This system will involve an area of low pressure ejecting out of the Great Lakes. A secondary, surface low will form near the Mid-Atlantic and strengthen. This surface low will become the primary low as it tracks to the south of New England, likely near the benchmark. This is a favorable track for a widespread snowstorm across southern and central New England.
ALERTS
TIMING
Overall, timing has slowed down a bit. The first flakes are expected to fly across western New England around mid-evening. Snow will quickly spread eastward and pick up in intensity through the overnight hours. By about midnight, snow should have overspread just about all of New England outside of eastern Maine. At this point, snow banding will likely ramp up, with 1 to 1.5 inch an hour rates.
Below: FV3 showing potential weather this evening (1st image) and around midnight (2nd image):
Intense snow banding will likely continue across southern and central New England through the early morning hours Sunday. By the pre-dawn hours, a dry slot may work into southernmost New England, reducing snow rates. The speed and depth of this dry slot could affect overall snow totals. This will be discussed further in the next section. Overall, snowfall will gradually begin to wind down by sunrise from west to east.
Below: FV3 showing potential weather during pre-dawn Sunday (1st image) and mid-morning Sunday (2nd image):
Snow will likely steadily break by late morning across much of New England. Widespread light snow will be ongoing across much of Maine. Much of the snow will shut down by Sunday afternoon. It wouldn't be surprising to see eastern Massachusetts and southeast New Hampshire hang onto snow a bit longer due to potential ocean enhancement as the storm pulls away.
SNOWFALL
There are several factors lining up that are favorable for a decent thump of snow by Sunday afternoon for pretty much all of southern and central New England. These include a track near the benchmark, strong forcing & lift, the development of a coastal front, abundant moisture and thermal profiles supportive of an all-snow event (for the most part). On top of this, temperatures are favorable for snow ratios at upwards of 15-20:1, indicating a light and fluffy snow. This snow should be able to pile up quickly and easily.
With a period of intense snow banding overnight, all of this should support a widespread 6-10 inches of snow across southern New England, southern New Hampshire and southern Vermont. The area with the best chance to reach toward double digits will be near the northern Massachusetts border and up into the southern Green Mountains. Snowfall will drop off across southernmost New England due to a wetter snow and the potential for dry slotting. Amounts will gradually taper moving northward, away from the center of the storm.
Only minor tweaks were made to the snowfall map compared to yesterday evening's update. The big question was whether or not to add an 8-12 inch zone over northern Massachusetts and southern New Hampshire/Vermont. While it does seem likely that some communities will push for double digits, we opted against adding the zone as we're not confident in widespread amounts over 8 inches. Probabilities for at least a foot of snow remain capped at just 10%.
Below: Current probability of seeing at least 8 inches of snow:
At this point, everything appears to be lined up for a period of intense snow banding during the early morning hours Sunday across southern New England (extending into southern NH/VT). A period of strong forcing amid frontogenesis is likely as the warm front nears New England. A deep snow growth zone is expected to develop during this time. On top of that, the strongest winds aloft appear to be above the snow growth zone, which is favorable for snow development. High winds in this zone act to break up snowfall formation.
With that said, the chances for at least an inch an hour snowfall rates are very high from about midnight through 4-5am. Widespread snow banding is expected across southern and central New England. On top of this, there is a 40-50% chance of snowfall rates reaching 2 inches an hour for a brief time. This is when a majority of snow will be received for the storm.
Below: Likelihood of at least 1" an hour snowfall rates early Sunday morning, showing chances exceed 80-90%:
With everything working for the storm, there are a couple limiting factors that must be brought up. The first is the duration of the storm. This will be a quick-mover and the entire storm will likely only last about 12 hours for any given area. There is a 4-5 hour window for more intense snowfall rates as it stands now. Should everything mentioned in the above paragraphs line up a bit differently, this window will be shortened, reducing snow totals.
Another issue may be the aforementioned dry slot. Drier air is expected to move into the snow growth zone in the early morning hours. This dry slot likely won't end precipitation, but it could reduce snowfall rates and create very small snowflakes or even freezing rain/drizzle. This is what happened this past Thursday, which led to amounts coming in on the lower end of the ranges for the most part.
This has the best potential to impact totals south of the Mass Pike, but the northern extent remains a bit of a question. Some guidance has the drier air and lighter snowfall or even mixing making it close to the northern Massachusetts border. Should this slot move in quickly, it will have an impact on final totals, especially for Connecticut and Rhode Island.
Below: HRRR showing potential weather in the pre-dawn hours Sunday. Note the mixing being shown to the Mass Pike. This would be a result of a quick arrival of the dry slot. This model is the most aggressive with this; all others don't show this level of mixing making it this far north, but it's worth bringing up:
BUST POTENTIAL
Bust potential is on the lower end with this storm. The best way the storm could bust will be due to the reasons above (quick motion and potential dry slotting). The storm is coming through in a zonal flow, which will limit the amount of strengthening the storm can achieve. It won't be undergoing rapid intensification. These are the main reasons why amounts are forecast where they are now instead of much higher. Overall, more things are working in favor of snowfall with really only a couple things working against, leading to a lower bust potential.
THE NEXT STORMS
The fact that this will be the second storm in a succession of storms nearby New England has now been widely publicized, so we'll just jump right into a quick overview of what could come next. Tuesday night to Wednesday's storm is still poised to track farther south. Currently, a glancing blow is favored for southernmost New England, but the exact track still needs to be ironed out.
Below: Probability of impactful winter weather Tuesday to Wednesday morning. This has continued to drop:
The next storm on tap will likely come in the Wednesday night to Thursday time frame. This one has a better chance of bringing more widespread precipitation to New England. Another larger storm may come next weekend. Both of these storms have a better chance for some level of mixing in New England rather than all-snow everywhere.
Below: Probability of impactful winter weather Thursday:
Comments