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January 28, 2010

Weekend snow ... or not

UPDATE: A Winter Storm Watch is up for central and southern Virginia, with 5 inches of snow or more possible for Charlottesville. Three to 8 inches are possible across the watch area, including the Virginia Eastern Shore. Farther north, in Maryland, there are no watches or warnings, just a Hazardous Weather Outlook.  

This morning we have a pretty good demonstration of why forecasters at the National Weather Service decline to make snow accumulation predictions more than 36 hours in advance of the event.

Early this week, as AccuWeather.com and FootsForecast.org began chirping about a 6-to-12-inch snowfall (or more) in Baltimore by Friday and Saturday, the NWS was content to post 60 percent chances for some sort of snow on the weekend. It was too far out to be confident about such things, they insisted.

The federal forecasters took some heat from WeatherBlog readers for their reticence. After all, Accuweather's bloggers were all aflutter about the storm. Mr. Foot acknowledged his team's stance was "bold," but stuck with it.AccuWeather.com

Until today.

Now the computer models - which all agreed on Monday that we'd see a pounding by the weekend - now all agree that the storm track will send the low across the Carolinas and out to sea. 

The NWS this morning predicts no more than a 30 percent chance for snow in the Baltimore region Friday night and Saturday, with North Carolina and Southern Virginia looking at the best chances for snow. Accumulation forecasts, if any, should be out this afternoon.

Maryland may not get off scot-free. "Accumulating snow will still be possible, especially the southern zones," Sterling says in its morning forecast discussion. "But at the moment, [moisture] appears insufficient for more than 1 to 3 inches in southern portions of the forecast area ... Some light snow may approach the Washington, D.C. metro ... but any accumulations should remain light."

AccuWeather.com began shifting its snow track south (map) on Wednesday, with Southern Maryland and the Lower eastern Shore still in the bullseye.  "MeteoMadness" blogger Henry Margusity has scaled back his prognostications, but this morning still manages to make it sound scary for the urban corridor: "I know folks in Baltimore-Washington are watching this real closely. You're going to be pretty close to the heavy snow area."  And then, "It could be a case where DC gets maybe 4-5 and Baltimore gets 1 to 3. It's a real tough call."

Mr. Foot, too has had to back down. "The polar vortex is in charge," he concedes. "We will have to remain patient for a fantastic February."

UPDATE: Mr. Foot's team of student meteorologists has been watching developments. One Sparrows Point 10th grader has authored an update suggesting the storm track has moved north again, a bit. See below: 

SNOW THREAT UPDATE

Ryan K. Grade 10 (01/28/10: 12:15PM)

So the waiting game continues here in Central Maryland to see what happens with the previously expected snow event. Things went away, but the trends definitely point to one thing: this is coming back north. Precip is back into the area, and if this occurs, say only 50-75 miles more north which is definitely possible, we could get a decent hit. At this point, the amount of snow only looks to be 1-2 inches, but as I said in last nights e-mail things could change (and that has already begun to occur.) All of the afternoon models so far have pointed to that farther north solution, leaving DC in a good area for snow and our area on the northern fringe.

The most aggressive model at this point is the Canadian model which at its latest run gave the area 4-6” of snow. This model has led the models on their trek northward, and in the 12-19/20 blizzard, this model led the way. Also, the ECMWF (European model) which has been the best model according to statistics, trended north last night. In my opinion, if this trend is one that continues this afternoon with the 1PM run, then we will have a legitimate risk for a nice snow event.

Thoughts at this point:

---Currently model runs depict a 1-3’’ snowfall in our area

---The storm is currently trending north and certainly has the potential to continue that trend, giving us the formidable snow threat

---The storm’s timing is steadily moving back so at this point an overnight Friday into Saturday threat would be the time when the storm (if things come to fruition) arrives.

Things to watch: The way the media outlets present the storm and the way they present the storm, as well as the emails we send out. If you want to do basic observations, simply check out the way the storm is moving on radar and nowcast a bit.

Indicator of threat:

This map (12z GFS snow output) shows how close we are to the good snows, the 1-2 is here now, but the slightest shift, 25-50 miles puts us in 3-4’’ with any more than that giving us a 6’’ snowstorm. The chance is definitely there, so stay alert.

Next Update: This afternoon and a possible frequent updates tonight and tomorrow. Will have a snowfall map done as well to be sent out.

