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Winter Weather Advisories issued for western and central Massachusetts Wednesday afternoon and evening.
There is increasing confidence in the risk of snow and freezing rain Friday into Saturday.
Still watching a potential winter storm Sunday into Monday. At the very least we may see potential coastal flooding along the eastern Massachusetts coast as well as marine impacts on the coastal waters.
There is increasing confidence in the risk of snow and freezing rain Friday into Saturday.
Still watching a potential winter storm Sunday into Monday. At the very least we may see potential coastal flooding along the eastern Massachusetts coast as well as marine impacts on the coastal waters.
1 Key Message 1
Travel impacts from accumulating snow Wednesday afternoon and evening.
2 Key Message 2
A system on Friday/Friday night will bring a mix of snow, freezing rain, and rain to southern New England while scattered snow showers linger into Saturday.
3 Key Message 3
Watching a potential winter storm Sunday into Monday.
KEY MESSAGE 1... Travel impacts from accumulating snow Wednesday afternoon and evening.
Still a challenging forecast regarding precipitation type and where a narrow band of snow sets up, but we have more confidence that much of western and central MA will see 2-4" of snow Wednesday afternoon and evening, where we are issuing Winter Weather Advisories.
That said, confidence is a bit lower farther east, including the Boston and Providence areas, since temperatures initially may be too warm to allow snow to accumulate, so we think 1-3" totals are more likely in these areas. It's possible we will need to extend the Advisories into these areas with the Wednesday early morning forecast if things trend a bit colder.
12z HRRR and HREF closely match our thinking, but we are still wary of the "colder" 12z 3km NAM which would bring slightly higher totals than what we have now, or even 12z GFS which has the axis farther south into CT, RI, and SE MA. On the flip side, 12z RRFS is much warmer and would mean much less of an impact, but that seems to be the outlier. Trying to pinpoint banding in these setups is always difficult!
A weak low will pass off the coast and maintain a cold N/NE flow across southern New England. Initially, the airmass is relatively "mild" but as the precipitation arrives around midday, in the form of either light rain or light snow, we expect to see wet bulb cooling with temperatures falling into the low to mid 30s. Exactly how quickly this takes place is still a question, but we are more confident that the higher elevations of western and central MA will begin as snow. In the lower elevations including closer to the coast, even if it does change to snow quickly, the snowfall rates will be light and with marginal temperatures it will be tough to get accumulations right away. However as we approach late afternoon and especially evening, that's when most of the accumulation will occur (or if we see any briefly heavier snowfall). now will taper off before midnight as low exits offshore.
Key Message 2... A system on Friday/Friday night will bring a mix of snow, freezing rain, and rain to southern New England while scattered snow showers linger into Saturday.
The active pattern continues late week into the weekend as, after brief ridging and surface high pressure on Thursday another vertically stacked shortwave/surface low moves out of the Great Lakes and over New England Friday night into Saturday. Temperature profiles will be complex and need to be honed in as we get closer (better, high-resolution data) but it looks to be a mixed precipitation event as a warm front lifts north providing lift from warm advection as well as some decent frontogenesis in the 700mb/850mb level. Model soundings show a period of strong omega in the DGZ on the front end (Friday) which could allow for some decent snowfall rates especially further north. Closer to the south coast marginal temps may lead to a mostly rain event while a mid level warm nose also introduced the likelihood of freezing rain for parts of the interior. Another factor to consider is a secondary low that forms and deepens offshore. Looking at it from a probabilistic perspective, ensemble guidance presently shows a 15-40% chance of 4+ inches of snow through Saturday along and south of the MA Pike with a 40-55% chance to the north. This, with the potential for several hundredths of an inch of freezing rain. The bulk of the precip looks to fall before sunrise on Saturday but scattered snow showers continue during the day.
KEY MESSAGE 3... Watching a potential winter storm Sunday into Monday.
Guidance continues to show a potentially significant winter storm developing off the East Coast Sunday into Monday, but as usual at this time range, we are seeing a large spread in possible storm tracks with anything from an offshore pass to a direct hit on southern New England.
All of this uncertainty ties to how quickly a northern stream short wave can close off as it tracks through the Great Lakes and toward the East Coast, which is dependent upon the strength of the upper ridge over the North Atlantic. A stronger ridge, as seen in latest GFS and Canadian runs, would help the low to close off more quickly and gain a negative tilt, allowing the coastal storm to track closer to southern New England with higher impacts. Conversely, a weaker ridge, as depicted by 12z ECMWF, would mean the upper low closes off later and maintains more of a positive tilt, keeping the coastal storm more out to sea. It's also interesting to note the AI versions of GFS and ECMWF, which have performed well this winter, are fairly similar and both bring low close enough to impact at least the South Coast, Cape Cod, and Islands.
Right now odds favor at least some impact to CT, RI, and SE MA if not more of the area, but keep in mind we are several days out and probably won't see any notable trends in guidance until Thursday at the earliest. So for now, expect to see the usual run-to-run variations in the deterministic models and some showing big hits. It's just way too soon to lock into any one model solution.
