One of the biggest points of emphasis here at New England Storm Center when it comes to forecasting is transparency. With that said, we've just passed the midpoint of the cold months (November-March), so we're taking a look back at our snowfall forecasts and seeing how they panned out against what actually fell. We'll do this one more time around the end of March or start of April.
The following are storms we've issued snowfall forecast maps for this season, ordered from the most recent to the first of the season, along with some notes on what we got right and wrong:
JANUARY 19-20, 2025
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
This storm played out pretty much exactly as expected. A wide swath of 5-8 inches was observed across southern and central New England with a steady drop off to the north. The northern cutoff was a bit sharp across northernmost New England. We did spend time trying to decide if an 8-12" zone should be put over northern Massachusetts/southern New Hampshire, but opted against it as probabilities of at least 8" of snow began to shrink in the final run-up to the storm. This decision to never add it was the correct decision as the highest amount recorded in this area was 8".
JANUARY 11, 2025
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
This weak, moisture starved system zipped through New England with an expected 1-3 inches across the region. The ocean did help enhance totals across the North Shore and southeast New Hampshire, as well as Maine's Mid-Coast. Vermont generally under-performed, but only minimal snowfall was expected anyway.
JANUARY 1-3, 2025
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
A major and persistent multi-day upslope snow event began after a quick hit of snow and rain on New Year's Day. As one would expect with an upslope snow event, it was very elevation dependent and brought very varied amounts to the region, especially over Vermont. The mountain tops came out much better than the slopes and valleys, which is what our map was catered to.
This was an instance of light snow showers over many hours and days adding up in some cases to 12-20". Our map fell short of totals across western New England, though our map was only made to cover through January 2 (a majority of this snow did fall through January 2 despite snow showers persisting into January 3).
DECEMBER 24, 2024
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
A festive clipper system zipped through New England on Christmas Eve, bringing some very nice ambiance. Snow totals continued to trend upward leading up to the storm due to increasing moisture off the Gulf of Maine. Snowfall from these clippers tend to see more snow on the northern side with lesser amounts on the southern side. This rang true with minimal accumulations across southern New England.
This increasing moisture combined with the fluffy nature of the snow allowed totals to over-perform across northern New Hampshire and Maine. Downeast Maine was expected to be the jackpot zone along with the northern Greens, but not with 6-12 inches. We leaned too far on the lower guidance for northern areas This was despite trends heading toward higher amounts at the last moment. This ended up being the incorrect decision. Southern New England and northern Vermont landed on point.
DECEMBER 20-21, 2024
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
A nor'easter grazed New England with its outermost bands. A coastal front helped enhance snowfall across eastern Massachusetts. The storm brought a decent thump of snow given the storm's track outside the benchmark. This storm over-performed across eastern Massachusetts. This was thanks to a coastal front that created enhanced snowfall rates. In our final forecast for this storm, we wrote:
"Another factor to watch will be the potential for a period of enhanced snowfall rates across interior northeast Massachusetts and southeast New Hampshire. A coastal front will set up in this area this afternoon, separating the sub-freezing air from the above freezing air. The front will collapse southward as the evening goes on. This coastal front could provide increased forcing for snow showers with more snow falling near the front as opposed to areas farther north and farther south from it."
We leaned too far on the lower end of guidance as we did not anticipate the coastal front's enhancement to have the impact that it did given the storm's track well offshore. Our map performed generally well outside of eastern Massachusetts. The 3-5" amounts were also a bit more widespread across Downeast Maine than we anticipated, however.
DECEMBER 7-8, 2024
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
This quick clipper system brought an expected 3-6" to northern Vermont and New Hampshire along with a dusting to southern and central New England. Overall, this storm fell in line with what was expected.
DECEMBER 4-5, 2024
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
A potent Alberta Clipper zipped through New England, bringing a wide swath of 3-6 inches with 6-12 inches in the mountains and minimal accumulations near the coast. This storm was highly elevation dependent. It played out closely to what we were expecting. The higher elevations of western New England over-performed, particularly the Litchfield Hills. The greatest uncertainty came close to the coast. In our forecast, we wrote:
"At this point, the area with the greatest uncertainty is about 25-35 miles from the coast. This uncertainty is highest from southern New Hampshire through central Maine. The stronger the storm gets, the more moisture will get pulled into the system. This would allow for heavier snowfall rates across the interior. This increased moisture would also draw more mild air farther north. So, while a stronger storm would result in heavier snowfall, it would also push the rain/snow line farther north, limiting total snowfall farther inland."
In the end, we made the right call on snowfall near the coastline. What we missed was how much the additional elevation of the Berkshires and Litchfield Hills would influence the totals despite knowing this would be an elevation-based snowfall. The jackpot zone ended up being a bit farther south in Maine than anticipated as well.
NOVEMBER 28-29, 2024
Blow: Our final forecast map before the event (1st image) and the actual snowfall observed (2nd image):
New England's Thanksgiving Day nor'easter vastly over-performed from our forecast. We laid out our reasoning for why we opted for the lower end of guidance in our last forecast for the storm by saying:
"We mentioned in previous days that if the storm were to take a more northerly route, the storm would be stronger (due to more interaction with the northern stream system in Canada) and lead to heavier snow banding. These northerly trends came true yesterday with the storm track shifting from near Cape Cod to near Boston. Some guidance is showing up to a foot of snow, but we're hesitant to buy into amounts that high due to the fact that this won’t be a very deep or powerful storm and it will be moving along at a decent clip.
There's limited blocking with this system, leading to a less amplified and more progressive storm. There is a distinct lack of colder air ahead of the storm. There is also no strong area of high pressure to the north of New England to filter colder air into the system as it occurs. The main way heavier snowfall rates will develop is through some strengthening of the system with limited interaction with the northern stream."
In the end, the storm was able to sufficiently strengthen, and with enough cold air on the back side, it allowed for heavy bands of snow to develop. A swath of 8-12 inches of snow fell across interior northern New England with a jackpot zone setting up in the southern Green Mountains, where a general 12-18 inches fell. All higher elevations in New England over-performed. The northerly trend indicated a more amplified storm with more interaction with the northern stream. This was an indication that the storm could end up producing a large quantity of snow for northern areas. We should have put more emphasis on that.
CONCLUSION
We have been leaning on the lower end of guidance more often than not this season. This has led to over-performing totals in some cases with no instances of notable under-performances. We've generally been correct about the location of where the highest and lowest snowfall would occur. We'll keep these trends in mind as we work through the second half of the cold months.
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