The arctic cold has settled into the Hudson Valley, and now a coastal storm system will develop on Thursday, and bring our first winter weather event of the season.
Timing:
– 3pm to 6pm : Snow develops from south to north (falls heavy at times)
– 7pm to 11pm : Snow mixes with/changes to sleet from south to north
– 10pm to 6am : Light wintry mix of snow, sleet and freezing drizzle
– 6am to 10am : Burst of heavier sleet & snow possible, then precip tapers off
Impact:
– Temps at or below freezing, snow will accumulate on all surfaces
– Snow rate of 1 to 2 inches per hour possible 5pm – 9pm
– Low visibility, snow covered roads, PM commute very slick
– Snow covered & Icy roads possible thru the night
– Potential snowy & icy Friday AM commute as well
Snow Accumulation:
– Catskills (Zone 1 & 2) : 4 to 8 inches (localized higher amounts)
– Mid & Upper HV (Zone 3,4,5,6 & 7) : 3 to 6 inches
– Lower HV (Zone 8 & 9) : 2 to 4 inches (with minor icing on top)

Discussion:
The first storm of the season, and it is proving to be a challenging forecast right out of the gate. Our coastal storm’s energy is coming from the Gulf of Mexico, and will redevelop off the coast of Virginia Thursday afternoon. It will spread moisture north, pushing into the Hudson Valley between 3pm and 6pm from south to north…

Notice in this futurecast radar image, that the snow is moving into the Mid Hudson Valley as of 5pm. The snow quickly becomes moderate to heavy at times, once it starts falling. That means that the snow will begin to accumulate quickly, and roads will quickly become snow covered. Rates of snow could exceed 1 inch per hour, and result in very low visibility. This would cause for a treacherous evening commute in the middle of winter. Factor in that this is the first snow event of the season… and travel will be very hazardous, if not dangerous in some areas. It is worth factoring this in, while planning your PM commute on Thursday.

This futurecast map is the key to the forecast. It suggests that even as of 9pm, the majority of the Hudson Valley is seeing moderate to heavy snow falling. If this is correct, snowfall rates of 1 to 2 per hour will be possible. We would see some areas see 5 or 6 inches of snow by 9 or 10pm, which will cause major travel headaches.
If this map is slightly incorrect, and the sleet mixes in earlier… snowfall amounts will be lower, but sleet will make things icy on top of the snow. This has been one of the major challenges with the snowfall forecast. The data has been rather conflicting regarding the timing of sleet mixing in. So we will be fine tuning snowfall projections as we get closer to the event, as we hopefully get better precision on the transition to a wintry mix.

But the confidence is very high, that at some point, a transition to wintry mix will occur. By midnight, the majority of the valley will be seeing a light wintry mix… as the heaviest precipitation should move north of the region by midnight. A light wintry mix is expected through the night… making for icy conditions through the night. Most locations will remain at or below freezing, so icy travel and icy walkways are expected through the night. So just because it’s not snowing… and the wintry mix is light… conditions will not improve overnight. Some locations well south of I-84, will warm up above freezing… and those locations could see travel conditions improve.
From here… the forecast gets even tricker. We will monitor an upper level low pressure feature pass by to our south, early Friday morning. When that happens, it will pull colder air into the region… and generate considerable upward motion. This will very likely lead to a burst of moderate to heavy snow across the Hudson Valley on Friday morning. This could cause enhanced headaches for the AM commute on Friday… since temperatures should still be near or below freezing. We’ll focus more on this Thursday… as the event gets closer, and we see how the storm is unfolding.
We’ve got a VERY full plate for the next 36 to 48 hours. The major key to the snowfall forecast, has to do with the temperature profile of the atmosphere… and how long the snow falls, before mixing with sleet and freezing rain. There is a good chance we adjust snowfall forecasts on Thursday, as we get a better idea. Don’t be shocked if we have to increase the snowfall forecast. We will be walking with you the entire way. Thank you so much for your support!