December 8-10, 2018 Winter Storm

[Cold Rain]

8 minutes ago, jjwxman said:

12z EPS: You really can't ask for much more than this at this stage in the game. Roll on!

The placement of features is about as good as it gets for the upper SE.  Unfortunately, as ILM said, the air mass isn't extremely cold.  That's fine, if everything is perfectly timed.  Just cold enough is still cold enough for snow, just like extreme cold is cold enough for snow.  The issue is, you have less room for error when temps are 1 degree below freezing at key levels.  Also, those highs are pretty weak.  When you're dealing with marginal cold, you need all the help you can get from a strong high pressure.  Hopefully, the timing can work out.  Anyway, I like the placement of the key features.  And I stick with my motto of getting cold first, then worrying about precip.

[Rankin5150]

Just now, SnowNiner said:

Man if we can't get a warning criteria snow in the NC piedmont/Upstate out of that sweet look in December, I will never expect snow again in December.  Geez.  I don't know how I could draw it any better, other than a stronger high. We suck if we can't snow with that. 

Unfortunately...for our areas...if it can go wrong, then it WILL go wrong. It ALWAYS seems to be just right and there is no way we can miss out and then BOOM...something happens and we are screwed. LOL. I am with you brother...the setup is TOO AWESOME to NOT get something decent out of this. Fingers crossed we can get the cold source we need to SEAL THE DEAL! SIGH...

 

[burrel2]

Euro Ensemble members are also back to being absurdly bullish for the upstate.  Over half of them paint >3 inches here, with a mean close to 6 inches.

Incredible that both the GFS and Euro ensemble means are roughly 6 inches here this far out. 

[wncsnow]

Just now, burrel2 said:

Euro Ensemble members are also back to be absurdly bullish for the upstate.  Over half of them paint >3 inches here, with a mean close to 6 inches.

Incredible that both the GFS and Euro ensemble means are roughly 6 inches here this far out. 

Where do you get ensemble numbers? 

[Waiting on snow]

13 minutes ago, jjwxman said:

12z EPS: You really can't ask for much more than this at this stage in the game. Roll on!

I'm not one to be very optimistic about winter weather because if there is a way to screw it up we will. That said there is no way the Euro op is even close to correct if its ensembles are even close. That has big boy written all over it for the majority of the board!

[lilj4425]

3 minutes ago, burrel2 said:

Euro Ensemble members are also back to being absurdly bullish for the upstate.  Over half of them paint >3 inches here, with a mean close to 6 inches.

Incredible that both the GFS and Euro ensemble means are roughly 6 inches here this far out. 

That’s all? Six inches? I might as well move to North Dakota. 

[jjwxman]

Does anyone have the 12z EPS mean snowfall they can share? Or what does it show for the NW Piedmont of NC? Thanks.

[Rankin5150]

1 minute ago, burrel2 said:

Euro Ensemble members are also back to being absurdly bullish for the upstate.  Over half of them paint >3 inches here, with a mean close to 6 inches.

Incredible that both the GFS and Euro ensemble means are roughly 6 inches here this far out. 

Thank you for the info. Would you mind posting them, when you have time. Thanks in advance...

 

[burrel2]

5 minutes ago, wncsnow said:

Where do you get ensemble numbers? 

weatherbell; don't think I can post b/c it's a paid site.

[SouthernVAwx]

This is from Virginia Weather Network on Facebook.

[wncsnow]

3 minutes ago, burrel2 said:

weatherbell; don't think I can post b/c it's a paid site.

Thats what I figured. Thanks though, I may have to pony up and get a subscription. 

[Iceagewhereartthou]

Well what we're pretty sure of:

- An LP will bring significant amount of QPF into the SE next weekend

- There are several key ingredients in play for a winter storm somewhere in our area

                              > S/W, HP somewhere to our north, early season cold

- It's climo for some areas such as the high country of NC and VA, and early climo for adjacent areas. 

 

 There are some other factors that appear to be going in our direction at this time, such as the relatively weak baja low,  a bit of a 50/50 low, and possibility of 2 highs; one in the MW and one in the NE. And the fact that most models have been showing something wintry for a few days now.

Some things to consider:

The Baja to Jax track of a 1008ish LP with a 1035-1040 HP over Pen/NY  (and another high over MN) would give most of the board the best chance for a decent storm (with timing considerations). Many of the model runs we have seen have shown deviations of that and even slight changes would yield nice results for some folks, while sticking it to others. This looks to be a high QPF scenario (we're usually trying to scrape a few tenths) with many areas possibly receiving 1-3 inches of it! With high QPF will come a HUGE bust factor based on the temp profile. Cold = big snow (or mix); not cold =big rain (big disappointment). Someone is likely to get a very nice dump out of this, but there will be big gradients in short distances and elevation changes, and lots of heartbreak. As always, NC Mtns and SW VA will have the best chances, and are in great shape for a nice storm. Next would be NC piedmont, Upstate, and NEGA, though the odds of serious mixing increase considerably even if those areas are fortunate. IF we get the trends we need, more folks will have a chance. Right now both the GFS and Euro Ensembles are pretty close (even though the OP runs are wildly different) which I think is pretty unuual at this point. Hope for the best but expect cold rain and we'll see what happens! 

