Thursday, February 7, 2013

New England Historic Storm Taking Shape

If there is one thing that is pretty certain here, is that New England is going to get smoked. These estimates of 24-30" of snow are realistic. This is going to be an old fashioned, New England blizzard. For the rest of us, from NYC south, the uncertainty remains king. We are dealing with two separate low pressures. One, a disturbance diving out of Canada towards the East Coast. The other, a low pressure in the Gulf States. These two low pressures will phase, or merge, along the East Coast and move ENE around the "benchmark"

EDIT- I have mentioned the "benchmark" on several posts, but I have probably not done a good job explaining why this is important. The "benchmark" is located at 40N and 70W and the significance is that a large majority of winter storms pass over this area bringing the perfect balance of distance to bring the biggest storms.

So, the questions remain where exactly these two low pressures phase, how phased the evolving storm can intensify, speed of travel and track of the storm. Each model is still showing some different outcomes based on these variables. Each model is also able to pick up on subtle characteristics that are making the forecast very difficult. Overnight, the NAM model had zero snow for Philly. The GFS showed a couple inches for Philly and the Euro was like 6" for Philly. Whats more mind boggling is while Boston is looking at 30", NYC could very well hit 12" of snow, while Philly sits at zero. This is the type of spread we have. Any earlier phase, we could be looking at substantial snows. Any later, or a further east track, we will be looking at showers with next to nothing.

For now, I am going with snow starting very early tomorrow morning (5- 7 am). Late morning we switch to mixed precipitation and rain. Late afternoon we switch back to snow and may get some period of moderate snows. I think from 195 north to NYC, 3-6" can be expected while areas from 195 south to Philly can expect 1-3". This is based on my current thoughts, but confidence is still low on this. By tonight I will issue a final. Places in NW NJ and the Lower Hudson Valley 8-12" can be expected while areas to the east from I87 - I91  12-20" and then from I91-East Coast 20-30".

Please remember for those areas looking to get walloped that this will be a rapidly intensifying storm and the winds will be whipping. There is also a higher than normal chance for thundersnow. Snowfall rates will easily make 1-3"/hour in many locations, if not more. This will be a very intense and dangerous storm.

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