Snow tonight, chance of snow this weekend -Details

Forecast Discussion

Remy Mermelstein


First off, final snow call for tonight’s light snow. Not a whole lot, but watch the fluff factor as ratios will likely be higher than the normal 10:1 due to the cold temperatures. This could amplify the amount of snow given the same liquid equivilant, but only by a bit. For example, with the 0.15″ liquid forecast, 10:1 ratio would be 1.5″ snow. Increase that to the 12:1 ratio that is more likely for this system and you get 1.8″…soo, you will see in our map that Coating to 2″ is the forecast, with 2″ favored on the southern part of the C-2″ Zone. The farther South and East you get, the better chances for more snow, with 2-4″ likely across much of Eastern LI, Cape Cod and parts of ESE Jersey. See the picture below, showing dynamics that favor coastal areas the best:

Snow will fall between 1-8am, tapering off between 8-9am if any left by then. This is a progressive, weak system. Most of the snow will fall between 5-7am. 

All precipitation should be out of the NYC Metro area by 9am. Boston will be out of it early to mid afternoon.

NOW, on to the next possible storm. When I said last night that the 0z runs could bring some changes, I did not think we would see that much of a change. We did not see a BIG change in the modelling, but it is however enough for us to start worrying about snow for Saturday. Whether or not we get meaningful accumulation is in the air, at the moment…but let’s explain.

Right now the energy and system that will form our storm is coming into the West Coast. A 3/4 full sampling was achieved last night, and Today the models should have had 100% full sampling of it in all of its glory to help with the modelling. Consensus should come about tonight, and the details are up to the Short range guidance.

Above in black is the S branch, or piece of energy that will ultimately form our storm. The pink circle above is the UL Low that will steer the storm, or the trough. How these two piece interact are KEY to how our storm tracks. How the Southern Piece of NRG evolves and forms is key to how strong our storm will be. First step, we have the cold air. Along that boundary, our NRG will form the storm Friday night.

For us, the key at this point is not the track of the storm. That is likely not going to change in any meaningful way. Of course, a shift W or E can mean a difference, but right now lets focus on the dynamics. One thing to note, is that this is not going to be a BIG storm for us. In no way. At best, we see a couple inches…the way things look right now. But lets take a look. The modelling has changed in subtle ways recently, not in the orientation or tracks of things, but in the strength of the energy. The stronger the energy, the stronger the storm, and the bigger the precipitation shield. We want as big of a precip shield as possible, because this means the snow can potentially reach us.

Here is our energy, storm moving ESE of the area, and UL trough to the NW of us with our storm out ahead of it. The area circled in Purple is important for us because it is the where the heaviest precipitation will fall, aided by a WSW fast flow and WSW Jet streak in the mid/upper levels. The STRONGER this is, and the further W it gets, the bigger the precipitation shield will be and the better chance for us to get meaningful snow. Jet streak below.

Right now, do not bet on anything other than possible light snow and a coating. Best areas, are again S and E of the region, LI, Cape Cod, ETC. For the SE this will be a big storm. If this changes we will let you know, we are definitely keeping a close eye on it as the trend for storms this year has been to go NW of original modelling. Please check back for updates!

Forecaster: Remy

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