Area Forecast Discussion
Issued by NWS Jackson, KY-- Highlight Changed Discussion --
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FXUS63 KJKL 182037
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
337 PM EST Wed Jan 18 2017
Issued at 1259 PM EST WED JAN 18 2017
Clearing has occurred over parts of Eastern TN and Southwest VA
and some of this has spread into some of the higher terrain near
the VA and TN borders over much of Harlan County and the Log Mtns
in Bell Co. Meanwhile breaks in the low clouds are occurring
across other portions of the Cumberland Valley Region and the Lake
Cumberland Region as sfc and upper ridging continue to build in.
However, deep enough moisture and an uslope low level component is
still leading to a few patches of drizzle east of JKL that are
diminishing. A gradual mixing out of low clouds should continue
throughout the afternoon and into the evening. The clouds should
linger longest in the central and norther part of the area where
temperatures may average near normal for highs, but locations in
the central to south that receive sun should climb above average.
UPDATE Issued at 1005 AM EST WED JAN 18 2017
Low level moisture remains across the region with weak upslope
flow. Radar indicates drizzle still lingering across the northern
and eastern counties. This moisture should become more shallow by
midday into early afternoon as sfc and upper level ridging build
into the area. However, the it appears that the drizzle should
linger a bit longer than the previous forecast and has been
extended in the weather grids by about 2 hours. Otherwise, no
changes were needed at this time.
UPDATE Issued at 620 AM EST WED JAN 18 2017
Did a quick update to the grids to account for the latest obs and
trends - keeping the patchy drizzle and sprinkles in there for a
couple of more hours. These have been sent to the NDFD and web
.SHORT TERM...(Today through Thursday)
Issued at 355 AM EST WED JAN 18 2017
08z sfc analysis shows a cold front departing to the east while
high pressure builds in from the west. However, plenty of low
level moisture remains in place and, along with the passage of a
compact upper trough to the northeast early this morning, this is
keeping the cigs low and a potential for drizzle or sprinkles in
the forecast through dawn. Temperatures remain mild overnight for
this time of year with readings varying from the low 40s northwest
to the lower 50s in the southeast. Dewpoints are not far off from
the dry bulb temperatures - just a few degrees lower in most
places. Meanwhile, winds are from the northwest to west at 5 to
10 mph with occasional gusts to 15 mph. Patchy fog also is found
through the area early this morning.
The models are in better agreement aloft than last night as they
all depict a sharp trough - with minimal spread - diving into the
Central Appalachians from the northwest early this morning. This
is followed by a quick shot of ridging today and renewed deep
layer southwest flow later tonight and Thursday in the face of a
deep and broad closed low over the High Plains. In this flow, a
lead batch of energy will lift into the Tennessee Valley early
Thursday with more support and height falls arriving by evening.
Given the better model agreement will favor a blend, though with a
strong lean toward the HRRR in the near term.
Sensible weather will feature patches of sprinkles and drizzle
around this morning before a lull for drying sets up later today
and tonight as high pressure passes quickly over the area. The
next system then approaches from the southwest late tonight
pressing into the Cumberland Valley on Thursday. All the while
warm weather continues so that all pcpn will continue to be only
in the form of rain across eastern Kentucky through the short
term and well beyond.
Again started with the CONSShort and ShortBlend for most elements
through the short term portion of the forecast - making only minor
adjustments to the low temps tonight. Also, adjusted PoPs to
spread the next round of pcpn in a bit quicker and slightly more
extensively on Thursday than suggested by the CONSShort.
.LONG TERM...(Friday through Wednesday)
Issued at 337 PM EST WED JAN 18 2017
The extended forecast period begins on Friday with an active and
progressive pattern in place. A short wave will track northeast
through the Midwest and Middle Atlantic states on Friday. The
general progression of this feature seems to push through rather
quickly and the Euro and GFS agree on this. Precip will be brief
as it will exit the area by Friday night. In this active pattern
and on the heels of Fridays system another wave develops in the
lower MS River Valley and tracks northeast into the central
Appalachians by Saturday afternoon bringing another shot of
rainfall to the area. Isentropic ascent with this next feature
will pose the possibility for thunder but being well capped at
onset will hinder this possibility so will leave out of the
forecast for now.
The active pattern continues into the beginning of next week as a
secondary upper low dives into the lower MS Valley and lifts
northeast again through the area late Sunday and into Monday. This
shot of rainfall will appear to be the most out of the series as
the GFS and Euro agree with up to an additional 3 quarters of an
inch QPF expected in far eastern Kentucky by Tuesday. Most of this
rainfall appears to fall in the headwaters of Eastern Kentucky.
Total rainfall for this period looks to be up to 2 inches over a
48 hour period. At this time, its nothing to be too concerned
about with rainfall but will put a mention in the HWO.
Through the extended forecast, the warm trend continues with
temperatures in some days nearly 20 degrees above normal. So, will
not expect any frozen precip through the extended.
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 105 PM EST WED JAN 18 2017
Low clouds leading to MVFR should gradually decrease through the
first 9 to 11 hours of the period as surface and upper ridging
build in. Meanwhile, clouds will begin to increase and lower ahead
of a warm front beginning first in the southwest between 6Z and 9Z
and then shifting to the northeast through the end of the period.
However, VFR is expected with this through the end of the period.
Light winds are expected through the period.