 

 

[jjwxman]

2 minutes ago, SouthernVAwx said:

This is from Virginia Weather Network on Facebook.

Wow, almost a carbon copy of the GEFS mean. Incredible really.

[Iceagewhereartthou]

27 minutes ago, jjwxman said:

12z EPS: You really can't ask for much more than this at this stage in the game. Roll on!

Looks good, just a stronger NE high! 

[Rankin5150]

I feel NWS-GSP worded this spot on: 

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 230 PM Monday: No major changes to the overall forecast from
the 12z guidance. If anything, they continue to trend a little
slower/delayed on the onset of precip, and also a little heavier in
QPF. The 12z ECMWF has come in more northerly/inland with the sfc
low track, and results in warmer thicknesses across the FA thru the
event. This allows a stronger warm nose, and perhaps, more of a
mixed bag of p-types, versus more ra/sn that previous runs
suggested. I opted to blend a little 12z ECMWF into the partial
thickness p-type nomogram tool for this forecast. Still get a lot of
snow in the mountains and the I-40 corridor with this solution, but
if the new ECMWF trend holds, these values will likely be a lot
lower, due to the sleet/frza mixing in. With all that said, it still
looks like a significant winter storm on tap for most of the
mountains and adjacent foothills in NC, while the Piedmont south of
I-40 is highly uncertain. Temps will start out below normal Friday,
as a reinforcing cold front pushes thru. Then classic cold air
damming sets up Friday night thru Sunday, as a strong sfc high
builds in across the Ohio Valley to the Mid-Atlantic. The heaviest
precip looks to be mainly Saturday night into early Sunday, but that
time may change slightly as we get closer to the event. Temps will
be tricky with the CAD. I stuck close to WPC, but these may be too
warm within the heart of the CAD wedge.

[BullCityWx]

12z GEFS for IGX

Mean: 6"
7/20 members have T-2"
3/20 members have 3-5"
4/20 members have 6-8"
6/20 members have 10"+

[BornAgain13]

1 hour ago, wncsnow said:

Still impressive for western sections. Keep in mind much of this would be sleet/slop 

Wouldn't really call that much slop/mess... even if a little sleet mixes in in Danville and Pittsylvania county,  that's a 1-2 Foot Snowstorm still.

[FallsLake]

I like RAH's afternoon discussion:

Sat-Mon: A strengthening mid-upper trough/low will cross the S Plains, Gulf States, and Southeast during this period. Models are fairly uniform in showing some polar stream interaction such that the system should slow and deepen as it crosses the Southeast. This will allow for cyclogenesis over the NW Gulf (where so many of our wintertime storms are born) and foster further intensification as it crosses the Gulf Coast / N FL and off the Southeast coast by Sun night or Mon. The ECMWF remains significantly slower than the GFS (by 6-12 hrs) and takes a farther-north path, such that it is generally a bit warmer but with greater QPF as its slower movement allows for greater deepening near the coast with a long-lived deformation back extending well inland through Mon. While confidence is rising that we`ll get a decent precip event and that a single dominant low is the most likely pattern of cyclogenesis, there is still too much model spread for much specificity. This model spread is not surprising considering the mid level feature in question is still currently well out over the Pacific. Will maintain high chance to likely pops, higher across the S and SE, starting early Sat but peaking Sun. Climatology for immature (still-developing) Miller A patterns supports broad corridors of mixed precip type, and the deterministic forecast will indicate this. It`s far too early to speculate about amounts of wintry precip, but we could be looking at a few inches of liquid (or liquid equivalent) before all is said and done. Highs each day will generally range from the upper 30s to mid 40s NW to SE, with nightly lows in the 30s. -GIH

[Solak]

RAH afternoon disco:

