UPDATE On Tuesday's Snowfall

Based on the latest data coming in, I am drastically cutting snow totals across the entire area. Further reductions in the snow totals are possible should this storm system slide further offshore.

I absolutely HATE (and it makes me very grumpy) having to change the forecast like this and I absolutely know all of you don't like having to deal with a significant forecast change like this. That said, let me explain once again why the forecast needs to be changed like this.

Starting yesterday afternoon and continuing through last night, the model guidance began showing a notable push to the south with the expected area of heavy snow. This has led to the possibility of far northern parts of our area to miss out on most of this storm.

That said, the latest model guidance this morning has begun showing a shift back to the north with the forecast area of heavy snow. The question then becomes whether this is real and will this shift to the north continue with this afternoon and tonight’s model guidance forecasts.

The reason for these changes in the model guidance has to do with a couple of important weather factors. The first is the orientation and strength of the upper level trough of low pressure that’s pushing across the southern United States. This upper level trough is not producing the amount of thunderstorm activity that was originally expected and because of this, the trough may not be able to lift as far northeast towards our area as originally thought. This leads to the heaviest precipitation to be guided further south leading to some to possibly miss out on any snow at all.

The second weather factor playing into these changes to the forecast is another upper level trough of low pressure that’s moving through the Great Lakes region. Weather forecast guidance is showing this trough being stronger than what was previously forecast. This causes the low pressure system that’s expected to form near the Mid-Atlantic coast to be pushed further south and also causing a very sharp cutoff on the northern side of the snow shield. This sharp cutoff is likely to cause a drastic reduction in snowfall amounts from the Pioneer Valley up into northernmost Worcester County where some areas within 30 miles of each other may go from several inches of snow to nearly nothing at all.

I want to state that there is a lot of sensitivity in the storm track and any small changes in atmospheric factors such as increased thunderstorm activity over the southeastern United States could lead to more changes in the forecast.

HERE ARE MY LATEST THOUGHTS AS OF 5:30 PM MONDAY: Snow is expected to overspread the entire area between about 5 am and 7 am Tuesday morning.

Steady snow is then expected throughout the day on Tuesday. The intensity of the snow will depend on where you're located. Areas of far southern and southeastern Worcester County may still see periods of moderate to heavy snow from mid-late morning into early afternoon while all of Western Mass and northern Worcester County stays as light snow all day long.

The snow is then expected to come to an end from west to east starting with Western Mass by late afternoon Tuesday and then across Central Mass by very early Tuesday evening.

Our UPDATED snowfall forecast map for this storm is attached to this post.

A Tuesday Snowstorm Continues To Look Likely For Much Of Central Mass & Parts Of Western Mass

It still looks like a snowstorm will impact all of Central Mass and parts of Western Mass during the day on Tuesday. The area that may miss out on seeing significant accumulations of snow could end up being the upper Pioneer Valley of Western Mass and the northern Berkshires. Also, I do think that areas of Central Mass that are along and south of the Mass Pike (includes I-84, I-395 and Route 146 corridors) will probably see a solid foot of snow from this storm.

The model guidance today is in complete mayhem and most of Western and Central Mass is straddling a razor thin line between a very minor snowfall and a full-blown major snowstorm. This, obviously, makes for an extremely difficult forecast leaving me with one very big headache.

So, here is the reason for the extremely difficult forecast: Starting yesterday afternoon and continuing through last night, the model guidance began showing a notable push to the south with the expected area of heavy snow. This has led to the possibility of far northern parts of our area to miss out on most of this storm.

That said, the latest model guidance this morning has begun showing a shift back to the north with the forecast area of heavy snow. The question then becomes whether this is real and will this shift to the north continue with this afternoon and tonight’s model guidance forecasts.

The reason for these changes in the model guidance has to do with a couple of important weather factors. The first is the orientation and strength of the upper level trough of low pressure that’s pushing across the southern United States. This upper level trough is not producing the amount of thunderstorm activity that was originally expected and because of this, the trough may not be able to lift as far northeast towards our area as originally thought. This leads to the heaviest precipitation to be guided further south leading to some to possibly miss out on a snowstorm (we’ll see though).

The second weather factor playing into these changes to the forecast is another upper level trough of low pressure that’s moving through the Great Lakes region. Weather forecast guidance is showing this trough being stronger than what was previously forecast. This causes the low pressure system that’s expected to form near the Mid-Atlantic coast to be pushed further south and also causing a very sharp cutoff on the northern side of the snow shield. This sharp cutoff is likely to cause a drastic reduction in snowfall amounts over the upper Pioneer Valley, the northern Berkshires and possibly extreme northern parts of Worcester County where areas within 30 miles of each other may go from a pretty decent snowstorm to nearly nothing at all.

I want to state that there is a lot of sensitivity in the storm track and any small changes in atmospheric factors such as increased thunderstorm activity over the southeastern United States could lead to more changes in the forecast.

Bottom Line Is That there is some weather forecast guidance today that’s forecasting no snow at all tomorrow across most of the area and there are some that are forecasting a widespread region-wide raging snowstorm tomorrow. My job is to try to figure out which ones are the least wrong and then come up with an actual weather forecast, based on my experience. The boom-bust potential with this storm is extremely high.

Here Are My Latest Thoughts As Of Early Monday Afternoon: Snow will overspread the entire area between about 4 am and 6 am Tuesday morning.

The snow is then expected to become heavy to very heavy in intensity between 8 and 10 am Tuesday morning across much of Central Mass and across the lower Pioneer Valley of Western Mass. Meanwhile, the middle and upper Pioneer Valley and the Berkshires should see light to moderate snow in intensity.

