Timing the onset and precipitation types-
Precipitation arrives from west to east between 2-5AM, for parts of Ulster, Sullivan, Greene and Delaware Counties the precipitation will start off as snow. It should be noted that the HRRR model is slight colder than the NAM model this evening, in challenging it verse current observed temps across the region, the HRRR model seems to have a better grasp on the surface temps. Here’s a look at how these small temp profile differences impact the forecast for tomorrow morning. 
You have to have a keen eye to spot the differences as they are subtle but worth noting. The HRRR is the first image and the NAM is the second, the colder temps overnight on the HRRR allows the snow line to be a touch further S and E with more of Sullivan,Ulster and Greene’s lower elevations starting as snow. Given tomorrow’s heavy travel, it’s important to shout out the potential for this onset snow to have a larger coverage area outside of where the current winter weather advisories are in place.
Timing The Changeover-
Between 11AM and 1PM the rain snow line will be driven north as warmer air floods into the region from the nearby passing low pressure to our south. This change over looks to impact the entire region and most habitable elevations of the Catskills. The exception may be some of the highest peaks and summits where freezing rain or snow may hold on. This will compress down previous snowfall across these regions with final measurable snowfall being less than total fallen snowfall. Snowfall amounts of Coating- 4” across the hill towns and foothills of the Catskills between about 500’-1200’ elevation, above 1500-2000’ elevation snowfall amounts of 4”-8” with some 10” amounts across the highest elevations above 2000’. The questionable locations are parts of eastern Ulster, Eastern Green, SE Sullivan County, where slight colder temps may lead to a early burst of snow, this is where a Coating to an inch may surprise us. Here’s a glance at both short range models projection for snowfall, which is helpful to visualize the higher elevations and also the subtle difference with HRRR having a bit of snow in the lower elevations as well. 
Timing the Departure of Precipitation/Friday AM-
Rain/Snow departs the region from SW to NE between 7-9PM, temps will drop in the wake of the storm with some locations dropping back below freezing overnight. For you early Friday shoppers or those with early commutes, be alert for areas of refreeze that may occur and lead to some slick parking lots, less traveled roads and surfaces. Otherwise breezy and cool day on Friday with a much colder airmass moving in for end of Nov and early Dec.
Happy Thanksgiving from all of us at HVW we are certainly thankful for all of you!