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2016 Mountains & Foothills Fall & Winter Thread

nchighcountrywx

By nchighcountrywx,
in Southeastern States

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FlatLander48

FlatLander48

Posted
Posted
26 minutes ago, BlueRidgeFolklore said:

Nelson said to watch this system coming across Tennessee. It looks good. It also already looks to be building a little more NW through Louisiana and Arkansas, up towards that system in Tennessee. 

 

Screenshot_20170106-072306.jpg

According to future cast that band is going to weaken a lot before it gets here, but we'll see.

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FlatLander48

FlatLander48

Posted
Posted
4 minutes ago, Met1985 said:

Well it will be another day of watching the models especially the hi res models but it's game day. For me whatever we get is a plus. This season has sucked big time so I'll try not to be picky. Good luck to all.

We've been following this storm for almost two weeks and it's finally here! Let's enjoy it while we can cause we don't know when our next one will be.

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NavarreDon

NavarreDon

Posted
Posted

Morning fellas!, I'm rooting for you all to cash. In the meantime enjoy one of the best disco's ever by a met.......of course it's GSP. 


.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM EST Friday: No real changes to the immediate near term
(is that redundant?). Temperatures are running pretty close to
observed. Biggest change has been to reduce pops just slightly as
returns haven`t quite moved into the area. Seeing some webcams in
the mountains with some light snow so even without returns left some
light pops in.

Otherwise, synoptic setup is no surprise, with broad trough
dominating the eastern half of the country and a sharp shortwave
diving out of the Rockies this morning and progged to push across
the Southern Plains and Southeast through the day. Moisture
attendant with the shortwave plus additional moisture that advects
up from the Gulf will begin to overspread the area today as
isentropic upglide increases. Synoptic lift in the form of CVA
increases ahead of the vort max, plus lift from the right entrance
region of the upper jet (looking at upwards of 150kt at 300mb over
the central Appalachians). Weak surface CAA will continue today but
will really gear up as surface cyclogenesis is induced along the
Gulf this afternoon and lifts up the coast in a Miller A pattern,
and the gradient will really pick up overnight tonight with
additional CAA. So for highs today under widespread cloud cover
aloft should see well below normal temperatures with really not much
of a diurnal range from this morning, with the colder air filtering
in after midnight.

So we go to the typical cold air vs. moisture argument - which one
arrives first and which dominates? For that we need to pick a model,
and the consensus is leaning slightly toward the GFS and ECMWF as
WPC seems to indicate the NAM has the surface low a little farther
north/northeast. Because of this, the NAM has slightly warmer
temperatures aloft at 850mb and brings occasional >0C to the
profiles along the I-85 corridor (to the north it`s all below
freezing so no p-type questions), but for the most part is similar
to GFS and other profiles with a deep near-freezing isothermal
layer, leading to lower snow ratios and a wetter snow (all the
better for making snowballs). So what it looks like is that rain
will begin this afternoon across the Piedmont (snow in the mountains
and foothills) but mix with and change over to snow as the cold air
arrives after 00z. As is typical, would not be surprised to see some
sleet mix in at onset (which may mess with snow amounts), but
generally think p-type will be all snow shortly after midnight.
Moisture begins exiting from the northwest toward the end of the
period (12z).

Oh, but we`re not done. Looking at QPF totals, looks like low-level
frontogenetical forcing to the northwest of the surface low along
with very low (negative) saturated geostrophic potential vorticity
above the frontogenesis (conditional symmetric instability) all
point to the likelihood of mesoscale bands setting up. At this
juncture it`s impossible to know exactly where this might occur, but
most of the guidance seems to indicate it will be somewhere along
the southern edge of our forecast area but possibly anywhere within
a few dozen miles of I-85. SREF plumes definitely show the variety
and large spread in snow amounts, with for example the 03z run
having one member almost 20" here at GSP and some with as little as
1", averaging to just over 6" (the spread is worse at CLT, for the
record). The anomalously high members are obviously skewing the mean
so taken together with the GEFS plumes (which have much more
reasonable spread) we end up generally where we started, pretty
close to WPC storm total snowfall. As a result, have bumped up
amounts a tad with over 6" at CLT and just under 6" here at GSP, and
with a wide range across the mountains due to terrain effects. On
the other end of the mesoscale banding, however, is if the warmer
850mb temperatures come to fruition and we end up with more sleet at
onset, or if the cold air takes longer to advect in and the rain
lingers a little longer than anticipated, we could have slightly
lower amounts. Hence the bust potential. In the end, still solidly
warning criteria everywhere, and the few places that might not make
it will be close enough. The good news is that we are talking
Saturday morning so except for those industries that are 24/7 (such
as yours truly) impacts will certainly be less than what they might
otherwise be on a weekday. The bad news is that as you can see below
in the short term and extended discussions, there won`t be much
recovery through the weekend.

In the meantime (assuming you ever finish reading this slightly
longer-than-normal AFD), and we cannot stress this enough -
PREPARATIONS FOR THIS WINTER STORM NEED TO BE RUSHED TO COMPLETION
*TODAY* (yes, that was in all caps for a reason). Once we`re talking
6" of snow (or more, depending on which ensemble member you choose),
we really increase the probability of power outages from snow
bringing down limbs. We expect very cold temperatures behind this
system so residents of the western Carolinas and northeast Georgia
need to take winter storm preparation seriously. Once that`s done,
stay safe but enjoy the snow!
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NavarreDon

NavarreDon

Posted
Posted 
A developing low pressure system in the northern Gulf of Mexico is
expected to bring a range of precipitation types from the lower
Mississippi valley to the southern Mid-Atlantic region today into
Saturday. A cold air mass in place will allow for a snow to fall today
from portions of the southern plains and lower Mississippi valley east to
the foothills of the southern Appalachians and the Piedmont of the
Carolinas. Tonight, snow is expected to spread north across portions of
the southern Mid-Atlantic region. Heavy snow is possible for some areas.
Sleet or freezing rain is also possible in the transition zone from snow
to rain across portions of the Southeast. Please refer to products issued
by local NWS forecast offices for details specific to your area. As this
low pressure system moves away from the East Coast into the north Atlantic
by Saturday afternoon, cold air is expected to linger across areas from
the southern plains to the Mid-Atlantic, with afternoon high temperatures
10 to 20 degrees below average.

Day 1 image not available

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