The light snow began much earlier than what was previously anticipated and it appears that snow will continue into early this afternoon before it begins to change to freezing rain from south to north.
The change from snow to freezing rain is expected to occur first from the lower Pioneer Valley eastward along and south of Route 9 around the 1 to 3 pm time frame. This changeover line is then expected to push northward reaching the Route 2 corridor by late this afternoon and early this evening.
The big question then becomes whether the freezing rain changes to rain this evening or will a majority of the area remain as freezing rain all night long.
Some of the high resolution weather guidance forecasts that the cold air will tuck in and remain stubborn leading to a prolonged freezing rain event all night long across the entire area.
Other high resolution weather guidance points to the freezing rain flipping to rain across most of the area this evening. The exception is the far northern Worcester Hills and the western Hilltowns of Western Mass where freezing rain hangs on much of the night.
At this point, I think that we may see the freezing rain last for roughly 3 to 4 hours across most of the area. This means that freezing rain should change to rain in the area from the lower Pioneer Valley to near and south of Route 9 around the 4 to 6 pm time frame. Freezing rain looks to change to rain as far north as Route 2 by about 8-10 pm this evening. It's possible that freezing rain may persist across the area north of Route 2 all night long.
All precipitation will come to an end by about mid-morning Tuesday.
Snow amounts before the changeover to freezing rain is expected to average around one inch across most areas. The exception looks to be across the far northern Worcester Hills where around two inches of snow accumulation looks likely.
The ice accumulation forecast is much more difficult to figure out as it's going to hinge heavily on how long the freezing rain lasts.
If my forecast turns out correct and we do see the freezing rain change to rain early this evening near and south of Route 9, then ice amounts of less than one tenth of an inch would occur. North of Route 9, ice amounts of one to two tenths of an inch look possible as the freezing rain may hang on a little longer into this evening. Areas north of Route 2 may see around one quarter of an inch of ice from the freezing rain due to the fact that it could persist all night long tonight.
On the other hand, if we don't see any sort of change from freezing rain to rain and instead we see the freezing rain persist all night long across the entire area, ice amounts everywhere would be much higher. In this "worst case" scenario, ice amounts of around one quarter of an inch would be possible across all of Western and Central Mass.
I am watching things very closely and will have updates as needed, especially if we do see a colder and icier scenario pan out.