaching I'm certainly going to be checking in daily! I'm so glad I found it!

Excellent, this will make substantial progress toward my prediction of 27 inches.

My birthday is on the 27th and this looks like a very satisfactory birthday gift.

I sure hope someone on my list is getting me eggs, milk and toilet paper for Christmas.
Merry Christmas everyone, and Happy Birthday Amy, where ever and who ever you may be.

Hey DTiz , and to think I actually thought they got the weather forecast from all the billions of dollars spent on contraptions flying around in space relaying radar and images down to predict storm tracking. Weather ballons...what a concept...I must have slept during that class.

We'll be fine. Big coastal storms have never materialized in a strong La Nina, which we have now. Atmosphere too progressive and pushed them out to sea. Take it to the bank.

FR: Never? How about the 22-inch Jan. 6-8 blizzard in 1996? Not a strong La Nina, but La Nina nevertheless.

Ah, Frank, you forecasters make planning to travel a nightmare because you all can't agree on anything. So let me ask can't the weather industry just come up with one dependable and reliable model or method to better predict storm tracking? Why do forecasters have to start predictions with the storm still way out west and days away? What's with the Europe model, what does it have to do with the U.S? And to Greg, are you the same Greg Shipley of the Maryland State Police?

FR: First, I'm not a forecaster, just a reporter bringing you what I can learn of the forecasters' predictions. Forecasters start noting storms days in advance because the technology today allows them to see things developing days in advance. It gives emergency planners, utility managers and the rest of us a heads up, and time to prepare and to consider alternatives. That can save money and lives. The European model (ECMWF) is operated by the European Centre for Medium-Range Weather Forecasts. It is based in the UK but includes 18 European states and 15 "co-operating" states. Its supercomputers contain the world's largest archive of numerical weather prediction data. It's a global model, and U.S. forecasters consult it daily, along with a variety of other models. They're all different - some are better in some situaiton, others are better in other situation. So their guidance varies when events are still days away. But as the time shortens, they tend to converge on a "consensus" solution. This time, because of the complexity of variables they're tackling, that's taking longer than usual.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff

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