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Wintry More SE Snow ? (1/16-1/18)

Its also the 84 Nam, it will change for better or worse.
 
accu35 said:
Its also the 84 Nam, it will change for better or worse.
Click to expand...

I would really like to see it slowed down by 24 hours, tbh. There is some extra energy that could get involved coming out of the West (in various angles) that could get involved into the base that would help us all out. Ugh! I have developed a serious problem with way-overanalyzing 500mb vorticity maps.

+ shawn is drunk + hes not getting along with girl + needs snow so he can calm down. :(
 
me likey, me takey:
snku_acc.us_ov.png
 
06z GFS still sucks, btw. It's even worse on surface maps for everyone.

UKMET + Euro are still intriguing. EPS slightly improved, even.

I still like to see 2-3 inch means on the ensembles to treat anything seriously. Example, my area got a bigger ice/sleet even in Feb of 2014. The ensembles, especially the GEFS had 6-8 inches of "snow" here. Of course we lucked out with sleet, while those to my South ended up with a hellacious ice storm. The point is, the ensembles were all honking the horn at a major Wintry event.

Seeing an ensemble mean of a trace to 1 inch, sucks and shows the signal is weak, imo. I feel like it just implies the chance at a light event, at best. At least in my back yard, it never works out and we end up with a flizzard at best. Maybe a light dusting on cars. Maybe some light freezing rain.

If the ensemble means aren't showing 2-3+ inches of snow accumulation then temps are marginal at best or precipitation amounts are low. There's no way around it. These dustings and fringe events you see on the mean just say "hi, there are one or two members of my ensemble suite that are way too excited". "Now, me as a mean, must calculate them in my final product, even though, they are likely wrong with no support from the other members."
 
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For those in the Midlands of SC, we had a slight ouptick on the Euro ensembles. Also, slightly skewing the mean, I am sure.. i circled the one problem member in green:

KCAE_2018011400_eps_snow_240.png


As you can see, at the bottom with the green and blue lines, the mean is skewed (compare the hours where the circled member starts showing out 96-108 or so) versus the operational.

I would want to at least see 25% of the members, like that one rogue member, to start taking the idea seriously. Don't get me wrong, maybe that member is correct and others will follow. In all likelihood, with the current setup and time of year, I'd argue against that one member beating all the other members along with operational. In fact, if I am not mistaken, there was a member around the same area (possibly the same one) a couple days ago, printing out 6 inches + (purple), which greatly skewed the mean for KCAE.
 
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It looks like many models have the best precip north of I-40 in NC at this point. Here's the 06z Canadian:
gfs_asnow_seus_15.png
 
Don’t know how to post it, but another great disco from Grantham at BMX regarding our snow... can someone post it please.
 
From BMX excellent writeup also mentioning low level trough and PWAT's like I was mentioning last night

Models are now exhibiting some interesting trends with an Arctic
vortex moving southward over the Northern CONUS on Tuesday. All
guidance is suggesting a slower progression and more of the trough
axis digging farther west across the Plains. Though model QPF is
still not very impressive as the Arctic front moves through our
area, the slower and more amplified nature of the upper-level
trough may yield a greater window of opportunity for moisture
return. Also, thermal gradients are slowly tightening with each
model run, and there is now more evidence of slight warm advection
in the 850-500mb layer. An 850mb trough appears more pronounced
and appears to strengthen over the forecast area as indicated by
the ECMWF. The NAM and ECMWF also show a late surge of enhanced
PWATS across the southern half of the area Tuesday night into
Wednesday morning. If there is enough lift remaining as this
moisture meets with the Arctic front, snow could become enhanced.
All of these factors are suggest that we are teetering on the edge
of potentially significant impacts, especially with temperatures
well below freezing. Model parameterization as it pertains to QPF
output may not be handling the situation very well. In fact, the
GFS shows fully saturated profiles in locations that receive no
QPF. My hunch is that QPF will trend upward as we approach the
event as models begin to resolve crucial features, but this
requires the aforementioned trends to continue with future models
runs. For now we are showing snowfall amounts up to 1/2 inch
north and west of I-59, tapering to trace amounts farther south.
Temperatures in the 20s should yield snow ratios of 15:1, and a
slight increase in QPF could yield considerably more snowfall.

http://forecast.weather.gov/product.php?site=NWS&product=AFD&issuedby=BMX
 
Yep, looks somewhat consistent for the Carolinas now. North Carolina will take the win and South Carolina will take the L.
 
Shawn said:
For those in the Midlands of SC, we had a slight ouptick on the Euro ensembles. Also, slightly skewing the mean, I am sure.. i circled the one problem member in green:

View attachment 2843


As you can see, at the bottom with the green and blue lines, the mean is skewed (compare the hours where the circled member starts showing out 96-108 or so) versus the operational.

I would want to at least see 25% of the members, like that one rogue member, to start taking the idea seriously. Don't get me wrong, maybe that member is correct and others will follow. In all likelihood, with the current setup and time of year, I'd argue against that one member beating all the other members along with operational. In fact, if I am not mistaken, there was a member around the same area (possibly the same one) a couple days ago, printing out 6 inches + (purple), which greatly skewed the mean for KCAE.
Click to expand...

Ensembles weren't too hot for my area back in Dec and I ended up with an inch of snow.
 
