Area Forecast Discussion
Issued by NWS Nashville, TN
FXUS64 KOHX 212333
Area Forecast Discussion
National Weather Service Nashville TN
533 PM CST Sat Jan 21 2017
FOR 00Z AVIATION DISCUSSION.
Rain moved off the Cumberland Plateau around noon today, with
decreasing clouds thereafter. Sunshine allowed temperatures to
rise into the 60s, and by 2 pm, the mercury was pushing 70 degrees
at the Nashville airport. Not bad, for the middle of January,
that`s for sure.
A warm front is still expected to lift northward tonight and
early Sunday, bringing along a band of showers and thunderstorms.
A few of those storms could be severe with large hail and gusty
winds. Forecast wet bulb zero values around 7,500 ft indicate a
decent potential for large hail, and with winds in the 925-850mb
layer between 25 and 35 mph, we could be seeing some brief strong
wind gusts as well.
The likelihood for thunderstorms will continue through the day on
Sunday, as an upper low moves from southern Arkansas to northern
Alabama, and a surface low tracks slowly eastward along quasi-
stationary front over southern Kentucky. Can`t rule out a few
strong thunderstorms, with hail and gusty winds, firing up again
on Sunday as atmosphere becomes more thoroughly saturated and our
unstable layer deepens.
Showers remain likely over most of our CWA Sunday night, then
taper off from the west on Monday and Monday night, as slow-
moving upper low finally pushes across Virginia and takes band of
backside moisture with it. Winds start to kick up out of the
northwest Sunday night and Monday as a cold front sweeps through,
with wind gusts to 25 to 30 mph possible.
By Tuesday morning, cooler air will be filtering in from the
north, with sunrise temperatures forecast to be in the middle and
Tuesday and Tuesday night of next week look to be dry and mild,
with surface flow becoming southerly once again. However, by
Wednesday and Wednesday night a weak frontal system moves in and
brings along an increase in clouds and at least a small chance for
Still looks like a turn toward colder, more seasonable winter
weather, for the latter days of the extended period--Thursday through
Saturday. Upper trough deepens over the eastern United States and
high temperatures drop into the middle 30s to middle 40s.
Relatively high amounts of 1000-850mb moisture come along with the
cooler air, with at least a broken deck of stratocu clouds will
likely occur for much of that period. Weak ripples in the upper
flow will allow for at least a small chance for mixed
precipitation along the Cumberland Plateau Thursday night and
Friday, where lows will be in the upper 20s and highs in the 30s.
00Z TAF DISCUSSION.
Difficult forecast for this TAF period in regards to timing
showers and thunderstorms overnight and again on Sunday. Models
have been slowing down the initial wave a bit, so have VFR
conditions through around 06Z or so. Orientation of the initial
line of showers and storms looks to be almost in line with the
terminals, so timing is currently about the same in each of the
forecasts. Looking like showers and thunderstorms will move into
the area between 06Z-09Z, and current consensus is to have
thunderstorms arrive at the terminals around 09Z. By 11Z-12Z
predominant precip should be showers, and cigs will have dropped
to low MVFR/IFR along with vis. Models are hinting at a break
between precip chances mid morning through the early afternoon, so
cigs may improve to MVFR or even VFR during this time. Kept cigs
mostly low in the forecast with KBNA possibly seeing high MVFR by
15Z. Winds will pick up out of the south to be around 10 knots and
gusting to 15-20 knots for the remainder of the TAF period. During
the early afternoon, showers look to return bringing cigs and vis
back down for the remainder of the afternoon and evening at all