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Wintry Jan 15-16 Winter Storm Discussion & Obs

iGRXY said:
NAM has a ton of mixing issues in WNC and I am not really buying that yet.
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Looks Canadian’ish and I’m starting to buy it. Stacking does not occur until north of the Carolinas, while H5 is maturing 850 takes off late, heaviest snow totals will be NW VA, western MD and parts of PA. If I were in the mountains I would want to be above 4000 feet.
 
Sunday...Confidence high that the predominate precipitation
type across the region will be freezing rain...with the most
icing during the morning. The greatest icing impacts are
expected during the morning...

The forecast problem remains how cold the near surface layer
will be. With strong upper level convergence over the Delmarva
region and offshore, expect the strong pressure ridge (Modified
Arctic air mass ) to build southwest across the western
Carolinas. This will set up a rather strong cold air damming
wedge. Prefer the colder Nam and ECMWF models over the GFS and
NBM Mos guidance for surface temperatures. If the wedge is a
little stronger, the significant icing may spread a little
further south. Will continue to monitor model trends. During
Sunday morning the region will be under a favorable upper level
jet structure ahead of the approaching cyclone. Strong upper
level divergence and very strong warm advection/isentropic lift
over the cold dome aided by low level 60kt to possibly 70kt low
level east/southeast jet may result in some heavy rain with
precipitable water > 150-175 percent of normal. With a deepening
warm nose aloft and surface temperatures near or below freezing
across the central and especially northern Midlands, the
precipitation will be mainly freezing rain. Significant icing
expected across the northern Midlands 0.25-0.35 in., and 0.10 in
the CAE metro area. In the southern Midlands and CSRA, expect
mainly rain but again if the cold surface layer is a few degrees
colder, some freezing rain may develop in those areas. Will
have to watch model trends. Some snow/sleet still possibly
mainly during the onset before the warm nose deepens but any
accumulations should be minimal. Another issue is the potential
for gusty winds 20 to 30 mph through early afternoon. These
winds could bring down a few trees due to icing.

They like the NAM and Euro better than the GFS for this and hint the major icing could occur farther south in their CWA. This is from CAE by the way.
 
iGRXY said:
NAM has a ton of mixing issues in WNC and I am not really buying that yet.
Click to expand...
Why not? It usually nails this stuff. I'd definitely be worried if I lived there and started seeing this from the NAM. Don't doubt the warm nose, when the NAM gets hold if it.
 
iGRXY said:
Lat
Latest HREF. Only goes out to 12pm on Sunday so more would be added to this.
View attachment 105591
Click to expand...

Interesting to see that band of 4-8 inches east of Atlanta....likely where you're getting dynamic cooling through very intense rates of precip.
 
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