Xtreme Weather said:
From BMX excellent writeup also mentioning low level trough and PWAT's like I was mentioning last night

Models are now exhibiting some interesting trends with an Arctic
vortex moving southward over the Northern CONUS on Tuesday. All
guidance is suggesting a slower progression and more of the trough
axis digging farther west across the Plains. Though model QPF is
still not very impressive as the Arctic front moves through our
area, the slower and more amplified nature of the upper-level
trough may yield a greater window of opportunity for moisture
return. Also, thermal gradients are slowly tightening with each
model run, and there is now more evidence of slight warm advection
in the 850-500mb layer. An 850mb trough appears more pronounced
and appears to strengthen over the forecast area as indicated by
the ECMWF. The NAM and ECMWF also show a late surge of enhanced
PWATS across the southern half of the area Tuesday night into
Wednesday morning. If there is enough lift remaining as this
moisture meets with the Arctic front, snow could become enhanced.
All of these factors are suggest that we are teetering on the edge
of potentially significant impacts, especially with temperatures
well below freezing. Model parameterization as it pertains to QPF
output may not be handling the situation very well. In fact, the
GFS shows fully saturated profiles in locations that receive no
QPF. My hunch is that QPF will trend upward as we approach the
event as models begin to resolve crucial features, but this
requires the aforementioned trends to continue with future models
runs. For now we are showing snowfall amounts up to 1/2 inch
north and west of I-59, tapering to trace amounts farther south.
Temperatures in the 20s should yield snow ratios of 15:1, and a
slight increase in QPF could yield considerably more snowfall.

http://forecast.weather.gov/product.php?site=NWS&product=AFD&issuedby=BMX
Click to expand...
Matt's been writing some great ones this week

Sent from my SM-J320VPP using Tapatalk
 
Love the trends overnight, especially with the Euro jumping aboard. 3 to 4 inches out if this would be great. Looks like all the models are showing snow here, too.
 
Storm5 said:
Yeah the drier trend look a to be over . Also and most importantly a slower trough progression seems to be the new trend. If correct, that is huge and exactly what we want
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Yep, slower means that it goes neutral and negative west of previous runs, and moisture gets flung further inland. It also means that the line of snow doesn't die as soon as older runs. Let's get a solid line that becomes a good storm, and let's get AR to NC and SC in on snow.
 
Here is FFC discussion this morning.
The long term period concerns will be dominated by the arrival of
yet another arctic airmass by midweek. Along and just behind the
leading edge of this feature, models continue to indicate a
saturated 1000mb-500mb column. Although some questions remain on
timing with this feature, by and large the bigger question
surrounds how much lift can be generated within this column.

Although mid level trough is impressive, there continues to be no
real individual shortwaves to enhance lift and instead will need
to rely in mainly baroclinic processes to generate precip.
Although overall sounding profiles as it moves into North GA are
more moist, just think with the absence of good forcing, adequate
QPF is going to be difficult to come by. Given these factors,
latest grids came out close to previous version with mid range
chance for far north, low end as it approaches the northern metro
and slight chance for points southward.

Precip is lagging a bit more in this run allowing more of the
cold air to move in. The result is less of a rain/snow mix at the
onset and going more quickly to an all light snow event. Still
outside the time period of amounts but still looks a tenth of an
inch or less QPF at best which would yield a dusting up to an inch
in the highest elevations. Will need to monitor the Euro trends
closely with subsequent runs as it did come in with more available
moisture this run.

Otherwise, continued very cold early with a warming trend late in
the period. Shortwave moves through Friday with possible precip
concerns with it as well although kept just rain for now.

Deese
 
Storm5 said:
Yeah the drier trend looks to be over . Also and most importantly a slower trough progression seems to be the new trend. If correct, that is huge and exactly what we want
Click to expand...
Agreed and a light to moderate widespread event would be great. Too bad Rah NWS don't think the drier trends are over... they say both EC and GFS are trending drier, rain, rain/snow mix to snow, blah blah blah. Just once in their AFD,, not forecast just discussion I'd like to see them at least acknowledge the potential especially when some models, ie: last nights Euro were showing an increase (in all fairness sometimes depending on who is writing they will). I get conservative in forecast but you'd think the discussion would actually discuss all possibilities if only briefly...
 
metwannabe said:
Agreed and a light to moderate widespread event would be great. Too bad Rah NWS don't think the drier trends are over... they say both EC and GFS are trending drier, rain, rain/snow mix to snow, blah blah blah. Just once in their AFD,, not forecast just discussion I'd like to see them at least acknowledge the potential especially when some models, ie: last nights Euro were showing an increase (in all fairness sometimes depending on who is writing they will). I get conservative in forecast but you'd think the discussion would actually discuss all possibilities if only briefly...
Click to expand...
If they would only brick write an AFD, just once . It would be epic

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Storm5 said:
If they would only brick write an AFD, just once . It would be epic

Sent from my SM-J320VPP using Tapatalk
Click to expand...
Now your taking it too far Lol...
Anyway to Shane's point above slightly shifting trough westward
5af130f8f1a1f81a20c2a8e58ea69f21.gif


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This NAM run could smoke many of us AL folks if it doesn’t dry up.
 
ForsythSnow said:
It's showing more moisture since there is a better tilt in the upper levels, which is allowing a better moisture flow.
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Much better moisture flow, 700mb level getting and it's already showing 4" in parts of Tn at this point too
700rh.us_se.png
 
Wow, through 57, the snow line hasn’t moved much. Looks like it could be a slow mover. Just hope it holds together
 
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