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Wintry Winter Storm Dec 7-10

Just another quick update on FFC's thoughts on later this week.

Extremely amplified upr lvl/longwave pattern across the CONUS will
allow a trough to dig far south across the eastern half of the
country. This will send (potentially) some of the coldest air of
this early winter season across the Southeast/Deep South regions by
the end of the week. Along with this, a low chance for wintry
precipitation (likely in the form of snow) across portions of north
Georgia beginning late Friday... as a series of upr lvl disturbances
drive down the backside of the main upr trough and across the region.
Still several days out, but at this time, should any precip develop,
it appears cold enough to support snow across far north GA,
especially Friday night into early Saturday.

http://forecast.weather.gov/product...FC&product=AFD&format=CI&version=1&glossary=1
 
Even if the moisture doesn't trend NW, North Georgia (all the way into Metro) likely will see flurries/snow showers and cooler than progged temperatures. 700mb to 300mb is absolutely sogged... saturated. Same level as the shortwave energy and most lift is present
 
Cad Wedge NC said:
Actually I was looking at that earlier and thinking how weird it would be to have 850's and 925's both <0C and still have rain at the surface. The only thing I could attribute it to was the southwest flow vs the usual northeast flow. This is a strange set-up and one that would be outside the realm of usual synoptic snowstorms for the southeast. It's still too far out for me to feel comfortable even out here in the foothills.
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It's certainly possible if the surface is warm enough but the 200 hPa deep isothermal layer induced by melting hydrometeors looks non-physical because it's below 0C and the snow aggregates wouldnt have begun melting by then
 
Cad Wedge NC said:
To answer your question, yes I do. Usually the isothermal temp is very close to the melting point. It is strange to have it colder than that for such a deep layer. Come to think about it, I don't believe I have ever seen that.
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Well there's a good reason you haven't on a real sounding because that's next to impossible to get unless you're right at 0C, and even still melting layers are rarely this deep... I suspect there's either something wrong with the model or the sounding plots used to make them. I'm going to reach out to someone to try and see what's going on because this sounding looks bogus
 
bouncycorn said:
Still dangerous, IMO, to say "probably not anything significant outside of the mountains" to the public. While that's often the case, until we can be sure, any flip can cause the effects here to be significant.

In terms of the public, I really like to approach the issue with outlining what COULD happen given the setup, climate, model trends, etc. To the public, "probably not anything significant outside of the mountains" means "flurries here.. nothing more.. no need to be vigilant".

BTW- I'm not attacking you or anything, i'm just saying that when approaching the public it may be misleading to every say that kind of thing when significant impacts are actually on the table as far south as Atlanta, imo. Doesn't mean I think they'll happen, just saying that we cannot discount it.

That's what bothers me about Chandley saying "0% chance of snow in Metro".
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I would absolutely love to see this guy eat some crow. One thing I have learned living here in the southeast ....... never say never. As the old saying goes ... "it ain't over 'til it's over"
 
Cad Wedge NC said:
I would absolutely love to see this guy eat some crow. One thing I have learned living here in the southeast ....... never say never. As the old saying goes ... "it ain't over 'til it's over"
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He's eaten crow more than once. One major one for Atl mets was when they called for flurries and a light dusting 24 hours ahead of snowpocolypse
 
Once again using an area averaged sounding there's still a 200 hPa deep isothermal layer at -1 to -2C on the GFS. Yeah that's not happening either because a) the melting layer should be right on top of the 0C isotherm not -1 to -2C and b) melting layers are rarely this deep unless the precipitation is absolutely ripping, but it's not impossible. Either way this sounding from the GFS is generally bs.
Unknown.png
 
Webberweather53 said:
Well there's a good reason you haven't on a real sounding because that's next to impossible to get unless you're right at 0C, and even still melting layers are rarely this deep... I suspect there's either something wrong with the model or the sounding plots used to make them. I'm going to reach out to someone to try and see what's going on because this sounding looks bogus
Click to expand...
Good catch.... I wasn't even paying that much attention to it. I saw the isothermal sounding and just went on.
 
The latest snow probability map from Peachtree City is showing that some areas of north Georgia have a bit of a chance to get at least a dusting of snow before Thursday...
FFC120317.png
 
Yellow Snow said:
The latest snow probability map from Peachtree City is showing that some areas of north Georgia have a bit of a chance to get at least a dusting of snow before Thursday...
FFC120317.png
Click to expand...
from the clipper, totally different from the "Potential" before hand if the NW trends continues
 
From BMX:

"Much colder and drier conditions are expected as the longwave
trough becomes parked over the Eastern CONUS. Several shortwaves
rotating around the base of the trough should bring reinforcing
shots of cold advection through the weekend. There could be enough
moisture with a clipper on Friday afternoon and evening for a few
rain or snow showers as very cold temperatures aloft move into
the region. Afternoon highs in the 40s/50s and lows in the 20s/30s
are expected during the Wednesday through Sunday period."
 
Either they are seeing something we are not seeing or the dates are wrong.
 
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