Sunday - Tuesday Storm - Updated Sat Morning

You would think that there would be a clearer picture for this coming storm by Sat morning ... but there are still many, many questions:

1. Track of storm: south of us or north of us? 
2. Speed of cold air moving south Sun night and Mon
3. Amount of precipitation left when cold air arrives
4. Strength of storm Mon night: strung out or deepening 

All of the above have impacts on any snow accumulation. But we have learned a few things:

1. NY State through New England will get another 12-18" of snow with locally higher amounts. 
2. South of the MD border there will not be any snow at all. 
3. If you are north of route 80 in PA you will see some snow, 6" or more. 
4. Warm air will win out Sun and Sunday night. 
5. Rain will arrive Sunday night. Sunday day will be mostly dry and mild (near 40 for a high.) 

A final update and forecast will be given later this evening, or early tonight. Enjoy the relative warmth (avg. high this time of year is pretty close to 40 by the way). 


Below you will find images that provide the various options that are presented for the so called Big storm on Sun-Tue.  The job of forecaster is to discern what the correct solution is. Often times it is a combination of the presented options, esp. when 3-4 days away from the storm itself. 


There are some things we do know: 
1) There will be a storm. 
2) Cold air will be available.


What don't we know: 
1) How far south will cold air lock in. 
2) Will storm deepen along coast or move out to sea more quickly.
3) How much precipitation will fall


Discussion below images. 

The above image shows the American GFS model showing a colder, snowier storm that is pulling away Monday Evening. 


The below image shows the European ECMWF model showing a colder, snowier storm that is deepening along the coast Monday evening leading to a period of heavier snow. 

The below image shows the Canadian GEM model with a warmer, rainy storm with it deepening along the coast Mon evening. This might give a small amount of snow at the end, as cold air sinks south Monday night. 

This is one complex set up for these three days. 


My first guess is that rain/wet snow will break out Sunday then change to all wet snow by late afternoon. The snow continues through Monday afternoon. Since the cold air will be filtering south, the snow will likely become fluffier.

The big question then becomes, does the storm move off the coast and away or does it deepen and hang around another 6-10 hours. If it deepens, then the snow could get heavy for a time, but if it moves away the snow ends by Mon evening.

This is not a huge storm. I would expect several inches at this point, but we are still 3 days away from the very beginning of the storm. Lots of details to work out. 

Again, it is possible that warm air stays in longer, and we get more rain and less snow esp. Sun and Sun night. 

Note: This arctic front really dried up once it hit the Appalachian Mountains. It over produced in many parts of the Midwest and Ohio Valley, but really fell apart once it came east, that is until Eastern New England. Might be because that southern moisture/lift from Gulf of Mexico energy, was really close to producing a major snowstorm. It was really close to happening.