So, for much of Central Mass and especially areas near and south of I-290 and the far lower Pioneer Valley of Western Mass, expect snowfall rates of 2 to 3 inches per hour between about 9-10 am Tuesday morning and about 2-3 pm or so Tuesday afternoon. It should be noted that areas of southeastern Worcester County, including the Route 146 corridor may see 4 inch per hour snowfall rates between about 12 pm and 2-3 pm Tuesday afternoon.

Across the middle and upper Pioneer Valley of Western Mass, the Berkshires and extreme northern Worcester County (near the border with New Hampshire), a generally light to occasionally moderate snow can be expected throughout the day on Tuesday with snowfall rates remaining in the one-half per hour to one inch per hour range.

The snow is then expected to come to an end from west to east starting with Western Mass by late afternoon Tuesday and then across Central Mass by very early Tuesday evening.

Our latest snowfall forecast map for this storm is attached to this post.

Expected Storm Impacts: Travel conditions throughout Tuesday morning into the first part of Tuesday afternoon is expected to be extremely difficult across all of Central Mass and across the lower Pioneer Valley of Western Mass. Areas near and south of the Mass Pike and especially the area from the I-84 corridor through the I-395 and Route 146 corridors could see extraordinarily difficult travel conditions at times mid to late morning Tuesday into the first part of Tuesday afternoon. This is all due to the expectation of extremely heavy snowfall rates of 2 to possibly 4 inches per hour. In fact, some roads may be impassable due to snowplow crews not being able to keep up with the very heavy snowfall rates.

In addition to this, wind gusts of 30-40 mph out of a north to northeast direction will cause areas of blowing snow and whiteout conditions at times throughout the day on Tuesday.

Road conditions will slowly improve during the late afternoon hours of Tuesday and Tuesday evening as the snow lightens up in intensity and ends and road crews are able to catch up with snow plowing.

I am still strongly recommending that all non-essential businesses should close on Tuesday and that all non-essential functions should be canceled on Tuesday across all of Central Mass, as well as across the lower Pioneer Valley of Western Mass. In addition, I continue to recommend that all schools across Central Mass and across the lower Pioneer Valley of Western Mass should be canceled on Tuesday.

Temperatures during Tuesday are expected to remain steady between 28 and 31 Degrees throughout much of the day. Temperatures will gradually fall to near 25 Degrees by late afternoon and early evening.

Winds during Tuesday will be North to Northeast at 15 to 20 mph with gusts to 30 to 40 mph.

I continue to closely monitor the progress of Tuesday’s snowstorm and I will most definitely have many more updates for you as needed.

Significant To Very Significant Snow Accumulations Are Expected On Tuesday Across Western & Central Mass

For The Rest Of This Afternoon: More clouds than sunshine can be expected throughout the rest of this afternoon. Temperatures will be between 40 and 45 Degrees. Winds will be Northwest at 10 to 20 mph.

Tonight: A weak high pressure system will build into the area leading to partly cloudy skies throughout tonight. Low temperatures will be near 30 Degrees. Winds will be Northwest at 5 to 10 mph.

Monday: A partly sunny day is expected on Monday with high temperatures near 45 Degrees. Winds will be West at 5 to 10 mph.

Very Significant Amounts Of Snow Are Expected On Tuesday: An area of low pressure is expected to develop near the Mid-Atlantic coast late Monday night. That low pressure system is then expected to rapidly strengthen as it tracks to the south and southeast of Southern New England during the day on Tuesday.

Overall there are no major changes to the forecast except for increasing snow totals across the entire area. Many areas of Central Mass will end up with a solid foot of snow with this upcoming storm. The other change to the forecast is to increase the winds expected for this storm since the low pressure system will rapidly strengthen leading to 30-40 mph wind gusts during the day on Tuesday. These gusty winds will likely lead to areas of blowing snow causing further reduced visibilities across the area.

Here Are My Latest Thoughts As Of Early Sunday Afternoon: Snow will overspread the entire area between about 4 am and 6 am Tuesday morning.

The snow is then expected to become heavy to very heavy in intensity by about 8-9 am Tuesday morning. Snowfall rates of 2 to 3 inches per hour with isolated 4 inch per hour snow rates can be expected across all of Western and Central Mass between about 8-9 am Tuesday morning and about 1-2 pm Tuesday afternoon.

The snow is then anticipated to lighten up in intensity by mid-afternoon Tuesday with light to occasionally moderate snow expected through late Tuesday afternoon.

The snow will come to an end by about early Tuesday evening.

Our latest snowfall forecast map for this storm is attached to this post.

Expected Storm Impacts: Travel conditions throughout Tuesday morning into the first part of Tuesday afternoon is expected to be extremely difficult across the entire area due to the extremely heavy snowfall rates. In fact, some roads may be impassable due to snowplow crews not being able to keep up with the very heavy snowfall rates.

In addition to this, wind gusts of 30-40 mph out of a north to northeast direction will cause areas of blowing snow and whiteout conditions throughout the day on Tuesday.

Road conditions will slowly improve during the second half of Tuesday afternoon as the snow lightens up in intensity and road crews are able to catch up with snow plowing.

I am still strongly recommending that all non-essential businesses should close on Tuesday and that all non-essential functions should be canceled on Tuesday. In addition, I strongly recommend that all schools across the entire area should be canceled on Tuesday.

Temperatures during Tuesday are expected to remain steady around 30 Degrees throughout much of the day. Temperatures may gradually fall into the upper 20s by late afternoon.

Winds during Tuesday will be North to Northeast at 15 to 20 mph with gusts to 30 to 40 mph.

I continue to closely monitor the progress of Tuesday’s snowstorm and I will most definitely have many more updates for you as needed.