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February 3-4 significant icing event for the interior, some sleet/snow possible. Coast mostly rain.


NJwx85
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12z GFS 925mb surface temperatures cross-referenced with MSLP+QPF, Friday morning (15Z) at peak of event in metro-area. At 925mb, the 0C/32F line goes south of NYC at 9z, with ongoing light-moderate precip preceding this time frame. At 850mb, 0C/32F is just north of city, bisecting Bronx/Westchester coinciding with this forecast time.

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2 minutes ago, Nibor said:

It’s going to be cold for a few days on the backside of this. Whatever ice falls is going to melt slowly. 

an ice storm can  shut things down faster and more dangerous than a snowstorm-time to start stocking up on various ice melt.....

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Im always a little skepitcal when the models are showing something that climo wise almost never happens. I sort of agree with this will end up either mostly snow or mostly rain camp near the coast although I can see with the high placement how the setup the models are showing makes sense  but wouldn't really take it that seriously beyond 72 hours. 

 

If the warmer scenario happens I could definitely see crippling icing in the climo spots of Sullivan, Ulster, Passaic and Orange counties. 

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49 minutes ago, jm1220 said:

Maybe maybe not. A stronger overrunning wave will push it north. But at this lead time the cold air might not be showing up as well as it would be at the surface. This would be a nasty ice storm for a pretty wide area if this setup stays as is. 

I think we just keep have to follow the track of the low and placement/strength of high, that should ultimately tell the story in terms of precip types. 

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29 minutes ago, NEG NAO said:

an ice storm can  shut things down faster and more dangerous than a snowstorm-time to start stocking up on various ice melt.....

Finally a use for that pesky "not-a-flamethrower" flamethrower, made by Elon Musk.   Collecting dust without barbecue weather.  

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Just now, HVSnowLover said:

Thats why its so nice to live in a place like Boston, you can get whacked from a coastal and then whacked from an overrunning event like this all in the same week.   

I would rather live here. Overall I like warm weather better and springtime in Boston is a disaster.

 

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21 minutes ago, Northof78 said:

Got to use the Kuchera formula, does a great job of separating ice, sleet, and snow, that has about 1-3"/2-4" of snow for most of metro along with much sleet, some ice

If by "ice" you mean, freezing rain, then this isn't true. Remember that these prognostic fields summate snowfall by multiplying an instantaneous field (temperature, in Kuchera's case) with an accumulated field (snow water equivalent) which is usually a 1/3/6 hour interval. Just be weary of this: Post-processed algorithms are vulnerable to significant errors due to temporal inconsistencies.  

Also, for "snowfall," all NWP models produce a snow water equivalent field which includes the accumulated contributions of all frozen hydrometeors which is diagnosed explicitly by its applied microphysics scheme (resolves moisture and heat tendencies in the atmosphere). Typically (but not always), this includes snow and pristine ice (sleet). This is why you see "includes sleet" text when associated with some snowfall products (websites uses this swe variable to calculate snowfall). Regardless, swe (as it relates to NWP) doesn't include freezing rain (not a frozen hydrometeor) so it's already removed from the post-processed algorithm.

If you're worried about taint, the RAP and HRRR produce a diagnostic snowfall field which calculates snowfall between modeled time steps. It calculates snow density by weighing the density of frozen hydrometeors individually. Hydrometeor density is a function of the temperature of the lowest temperature field (probably between 8 - 20 meters) - https://github.com/wrf-model/WRF/blob/master/phys/module_sf_ruclsm.F

I'd rank snowfall products as follows:  

Long range >5 days: Nothing... NWP accuracy is poor. 10:1 ratios if you really, REALLY want a fix.

Medium range: NBM - Snowfall is post-processed utilizing Cobb SLR's (and several other algorithms).

Short range: RAP and HRRR diagnostic snowfall field... Maybe even the NBM... SREF utilized the Cobb algorithm, but man', SREF sucks.

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