After a cold front moved across the region last night, colder air is settling in across the Northeast U.S. The cold air is bringing lake-effect snow to western New York and the Adirondacks this morning and is expected to generate snow showers across northern New England and the North Country throughout the day on Monday and Tuesday. 

 

Radar loop on Monday morning 16 November; courtesy intellicast.com.

We're not expecting much powder out of these snow showers and snow squalls across the North Country, with less than 1" expected across most of the ski-able terrain in Vermont, New Hampshire and Maine. Besides, most alpine environments currently lack snow cover and resorts are still closed. Some snow has already fallen across Vermont with cams at Killington showing a dusting of snow on top of their mountain. The best shot at finding powder will be across northern Vermont (e.g., Jay Peak) where 4" of new snow is expected over the next five days (through Friday 11/20). 

With daily high temperatures on Monday through Thursday below freezing, and overnight low temperatures in the teens, we can expect mountains to be firing up their snow guns and trying to lay down a base as we wait for more significant snow. The big story this week will also be wind with wind speeds and wind gusts of 20 to 40 mph expected across the higher terrain, with locally higher gusts above treeline.

New England can expect a roller coaster of temperatures as we head into the weekend (11/21-11/22) and next week through Thanksgiving. A series of big storms on the West Coast will flood the U.S. with warm Pacific air that will reach the Northeast U.S. on Friday (11/20). This warm air will push alpine (>3000-4000 feet) temperatures well above freezing through Monday (11/23). We can visualize this warm air across the eastern half of the U.S. by looking at a forecast map of the 850-millibar temperature anomalies (i.e., how much warmer the air is at ~4000 feet relative to normal) on Saturday from the ECMWF (European) model:

Image of temperature anomaly on Saturday 11/21 courtesy www.pivotalweather.com

The confidence in the forecast breaks down after Monday 11/23. Both the GFS (American) and ECMWF (European) models call for a brief shot of cold air on Tuesday/Wednesday with the ECMWF more bullish on another round of lake-effect, snow showers, and snow squalls across the mountains. We can visualize this shot of cold air across the Northeast by once again looking at a forecast map of the 850-millibar temperature anomalies on Tuesday 11/24 from the ECMWF (European) model: 

Image of temperature anomaly on Tuesday 11/24 courtesy www.pivotalweather.com

Both models then diverge on the details for the next storm, but one thing remains somewhat constant: more warm air from the Pacific being dragged across the U.S. keeping temperatures near or above normal. We can look at NOAA's Climate Forecast System (CFS) for some ideas on how the large-scale flow pattern may evolve over the next several weeks. Note that these types of forecast carry a lot of uncertainty, but can give us an idea if any big pattern changes that might be waiting in the wings. The animation below is weekly forecasts of the 500-millibar ( ~15-17,000-foot) flow and its anomaly through the end of December; red colors generally favoring warmer than normal and blue colors favoring colder than normal temperatures. 

Animation of CFS weekly 500-millibar flow and anomaly from www.tropicaltidbits.com

Jay Cordeira, Meteorologist

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