By Meteorologist John Cifelli for NJTV News
There are some subtle shifts in my thinking as to what the most likely storm path will be for our winter weather event on Thursday. It seems most likely that our nor’easter will track closer to the coast, bringing a flux of warm air across south and coastal New Jersey, and even making mixing likely further west toward the I-95 corridor as well. I talked about how important it was to forecasters to get key upper level features into regions with good data sampling. There is another option. If you can’t wait for it to come to you, you can go to it! Can you guess what this is?
That is the flight path for an air force craft that flew across the Gulf of Mexico earlier yesterday, dropping sensors into the developing low pressure system that will trek toward us today. Tonight’s computer models will have this new, extra data ingested to help us really fine tune things. You’ve heard of the hurricane hunters who fly through the eye wall of mature hurricanes? This is sort of the training ground for that stuff.
So things are coming into a more clear focus and yes, I expect this sucker to saddle up right next to the coastline. This does two things:
1. spreads warmer, maritime air aloft over the coastal plain
2. introduces the possibility of a “dry slot,” a punch of dry air during the height of the storm that often accompanies the center of the storm path. If this comes to pass, coastal NJ and NYC would see precipitation shut off late morning on Thursday after a solid stretch of snow and sleet falls.
Now that I have spent plenty of time discussing a few of the things that are strikes against winter, please allow me a moment to chum the waters so we can properly frenzy about snow and ice! Everyone will see snow, at least at the outset, beginning after midnight Wednesday evening. The changeover will be gradual, beginning as a snow to rain scenario after daybreak in Cape May and Ocean counties first, then a snow to sleet, then rain situation closer to I-95 later in the morning. There may be a small strip of freezing rain somewhere near the Route 1 corridor, depending on if we get enough of a warm push aloft to really melt things down upstairs before reaching the surface. Interior New Jersey, and north Philly into eastern Pennsylvania will get the brunt of the snow, and it will be the heavy pasty stuff that is hard to move, and causes power outages. Gas up the generator today, for sure.
Now the next tricky part of the forecast is the end time. Well developed mid-latitude cyclones develop a “comma head” that spread lighter but persistent moisture back south and west (across NJ in this case) as the storm pulls north and east (toward Boston this time).
If this develops the 500 mb vortmax, which lags behind the surface low, will trigger another round of steady snowfall even for those who see the dryslot end precipitation earlier in the day on Thursday. In this case, snow would persist into the late afternoon or restart for the dryslotted, and account for another few inches statewide, on top of what I expect from the bulk of the storm Wednesday night and Thursday morning. If we dodge the comma head/upper level vortmax scenario, we will be wrapping things up by dark. Right now I would say no, we avoid this. But it is on the table.
As for snow totals, I don’t see any need to change my projections, so I won’t bother with a new map, just a reissued time stamp. Winds will be an issue on the coast, and statewide, heavy snow on already stressed trees and limbs will put power at risk.