The million dollar question is if another nor’easter is on the way for portions of the Northeast. Within less than a week of time, the Northeast was hit by not one but two, highly-impactful nor’easters. The first one brought wind gusts up to 93 mph to southeastern Massachusetts and days of destructive flooding. Then the second one, which occurred on Wednesday, was a very heavy, wet snow producer, knocking out power to over a million customers. Now there’s the risk for a third nor’easter early next week (Between Monday and Wednesday), but this one has been the most difficult to forecast so far. The global model guidance has been having a tough time, which isn’t too unusual, the past few days on whether the Northeast should keep their eyes out for yet another coastal storm. There would be one run where the models highlight a very impactful storm, but then the next run will show a completely different scenario, barely showing a low pressure at all. We are still dealing with these fluctuations among the global models, so while the Northeast storm risk is present, there are no glaring signs that this storm will actually hit the region.
The main reason why this storm is so hard to predict is because of all the components and moving parts in the atmosphere. You need the setup to be perfect to produce a high-impact nor’easter for the Northeast. With this perfect setup, you tend to have one piece of upper-level energy moving eastward along the northern stream while a disturbance moves through the southern stream. If you get enough digging of the trough of low pressure, or jet stream dip, where it goes from positively-tilted to negatively-tilted and these two separate pieces of energy combine, or “phase,” then you have yourself an impactful coastal storm.
Below, we annotated the 500 millibar relative vorticity from the past two European model runs (0z Friday and 12z Friday) to show both the differences we are dealing with run-to-run as well as how complicated the atmospheric set up is. Any subtle change will lead to a different end result.
Based on this, if you’re looking for more snow and a high impact event, the 12z EURO run from Friday is what you would like to see, although even this run keeps the storm far enough offshore, allowing for only minor impacts at the coast. Of course we can’t focus on what just one model run shows. It’s important to look at other model guidance in order to get a better idea of the possible solutions. Here’s the tracks the European (EURO), American (GFS), and United Kingdom (UKMET) models are showing, as of the Friday afternoon runs:
The UKMET model shows the most impactful solution because it takes it very close to the 40/70 benchmark. Whenever coastal storms move over these coordinates, which is 40° North, 70° West, that typically means that impacts would be maximized for a large portion of the Northeast. The EURO is not far behind from the UKMET while the GFS has a much weaker storm due to a weaker and more broad trough of low pressure.
As of now, we remain in the wait and see period due to the extreme model uncertainty. We highlighted in blue the area at risk for snow from this potential nor’easter in the graphic above, which basically means to monitor the weather forecast from WeatherOptics as we continue to track what could be another winter storm for the snow-striken Northeast.