17:33 Sun Mar 04, 2018
With this last Nor’easter back on the 2nd of March still fresh on the minds of people, another Nor’easter is taking aim at New England. This time around, the storm is looking like it will be weaker than the last storm but it will be colder, so more areas will see accumulating snow fall. The March 2nd storm impacted Southern New England much more then it affected our region. The maximum winds we saw only topped out at 98 mph for the storm. The center of the low was just a little too far to our south to really bring the high winds. If this storm was even just 100 miles further north, we could have seen some epic winds. Wind gusts could have topped out over 130 mph, probably getting up into the 140 mph range. So enough with what could have happened, let’s move on.
For this next storm, I will be using the GFS modeled forecast. Many of the different global and local models are starting to come into agreement so a storm is looking likely for New England. This is preliminary and be sure to regularly check your local forecast over the next few days to get the latest information. I will not be going into any snowfall totals because for a coastal storm, it is too early to be throwing out possible accumulations.
Taking a look at the weather map below for 12AM Thursday, we can see that the storm is in a very similar place as the last Nor’easter but right now the central pressure is in the 990 mb range rather than deepening down into the 970’s like the March 2nd storm. Initially the storm will be brining rain fairly far inland as represented by the green and orange colors on the map. The low will still be strengthening as it moves into the Gulf of Maine so the rain snow line moves closer to the coast as cold air and dynamic cooling allows for precipitation to transition from rain to snow.
The image below is for 6AM on Thursday and you can see the rain/snow line nearly to the coast in Maine and getting further south.
Then for Noon on Thursday.
The low is going to stall near Maine/Canadian border on Thursday into Friday due to a blocking high up near Greenland so the unsettled weather will last in the White Mountain Region. Below is the predicted weather for Friday, around sunset, and there is still snow showing up for the Green and White Mountains.
The set up on the back is ideal for some upslope snow across higher terrain so the snow will keep piling up in the mountains even after the precipitation has ended for costal and southern valley regions. Below is a forecast sounding for the White Mountains just upstream of Mount Washington. This shows how the temperature and dew point changes as you go up in the atmosphere. In the low levels, the temperature decreases at the moist adiabatic rate all the way up to 700 mb, or about 9000’ feet in the atmosphere. When this air hits the mountains, it will force the moisture to precipitate out of it. The one thing preventing this from being a major upslope snow event is the low wind speeds in the lower levels of the atmosphere. Small changes in the intensity of the low could change that. If the storm ends up being stronger, the winds will be higher, thus forcing the moisture to precipitate out of the air mass at a higher rate, resulting in much higher snow totals.
Adam Gill, Weather Observer/IT Specialist