Snow, sleet, and freezing rain - all in a day and night

Update on tomorrow's WINTER WEATHER ADVISORY:

Take heed - tomorrow's Winter Weather Advisory for Amherst and the surrounding region has moved earlier - now starting at noon Tuesday through 7 am Wednesday. So if you, like me, were thinking you had until Tuesday night to start considering the possibility of hazardous travel, guess again.

All models are coming into good agreement on the timing. Precipitation is expected to break out in Western MA and northern CT in the afternoon and spread eastward toward evening. That said, the most difficult part of this forecast is what precipitation to expect and when. So we don't know exactly what kind of precipitation will be falling in the afternoon.

Since this morning, NOAA has expanded the Winter Weather Advisory to include Central Middlesex and Western Essex Counties in Northwest MA. They have also upped snowfall totals significantly over interior and especially northern MA.

All models are predicting at least 3 inches of snow, with perhaps as much as 6 inches occurring in the Route 2 corridor of Northern MA. Best estimate is for 3-4 inches around here. Following the snow, sleet and freezing rain will be the predominant type of precipitation in Western MA before, most likely, changing to all rain. Up to one-tenth inch of ice accretion is expected, although NOAA is not ruling out local two-tenths amounts, especially in the slopes of the Berkshires.

A lot could change with this situation. A small change in temperature, both at the surface and aloft, could result in big changes of precipitation type and corresponding snowfall amounts.

And while the difference between 2 and 4 inches of snow isn’t going to make any of us break out in a panic, ice is another beast entirely. Keep in mind that even a thin coating of ice on untreated roadways can be dangerous. Please slow down and use caution if driving Tuesday afternoon and Tuesday night.