Friday, February 15, 2013

Dynamics Are Winning, Just Not Always For You

It's an active 24 hours meteorologically for the East Coast with two features working through the area.  One will impact us, the second brushes us but produces a better outcome for New England.  Showers, changing to snow, look to be in the offing for the region tonight and early tomorrow as the first of two energy shots moves through the area.

Tonight's round of snow showers look to bring a general coating to an inch, perhaps two inches in a few favored spots, to the region as they move through after 11 PM.  There are some differences between the GFS and Euro, with the GFS showing a more robust look with precipitation in the first wave as it moves through while the Euro tends to downplay what falls.

If the more robust GFS look holds, the potential for two inch totals would be a bit higher than in the Euro scenario, which would yield mostly coatings on your car and lawn as surface temperatures are pretty close to 32 degrees.  Tonight's event is rather modest in nature, enough to gunk up the roads a little bit if the GFS is right, but because it's going through at night and into a weekend day the impact on you is generally minimal.

The second piece is Saturday afternoon into the evening hours and here the models disagree a fair amount on the energy evolution and how fast the development of the low pressure center takes place.  The GFS is more robust and tries to throw more snow back to the Shore, perhaps bringing a few inches to the Shore on Saturday afternoon and night while the Euro develops this second wave much more slowly and merely grazes the Shore with some snowfall.

It's a very robust pattern aloft. The main mid level trough coming in is sharp and will do a great job of pulling down cold air from Canada at the surface while developing a storm system off of the coast from the weak disturbances that are pivoting around.  It wouldn't take much adjustment in the timing of a disturbance to fire up a decent snowfall but winters around here are known for shoveling much more potential than reality.  2009-10 is probably the best example of potential and reality being closely tied together!   All that said, we will have a couple of periods of snow showers -- the first tonight along I-95, the second on Saturday evening along the Shore and northeast into New England.

Between those two waves, it looks like the region is in line for a coating to two inches in general.  I have painted a stripe of "best chance for two inches plus" along the Shore from Cape May north as it's possible some banding of steadier or heavier snow could pivot back off of the developing low on Saturday evening and hit them up with some snow.  Some, perhaps several, locations could end up with just trace amounts or even nothing from both waves but as a general rule we're rolling with coating to two.