This year, March will be starting off on a mild (and unsettled) note. How long will this mild weather last? There are mixed signals heading toward the latter half of the month, but it may end up being another generally above average month temperature-wise. Here's the breakdown of the players involved:
TEMPERATURES
The month of March has started off with a trough-in-the-west-ridge-in-the-east pattern, which will likely last through midweek. This will lead to continued warmer than average temperatures amid a persistent southwest flow aloft.
This is looking more like a "dirty ridge", which occurs when precipitation undercuts the ridge. Normally, ridging brings clear and calm weather. In this case, the ridge is not strong enough to keep the precipitation away completely. So while it will be above average, it won't be bright, sunny and calm the entire time through midweek.
This dirty ridge does appear to begin to break down heading into the latter half of next week. A cold front looks to sag into New England around midweek. This would support a cool down heading to the end of the week, although a cool down in this case is just returning closer to average.
At this time, major models tend to agree on positive 500mb heights over New England through at least the end of next week. This supports warmer air aloft over New England. With the absence of snow cover across most of the region, it will be easier for the surface to warm.
500mb height showing a positive anomaly across the northeast through next week:
This doesn't necessarily mean that everyday will be above average, but rather cold snaps will continue to be brief with a quick warm up after, which has generally been the case for a while now. This may end up being the case through the first half of the month.
Heading toward the second half of the month, there are mixed signals for how temperatures will generally play out. North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) are forecast to dive into a negative phase while the Pacific North American (PNA) Index rises to a positive phase. This could support more cold air intrusions heading deeper into the month.
At this point, a cool down in the second half of the month could be more centered to New England's south. As of now, the Climate Prediction Center has New England in the 70-80% chance of generally above average temperatures for the second half of March. Overall, there is low confidence heading toward the second half of March, which is expected as March is a dynamic, transitional month that is among the hardest to predict in the long term.
Week 4 500mb height anomaly showing a negative anomaly over the east. Being week 4, this certainly isn't locked in and overall confidence in this time frame remains low:
Overall, we're predicting a generally above average month with the most above occurring at the beginning. We also predict more cold air intrusions heading deeper into the month, but these cold air intrusions may be short-lived, continuing the general pattern seen throughout this winter.
PRECIPITATION
This weekend will see a cutoff low will very slowly move through the northeast. After that, weak disturbances will override the ridge through midweek, keeping the clouds and unsettled weather around. It won't be overcast or raining the entire time through midweek, especially for western New England.
The breakdown of the dirty ridge will only increase the odds for unsettled weather heading toward the end of next week. A more organized system may form for the end of next week as the ridge breaks down. Overall, March is looking like a more active month.
The million dollar question becomes will this March produce another bookend snowstorm? That possibility is always on the table in March. Last year, a major nor'easter dropped over three feet of snow in places in the region. While there are no definitive signals for a snowstorm at the moment, we need to watch a system at the end of next week.
If an area of high pressure can set up north of New England, it can lock in cooler air over New England, allowing that potential late-week system to bring some wintry weather. This certainly isn't a forecast for this storm as model spreads remain very high and much uncertainty is present. It'll be something to watch throughout the week.
LOOKING BACK
We predicted a near average February temperature-wise. This was based on the fact that we were expecting a warmer first half of the month followed by a generally cooler second half. Temperatures did generally cool off after some warmth in the first half of the month, however, they only cooled to around or slightly below average. Temperatures then jumped back above average to end the month. This led to an overall above-average month.
We also predicted a calmer month with below average precipitation. This was the case as Portland, Concord and Boston all saw their top five driest February on record. We did note that just one big nor'easter could push the month to above average precipitation as February tends to be peak storm season for New England, but a big nor'easter just couldn't form. One tried to in mid-February, but we all know how that turned out for most.
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