Sat-Mon: A strengthening mid-upper trough/low will cross the S 
Plains, Gulf States, and Southeast during this period. Models are 
fairly uniform in showing some polar stream interaction such that 
the system should slow and deepen as it crosses the Southeast. This 
will allow for cyclogenesis over the NW Gulf (where so many of our 
wintertime storms are born) and foster further intensification as it 
crosses the Gulf Coast / N FL and off the Southeast coast by Sun 
night or Mon. The ECMWF remains significantly slower than the GFS 
(by 6-12 hrs) and takes a farther-north path, such that it is 
generally a bit warmer but with greater QPF as its slower movement 
allows for greater deepening near the coast with a long-lived 
deformation back extending well inland through Mon. While confidence 
is rising that we'll get a decent precip event and that a single 
dominant low is the most likely pattern of cyclogenesis, there is 
still too much model spread for much specificity. This model spread 
is not surprising considering the mid level feature in question is 
still currently well out over the Pacific. Will maintain high chance 
to likely pops, higher across the S and SE, starting early Sat but 
peaking Sun. Climatology for immature (still-developing) Miller A 
patterns supports broad corridors of mixed precip type, and the 
deterministic forecast will indicate this. It's far too early to 
speculate about amounts of wintry precip, but we could be looking at 
a few inches of liquid (or liquid equivalent) before all is said and 
done. Highs each day will generally range from the upper 30s to mid 
40s NW to SE, with nightly lows in the 30s. -GIH

[SnowNiner]

24 minutes ago, Rankin5150 said:

I feel NWS-GSP worded this spot on: 

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 230 PM Monday: No major changes to the overall forecast from
the 12z guidance. If anything, they continue to trend a little
slower/delayed on the onset of precip, and also a little heavier in
QPF. The 12z ECMWF has come in more northerly/inland with the sfc
low track, and results in warmer thicknesses across the FA thru the
event. This allows a stronger warm nose, and perhaps, more of a
mixed bag of p-types, versus more ra/sn that previous runs
suggested. I opted to blend a little 12z ECMWF into the partial
thickness p-type nomogram tool for this forecast. Still get a lot of
snow in the mountains and the I-40 corridor with this solution, but
if the new ECMWF trend holds, these values will likely be a lot
lower, due to the sleet/frza mixing in. With all that said, it still
looks like a significant winter storm on tap for most of the
mountains and adjacent foothills in NC, while the Piedmont south of
I-40 is highly uncertain. Temps will start out below normal Friday,
as a reinforcing cold front pushes thru. Then classic cold air
damming sets up Friday night thru Sunday, as a strong sfc high
builds in across the Ohio Valley to the Mid-Atlantic. The heaviest
precip looks to be mainly Saturday night into early Sunday, but that
time may change slightly as we get closer to the event. Temps will
be tricky with the CAD. I stuck close to WPC, but these may be too
warm within the heart of the CAD wedge.

 

At this long lead, I wonder why the NWS doesn't lean more heavily on ensembles.  They seem to base their forecast on guidance from operational models in their discussion. 

[BullCityWx]

EPS Mean for Chapel Hill went from 2.75 to almost 5". Burlington went from just over 3" to half a foot. Lincolnton went from 3.5 to 7. You get the picture. 

[mackerel_sky]

1 minute ago, Queencitywx said:

EPS Mean for Chapel Hill went from 2.75 to almost 5". Burlington went from just over 3" to half a foot. Lincolnton went from 3.5 to 7. You get the picture. 

Like Burrell said, we still have a 6” mean @ GSP!!!!

[strongwxnc]

EPS Mean for Chapel Hill went from 2.75 to almost 5". Burlington went from just over 3" to half a foot. Lincolnton went from 3.5 to 7. You get the picture. 

Got it! Increase as you move west sort of


.

[lilj4425]

4 minutes ago, mackerel_sky said:

Like Burrell said, we still have a 6” mean @ GSP!!!!

That’s it?  What happened to our 20 inches? 

[rduwx]

1 minute ago, lilj4425 said:

That’s it?  What happened to our 20 inches? 

That thing in your avatar showed up!

[No snow for you]

2 minutes ago, lilj4425 said:

That’s it?  What happened to our 20 inches? 

I thought it was 30 inches. Glad I cashed out. I have so much fantasy snow this year banked already. One day I’ll cash in for real snow. 

[tramadoc]

I’ll take my cold rain and wait for January.


.

[mackerel_sky]

3 minutes ago, lilj4425 said:

That’s it?  What happened to our 20 inches? 

30 was an op run. Trust me, 6” mean is almost as impressive 

[Orangeburgwx]

I know it is the NAM... BUT...

https://www.tropicaltidbits.com/analysis/models/?model=namconus&region=us&pkg=T850&runtime=2018120318&fh=84

[Buddy1987]

7 minutes ago, Orangeburgwx said:

I know it is the NAM... BUT...

https://www.tropicaltidbits.com/analysis/models/?model=namconus&region=us&pkg=T850&runtime=2018120318&fh=84

I understand it’s the nam as well but there are some things you can look at with the nam to give you an idea of what it’s doing vs some of the other models. Most know the nam always tends to over amp things. It’ll be telling if the nam is over amped or is the southern outlier and will give a better insight as to what this beast is going to do.