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February 17, 2010

Melt, baby! Four days of sun and 40 degrees ahead

It's 10:30 a.m. and the mercury has already topped 32 degrees here at Calvert & Centre streets. And the forecast out of Sterling on this Wednesday morning promises little to fear from snow showers today, and much to look forward to from the four or five days of sunshine and 40-degree highs the forecast has on tap.

Not so in Western Maryland, where northwest winds continue to push moist air up the western slopes, which produces more snow. The Wisp ski resort has recorded 51 inches of snow in JUST THE PAST WEEK, and 189 inches for the season. That's a lot, even for Garrett County.

But as those winds cross the mountains and flow down the eastern slopes, they dry out and warm up. So maybe this is the week when the ice shelf hanging over my front door will collapse, the gutters will run free and North Calvert below Mt. Royal will magically expand to two full lanes of traffic Love will melt the snowagain. One can only hope.

The important thing is to move the melting process along at a slow-to-moderate clip before the next storm rolls in early next week, or the warmup predicted for the first week in March arrives and hits the accelerator. We don't want to follow crippling record snowfalls with wet basements and flooding rivers.

(Nor do we want to accelerate the melt with propane. Bad idea.)

But here's the deal: Forecasting models see another storm moving across the continent this weekend, arriving at the East Coast by Monday. They disagree on just where it reaches the coast, leaving a raft of questions about who gets rain, who gets snow, and who gets missed. If we can't take a pass, we may prefer more snow to rain that could produce flooding.

Sterling is looking for partly to mostly sunny skies through Sunday. Highs should hold in the low 40s during the day, dropping into the 20s at night to touch the brakes on the Great Melt. That's a good thing.

Then there's Monday. At this point, five days out, the weather service sees a 30 percent chance for "rain and snow" Monday, with the highs reaching 39 degrees. That shifts to a 30 Canadian snow melter in actionpercent chance for snow Monday night, with a low near 26. Here's a bit of this morning's forecast discussion:

"HAVE REASONABLE CONFIDENCE THAT THERE WILL BE A WAVE THAT
AFFECTS THE REGION IN THE MONDAY TO TUESDAY TIME FRAME... BUT
UNCERTAINTY ABOUNDS WITH THE DETAILS OF THIS SYSTEM...ESPECIALLY
TRACK/STRENGTH. WILL KEEP CHANCE POPS [FORECASTS FOR A CHANCE OF PRECIPITATION] DURING THIS TIME...NOTING THAT THIS COULD BE A MIXED PRECIPITATION EVENT."

AccuWeather.com's weather blogger Henry Margusity is watching the models for this one, too. He sees plenty of cold air moving in, and seems to see more snow ahead. "I kinda feel this is going to end up back with a bigger storm next week," he said. But even he sounds weary of it all. Finally. "I'm hoping this is the finale. I'm done." 

Eric the Red, a professional meteorologist from Baltimore, sees the blocking high in the arctic setting up by the weekend to assure cold air here, and suspects the storm will track across Virginia, not the Ohio Valley (which would mean rain and a nasty mix), putting us in line for snow:

"We can say with confidence that this upper-air pattern will support cold weather here into next week, and the placement of the large-scale features also supports another eastern U.S. winter storm. I mentioned earlier that - off the top of my head - I have seen this set up 4 times this winter; 3 times we got hit, and once there was a near miss (storm formed a bit off the coast)."

Mr. Foot and his team of student forecasters don't have a prediction this far out. But they're working on it. Watch for updates here.

(SUN PHOTOS/Amy Davis)

Posted by Frank Roylance at 10:24 AM | | Comments (8)
Categories: Forecasts
        

Comments

Boy Frank this winter is keeping you busy!!!

Most of the gurus bit way too hard on that clipper Monday night eh?

Well I don't think they're howling at the moon this time. The next Monday/Tuesday storm will have a Gulf (and later Atlantic) connection, that according to this mornings GFS would lay down ~ 0.7" liquid equivalent (BWI) of wet snow Monday mid day into Tuesday early AM. Depending on snow to liquid ratios that would be 6-10".

The Canadian and ECMWF models are equally wet, but take the low to our west and give us a nasty mixed mess of snow to ice and/or rain.

As Eric (a damn fine meteorologist BTW) mentioned above, the building heights over the Davis Straight will make it hard for the storm to plow up the spine of the Apps as depicted in the 12z Canadian and ECMWF.

The GFS 12z solution of taking the low further south and east makes more sense in light of the upstream blocking.

I wouldn't be surprised to see your gurus going 6-12" by the weekend.

State highway officials at Keysers Ridge in Garrett County reported 220 inches to date of snow this season.

FR: Earth to SHA: Abandon ship!

Fun weather today, from nothing, to flurries, to a random snow sqall with the sun trying to peek through, and back to nothing. On the bright side, my holly tree is full of fat robins eating their fill of holly berries. Spring can't be too far behind!

FR: Very cheery. The robins may be early arrivals from the South. But there is also an overwintering population of robins that stick around in flocks and take their chances in Maryland each winter. Dicey decision this year.

Let me guess, Mr. Foot predicts a foot?

Frank, I pretty much assumed they were the overwintering ones from the eastern shore. I've been waiting for them this year. My holly tree is pretty much stripped, after a day and a half. Fun to watch, too. I must have had a dozen or more sitting in the tree stuffing themselves yesterday.

Snow will melt somewhat slowly until dew points reach into the low-mid 30s....

Just curious, what's the effect of the snow pack on our current temperatures? Is there a way they can calculate the chill factor? Or how much higher our current temps would be if we weren't in a giant outdoor ice box?

FR: It is colder when the ground is covered wth snow. Bare ground is darker, and it absorbs more solar energy, radiating it back into the air as heat at ground level. Fresh snow reflects more of that energy directly back into space, leaving surface temperatures colder. One study found the average daytime differences can reach 6 to 10 degrees C. The difference is only 1 to 2 degrees C at night. As the snow retreats, and gets older and dirtier, it is less reflective, and the temperature difference decreases.

Nitpicking here, Frank, but I can't help myself. It's not only that the energy is reflected back, but also it's used to melt the snow.

http://ww2010.atmos.uiuc.edu/%28Gh%29/wwhlpr/fcst_temps_snow.rxml

FR: Fair enough. Thanks.

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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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