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wdrag

Minor to moderate winter event M-Tue Dec 16-17, 2019

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Good Saturday morning Dec 14,

Since I didn't see a specific thread for this coming event, thought it would serve to get something started. 

It's probably worthy to debate, watch trends etc etc...have started it off with what I think are some helpful perspective graphics. 

These graphics, some of which are ensembles, act as a decent starting point for today, remembering that the greatest error generally occurs along the gradient edges. 

Credit goes to WEATHER.US and the ECMWF for the first two graphics, and to the NWS (WPC) for the freezing rain graphic. 

First: Is the EC operational estimate of what may occur Mon-Tue---a nice idea. 00z/14 version

Second is the EPS (ECMWF ensemble chance of 1+ inches of snow). Legend suggests a 75% or greater probability of 1+ inch of snow I84 corridor and actually back to near STL/DEN. 00z/14

Third: Is the NWS ensemble probability of glaze... less than .10" ending 7AM Tuesday.  There is a chance there will eventually be more than 0.10 and higher probabilities for .01 glaze somewhere within 50 mi of I84. 08z/14.

If I missed a specific thread that had this started, I'll delete this.  Just let me know.  Thank you,

Walt 1450z/14

 

Screen Shot 2019-12-14 at 5.50.21 AM.png

Screen Shot 2019-12-14 at 5.58.49 AM.png

Screen_Shot_2019-12-14_at_6_09.40_AM.png

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2 hours ago, NEG NAO said:

sn10_acc.us_ne.png

Doubt it will happen, but 4.6 in my area does qualify as more than a minor event. Not a huge storm, but not one that won't cause problems, either....

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12z/14 EC looks quite good for a mess and a decent front end 2-3" 6 hour dump.  Still lots of detail to be ironed out but the 12z GFS and GGEM were a little  older.  Am expect the NAM to trend colder  but consensus on everything good shift back north... bottom line, a winter event is coming that will need to be considered for adjusting travel plans, especially near I80 north.  Hopefully tomorrow it still looks halfway decent.  (noticed 12z/14 Kuchera a little less than 10 to 1 and snow depth amounts though it might be my interp? Off line til tomorrow). 

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2 minutes ago, weatherpruf said:

Doubt it will happen, but 4.6 in my area does qualify as more than a minor event. Not a huge storm, but not one that won't cause problems, either....

I try to understate, thinking downside. Agree with you..some areas minor but overall I think this will be a moderate mixed event.  I'll post NWS WSSI stuff if its available in a day or so. Gotta run.

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13 minutes ago, wdrag said:

I try to understate, thinking downside. Agree with you..some areas minor but overall I think this will be a moderate mixed event.  I'll post NWS WSSI stuff if its available in a day or so. Gotta run.

Thanks. Will keep an eye on it.

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37 minutes ago, wdrag said:

12z/14 EC looks quite good for a mess and a decent front end 2-3" 6 hour dump.  Still lots of detail to be ironed out but the 12z GFS and GGEM were a little  older.  Am expect the NAM to trend colder  but consensus on everything good shift back north... bottom line, a winter event is coming that will need to be considered for adjusting travel plans, especially near I80 north.  Hopefully tomorrow it still looks halfway decent.  (noticed 12z/14 Kuchera a little less than 10 to 1 and snow depth amounts though it might be my interp? Off line til tomorrow). 

Yea, the 10:1 ratio snowmaps aren’t going to work for this one either. There’s a lot of sleet in there getting counted as snow and the ratios are lower than 10:1 again. This isn’t a deep arctic airmass in place Monday and the models always underestimate the mid-level WAA/warm nose until the last minute

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2 minutes ago, SnoSki14 said:

Usually these trend north last minute but that's a pretty steep AO/NAO drop being depicted so it could actually trend south/colder as we get closer. 

 

QPF wise the 12Z Euro looked good but the mid level WAA looked early.  LGA changes to PL by 23Z and gets maybe 1-2 inches before 

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25 minutes ago, snowman19 said:

Yea, the 10:1 ratio snowmaps aren’t going to work for this one either. There’s a lot of sleet in there getting counted as snow and the ratios are lower than 10:1 again. This isn’t a deep arctic airmass in place Monday and the models always underestimate the mid-level WAA/warm nose until the last minute

You are right on time making generalizations downplaying the event. This could be a real issue N and W with ZR on top of the 2-4 inches of snow/sleet on the front end. The Euro has been consistent with this for 3 days now. 

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58 minutes ago, SnoSki14 said:

Usually these trend north last minute but that's a pretty steep AO/NAO drop being depicted so it could actually trend south/colder as we get closer. 

The precip usually comes in faster  than modeled 

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54 minutes ago, SnowGoose69 said:

 

QPF wise the 12Z Euro looked good but the mid level WAA looked early.  LGA changes to PL by 23Z and gets maybe 1-2 inches before 

Yeah my biggest concern is FRZA. Surface cold looks to hold around 28-31F for a long time before warming. 

Those just N&W could be in for a miserable travel day.

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59 minutes ago, snowman19 said:

Yea, the 10:1 ratio snowmaps aren’t going to work for this one either. There’s a lot of sleet in there getting counted as snow and the ratios are lower than 10:1 again. This isn’t a deep arctic airmass in place Monday and the models always underestimate the mid-level WAA/warm nose until the last minute

north of NYC  (let's say 287) will do the best-Euro has those areas with 2-3 inches of snow then sleet and ZR on top.  By the time it nudges above 32, the storm is over.  Some areas, such as DXR and BDR and HPN could be above 10 inches for seasonal snowfall by then.    Arctic cold shot follows.

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2 minutes ago, RedSky said:

Taking a nice trip to the Tughill it should bury those guys

 

 

Not the front end

Its further south

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3 hours ago, SnoSki14 said:

Yeah my biggest concern is FRZA. Surface cold looks to hold around 28-31F for a long time before warming. 

Those just N&W could be in for a miserable travel day.

The icing threat NW of the city will be the big story, however as usual the city and immediate surrounding areas should warm enough for cold rain after the initial snow/sleet

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I'm back! This event looks like a little snow to start before changeover. This system is a strung out mess.  

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