Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 072018

National Weather Service Jackson KY
318 PM EST Wed Dec 7 2016

.SHORT TERM...(This evening through Thursday night)
Issued at 245 PM EST WED DEC 7 2016

Upper low north of Lake Superior will continue to move east
across Ontario, with trailing upper trough axis over the plains
shifting east. At the surface, cold high pressure will continue
to nose east into the Ohio Valley. The upper troughing and surface
ridging results in colder air working its way into KY, with lows
tonight mostly in the upper 20s and highs on Thursday from the mid
30s to around 40, about 10 degrees cooler than today. Even with
the trough shifting east, and the surge of colder air, there will
be very little moisture available. The outside chance for a few
flurries remains in the forecast for late tonight and early

Thursday night will be even colder than tonight, with lows in the
upper teens to lower 20s. Some clouds will affect the northeastern
part of the forecast area as a short wave trough swings by to our
northeast. The clouds are not expected until late in the night, so
temperatures should still fall off quickly in the northeast
Thursday evening. If the clouds move in earlier than expected
overnight lows would be warmer than current forecast in the
northeast. There is still an outside chance for a few flurries in
the northeastern part of the forecast area late Thursday night.

.LONG TERM...(Friday through Wednesday)
Issued at 318 PM EST WED DEC 7 2016

Models struggle right out the gate trying to capture strength and
timing of progressive features in a broad mean trough, or nearly
zonal flow pattern across the CONUS. First main shortwave
disturbance to deal with will track quickly out of the Pacific NW
and through the Plains, bearing down on the Ohio Valley region by
sometime Sunday, or possibly Sunday night into Monday. The 12Z
ECMWF is roughly 18 to 24 hours slower than the 12Z GFS with this
first system. The 12Z Canadian keeps the middle ground, showing
similar timing to the ECMWF while at the same time finding a way
to support the GFS by picking up on some energy into the area a
bit earlier on Sunday proper. The second main shortwave system to
affect our area, similar to the first with respect to its track
will drop into the region at the end of the extended window. The
ECMWF is considerably weaker with this shortwave than the GFS but
is similar in timing.

For sensible weather, temperatures remain seasonably cold to below
normal through the entire period. Models are still having difficulty
with the details of Sunday`s system and forecaster confidence is
low. This system appears to be trending slower overall. As such that
may provide enough time for the column to warm so that the bulk of
precipitation falls as rain. However, we still can not rule out a
little wintry mix at the onset of precipitation. For our second
system at the very end of the extended window, there is reasonable
agreement that this next system will be colder. Still way too far
out to say for sure, but this system may present our first real
chance at some accumulating snowfall. Time will tell.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)

An 30-50 mile wide band of broken to overcast cloud with MVFR
ceilings continues to hold fast across southeast Kentucky from
Lake Cumberland to Pike County. This should begin to lift and mix
out by late afternoon, but MVFR ceilings should persist at LOZ
and SJS through mid afternoon. SME should even see some MVFR
ceilings for a short time. VFR conditions will prevail from
tonight through Thursday. Winds will generally be light and
variable through tonight, but become westerly Thursday morning at
5 to 10 knots.





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