So the Northeast has gone through four nor’easters this March so far, but are any more on the way. The simple answer is that more snow is likely than not for the Northeast, especially across the interior, but there is some long-range modeling that suggests one to maybe two additional nor’easters through mid-April before the chance for snow becomes very low due to warming temperatures and the nearing of summer.
We are expecting an active weather pattern to continue across portions of the US. This time, however, the NAO (North Atlantic Oscillation) will be hovering near neutral for the extended period. If you recall, the NAO was in a negative phase for all of the first half of March. In fact, it reached a record low sigma value for this time of the year. A negative NAO is known to enhance the risk for strong, East Coast storms, and this recent negative NAO event certainly did not disappoint. Just take a look at the beautiful GOES-16 satellite views of the four nor’easters that impacted the Northeast this March.
One of the main instigators instead of the NAO for the long-range pattern is the MJO (Madden Julian Oscillation). In sample terms, the MJO is an area of enhanced convection or thunderstorm activity that moves around Earth near the Equator. Depending on the position or location of where the MJO is, that can actually have a direct impact on the Contiguous US’ weather pattern. Through early-April, the MJO is expected to transition to phases 7,8, and 1 in chronological order, as shown on the forecast chart below.. These phases are known in the past to produce a ridge of the West while a trough impacts the East. Remember, a ridge often delivers dry and warm weather; a trough usually brings stormy and cool weather.
This MJO forecast lines up very well with what the model guidance is showing, such as the ensemble mean of the European (ECMWF) model. It hints at a ridge over the East next week, then a return of the trough through at least early-April. Therefore, a brief period of warmth is expected followed by another prolonged stretch of cooler temperatures. Keep in mind, average temperatures increase as we transition from winter to spring and eventually summer. Therefore, the cooler temperature anomalies you’ll see on the model graphics below, the cooler than average temperatures may mean highs mainly in the 30s, 40s, and 50s opposed to the typical 40s, 50s, 60s, and 70s.
Therefore, with a trough of low pressure over the East expected to return by the end of March, the Northeast and back into the Great Lakes and Midwest will have to keep an eye out on additional snowfall. Whether it is significant or not, we don’t know, but the pattern will become favorable again for snow, especially away from the coast. Obviously the South won’t get snow, but instead the trough will allow for cooler weather. Even a flood event may set up in portions of the Southern Plains around the end of March.
Here’s a look at the average date of the last one inch or greater snowfall in select Northeast cities:
- New York City: March 10
- Boston: March 18
- Philadelphia: March 7
- Washington, DC: February 27
- Portland, ME: April 1
- Buffalo: April 2
- Pittsburgh: March 23
It’s interesting to note how New York City, Boston, Philadelphia, and Washington, DC have all recorded at least one inch of snow from the most recent nor’easter (March 21-22), showing a slow start to spring in terms of last date of snowfall. Keep in mind, the snow may not be over, especially in New York City and Boston.
Here’s a final map to showcase our thoughts: