Snowmen or Mud Puddles by Wednesday?

Santa Claus is coming to town for weather lovers! Well, that’s if the Euro is right. It’s been a hectic few days for me so I haven’t had time to jot much down here on the blog. Today’s set of model runs reveal a stormy pattern coming up that may wind up quite wintry over a portion of New England.

72 Hour GEFS Mean 500mb Height and Anomalies

72 Hour GEFS Mean 500mb Height and Anomalies

Here’s the setup 72 hours from now per the GFS ensemble mean. It’s a highly amplified pattern with a few things of note. First off, note the polar vortex off the North Pole that has slipped toward Siberia. At the same time a lobe of that polar vortex extends through Alaska. Coupled with a large ridge of high pressure north of Hawaii there’s a fire hose of a Pacific jet ripping south of Alaska – in fact it reaches 200 knots on the dynamic tropopause on the 12z op GFS run!

What’s also of note is the large height anomaly over Greenland and eastern Canada just north of the Davis Strait. That block over Greenland (-NAO) plus a very active train of shortwaves moving in from that ripping Pacific jet will make things fun over the coming days.

Prior to the storminess there’s a noticeable dearth of bitterly cold air over North America outside of Alaska. Here’s the 72 hours Euro Ensemble 850mb anomalies. That may make significant snow a challenge, but not impossible, for a large portion of Connecticut.

72 Hour Euro Ens 850mb T Anomalies (dark green +2 to +4C... color contour every 2C)

72 Hour Euro Ens 850mb T Anomalies (dark green +2 to +4C… color contour every 2C)

Regardless, with a beautiful looking -NAO block things may turn interesting. Here’s the 72 hour op Euro 500mb heights/vorticity. I labeled the 3 shortwaves of interest for us here in Southern New England.

72 Hour op Euro

72 Hour op Euro / 500mb Heights/Vorticity

With this being a 72 hour forecast there’s plenty of time for things to change particularly when these shortwaves are flying in at 0ver 200 knots off the Pacific jet. How those waves interact will determine where they track and how strong the resultant storms will be.

As we’ve become accustomed to lately the GFS ensembles and the Euro ensembles have wildly different solutions for the upcoming stormy period. The 12z Euro ensemble mean is absolute snow porn for southern New England.

Euro Ensemble Mean MSLP/500mb Heights 00z Monday

Euro Ensemble Mean MSLP/500mb Heights 00z Monday

Screen shot 2012-12-12 at 6.39.00 PM

Euro Ensemble Mean MSLP/500mb Heights 00z Tuesday

Screen shot 2012-12-12 at 6.39.07 PM

Euro Ensemble Mean MSLP/500mb Heights 12z Wednesday

That’s pretty much a 60 hour period of snow ending in a big snowstorm! I doubt that’s going to happen, however. Even though we do have blocking to our north we have little cold air to work with. That may be problematic for places outside the hills. In addition, it’s pretty challenging to get 3 individual shortwaves to produce storminess in such a short period of time. Normally one (or two) become dominant and the others fizzle and produce little excitement.

The 18z GEFS has a pretty ugly solution for snow lovers with the storm track a bit west with a mild solution for the parade of shortwaves. As usual, the truth probably lies somewhere in the middle.

It’s too early to get into specifics it does look like a stormy period is coming up. If the timing of the upper level impulses is just right we may wind up seeing a pretty significant winter storm early next week. A light wintry mix will begin on Sunday, that I’m relatively confident about, but from there it’s going to be a challenge to figure out how much and what.

If I were to pin down an area that is most likely to get a significant amount of snow it would be central and northern New England. I like how things look for ski  country coming up! With any luck, we’ll cash in on the action too.


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