Weather It Is (Extreme Cold)

 Good evening:

As a trough of low pressure dips southward from the polar jet stream, heavy rain should occur on Sunday.

The trough is forecast to move to our east Sunday evening, but as it does it will usher in the coldest air of the season (by far).  

Synoptic forcing for precipitation should be cut off as the trough moves to our east Sunday afternoon.  Normally, this would be the end of the precipitation.  However, the extremely cold air passing over the sea could combine with  lingering moisture in the middle of the atmosphere (at 700 mb) to produce snow squalls later Thursday afternoon and evening (with possible accumulation).  

Temperatures will be close to or below freezing in many locations on Monday and Tuesday mornings.  Similarly cold air should return on Thursday and Friday, and early next week there are stronger indications for our first snowstorm of the year (but the signal for this is just that, and we'll have to see if all the "pieces" fit together (the upper level trough needs to nose down not to our east -- as in the current situation -- but just to our west as the cold air sweeps in at the surface)). 

Cold temperatures are forecast until or through the last week in January.

Shavua Tov,

Barry Lynn