Relatively routine hazardous icing event I84 corridor mainly 1/1 and terrain above 1000 feet in particular.

[wdrag]

Advisory package (blue) and warnings (pink)...nationally at 355PM. 

[wdrag]

1 hour ago, crossbowftw3 said:

The SPC map does show the elevations well- but probably overdone anyway as you say. But I still wouldn’t be shocked if some instances of accretions .3-.4 happen above 1500’. 

agreed on all.  Lets watch that HRDPS for ice and see how it goes. 

[crossbowftw3]

41 minutes ago, wdrag said:

agreed on all.  Lets watch that HRDPS for ice and see how it goes. 

What are you seeing from the HRDPS?

[NepaJames8602]

2 hours ago, snywx said:

Greenville Mtn in western orange is slightly higher. Up near the mountain rd exit its around 1400'

Yeah, out here in the Poconos where route 84 begins, just east of Scranton; is several spots at or exceeding 1800’ feet along route 84.

[wdrag]

2 hours ago, crossbowftw3 said:

What are you seeing from the HRDPS?

I look at every model every cycle through 7 days. I just notice the HRDPS is slightly colder than the RGEM and consistently so.  Once the HRDPS loses freezing, then I think the door shuts on new ice...even if there is a 1 or 2 hour delay from th HRDPS time.   it has longer duration on western fringe of forum than many models are offering, 

With a grain of salt... HRRRX has quite a bit of sleet late NY Day...even LI will probably see at least spotty sleet during the first 2 hours of precip.  

Upshot of all this: a messy  advisory cause most don't like ice..  and at night---it's impact is a little larger. I see model qpfs are increasing again.  I definitely see whatever sleet-snow ice occurs, having a good chance for sunrise visuals Saturday, before melting increases. 

Someone noted big ice doesn't occur til we get down into the 20s.  I don't have stats on that, but freezing is freezing and the northeast facing slopes will do well... even at 30F. Might even have enugh ice to break some small limbs (1/4")...Cats, Litchfield and Berks high terrain.

33 here at 746PM... wish there was better cold pool to our northeast.

[gravitylover]

8 hours ago, snywx said:

Greenville Mtn in western orange is slightly higher. Up near the mountain rd exit its around 1400'

Yup but the stretch here in Putnam is the high point for NY, that was my point.

[wdrag]

Happy New Year!  No significant change to yesterdays post. This event will focus it's main impact on ne PA, se NYS, nw corner CT into w HFD county and the Worcester Hills, in that order of priority, Valleys in pretty good shape s of I84. A little sleet possible at the start many areas but less chance of a few minutes ice pellets LI. the leading of qpf  will increasingly grow sleet to an hour or two duration as it gets into far northern CT and maybe briefly mix snow there with snow on the leading edge along the MA Pike. Main risk of 1/4 inch glaze is ne PA high terrain, Catskills, and extreme nw HFD County into the northern Litchfield east facing slopes. 

graphics: Orange where best chance of problem icing in WPC ensemble, the second graphic is the SPC HREF ensemble FRAM icing potential=worst case scenario in my mind, showing ridge icing best but amounts may be a touch high? and finally the 06z/1 HRRR snow and sleet accumulator, which I think is a reasonable baseline for this event.

[wdrag]

Good Saturday morning everyone,  QUICK review: My guess, from a quick 430A check of temps from multiple resources... the ICON/NAM did best holding onto freezing temps this late into the event I84 northwestward. If others see it different, please speak up. Models are getting better but just 1 degree can be a BIG problem at critical temps.  imo, the Global Models cannot as precisely detect the subtleties. They're all getting closer but still advantage can be to those who know the nuances of the guidance in light boundary layer winds that do not have much CAD support from the typically desired east of south 850MB winds.