Saturday, December 15, 2012

December 26-28 Potential Winter Storm

The GFS model has now been showing a big Northeast snowstorm for at least 4 model runs, meaning it's time to take a look at this potential.

We'll start off with the oldest model forecast, the 0z model run from last night. This forecast of the GFS shows a wide swath of snow ongoing in the Plains and Midwest, with heavy rain in the Southeast and Mid Atlantic. The system in question is in the southern Midwest, and the way the precipitation and freezing line is angled tells me that, for many in the Northeast, such a solution would be a solid rain-to-snow event. Frankly, I'm going to discount the 0z GFS because of how different it is from the 6z GFS.

This is the second-oldest GFS model run forecast, the 6z forecast, which was made early this morning. For roughly the same timeframe, the morning of December 27th, we see a fairly strong storm system in New England with a wide swath of precipitation. The solid blue line is the rain/snow line, and its take on this forecast gives inland locations of New York, Pennsylvania and similar states a good batch of sticking snow. Coastal cities receive a nice dumping of rain per this forecast. In the wake of the storm, a  big blast of Arctic air flows into much of the nation, no doubt bringing the lake effect snow machines to  maximum power.

We now turn our attention to the second-newest forecast, the 12z GFS, which was made in the morning hours, about 6 hours later than the 6z. The 12z GFS isn't all that different from the 6z, with a system in the vicinity of the Northeast and a wide precipitation shield. Two main differences include a much weaker precipitation shield and the storm system isn't even onshore with this forecast. Coastal locations now see chances of snow, and Arctic air still flows south into the Plains and Midwest, cranking up the lake effect snow machines. Note the heavy snow ongoing in the Virginias.

And now the newest, and most startling GFS model forecast- the 18z. The 18z GFS, valid for the evening of December 26th, brings an epic storm system up the coast. The storm system bombs out to a minimum central pressure of 968 millibars- not your everyday low pressure system strength. The precipitation shield is wild, with up to 1.5 inches of rain hitting New Jersey. You weather enthusiasts know that average snow-to-rain ratios is 10:1 (inches), so this could mean 15 inches of snow for New Jersey! Heavy snow falls in the immediate coastal regions, with relatively lighter snow farther inland. Again, the arctic air continues to come on down into the Plains and Midwest, Ohio Valley and Mid-Atlantic behind this system to provide a base for lake effect snow and enhanced chances for snow in the Northeast.

It's obvious that we are dealing with something on our hands, the question is exactly how strong could this system be, where could it go, what type of precipitation could it bring, and the most important question: Will it even happen??

We still have a lot to learn on this potential, but it looks like the potential could be there.



Katie said...

Very exciting andrew! I hope this pans out well

I live just outside of DC and we barely had any snow last winter. This could be the ticket! Wich of the model runs you just showed tp you think is the most favorable in terms of snowfall to the DC metro area?

Thanks so much! Keep us updated on this :)

Anonymous said...

Is this related to the New Year's Day/Eve potential storm? Or are these totally separate systems?