January 12-14, 2019 Storm Threat

[Interstate]

Just now, yoda said:

Start with the lowest shade of blue bordering the dark gray.  That is the 2" line.  Each line you pass as you move toward DC is an increase of 0.5"

Or just count down from the purple which is 6. 

[psuhoffman]

5 minutes ago, yoda said:

 

4 minutes ago, osfan24 said:

It's really teetering on that line, especially north of DCA, between a near non-event and a really nice event.

naw that GEFS run is NICE...I would say stick and be totally happy with that.  Unfortunately we know that isn't how it works.  I have to look at the ind members too and see if the pretty good snowfall mean to the north of DC is due to a few big hits skewing what is otherwise a high bust risk or if its a pretty uniform 4-5" in Maryland.  

[psuhoffman]

4 minutes ago, Bob Chill said:

The thing about the GEFS is it's skewed by approx 5 big hits. All 5 of those solutions run the coast and pummel NJ and NE of there. While that solution is still possible, it doesn't have a lot of support right now. Like none. lol

that is exactly what I was afraid of.  Big difference between a 5" mean from a lot of 4-6" hits and a 5" mean from a few 12" hits and a lot of misses.  

ETA:  thats why the snowfall mean maps are useless as you said...seeing the plots for each member is more telling

[Ji]

Its 5

Not in my book

[yoda]

[Bob Chill]

1 minute ago, psuhoffman said:

that is exactly what I was afraid of.  Big difference between a 5" mean from a lot of 4-6" hits and a 5" mean from a few 12" hits and a lot of misses.  

I'd dig deep and analyze the run but the euro will be out in less than an hour so I'll just completely toss the run and wait. 

[yoda]

Just now, Ji said:

7 minutes ago, yoda said:

Its 5

Not in my book

Well WSW criteria per LWX is 5"... 

[Bob Chill]

1 minute ago, Ji said:

8 minutes ago, yoda said:

Its 5

Not in my book

Ratios dude...ratios... The .5 @ 25:1 = A foot!

[Ji]

The thing about the GEFS is it's skewed by approx 5 big hits. All 5 of those solutions run the coast and pummel NJ and NE of there. While that solution is still possible, it doesn't have a lot of support right now. Like none. lol

Sure it does. It has 5 members

[osfan24]

There's actually a fair amount of big hitters though. Obviously not the most likely scenario, but there are four big hits among the GEFS and some that are either close or pretty solid hits.

[Roger Smith]

The three best features (to balance out all the obvious risks that argue for low outcomes) --

(a) very warm offshore SST values near 24 C east of southern Delmarva -- should energize the low on Sunday and provide higher moisture contents in frontal bands

(b) linking up of main arctic high in SK to very cold western slug now close to n AB s NWT border (-42 C) -- will produce a conveyor belt effect for double-centered low

(c) energy peak well positioned and timed to impact storm development 12z 13th

... so blending that into what might otherwise be an anemic system, should cancel out some of the negatives and result in a moderate outcome, hence the 4-7" call. But yes, I would divide that by three if a solution like the GEM verified. OTOH would double the 4-7 if this gets some muscles and lifts like the five outlier solutions mentioned. 

[Superstorm]

There's actually a fair amount of big hitters though. Obviously not the most likely scenario, but there are four big hits among the GEFS and some that are either close or pretty solid hits.

And very few whiffs.


.

[WxUSAF]

Just now, Ji said:

7 minutes ago, Bob Chill said:

The thing about the GEFS is it's skewed by approx 5 big hits. All 5 of those solutions run the coast and pummel NJ and NE of there. While that solution is still possible, it doesn't have a lot of support right now. Like none. lol

Sure it does. It has 5 members

Actually looks more like 8 of the members to me based on the snowfall maps alone.  The mean map is sort of by itself, there's only a handful that have a general 2-4"/3-6" without a clear coastal component.  About 8 with significant coastal contribution, 8-9 with 1-2" snows, and the rest with the 2-4"/3-6" scenario.  

[SomeguyfromTakomaPark]

Just now, osfan24 said:

There's actually a fair amount of big hitters though. Obviously not the most likely scenario, but there are four big hits among the GEFS and some that are either close or pretty solid hits.

And 13/20 get us to 2+ inches in DC, so at least we're not staring at a bunch of complete misses. 

[psuhoffman]

2 minutes ago, Bob Chill said:

I'd dig deep and analyze the run but the euro will be out in less than an hour so I'll just completely toss the run and wait. 

Ehh its not as bad as I feared.  Those 5 big hits are NICE though and I guess having a 25% chance of that outcome is not too bad a bet to take.  Another 5 would be moderate hits and I would be totally happy with it.  10/20 would be unacceptable to me (here).  A few more of those would probably be deemed acceptable to the DC area.  

[showmethesnow]

6 minutes ago, showmethesnow said:

As with the 06Z we once again saw improvement on the 12z where we need to see it. NS is withdrawing/pulling out quicker allowing heights to rebound quicker in the east. Think this feature will what makes or breaks this storm for us. 

LOL. What do you know. Chucks low over the Hudson Bay looks like it is the driving force on pushing the NS out of the NE quicker. Of course I think Chuck said it would be the reason we wouldn't see snow. But let's not quibble over details. 

