December 8-10, 2018 Winter Storm

[lilj4425]

Three different snow total maps from the same model and run giving me three different amounts. Alrighty then. 

[WeatherNC]

3 minutes ago, Poimen said:

This is almost comical. Close in: 

Pivotal is 29" from Morganton to Lenoir to Hickory, 28" in Blowing Rock.  As things stand now, Blowing Rock is where I will be Saturday afternoon - Tuesday.  I like the elevation
(wind potential), eastern side of the escarpment, 321 should be plowed with a backdoor through Boone and 421 if needed.  Not ready to commit further south than there at the moment, SW VA appears to be safely out of play.  Slower timing will allow ingest of the 12z run on Saturday for any last minute adjustments as I am on the road.  

[ryan1234]

Given the current trends, I really feel confident that most of us are in for a nice surprise. Granted, I’m merely an amateur, but I really feel like this CAD is going to over perform. Sure, there is plenty that could go wrong. But I think the overall consistency speaks volumes.


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[isohume]

1 hour ago, SnowDawg said:

Mets on twitter are absolutely bashing GSP for this ridiculous basically unreadable graphic lol

Aww, I think it looks rather pretty. Unfortunately it's part of WPC's suite of probabilistic forecasting, which only goes out 72 hrs. It's automated and we can't touch it or delete it. I'd say it needs some tweaking. 

[olafminesaw]

More than enough to digest while we wait for the 0z party to start here:

http://www.stormhamster.com/entry/e120618.htm

[WxKnurd]

5 minutes ago, isohume said:

Aww, I think it looks rather pretty. Unfortunately it's part of WPC's suite of probabilistic forecasting, which only goes out 72 hrs. It's automated and we can't touch it or delete it. I'd say it needs some tweaking. 

Then that makes the other maps that were confusing us when compared with the current forecasted amount map make sense now, probably also automated via WPC suite.

[GunBlade]

4 minutes ago, isohume said:

Aww, I think it looks rather pretty. Unfortunately it's part of WPC's suite of probabilistic forecasting, which only goes out 72 hrs. It's automated and we can't touch it or delete it. I'd say it needs some tweaking. 

Thanks.  Nice to know it’s automated.  I initially felt bad for whoever had to put that puzzle together!  Thanks for all you do!  Definitely a mess trying to piece together this storm. 

[olafminesaw]

17 minutes ago, Poimen said:

This is almost comical. Close in: 

It's all like... Come hither with the finger over Greensboro

[isohume]

1 minute ago, WxKnurd said:

Then that makes the other maps that were confusing ya when compared with the current forecasted amount map make sense now, probably also automated via WPC suite.

Yeah the probabilistic scheme needs some work. Basically it starts with WPC's gaussian which is fitted to our own normalized fcst curve. The outputted range bins are problematic. If any part of a zone is say above 12 inches, it puts that whole area in a 12-18 inch bin. 

[SnowDawg]

13 minutes ago, isohume said:

Aww, I think it looks rather pretty. Unfortunately it's part of WPC's suite of probabilistic forecasting, which only goes out 72 hrs. It's automated and we can't touch it or delete it. I'd say it needs some tweaking. 

Yeah that honestly makes a lot of sense. WPC might want to take a look at changing that though. Definitely unsuitable for public consumption in that state. Then again I’m sure the messiness and duration of this storm make it much worse than it normally is.

[ldub23]

I am quite skeptical of this  new  GFS. I would expect to see alot  of that snow not to occur in the east and se  parts  of the  snow  coverage shown on the  map. We will see. I certainly havent  been terribly  impressed with it  since  it was unveiled.

[Buddy1987]

Does anyone have any correlation to what “weaker” lows have with a significant and untapped potential regarding tropical connected moisture from the Baja vs lows that bomb out and almost make there own moisture flux say from the gulf? I read some interesting things on what @olafminesaw posted on that hamster link and I feel like after reading that this may be one of the “big” ones for the lower mid Atlantic and the southeast. That tropical connection, along with pwats, waa and subsequent atmospheric processes should lead to some serious rates of snow and in my opinion one heck of an expansive qpf shield, maybe more so than what the models are predicting. Wanted to get an opinion from a met or a pro in regards to this, if there was any studies done or anything like this. This southern low is traveling a long ways and picking up immense moisture along its path. 

[Poimen]

My general rule on clown maps is a   50% reduction, which in this case yields a 10-15” event. That seems plausible.

[Orangeburgwx]

5 minutes ago, ldub23 said:

I am quite skeptical of this  new  GFS. I would expect to see alot  of that snow not to occur in the east and se  parts  of the  snow  coverage shown on the  map. We will see. I certainly havent  been terribly  impressed with it  since  it was unveiled.

TT mixes sleet in with it, Pivotal is the site to use for snow only

[SENC]

32 minutes ago, Wow said:

It really has been quite consistent.  Here's a trend loop of the last TWENTY runs of the FV3 total snowfall...

Thanks for this @Wow, shows quite a bit of "variables" in these Forecast(s),, Quite a complex System.. Lotsa "players" on the Field ATM..

Realistically, anything is still on the Table at "Gametime" ,, Will this be a  "Run out the Clock" to the Last Moment in the "End-Zone"?? 4th & Goal w/ .01 on the clock? While down by 2 points?

Until We see the LP position sets-up/transitions in the Gulf, or around New Orleans, into Florida, Anything is still quite possible? 

