Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 180600 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
200 AM EDT Fri Aug 18 2017

.UPDATE...
Issued at 130 AM EDT FRI AUG 18 2017

Updated the forecast to time the front and its best convection
chances across the CWA through dawn based on the current radar,
trends, and HRRR guidance. Also touched up the T/Td grids per the
latest obs and trends. These have been sent to the NDFD and web
servers.

UPDATE Issued at 1055 PM EDT THU AUG 17 2017

Scattered to numerous showers and thunderstorms will move across
eastern Kentucky overnight. The rain will gradually taper off
through out Friday morning and should be out of the area by early
Friday afternoon. The forecast has been updated to reflect the
latest evolution of the ongoing storms. The overall trend has been
for a slightly faster eastward progression of the current shower
and storm activity, so the forecast was updated to reflect this.

UPDATE Issued at 747 PM EDT THU AUG 17 2017

The forecast is on track for the most part so far this evening.
The model consensus in general is suggesting that ongoing showers
and storms will continue moving eastward, and will eventually
move across eastern Kentucky. There are some differences amongst
the models as to the exact timing and coverage of convection this
evening and tonight, but the inherited forecast is handling the
current evolution of ongoing showers and storms well enough to
warrant not an update at this time. Will need to issue and update
later in the shift, however, to at least remove any outdated
evening wording.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 438 PM EDT THU AUG 17 2017

A rather strong storm system near the upper Great Lakes was
bringing a flow of warm and humid air to the area ahead of a cold
front today. An upper level wave was also approaching from the
west. This has led to scattered showers and thunderstorms. The
most significant area of showers and thunderstorms was over
southern OH and northern KY late this afternoon. Other storms
tailed southwestward int western KY. The most significant winds
aloft were also located to our north, and that is where the
greatest threat of severe weather is. Models suggest that the
precip developing over northwest and western KY will progress
into our area tonight, but be on the decline as it moves through
late tonight. The actual cold frontal passage and change in air
mass is not expected until Friday, and additional showers and
thunderstorms can not be ruled out ahead of the front on Friday,
especially in southeast KY where the front will arrive the latest.
Friday night the entire area should be dry as surface ridging
builds in from the west. The drier air mass should also allow for
somewhat cooler lows.

.LONG TERM...(Saturday through Thursday)
Issued at 343 PM EDT THU AUG 17 2017

The period will begin with the upper level trough axis swinging
across the Ohio Valley on Saturday. After this heights rise and
pattern flattens through Tuesday before another trough digs into
the eastern US to round out the period. The models are in decent
overall agreement upper level wise through the long term period.
This initial trough will bring a small chance of showers and
thunderstorms to the far north Saturday afternoon. Then a break
will come for late Saturday into early Monday. There remains some
question on what will develop for Monday and right now there is
only a small chance of showers and thunderstorms north of the
Mountain Parkway in the afternoon. However, this is really only
showing in one model solution and therefore confidence remains
low. Then the next trough will approach by Tuesday and bring best
chances of showers and thunderstorms by late Tuesday into
Wednesday. This trough will swing east and push a cold front
through the region, with chances lessening through the day on
Thursday. That said, there is some disagreement on how much the
front pushes through in the guidance and this could lead to
changes in the timing and coverage on Thursday. Temperature
through the period will remain near to above average for this time
of year.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 200 AM EDT FRI AUG 18 2017

Small clusters of showers and a few embedded thunderstorms are
pushing deeper into the CWA and will start affecting the other
TAF sites over the next couple of hours continuing through dawn -
similar to what KSYM is seeing currently. Could have some IFR
conditions, mainly from VIS during this time. After 10Z the
showers and storms will taper off west to east into the hours
just before and after sunup today. Some patchy fog will be
possible at the TAF sites as the rain starts to clear up heading
toward 12z but will leave that out for now and cover the visby
limitations with the prevailing showers and VCTS during that
timeframe. Winds, outside of any storm, will be light and
variable through mid morning before picking up from the west at 5
to 10 kts post fropa.

&&

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

$$

UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...DJ
AVIATION...GREIF



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