One of the most dynamic months of the year has arrived for New England. Winter and spring battle for dominance with highly changeable temperatures and precipitation types. This has begun right on time this year as meteorological spring begins.
Summary: March is typically a dynamic month as winter and spring constantly battle. That appears to be especially true this year as highly variable temperatures with multiple up and down swings appear likely throughout much of the month. Overall, these swings may cancel each other out and lead to a near-average month as a whole. Another generally active month for precipitation is also looking likely. Read below for the in-depth discussion.
TEMPERATURES
The battle between winter and spring temperatures has arrived right on time this year. The end of February and first days of March have featured large temperature swings. The very beginning of March will feel like the depths of winter, though it won't last long as another bout of much milder conditions are in store by the middle of this week. Another cool-down will likely be on the way by late next week as a large-scale storm system exits the northeast.
Overall, much of the first half of March will likely feature an amplified flow across the United States with a progressive, active pattern. The beginning of March opens up with general ridging over the west and troughing over the east. With that said, an active southern stream is poised to send waves of low pressure into the west, which will then track across the United States. With a progressive pattern amid an amplified flow, this will likely lead to a continuation of highly variable temperatures through the middle of the month.
Below: 500mb height anomaly through the first week of March showing waves of troughing entering the west and progressing across the country:
This setup is perfect for temperatures to continue their up and down swings. This is especially true considering its March, which is the most volatile month of the year as two seasons collide and battle for dominance. The variable temperatures can be seen by looking at how February ended and into the next week or so. After a mild first day of the month, an Arctic blast has arrived for Sunday and Monday. A large-scale warm up is likely around midweek ahead of a storm before cooling off again, likely to near average.
Heading toward the middle of the month, a less progressive pattern is expected. Overall, the large-scale pattern will likely be undergoing a transition. This transition will likely include a flip toward general ridging over the eastern half of the United States and troughing digging into the west.
Below: 500mb height anomaly average for the week of March 10-17, showing a trough-in-the-west-ridge-in-the-east pattern developing:
The highest confidence in a ridge of high pressure bringing a more prolonged warm-up around the middle of the month is to the west of New England, across the Central Plains and into the Ohio Valley/Great Lakes. While much of the east is expected to warm up, the exact eastward extent of the core of milder conditions is a question.
This is heightened by a potential pool of colder air located to the north of New England during this time. For this reason, the chances of warmer than average conditions begin to drop moving into New England versus the center of the country, though some form of a warm-up is still expected. This can all be seen on the Climate Prediction Center's 8-14 day outlook, which currently covers March 9-15.
Heading toward the second half of the month, things get a bit murky for New England. A trough-in-the-west-ridge-in-the-east pattern may try to persist. This is supported by the PNA index trending negative and NAO trending positive. The Stratospheric Polar Vortex, which is currently stronger than normal, may rapidly weaken in the second half of March. With that said, the Tropospheric Polar Vortex (more closely linked to the polar Jet Stream) may have a delayed response to this weakening.
This is seen by the Arctic Oscillation (AO) trending strongly positive, which would help keep Arctic air locked to the north. This could all lead to a generally mild east coast for the second half of the month. With that said, cold air likely won't be far away and cold air intrusions remain likely through the entire month.
March is typically a difficult and dynamic month to try to decode in the long term. This is certainly ringing true this year, with both mild features and cold features hanging around and battling for dominance. Overall, we're going to say both winter and spring will get victories throughout the month, leading to continuous up and down temperatures. These swings could very well cancel each other out and lead to a near average month as a whole. The best chance for more persistently mild weather will likely be to New England's west.
PRECIPITATION
A generally active pattern across the United States looks to set up for much of March. This will come as multiple troughs of low pressure are expected to eject into the western United States on the southern stream. With a potentially progressive pattern set up, these systems will traverse the country and likely end up in the vicinity of New England. Coming off the southern stream, they will be capable of producing steady precipitation events in New England, as evidenced by the incoming midweek storm.
With that said, we're going to be predicting a slightly above average month for precipitation. March is a dynamic month, so precipitation outlooks are difficult to pin down for the month. It's also difficult to pin down precipitation types as well. The past couple years have seen major March snowstorms across New England. Whether this occurs, or if soaking rain events (like the one coming this week) rule month remains to be seen. This will come down to small-scale factors that can't be predicted weeks in advance.
With a potentially above normal month for precipitation, March will present another chance to see drought improvement. Last month did not see drought status removed across northern New England. Should an above average month transpire for New England, drought conditions will improve. Another chance for drought removal and improvement will be presented this month.
LOOKING BACK
Overall, February ended up as expected, with most major climate sites in New England seeing slightly below average temperatures for the month as a whole. Boston, Burlington, Concord and Providence all saw average temperatures around 1-3° below average. We did predict highly variable temperatures with plenty of ups and downs. As a whole, there were plenty more downs than ups, helping to get us to our below average month.
We also predicted an above average month for precipitation. Overall, northern New England saw much more precipitation than southern New England, which ended up near average. Burlington, Vermont ended up with nearly double their average snowfall for the month. The city saw their highest number of days with measurable snowfall on record for the month (19).