Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 191831 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
231 PM EDT Tue Sep 19 2017

.UPDATE...
Issued at 215 PM EDT TUE SEP 19 2017

Updated the forecast to fine tune the PoPs and wx grids through
the rest of the afternoon based on radar trends and latest
guidance. Did also tweak temperatures and dewpoints per the
current obs and trends. These have been sent to the NDFD and web
servers.

UPDATE Issued at 1020 AM EDT TUE SEP 19 2017

13z sfc analysis shows a weak pressure pattern through the area as
an upper level disturbance rolls toward the area. This is
prompting an area of showers and embedded isolated thunderstorms
over central Kentucky. This area is progged to weaken by the CAMS
but still move into the western parts of the JKL CWA this
afternoon. Have retooled the PoP and sky cover grids through the
rest of the day with the latest guidance and trends incorporated.
Any fog has dissipated so will also update the text products to
drop its mention. Temperatures are rebounding into the upper 60s
and lower 70s while dewpoints are still up there in the low to mid
60s and winds are light and variable. Did update the T and Td
grids per the latest obs and trends. These have been sent to the
NDFD and web servers.

UPDATE Issued at 623 AM EDT TUE SEP 19 2017

Showers and storm coverage in western Kentucky has really
increased this morning as expected. Hi-res models continue to
support this activity dying off as it slowly advances into central
than eastern Kentucky by midday or early afternoon. Thus, current
weather and pop grids remain on track. Better threat appears to be
shifting into the evening hours centered around 00z in the west.
This activity will then die off as it tries to shift east after
00z. Plan to freshen up grids this morning.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 307 AM EDT TUE SEP 19 2017

Valley fog is once again in place early this morning, but has not
been quite as extensive as in past nights. In fact some of the
more typical foggy spots haven`t reported any dense fog yet,
unlike the past few nights. The fog will likely dissipate a bit
faster this morning for this reason.

Another mild day is on tap as we should see a good deal of
sunshine again today. A mid level vort max will work east across
the Ohio river valley today, producing scattered to numerous
showers/storms across western, then central Kentucky. The wave
will begin to dampen as it works east into the ridge axis over the
southeastern states. This combined with decreasing instability and
almost no shear will lead to a rapid weakening as this activity
attempts to move into eastern Kentucky. It looks like activity
should start to move into the area after 4 pm this evening. Hard
to gage how far east activity will make it before fading away, but
will carry some isolated showers into the east before going back
to a dry forecast tonight. If we can clear out behind the
weakening showers, we will stand a decent shot for more dense
valley fog tonight as dewpoints will start off a bit higher going
into the overnight period.

The slow moving mid level trough will be slow to exit to the east
on Wednesday and could spark a few showers or storms in the east
or southeast before it moves away from us by mid to late
afternoon. Again lack of shear will keep activity fairly weak, and
may even be hard to see any thunder with such poor storm
organization expected. Going with persistence on highs for
Wednesday as the mild weather will persist for another day.

.LONG TERM...(Wednesday night through Monday)
Issued at 320 AM EDT TUE SEP 19 2017

The models are in good agreement with an amplified long wave
pattern to take shape across the CONUS into the weekend, as
deeper troughing anchors across the West. Meanwhile, a seasonably
strong ridge will develop from the lower Mississippi Valley into
the Ohio Valley. By early next week, the western trough and
western Atlantic tropics will put the squeeze on the ridge,
dampening it as it shifts off to the east and northeast.

For eastern Kentucky, above normal temperatures will continue to
be the main weather highlight through the period. Highs will
average in the low to mid 80s each day. Lows will start out in the
low to mid 60s, before drier air advects in by the second half of
the weekend, allowing for some upper 50s in the valleys. Thursday
looks to be the only day when a few showers may threaten the
area, before the ridge becomes established. After Thursday, it
looks to be mainly dry through early next week, as the ridge
dominates across the region.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 230 PM EDT TUE SEP 19 2017

Showers and a few thunderstorms are crossing the area this
afternoon as a disturbance moves in aloft. While convection will
be rather scattered it is already impacting the JKL and SYM TAF
sites with the SME and LOZ ones skating by at the moment. Have
allowed for some VCTS in the south, but went prevailing at JKL.
SYM and SJS are be more questionable for seeing a direct hit from
a storm so have also gone with VCTS there for a few hours. After
the convection diminishes this evening, skies may clear off
again, leading to another night of likely valley fog. Indications
are that the fog tonight could be a little worse than it was this
morning with dewpoints running a tad higher. Any fog burns off by
14z with VFR conditions returning. Winds, outside of any storm,
will be light and variable through the period.

&&

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

$$

UPDATE...GREIF
SHORT TERM...KAS
LONG TERM...GEOGERIAN
AVIATION...GREIF



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