Wednesday, December 19, 2012

December 25-28 Potential Significant Winter Storm (Updated 12/19)

We continue to see the potential for a significant winter storm somewhere in the East US between December 25-28. Let's see what the models are saying today.

I've decided today will be dedicated to the ensembles, because I just don't trust the operational models this far out to handle a storm like this on their own. As we saw with the Dec. 19-22 blizzard, it can take a while before a reliable solution can be developed, so we'll look to the ensembles for the time being. This forecast is for Christmas morning, and we can see our storm system sitting in the Gulf Coast region. The ensembles seem pretty disorganized as far as exact location goes, seeing as there is no defined low pressure area on the image for this body of precipitation.

Moving ahead to the morning of December 27th, we see the ensembles have solidified in a system more confidently, with a low pressure signature now showing up just offshore of New Jersey. We see the rain/snow line hugging the storm as well, a solution that would bring heavy snow to much of the Northeast.

Considering the general neutrality of the North Atlantic Oscillation through this timeframe, with a slight positive PNA, I wouldn't go as far as to completely trust this solution. It will need to be watched, but I'm not totally confident in it.

Moving on to the Canadian GGEM Ensembles, we find our system stationed in the Southwest, producing copious amounts of precipitation on the evening of December 26th. Keep an eye on these timing issues. The GGEM Ensembles appear to be following a track similar to the GFS Ensembles, although they appear to want to pull the storm slightly further north, possibly in response to a weak positive PNA.

The morning of December 28th brings the storm well offshore per the GGEM Ensembles. Some precipitation is reaching the immediate coastal areas as snow, but with the system so far offshore, I would like to disprove that precipitation forecast.

I don't trust the GGEM Ensembles usually due to their base off the GGEM model, but they do seem to agree with the idea of a slight positive PNA having an effect on this system. It will have to be watched.

Morning of December 26th

Morning of December 27th
The ECMWF Ensembles take a totally different track on this system, preferring to have the system start out in southern Tennessee before moving northeast into the Northeast US, not offshore. A sharp cold outbreak then follows the energy. Such a track would likely bring the best snows to the Ohio Valley and central Great Lakes, but because the ECMWF EPS precipitation graphics are so expensive (if the European weather center even produces them), we have no way of knowing.

For those wanting the ECMWF model itself, here's a couple precipitation graphics:


All precipitation above the dark blue line would be snow- and that would be a LOT of snow for the western Great Lakes and Midwest, possibly in excess of 10 inches.

Forecast preference: ECMWF ENS
Confidence: 20%

Andrew

7 comments:

Aran Jacobs said...

Why is your confidence so low?

Anonymous said...

Is this storm going to effect nyc in the form of rain or snow

Art Vandelay said...

Andrew whare are you from? are you from the ohio valley area? I need to know this because that will help me better understand your forecasts and why you seem bias towards certain areas, thanks.

Rob ice said...

Looks like NYC "once again" be rain! Ughhh whatever... .I'm traveling to Alaska for snow and cold..

Anonymous said...

Tom Skilling, for Chicago, a chief meteorologist for 32 years is flabbergasted to say the least. He was at a loss of words when he showed the newest model run at 9:50 this evening! With that, you know this is going to be big and has it's eyes centered right over Chicago and NW Indiana! This is going to be very interesting to see what pans out! Epic!

Anonymous said...

Tom Skilling, for Chicago, a chief meteorologist for 32 years is flabbergasted to say the least. He was at a loss of words when he showed the newest model run at 9:50 this evening! With that, you know this is going to be big and has it's eyes centered right over Chicago and NW Indiana! This is going to be very interesting to see what pans out! Epic!

ERN WX said...

Mdls are lost on this storm. A slgt +PNA and slgt -NAO could support an E coast snowstorm. Soln range from a monster MW storm to weak wave ejecting off the coast with little pcpn for anyone. COLD AND SNOW ARE LOOKING PREVALENT in the long range. With a +PNA, -AO, and -NAO looking possible in early Jan. this could be true.