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January 26, 2010

Friday-Saturday snowfall could reach 12 inches

Much still depends on the final track and timing of the storm, but forecasters seem to be converging on a major snowfall for the Baltimore-Washington region, beginning here sometime NOAAFriday afternoon.

The low-pressure system is still closing on California this (Tuesday) morning (left). It's the latest in the series of Pacific storms that have been dumping heavy rains on California in recent weeks.

The low is forecast to move across the continent this week to the Carolinas. There, forecast models predict it will intensify off the Atlantic seaboard, and draw in more Gulf and Atlantic moisture.

With cold air surging into the region out of the Canadian arctic, and being held in place by a "blocking" low over eastern Canada, we should be seeing the classic setup for a snowstorm to swing around the edge of the cold air and give us quite a storm. But how much?

The National Weather Service forecasters out at Sterling are always cautious this many days out. Too much depends on the final track the storm takes, the amount of moisture it makes available, and the temperatures in the mid-Atlantic

Officially, Sterling is calling for a 50 percent chance of snow at BWI by Friday, rising to 60 percent Friday night and Saturday. Their morning forecast discussion offers no accumulations guesses, only a "later Friday through Saturday night" timeframe.

Uncertainty doesn't phase some other folks. Assessing the likely impact from Texas eastward, says: "The winter storm threatens to cause substantial disruptions to travel and daily routines. Schools will likely be cancelled Thursday into Friday. Residents and visitors to the mid-Atlantic may be forced to alter their weekend plans." Here's more.

"This is going to be a good snowstorm for you folks down in Baltimore-Washington, probably a good 6 to 12 inches the way we see it right now," said blogger Henry Margusity. "Not a blizzard. Just your normal February heavy snowstorm."

Mr. Foot and his legions are just as excited about this one. Low temperatures and high snow-to-water ratios, they say mean that snow totals "could easily exceed 12 inches by midnight Saturday." But, for now, they're going with 6 to 12 inches, too. As we get closer, and the storm's start time becomes more clear, school districts will have to decide whether to close, order an early dismissal, or hope to get the buses off before the driving gets dicey.

A 12-inch storm at BWI would place this one - just barely - among the top 20 on the record books for Baltimore, according to the NWS.

Posted by Frank Roylance at 10:22 AM | | Comments (20)
Categories: Forecasts


If we get another weekend storm and I miss no work because of it I will seriously be disappointed.

I am 100% with Rank. Why oh why do we always have snowstorms on the weekend?

The NWS is a joke. They never commit to a snow forecast more than 48 hours out. They should have a Winter Storm Watch up now, so that people can be aware of a chance that their weekend plans could be affected by a snowstorm. A watch is just that---watching the possibility of a snow event--not a definite forecast that it's going to occur. They won't post a WSW until late Thurs at the earliest, then the warning 12 hrs before the snow starts.
Their biggest problem is that they rely almost entirely on the GFS model for their forecasts, and that model blows when it comes to winter storms--fluctuating storm track from run to run. I rely on for my forecast, and I think you do to Frank :)

FR: By definition, a Winter Storm Watch refers to conditions possible "within the next day or two." I guess they leave the long-term speculation up to the private companies, like AccuWeather. I think people are well aware there's a chance for significant snow this weekend.

As a teacher, I've got mixed opinions about the snow. It's nice to get off school now, but the inevitable headaches it causes trying to get students refocused when we come back and the makeup days at the end of the school year make it a mixed blessing at best.

FR: As a reporter, I agree. Snowstorms provide some excitement, and something to write about. But they also mean more work, and sometimes weekend work. In both cases, my wife (a teacher) is off. Bummer.

Latest computer models show the storm being shunted to the south. Let's give this a couple days, or at least until the next model run pushes it back up to the north. Ha ha.

I'm telling you it snows more on weekends than on weekdays. Know you said it was probability but its always seems to be on a friday afternoon, saturday like clockwork. Argh!

Frank, you'd be surprised how many people are clueless about the chance of snow this weekend. Of course, that probably wouldn't change even with a NWS WSW. People only pay attention to what's going on in their little worlds, that's why politicians can continue to ignore us, but that's a topic for another blog.

We have a one-night weekend getaway planned, so I guess that means we'll get a big snowfall! DARN!

Baltimore County school kids will be ticked off if it is a big storm that closes other school systems because they are already closed.

I am praying that it snows. I have a 12 year old labrador and a 2 year old labrador and the look on their faces is worth a whole morning of shoveling thick heavy snow. Nothing like seeing a dog's face when he's greeted in the morning with a fresh blanket of snow. I almost have to drag my boys in before they freeze to death.

Here's hoping we get a nice foot of snow!!

milk ... bread ... bee, er, toilet paper ;)

I'm supposed to take my wife to my sisters on Saturday at 4 p.m. for her surprise baby shower so I'm expecting the worst (12 inches) and hoping for the best. (a few inches)

FR: Hope she doesn't read this.

Yesterday all the major long range models had a snowstorm of some sort for MD. This was very unusual agreement for being this far away from the supposed event.

Sure enough, today almost every one of the models have backed off. They are showing that there will now not be phasing with a northern stream shortwave and that a weaker and more southerly suppressed system results. This would mean the majority of precip with this system would hit VA and Western NC.

The fact that all these models jumped on to a solution and jump off at the pretty much the same time is just strange.

The two things that are as certain as you can be with this stuff is that there will be a low emerging from the Gulf Coast states and there will be cold artic air in place over MD.

After that it depends on whether there is any phasing with the northern jet stream (would strengthen the storm, slow it down and keep it closer to the coast) or whether a weaker southern stream low stays far enough to our south that the whole business is just a big swing and a miss.

The models could switch again. These systems are just so jiggy its tough to have much certainty this far out.

Potential is one thing realization is another. This system has potential, but a number of things could still make it just another tempest in a teapot...

FR: Thanks for the reality check.

We're all going to die!

FR: True. But probably not this weekend.

I hope and pray it does not snow...I'm leaving Saturday afternoon out of BWI and heading to Florida to visit my mom whom I haven't seen in a year...with my almost 1 and almost 3 year old children (by myself). Please only a dusting...please oh please oh please.

cry if it does and cry if it doesn''re all fruit loops!!!

FR: Why not? Some like snow, some hate it. Most just deal with it.

It appears that it was warmer in Maryland than it was here [in Southern California] yesterday. It's supposed to rain about an inch later today. It's cold and miserable here in So Cal at the moment.

For what it's worth, Bob Ryan (of DC's WRC-TV) seemed to think, as of 4:30 this afternoon, that the storm will track largely to the south of the District.

Oh my goodness, this is for real, right?

Wow it really will be White Polar Bear Plunge this Saturday.

Now I can tease my southern co-workers; I went swimming on a snowy day.


Frank you mentioned accuweather is a private company. For some reason I thought they were part of Penn State? How do they get revenue? Just curious.

FR: They're located in State College, but they're a for-profit company. They sell customized forecast services worldwide to 175,000 TV stations, government and private enterprise with weather-critical interests.

Copy editors: Please note the difference between "phase" (stage or interval in a development or cycle) and "faze" (to disturb the composure of).

FR: "Phasing" is a meteorological term and is used correctly in the reader comment above. Besides, we don't copy edit readers' comments. It would take another full-time hire.

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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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