That was quite a storm that rolled through New England overnight, as we went from almost no wind on Sunday morning to gusts of near 70 miles per hour early Monday in some places.
Most areas had winds between 40 and 50 miles per hour. This of course created tree damage and numerous power outages.
You might be wondering what caused all this wild weather and why it moved in and out so quickly. Let’s take a look:
In order to understand last night’s weather, we need to think about low-pressure systems and why they develop. A low-pressure system — the weather pattern that produces storms — is an area where there is less air in the area around it. The air in a low-pressure system is rising, and so air from the surrounding area rushes in to replace it.
When the air rising from the low pressure system is greater than the air coming in at the surface, pressure rapidly decreases. The lower the pressure gets, the stronger the storm becomes.
Another way to think about this is that if you have a big leak in a swimming pool, the water level will go down even if you have a garden hose replacing the water. Air was rushing into the low-pressure area, giving us all that wind here on the ground, but air was being evacuated over the top of the system even faster by a powerful jet stream with even stronger winds. Mount Washington’s winds were gusting over 130 miles per hour early Monday.
The jet stream has been in a meridional configuration the past week, which means it has a lot of loopiness to it. When the jet stream has large dips, known as troughs, it helps create something called divergence and diffluence in the upper levels of the atmosphere. These two phenomena help lift the air off the ground and make storms more powerful.
As the storm developed off the Mid-Atlantic coast on Sunday evening, the jet stream going over this low pressure system lifted so much air off the surface that the pressure began to fall rapidly, causing all that wind.
Notice the air rushing toward the low-pressure area over upstate New York on Monday morning.
The low-pressure system is now moving off toward Canada, but that doesn’t mean we’re done with wind in New England. Pressure here will be rising, but that means air here will be rushing from the area up into the storm. Winds will finally relax on Tuesday night as the storm’s influence moves far enough away from New England.