Discussion: A large upper level vortex over the Arctic moves south into east central Canada by the end of next week. A cold front comes through during the day on Monday, followed by a weak area of low pressure offshore on Wednesday. High pressure over the central US and Low Pressure over Eastern Canada opens the floodgates for Cold air on Friday.
Here’s a look at the 0Z ECMWF 1/11/2013 HR 192 From the PSU Ewall Site. You can see tremendous cold air advection at the 850 MB level. That’s the -20C line over Northern Massachusetts!
The questions remain: how long does it last? and Will we see any snow?
FORECAST: Monday and Tuesday could be unsettled with that cold front passage. Much of this precipitation should be in the form of rain, since the cold air will arrive pretty late in the game. Across the interior, however, some snowflakes at the end cannot be ruled out. Wednesday through Friday look dry. I think any low pressure that tries to move through on Wednesday scoots away to our south. The main story here is a significant progression towards colder weather, especially Thursday and Friday.
In the Longer term the PNA is forecast to remain neutral to slightly negative for the next couple weeks which essentially means I expect Southern New England to be a battle ground zone between warm and cold air-masses. This can be good for significant weather events in the area. Even that is wishful thinking at this point as there is no evidence through the early part of the long range to support major snowfall. Both the GFS and the ECMWF continue to show additional robust shots of cold air around the 216+ forecast hour period. That Can’t be ignored either. Your five day forecast graphic can be seen below. Have a great day everybody!