One thing that we are becoming more confident in is the potential for coastal flooding and marine impacts, even with a more offshore track. We are approaching higher astronomical tides Sunday and Monday and much of eastern MA coast could be vulnerable to at least minor coastal flooding and beach erosion. On the coastal waters, there is the potential for NE gale force winds and rough seas, given fact that much of the guidance is showing a potentially strong coastal storm.
Still a challenging forecast regarding precipitation type and where a narrow band of snow sets up, but we have more confidence that much of western and central MA will see 2-4" of snow Wednesday afternoon and evening, where we are issuing Winter Weather Advisories.
That said, confidence is a bit lower farther east, including the Boston and Providence areas, since temperatures initially may be too warm to allow snow to accumulate, so we think 1-3" totals are more likely in these areas. It's possible we will need to extend the Advisories into these areas with the Wednesday early morning forecast if things trend a bit colder.
12z HRRR and HREF closely match our thinking, but we are still wary of the "colder" 12z 3km NAM which would bring slightly higher totals than what we have now, or even 12z GFS which has the axis farther south into CT, RI, and SE MA. On the flip side, 12z RRFS is much warmer and would mean much less of an impact, but that seems to be the outlier. Trying to pinpoint banding in these setups is always difficult!
A weak low will pass off the coast and maintain a cold N/NE flow across southern New England. Initially, the airmass is relatively "mild" but as the precipitation arrives around midday, in the form of either light rain or light snow, we expect to see wet bulb cooling with temperatures falling into the low to mid 30s. Exactly how quickly this takes place is still a question, but we are more confident that the higher elevations of western and central MA will begin as snow. In the lower elevations including closer to the coast, even if it does change to snow quickly, the snowfall rates will be light and with marginal temperatures it will be tough to get accumulations right away. However as we approach late afternoon and especially evening, that's when most of the accumulation will occur (or if we see any briefly heavier snowfall). now will taper off before midnight as low exits offshore.
Key Message 2... A system on Friday/Friday night will bring a mix of snow, freezing rain, and rain to southern New England while scattered snow showers linger into Saturday.
The active pattern continues late week into the weekend as, after brief ridging and surface high pressure on Thursday another vertically stacked shortwave/surface low moves out of the Great Lakes and over New England Friday night into Saturday. Temperature profiles will be complex and need to be honed in as we get closer (better, high-resolution data) but it looks to be a mixed precipitation event as a warm front lifts north providing lift from warm advection as well as some decent frontogenesis in the 700mb/850mb level. Model soundings show a period of strong omega in the DGZ on the front end (Friday) which could allow for some decent snowfall rates especially further north. Closer to the south coast marginal temps may lead to a mostly rain event while a mid level warm nose also introduced the likelihood of freezing rain for parts of the interior. Another factor to consider is a secondary low that forms and deepens offshore. Looking at it from a probabilistic perspective, ensemble guidance presently shows a 15-40% chance of 4+ inches of snow through Saturday along and south of the MA Pike with a 40-55% chance to the north. This, with the potential for several hundredths of an inch of freezing rain. The bulk of the precip looks to fall before sunrise on Saturday but scattered snow showers continue during the day.
KEY MESSAGE 3... Watching a potential winter storm Sunday into Monday.
Guidance continues to show a potentially significant winter storm developing off the East Coast Sunday into Monday, but as usual at this time range, we are seeing a large spread in possible storm tracks with anything from an offshore pass to a direct hit on southern New England.
All of this uncertainty ties to how quickly a northern stream short wave can close off as it tracks through the Great Lakes and toward the East Coast, which is dependent upon the strength of the upper ridge over the North Atlantic. A stronger ridge, as seen in latest GFS and Canadian runs, would help the low to close off more quickly and gain a negative tilt, allowing the coastal storm to track closer to southern New England with higher impacts. Conversely, a weaker ridge, as depicted by 12z ECMWF, would mean the upper low closes off later and maintains more of a positive tilt, keeping the coastal storm more out to sea. It's also interesting to note the AI versions of GFS and ECMWF, which have performed well this winter, are fairly similar and both bring low close enough to impact at least the South Coast, Cape Cod, and Islands.
Right now odds favor at least some impact to CT, RI, and SE MA if not more of the area, but keep in mind we are several days out and probably won't see any notable trends in guidance until Thursday at the earliest. So for now, expect to see the usual run-to-run variations in the deterministic models and some showing big hits. It's just way too soon to lock into any one model solution.
One thing that we are becoming more confident in is the potential for coastal flooding and marine impacts, even with a more offshore track. We are approaching higher astronomical tides Sunday and Monday and much of eastern MA coast could be vulnerable to at least minor coastal flooding and beach erosion. On the coastal waters, there is the potential for NE gale force winds and rough seas, given fact that much of the guidance is showing a potentially strong coastal storm.
CT: None
MA: Winter Weather Advisory from 1 PM Wednesday to 4 AM EST Thursday for MAZ002>004-008>012-026.
RI: None
MARINE: Small Craft Advisory until 7 AM EST Thursday for ANZ250-254>256.
MA: Winter Weather Advisory from 1 PM Wednesday to 4 AM EST Thursday for MAZ002>004-008>012-026.
RI: None
MARINE: Small Craft Advisory until 7 AM EST Thursday for ANZ250-254>256.
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