Summary: It looks likely that Berkshire County should have a White Christmas as we receive about 1-3″ tonight into tomorrow morning from a weak surface low pressure system passing by to our south. The higher amounts in that range should fall in South County with the lower end of that range more likely in North County. The snow should spread across the county from south to north, starting around 11 pm in South County, midnight in Central Berkshire and around 1 am in North County. The precipitation may start as a burst of moderate snow but, in general, the snow will be light and intermittent. Light snow is still likely at daybreak but it should taper off fairly quickly and end during the late morning hours.
The biggest weather story of the week and probably the season so far will likely be the much stronger storm (Nor’easter) that appears headed our way for Wednesday night and Thursday. The surface low pressure center will move along the western slopes of the Appalachians during the day Wednesday and then redevelop along the Delmarva Peninsula Wednesday evening. It will then move slowly northeastward hugging the New Jersey and Long Island coasts Wednesday night and Thursday morning and then over Cape Cod by Thursday afternoon. The precipitation will begin as snow Wednesday evening and will likely come down heavy at times. With this track, the counterclockwise circulation around the low will also generate strong Northeast winds (i.e. Nor’easter). However, with the track hugging the coastline, this same circulation will cause milder air from the ocean to lift up and over the cold dense air near the surface. This warmer air aloft could cause the precipitation to change to sleet (ice pellets) for a time. This is more likely to occur in southern portions of the county than northern portions. If all snow falls we should be looking at at least 8-12″ and possibly more that a foot. If there is a transition to sleet, this will diminish snowfall amounts considerably. Once any warmer air gets in place aloft, and the sleet begins, the remainder of the precipitation in any location that this occurs will likely continue as sleet. At this point, I think the all snow scenario for most of the county, with a possible changeover to sleet in South County, looks most plausible and I believe we will get substantial accumulations.
After that storm moves by it should turn colder for the remainder of the week and then we could get another coastal storm over the weekend….
Monday Night
Increasing, lowering and thickening clouds this evening with snow developing from south to north near midnight. There may be a brief burst of moderate snow at the outset but the snow will generally be light and intermittent through the remainder of the night. Probability of precipitation 90%. Snowfall totals overnight should range between 0.5″ and 2″.
Temperatures should fall into the mid 20s in the lower elevations and low 20s over the elevated terrain with the onset of the snow and then hold steady for the remainder of the night.
Calm winds this evening will become light (less than 5 mph) out of the north-northeast after midnight.
Tuesday
Intermittent light snow tapering off during the morning and ending by noon. A low overcast should persist for most of the afternoon, although there may be a few breaks in the clouds late. Probability of precipitation 70%. Total snow accumulations for Monday night and Tuesday will likely be 1-3″ with the higher amounts to the south and lower end of the range to the north.
Temperatures will not rise much with highs near 30 to low 30s in Pittsfield, Adams, North Adams and Williamstown, low 30s in Great Barrington and Sheffield, and mid to upper 20s over the elevated terrain and hilltowns.
Northwest winds at 5-10 mph.
Tuesday Night
Clearing skies during the evening, becoming clear after midnight.
We are set up for a fairly good radiational cooling night with clear skies, light winds and a snow cover. However, the winds won’t be completely calm and the snow cover will be thin. Still, it may be the coldest night of the season so far with low temperatures in the low to mid teens.
Light northwesterly winds becoming northerly after midnight.
Wednesday
It will start out mostly sunny but clouds will be increasing, thickening and lowering during the afternoon. There is a slight chance that snow could begin late. Probability of precipitation 20%.
High temperature in the low 30s in Pittsfield, low to mid 30s in Adams, North Adams and Williamstown, mid 30s in Great Barrington and Sheffield, and mid to upper 20s over the elevated terrain and hilltowns.
Light northeast winds early will increase to 8-12 mph by dark.
Wednesday Night and Thursday
Snow will likely develop Wednesday evening and continue moderate to heavy at times through the morning on Thursday. The precipitation likely will change to sleet in South County and possibly in Central Berkshire. However, I think it will more likely stay all snow in Central and Northern Berkshire. It could even stay all snow in the south. The precipitation should change back to all snow and taper off during Thursday afternoon. Probability of precipitation near 100%. Areas where the precipitation stays all snow will likely receive at least 8-12″ and possibly more than a foot, particularly over the favored east-facing slopes over the elevated terrain. Places where it does turn to sleet will likely receive 3-6″ before the transition with an additional inch or so of ice pellets.
Temperatures should hold steady overnight in the mid to upper 20s in the lower elevations and low to mid 20s over the elevated terrain. Temperatures will only rise a few degrees during the day on Thursday. It should remain freezing or below everywhere.
Northeast winds will increase to 15-25 mph overnight Wednesday night, probably higher over the elevated terrain, particularly exposed east-facing slopes. Gusts to 40 mph are likely. During the day on Thursday winds will diminish and shift to northwest during the afternoon.