Thursday, February 11, 2010

By Forecasters Dakota and Winterman
Next Storm Please...
12:30 AM Sunday 2.27.2010  
Except for a stray rain or snow shower tonight and tomorrow, things should be relatively calm in the upcoming days. However, we once again we have a potential storm system that has it's eyes on the East Coast for midweek.

The "snowicane" that pounded the northeast has now dwindled as a retrograding low pressure that has kicked up some snow showers across Ohio, Pennsylvania, and New York. A couple of these snow showers may sneak into our region tonight and tomorrow morning bringing a flurry or two. Temperatures Sunday, Monday, and Tuesday will reach the low to mid 40's during the day and dip into the mid 20's during the nighttime. Slight colder temperatures will be brought by the passing storm system on Wednesday whether it goes to the south or brings snowfall. Conditions will return to normal for the end of the week with mostly sunny skies and 40 degree temperatures. ~Forecaster Dakota 

The key to forecasting this storm will be the low pressure system that will be in the  North Atlantic when the storm affects the East Coast. This low pressure will actually be a merged pressure system. The "snowicane" low pressure and the low pressure system currently scooting off the Southeast U.S. Coast will merge over the Atlantic early this week. A strong low pressure system quite a ways off the coast can suppress a just as strong low pressure system on the East Coast. If the Atlantic low were to stay east in the North Atlantic during the development of the coastal low, we would stay primarily snow free. If the Atlantic low were to move more east and north, a significant snowfall (4"+) could occur. 

While looking at models I have noticed some trends. During the day today the NAM model shifted the Atlantic low west and the GFS shifted the Atlantic low east. Over the last two model runs, it seems they have some to somewhat of a consensus on the Atlantic low position. With this low at a consensus, the NAM brings the coastal low to near Cape Hatteras and then out to sea. The GFS brings the coastal low a ways east of Cape and then out to sea. This GFS has remained relatively consistent throughout the last several model runs with this coastal low track. Both of these tracks only bring light precipitation into southern Maryland and northeastern Virginia, and then bring more precipitation amounts as you go south. I say "precipitation" because there will most certainly be a rain/snow line that sets itself up across the Mid-Atlantic. With that in mind, this storm appears to be a warmer one, without a feed of arctic air. This would cause some areas to receive all rain and/or mixing with rain. This would also cause lower QPF to snow ratios in places that do receive snow. But as of right now, no model shows a significant snowfall for the Mid-Atlantic region. 

Moral of the story, closely follow the trend of the position of the Atlantic low and that will give you a good idea of where the track of the coastal low will trend.

***Something to note... 
Currently the focus has been on the NAM and GFS models because of accessibility and time. Foreign models should always be into account, however I believe for tracking the Atlantic low, the GFS and NAM are sufficient models to use. On a final note, there are other factors to this storm system, however it is believed that the Atlantic low is an extremely important factor that will affect the coastal low's track.      
~Forecaster Dakota 

Baltimore-Washington NWS | Current Temperatures

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