MRX AFD:
000
FXUS64 KMRX 040917 CCA
AFDMRX
Area Forecast Discussion
National Weather Service Morristown TN
350 AM EST Wed Jan 4 2017
.SHORT TERM...(Today and Tonight)...
Cold front continues to push east through the forecast area
early this morning. Rain showers will quickly taper off this
morning and cloud cover will become scattered as cooler, drier air
moves in behind the front. With the cooler air moving in, afternoon
temperatures will be steady or slowly falling. Cloud cover will
increase from the west again tonight, ahead of our next weather
system. With the colder airmass firmly in place, lows will dip
into the 20s across the area.
.LONG TERM...(Thursday through Wednesday)...
Forecast confidence is growing as models continue to come into
alignment over the upcoming snow event late Thursday through Friday.
Although there are still some discrepancies between accumulation
amounts, timing and areal extent of the frozen pcpn looks to be
increasing in consensus among the models.
Most of Thursday should be dry area wide as cold air pushes in.
Temperatures will struggle to climb into the middle 30s during the
day over SW Virginia and northern portions of the Cumberland
Plateau. By afternoon, the leading edge of the arctic airmass pushes
into northern areas as shortwave trough passes along the TN-KY-VA
border. As that passes larger scale trough axis begins to push into
the area early Friday. Result is increasing clouds with pcpn to
develop by late afternoon. With a very dry airmass at the surface,
expect much of the pcpn to start and stay as snow, even though
initial sfc temps may be above freezing. Biggest disparity in
guidance is on amounts, particularly over SW VA. However, all
solutions seems to agree that there will be more moisture available
from Thursday night through Friday to see snow totals of 2-3 in SW
VA. Expect highest elevations of SW VA to see up to 3 inches of snow
while the rest of that area gets around 2 inches over the course of
the 30 hour event.
For Saturday, models are in general agreement on the track of
developing Gulf low expected to move east across the northern Gulf
coast then NE thereafter. ECMWF has the more northern low track and
therefore the greater pcpn amounts in our SW NC counties. GFS soln
is much further south tracking across central Florida before turning
up the coast, and that solution is much drier for our area. Tended
to lean a little more toward the ECMWF solution for now as there are
enough GFS Ensemble members keeping the system further north hinting
at a possible solution which lies closer to the ECMWF at this time.
Therefore keeping chance POPS over the eastern half of the area
early Saturday before shifting chance POPS to just mountains of east
TN and SW NC by Saturday afternoon.
Beyond Saturday, good model agreement on cold and dry weather
through Tuesday with gradual warming ahead of the next sensible
weather maker approaching the area on Wednesday.