Area Forecast Discussion
Issued by NWS Jackson, KY

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749
FXUS63 KJKL 172019
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
319 PM EST Tue Jan 17 2017

.SHORT TERM...(This evening through Wednesday night)
Issued at 315 PM EST TUE JAN 17 2017

As of mid afternoon, an upper level ridge extended from the
Caribbean and Eastern Gulf of Mexico the north to off the Eastern
Seaboard. Meanwhile, a general area of troughing extended from
Ontario southwest to the Mid MS Valley Region and then southwest
and then south into the Four Corners Region and Northwestern
Mexico. Within this trough, a lead shortwave in southwest flow was
currently moving across the Lower OH Valley Region with a more
significant shortwave trough moving across the MS Valley Region
and nearing the Great Lakes and Lower OH Valley region. Another
upper level low was currently centered over the Southern Rockies
and Norther Mexico. At the surface, low pressure was centered over
the Great Lakes region with the trailing cold front nearing
Eastern KY.

This evening and tonight, the mid level shortwave trough should
progress across the Great Lakes and OH valley area with the axis
of this trough nearing the WV and VA borders by around dawn. The
cold front meanwhile should move into VA this evening. Scattered
to possibly numerous showers will remain possible until the cold
front moves through. Sfc high pressure will begin building into
the area. However, some low level moisture will persist even
behind the cold front and with the shortwave trough axis yet to
cross the area clouds, and isolated to scattered showers or light
drizzle will be possible as the low level flow becomes more
upslope. Behind the front some stratus build down fog will also be
possible. The moisture depth is a bit in question so confidence
in timing or extent of any drizzle is not all that high.

The shortwave trough axis should depart during the morning hours,
and with this so should the threat for any isolated showers or
drizzle. Any stratus build down fog should also diminish. The
upper level ridge axis should approach tomorrow afternoon with
rising heights in the afternoon and evening. However, the ridge
axis will be shifting east of the area Wednesday night. At the
same time, the upper level low will have meandered into the
Central and Southern Plains. Low pressure and an associated warm
front at the surface will begin to approach late and moisture and
isentropic lift will increase across the OH and TN Valley late. An
increase in high clouds is expected late and mid clouds may move
into the Lake Cumberland Region. However, the threat for showers
should hold off until sometime on Thursday. This should allow some
valley locations to experience lows in the low to mid 30s on
Wednesday night, which would be warmer than average for late
January but colder than the past several mornings outside of the
northern counties. Valley fog should also develop, but the extent
is uncertain due to the increase in clouds late.

.LONG TERM...(Thursday through Tuesday)
Issued at 258 PM EST TUE JAN 17 2017

Good model agreement continues into the upcoming weekend. An
active pattern will continue into early next week with several
rounds of showers expected. The added rainfall, combined with
rivers already running high could lead to some high water issues
as we head into early next week. However, confidence on actual
amounts remains low, so will continue to leave out any flooding
concerns into next week. The first round of rain will move in on
Thursday and Thursday night as a shortwave trough pushes
northeast across the region. Good forcing and lift will yield
widespread showers. As the trough exits north on Friday,
conditions will temporarily dry out, especially by Friday
afternoon. Looks like dry weather should last through Saturday,
although models are showing some support for a few widely isolated
showers on Saturday. Moisture is fairly limited and lack of any
significant forcing will keep the chance of rain out of
the forecast for now. If a shower were to pop up, best shot would
be somewhere across central Kentucky. As we head late into
the weekend, chances are increasing of a large cut off low
developing across the deep south, then slowly pinwheeling up the
spine of the Appalachians. This slow moving system could bring an
extended period of rainfall to the area late Saturday night
through Monday night. Depending on the exact track of this system
will determine exactly how much rain we receive. If southeast
downsloping flow prevails through much of the time, it would eat
away at potential rainfall. For now, going to go high on the rain
chances through this period with more of the uncertainty falling
on actual amounts. It certainly looks like it will be a mild and
damp period which has been the theme lately. It looks like a
brief shot of more normal temperatures for January will drop in
by Tuesday, but again this may just be a quick shot before we
start to warm again. Right now, no threat of any wintry weather
for eastern Kentucky through Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 115 PM EST TUE JAN 17 2017

MVFR is currently observed across the area with some IFR locally
in showers near the VA border. MVFR and possibly brief periods of
VFR in breaks in the clouds should prevail through the 21Z to 3Z
period in norther section with showers possible. Shower and
perhaps a stray thunderstorm near JKL, SME, and LOZ are also
possible during this period. Some IFR will also be possible during
that time near the TN and VA borders. Otherwise, low level
moisture should return from the north and west behind the front
and MVFR or IFR expected to return and generally persist through
the end of the period. Some stratus build down fog and mist will
also be possible 3Z to 15Z especially on ridges. Southwest winds
will be gusty initially sustained generally 10 to 15 kts, with
gusts up to 25 KT or so. These should diminish and become more
west during the 21Z to 0Z period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...JP
LONG TERM...KAS
AVIATION...JP



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