Including "Bomb-O-Genesis" Off the SE Coast A-la Jan 3~4 2018? (Yes; fantasy) I know but still,, it could somewhat be on the Table if the LP gets further south? Say off Jacksonville to Daytona Beach?

Asking for a "friend"..  

[calculus1]

@isohume, could you comment on why the ECMWF was not factored into the official forecast this afternoon? Why was the GFS solely relied upon? Thanks.

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[SnowGoose69]

9 minutes ago, Poimen said:

My general rule on clown maps is a   50% reduction, which in this case yields a 10-15” event. That seems plausible.

They’re usually only highly accurate in scenarios where you’re locked into a 10 to 1 or more event with no mixing and you’re comfortably below freezing through the event.  

[IUsedToHateCold]

Seems like the models have locked this in, so congrats to everyone. My Mom in Black Mountain looks to get crushed. I lived in NC for many years and if I was southeast of that diagonal from Charlotte to east of Raleigh I'd be wary of that mix line and the slight tick north these things seem to take at the last minute. When I lived in Charlotte it often rained south of the city while the north would get snow. 

[isohume]

3 minutes ago, calculus1 said:

@isohume, could you comment on why the ECMWF was not factored into the official forecast this afternoon? Why was the GFS solely relied upon? Thanks.

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The EC was used and weighted along with some GFS/CMC fields. The NAM profiles were not incorporated as it was deemed too warm at h85 and was an outlier, but will be watched for further trends. In my personal experience the NAM normally does quite well with the warm nose in this area.

[WxJordan]

My first call map for this storm. It will probably change moving forward, but this is what I expect at the moment.

 

As always, I have a full discussion available at wxjordan.com. The warm nose worries me greatly, so I kept totals lower than most guidance is showing. I also expect the snow to rain ratio to be less than 10:1. Eastern locations will battle surface temperatures and the warm nose as well, that is why the totals are less. Mountains should do very well in this set up, and I would not be shocked to see some locations exceed 20 inches IF it remains all snow.

[griteater]

18z Euro compared to 12z was similar overall with temperatures.  It brings the 850 0 deg back to just east of the NC Mtns during, say, the 2nd half of the heavy precip portion of the storm.  It was wetter this run thru NC where there is a large area of at least 2 inches liquid.  Here are the last 4 runs of total precip for the storm to Monday morning (12z Mon)

[HKY1894]

4 minutes ago, griteater said:

18z Euro compared to 12z was similar overall with temperatures.  It brings the 850 0 deg back to just east of the NC Mtns during, say, the 2nd half of the heavy precip portion of the storm.  It was wetter this run thru NC where there is a large area of at least 2 inches liquid.  Here are the last 4 runs of total precip for the storm to Monday morning (12z Mon)

QPF seems to be on an upward trend since last nights 0z run on many models specfically on FV3 and euro

[olafminesaw]

7 minutes ago, griteater said:

18z Euro compared to 12z was similar overall with temperatures.  It brings the 850 0 deg back to just east of the NC Mtns during, say, the 2nd half of the heavy precip portion of the storm.  It was wetter this run thru NC where there is a large area of at least 2 inches liquid.  Here are the last 4 runs of total precip for the storm to Monday morning (12z Mon)

Just now, HKY1894 said:

QPF seems to be on an upward trend since last nights 0z run on many models specfically on FV3 and euro

You can see how the precip gets enhanced as it hits the wall. It will be interesting to see where banding sets up, because wherever the jackpot zone is East of the Mountains, will be sitting under a heavy band for a while. My guess would be up near the VA border.

 

 

[WidreMann]

12 minutes ago, isohume said:

The EC was used and weighted along with some GFS/CMC fields. The NAM profiles were not incorporated as it was deemed too warm at h85 and was an outlier, but will be watched for further trends. In my personal experience the NAM normally does quite well with the warm nose in this area.

So does that mean you were outvoted?

[Rankin5150]

6 minutes ago, isohume said:

The EC was used and weighted along with some GFS/CMC fields. The NAM profiles were not incorporated as it was deemed too warm at h85 and was an outlier, but will be watched for further trends. In my personal experience the NAM normally does quite well with the warm nose in this area.

I was wondering what this meant from reading the AFD. Thank you for clarifying. BTW, I think you all do one helluva good job! Thanks for always holding it down! 

[WidreMann]

12 minutes ago, griteater said:

18z Euro compared to 12z was similar overall with temperatures.  It brings the 850 0 deg back to just east of the NC Mtns during, say, the 2nd half of the heavy precip portion of the storm.  It was wetter this run thru NC where there is a large area of at least 2 inches liquid.  Here are the last 4 runs of total precip for the storm to Monday morning (12z Mon)

What is the second half of the storm?

[olafminesaw]

Bullish as always

[griteater]

2 minutes ago, WidreMann said:

What is the second half of the storm?

Just mean that it doesn't jerk the 0 deg line NW right during the "1st half of the heaviest precip", but rather, during the 2nd half of the heaviest precip that rolls thru

[WidreMann]

4 minutes ago, olafminesaw said:

Bullish as always

Yeah, that might have been reasonable two days ago.

[WidreMann]

1 minute ago, griteater said:

Just mean that it doesn't jerk the 0 deg line NW right during the "1st half of the heaviest precip", but rather, during the 2nd half of the heaviest precip that rolls thru

I mean what are the time frames for first half and second half. Are you talking about the ULL moving through Monday, or are you talking about Sunday afternoon?