Posted by Frank Roylance at 10:47 AM | | Comments (17)
Categories: Forecasts
        

Comments

Frank, I have no problems with Accu-weather and others coming out early talking about the possibilities of snowstorms--they're making us aware of just that--possibilities. They were by no means saying it was definitely going to happen for the Balto/DC area--just what it looked like on Monday.

FR: Agreed. But I thought it was important to point out that the NWS, by design, is more cautious, for good reason.

shucks...I have a feeling we are done with snow for the year.

Are there any message boards or active local weather sites where people can talk back and forth about observations, predictions, etc. Mr. Foot's blog is pretty neat and gives very technical details, but it would be nice to have a great site with active discussions from others as well. Getting a mix of amateur, begginners, and even professionals. Just an idea. If there isn't one, maybe I can work something up. Suggestions?

FR: You're welcome to have the discussions here, but comments are only posted when I get a chance to read and approve them. Otherwise, AccuWeather.com has a forums section. Another possibility is the Eastern US Weather Forums site. http://bit.ly/b7OYiP Readers may have other suggestions.

Gee- I wonder if Accuweather got a lot more hits on their website this week? Remind me not to forget how unreliable their medium range forecasts are.. or do they just skew them to be more sensational to get attention so they can sell more ads? If yes, shame on them.

I wouldn't knock what Accuweather or anyone else is doing, and I think it is a far stretch to claim they do it for hits. They, like everyone else, are looking at model guidance, and interpreting and analyzing it.

It isn't as if on Monday Accuweather was calling for a big storm, and now the storm isn't going to happen at all. There is still going to be a big storm, and it is still going to affect a lot of people. It is just taking a slightly more southerly track, that's all.

In some ways, it may be even more "newsworthy", as folks in the Carolinas and southern Virginia do not see snow as often, and are not as equipped to deal with it. Lets also not forget the effect this storm is already having on Oklahoma and Kansas.

So, on the grand scale, I wouldn't say that anyone (Henry, etc) has "scaled back" any prognostications as much as those prognostications have merely been shifted south.

Still pouting about missing this one? Drive south tomorrow night. Or, wait until next week. Winter isn't done yet.

I'd rather get the weather from a High School student...Kudos!!

For anyone who would like to view or sign- up for a forum, Foot's Forecast has one @:http://footsforecast.findtalk.net/forum.htm... we would appreciate any appropriate thoughts.
~Forecaster Winterman

Very well-written overview by Ryan K. Well done, young man! I think we've found our next Tom Tasselmeyer.

They may wind up adjusting it way north. The PV influence is pulling away, and the storm has slowed down considerably. Also, each model run is showing more southern strength and a possible phasing event. We'll just have to wait and see, but I've thought all along that feedback on this northern system was causing the problem with the models bringing this storm further north.

Ryan K. has done a fantastic job on his forcasting report! Keep up the good work, keep writing and good things are bound to happen for you.

Very good analysis by Ryan. My compliments! Keep up the good work. Sounds a lot better than some other mets in the field.

And thanks to Frank, for mentioning them on your blog.

Why is this storm not going to form a secondary and track up the coast as a nor'easter.....
Why do other storms do that off the Carolina Coast and others not? What are the dynamics of these phenomena?

The much-maligned GFS, the primary U.S. computer model, did a good job of hinting even early in the week that the upper-level flow pattern would favor a southern storm. That didn't stop a Cat. 5 Hype-O-Cane from developing in the blogosphere, however.

sorry folks no snow
A friend of mine just fixed his snow blower, based on past experience that means no more snow this year.

"Sorry folks no snow A friend of mine just fixed his snow blower, based on past experience that means no more snow this year."

HAHAH!! I totally rely on observations like that too. The reason for all the snow in our region this year is b/c my husband has been gone since summer and won't return until spring. Traditionally, we get large accumulations whenever he's out of town.

Great updates! I'm hoping for no snow! Can anybody tell me where I can buy a shovel? I still can't find one since the Dec storm.

You can't even predict what will happen in two days and yet you want me to believe in global warming.

FR: You're free to believe what you please. But if you want to understand what's going on, you need to try to understand the science, which can explain both the difficulties of mid-range local weather forecasting, and the confidence scientists have in their long-range global climate predictions. They are not the same thing.

Storm is now trending north. Mr. Foot's team wins again!

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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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