Sunday AM Thoughts

Good Morning! Happy Sunday!

Clouds associated with out incoming storm system have overspread the region, our thoughts on the storm remain very much unchanged since Friday and our snow map remains unchanged for now. The data with this system has been doing a lot of waffling, we’ve found it best to not react with every 6-12 hours of data. We’ve seen some track shifts and with that some thermal changes that have resulted in data showing more or less snow across more of the region from run to run.
At this point we nowcast, and look at the real-time data, for example we are closely monitoring actual temps vs what the short range models are initializing temps at for the current hour. If we’re colder or warmer that is an early indicator of how things may evolve. So far since about 4AM we’ve been running 1-3° cooler in most spots with the a significant discrepancy on the colder side across parts of the Catskills, which seeing the fact that more snow is already forecasted in that region, that piece it irrelevant.
I’ve attached the current temps vs latest HRRR temps for the same hour for comparison, as has been the theme this winter and really last winter as well, we have a lot of storms running into weak or decaying cold air masses, with the 32° or less boundary seemingly always setting up across the region. It is true that the atmosphere can get muscle memory, as an example the ice storm last winter was a result of a boundary of colder air just to our north, the persistent severe weather that plagued Ulster and Dutchess Counties over the summer was a result of this pattern and it’s one that has carried into this season as well.

When forecasting these type of events, everything is always on a knifes edge, as a few feet of elevation, or a few miles further north, or a degree or two colder can either bust or boom these systems. When the data shows boom, but the 18 month pattern is meh, we like to stay conservative.

Precipitation arrives around 430-6PM, southern most zones look like rain from the onset, as you get closer to i84, we start as snow but it may be brief in the valley locations. North from there the period of snow before change over is of longer duration, how long it stays snow will determine low end or high end of current snow map. The further west and east away from the valley and higher in elevation, the higher probability of a moderate to heavy snowfall. Western Ulster,Western Greene and Delaware Counties continue to look to be the places to exceed 6”+.

-Alex

Images-
Mesonet- current temps
HRRR-8AM Temps
HRRR-Sim Radar 4PM
Current HVW Snow Map