Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 190041
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
841 PM EDT Wed Apr 18 2018

.UPDATE...
Issued at 841 PM EDT WED APR 18 2018

Showers and isolated thunderstorms were occurring along a strong
cold front over central KY, moving toward the JKL forecast area
from the northwest. Clouds have been slow to increase ahead of the
front, and have trimmed back sky cover ahead of the cold front
this evening. As far as thunder is concerned, forecast soundings
suggest weakening instability as the front moves southeast, and
trouble breaking a mid level cap, so have continued to hold off on
the inclusion of thunder in our forecast area. In terms of wind,
gusts to advisory criteria are likely to be limited to areas near
and just behind the front, and not affect the region for the
entirety of the current wind advisory period. However, the
advisory will be left in place as-is to cover the window of time
when there is potential for gusts near 40 mph.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 357 PM EDT WED APR 18 2018

The latest surface map features quick-moving low pressure
currently centered across western Indiana, with a trailing cold
front aligned southwest, just west of the Mississippi River.
Aloft, an amplified pattern is dominant across the northern
half of the CONUS, with an upper level low spiraling across
northern Iowa, and a short wave trough rotating down from
southeast Ontario. Eastern Kentucky has been enjoying a nice warm
up today out ahead of the approaching cold front, with current
temperatures exceeding 80 degrees in several places.

Clouds will be on the increase this evening, as the cold front
approaches from the west. Shower activity will develop along the
boundary and should yield likely rainfall across eastern Kentucky,
although QPF will average less than a tenth of an inch. Winds
will be strongest along and behind the front, with gusts still
looking to approach 40 mph in the western half of the area, with
30 to 35 mph in the east.

There will be a lull in the action after midnight from west to
east, with even some partial clearing, before a trough axis
swings through the Ohio and Tennessee valleys by dawn.
Temperatures will turn quite a bit colder behind the front, with
upper 30s expected for lows by early Thursday morning. The passing
trough will bring another influx of low level clouds and perhaps
a few showers across northeastern Kentucky through the morning.
Clouds will hang tough through the day, gradually diminishing from
southwest to northeast in the afternoon. Highs will be some 25 to
30 degrees colder compared to today, with upper 40s to lower 50s
expected.

Skies will clear out Thursday night, as high pressure builds in
from our northwest. Lows will dip to around the 30 degree mark in
the valleys, with areas of frost likely. Will continue to
highlight this concern in the HWO.

.LONG TERM...(Friday through Wednesday)
Issued at 340 PM EDT WED APR 18 2018

An area of surface high pressure is expected to be centered across
the Upper Midwest on Friday and upper level ridge will progress
east with the surface high Saturday. This will lead to a period of
mostly clear skies and dry conditions through the first portion of
the long term period. The temperatures will modify through the
weekend, but does remain cold enough for Friday night into
Saturday morning to lead to frost. Then a southern stream upper
level low will progress out of the four corners into the Lower
Mississippi River Valley by Sunday afternoon. The model guidance
has struggled with continuity and consistency, with regards to the
southern stream system. The GFS has leaned the wettest for the
late weekend and the other models have leaned wetter toward Monday
and Tuesday time frame. This becomes further convoluted as we see
phasing potential by early to middle of next week. Given the lower
confidence leaned toward the blended guidance which brings slight
to chance POPs slowly north late Sunday into Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 841 PM EDT WED APR 18 2018

VFR conditions still prevailed at the start of the period, but
changes are on the way this evening. A cold front was over central
KY, with a narrow area of showers and isolated thunderstorms along
it. The front will move southeast through eastern KY tonight. The
thunderstorms area expected to diminish before the front arrives
in eastern KY, but showers will likely persist. A period of MVFR
is forecast near the front. Many areas could see an improvement
back to VFR for a time tonight, before another fall to MVFR which
is expected to affect the region overnight and into Thursday
morning. Clouds are expected to clear out and allow a return to
VFR conditions on Thursday afternoon.

Gusty southwest to west winds will continue tonight, with a peak
near and just behind the cold front. A few gusts could top 30 kts,
but they are not likely to be persistent. An overall lessening of
winds is forecast for late tonight and Thursday.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 2 AM EDT Thursday for KYZ044-050>052-058>060-
068-069-079-080-083>085-104-106-108-111-114.

&&

$$

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



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