[mappy]

12 minutes ago, Ji said:

15 minutes ago, yoda said:

12z GEFS snow mean is 4-5 inches for DCA through 132

Boo.....wsw is 6

LWX winter storm warning criteria is 5". I get that you aren't happy unless you get a foot or more, but at least be correct with warning criteria information. 

[MD Snow]

5 minutes ago, osfan24 said:

There's actually a fair amount of big hitters though. Obviously not the most likely scenario, but there are four big hits among the GEFS and some that are either close or pretty solid hits.

But each of the last 3 runs since 0z last night have had less solid hits and more misses. Like less than one inch or 2. I count roughly 8 of those for the cities. That's the most misses it's shown for a while. 

[Bob Chill]

2 minutes ago, psuhoffman said:

Ehh its not as bad as I feared.  Those 5 big hits are NICE though and I guess having a 25% chance of that outcome is not too bad a bet to take.  Another 5 would be moderate hits and I would be totally happy with it.  10/20 would be unacceptable to me (here).  A few more of those would probably be deemed acceptable to the DC area.  

We can probably just blend ops at this point. The wide spread on the ensembles adds more confusion than it helps. If we see any legit trend towards a coastal runner then we can start talking about big hits but for now it seems that a light to maybe moderate event is the most likely by far. 

[Ji]

LWX winter storm warning criteria is 5". I get that you aren't happy unless you get a foot or more, but at least be correct with warning criteria information. 

We both know 5 is not wsw in our counties:)

[psuhoffman]

4 minutes ago, Ji said:

11 minutes ago, Bob Chill said:

The thing about the GEFS is it's skewed by approx 5 big hits. All 5 of those solutions run the coast and pummel NJ and NE of there. While that solution is still possible, it doesn't have a lot of support right now. Like none. lol

Sure it does. It has 5 members

yea I mean if I am being a deb there is a 50% chance of a crap outcome.  But that also means a 50% chance of a VERY good outcome, keeping in mind those are 10-1 and some of those 3-4" members are actually 5-6" given ratios here.  And a 25% chance of a big hit which isnt something to sneeze at considering how rare those 8" plus storms are.  

[mappy]

Just now, Ji said:

3 minutes ago, mappy said:

LWX winter storm warning criteria is 5". I get that you aren't happy unless you get a foot or more, but at least be correct with warning criteria information. 

We both know 5 is not wsw in our counties:)

sure it is, otherwise LWX wouldn't issue winter storm warnings if it wasn't. 

[Fozz]

17 minutes ago, yoda said:

Its 5

It's 5" for shorter duration events (12 hrs or less), which tend to be most of our storms. But for longer duration, it's 7"+.

[psuhoffman]

3 minutes ago, MD Snow said:

But each of the last 3 runs since 0z last night have had less solid hits and more misses. Like less than one inch or 2. I count roughly 8 of those for the cities. That's the most misses it's shown for a while. 

As this evolves more towards a coastal coming from the south vs a west to east wave with WAA it is becoming a higher risk/reward type situation where the chances for a big event might be going up, so are are the chances of a miss or mostly a miss after some very light snow with the initial wave.  

[BristowWx]

Just now, Fozz said:

It's 5" for shorter duration events (12 hrs or less), which tend to be most of our storms. But for longer duration, it's 7"+.

that I did not know.  Thanks.  Thought it was 5 regardless. so 12hours or more is 7+?

[midatlanticweather]

1 minute ago, Bob Chill said:

We can probably just blend ops at this point. The wide spread on the ensembles adds more confusion than it helps. If we see any legit trend towards a coastal runner then we can start talking about big hits but for now it seems that a light to maybe moderate event is the most likely by far. 

It gets easy to put on weenie glasses when looking at the models. Also, the desired and believed North trend. Nothing seems to point to shutout, but we are not super far from something more substantial. I am ok with a light snow when I was thinking it was a long shot last week, but we always think the chances of snow in the region are limited, so we want to capitalize on every opportunity and have it in our back yard. My thinking is just N of Richmond does best and of course SW VA and Mountains are a given. Hoping for the run up the coast though... at least there is a chance!

[Bob Chill]

Just a thought... we can prob save the WSW discussion when the flag is raised. Getting WAY ahead of ourselves aren't we?

[yoda]

Just now, BristowWx said:

that I did not know.  Thanks.  Thought it was 5 regardless. so 12hours or more is 7+?

https://www.weather.gov/lwx/WarningsDefined#Winter Storm Warning

[yoda]

Just now, Bob Chill said:

Just a thought... we can prob save the WSW discussion when the flag is raised. Getting WAY ahead of ourselves aren't we?

Only came up since Ji claimed it was 6" after being upset that the GEFS mean showed 4-5

[87storms]

9 minutes ago, Bob Chill said:

We can probably just blend ops at this point. The wide spread on the ensembles adds more confusion than it helps. If we see any legit trend towards a coastal runner then we can start talking about big hits but for now it seems that a light to maybe moderate event is the most likely by far. 

looks like there's going to be a tight gradient with that high pressing down.  i think as long as the wave is legit and doesn't shear/dry out, then we can overperform with the temps.  dc is even modeled to be at or below freezing and we have a couple of cold days leading up to it.  and it might be an overnighter, or at least the initial portion.  hope that coastal is a bit further north/west than modeled, though.

would like to see the surface low 50 miles north to get into a real nice event...

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=z850_vort&runtime=2019010912&fh=108