Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 240245 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1045 PM EDT Mon Apr 23 2018

.UPDATE...
Issued at 1045 PM EDT MON APR 23 2018

Updated the grids to fine tune PoPs and Wx through the rest of the
night per radar trends and the latest guidance from the HRRR.
Also adjusted the near term T and Td grids per the current obs
and trends. These have been sent to the NDFD and web servers.
Updated zones and an HWO were sent as well, still kept gusty
winds on the ridges in the far east into the overnight hours as
they have been staying up over there through the evening and look
to continue past midnight.

UPDATE Issued at 745 PM EDT MON APR 23 2018

23z sfc analysis shows the center of a slow moving and large area
of low pressure approaching from the southwest. The pressure
gradient associated with this system is still keeping the
southeast to east breezes and gusts going over far eastern
Kentucky, especially in the elevated terrain. These winds are
supporting downsloping flow and helping to dry out the showers for
the far east while they continue in the scattered to numerous
category over the western parts of the area. Still cannot rule out
a stray thunderstorm in the far southwest, but for the most part
anticipate a downward trend in the pcpn for most of the area to
continue through at least the first part of the night. Will update
the forecast and HWO shortly after sunset once the thunder threat
dissipates. Otherwise, the temperatures are running in the mid
50s with the rains to the low and mid 60s in the drier parts of
the east. That dryness shows up quite well in the dewpoint
analysis with low to mid 50s noted west and mid to upper 40s in
the far east. The winds will settle more with the approach of the
low`s center as well as sunset. Have updated the grids with these
thoughts in mind through the night. These have been sent to the
NDFD and web servers. Look for updates to the text zones and HWO
shortly once the thunder threat is gone.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 421 PM EDT MON APR 23 2018

Kentucky mesonet continues to show some gusty winds (30 to 40
mph) at the higher elevations this afternoon but these do appear
to be waning just a bit. Also, these higher wind gusts generally
seem confined to the higher elevations. Will continue to address
this in the HWO through early evening. Have not seen any thunder
yet but MOS guidance still suggest a slight potential in the far
south. There are some stronger cells further south in TN. See no
reason not to hang onto a slight potential through early evening.

Mid/upper level low over the mid Mississippi Valley will meander
eastward very slowly through the short term period, moving from
the Mid-South to the Piedmont by Tuesday night. Short wave
disturbances will continue to rotate around the parent low
bringing a few bands or rounds of rain to the area. Surface wave
will also track eastward in step with the low center aloft. Do
expect a relative lull in activity between each round, including
one tonight where activity will be generally more scattered in
coverage but with a good portion of the forecast area seeing at
least some precip through the night. The threat of rain increases
again Tuesday as the low gets closer to our area. Like today can
not rule out the threat of thunder Tuesday afternoon as mid level
lapse rates steepen under the influence of the passing low and
diurnal heating helps destabilize the boundary layer.

Afternoon highs Tuesday afternoon will only climb into the lower
to mid 60s with rain and cloud cover, about 5 to 10 degrees below
normal. Extensive cloud cover will keep overnight lows slightly
above normal levels, around 50 to lower 50s. However, patchy
clearing will allow for some cooler spots and probably a little
patchy fog at times.

.LONG TERM...(Wednesday through Monday)
Issued at 421 PM EDT MON APR 23 2018

A broad upper level trough will remain over the eastern United
States into the upcoming weekend. Several waves will move through
the mean trough, but at this time it appears their impact on eastern
Kentucky will be minimal. By late in the weekend or early next week
the mean trough will be shifting east, and upper level and surface
ridging will begin to build into our area.

By 12Z Wednesday the slow moving stacked low pressure system which
brought the rainy start to the work week will finally have shifted
off to our east, but it will continue to influence our weather with
rain chances lingering into Wednesday. The models are in general
agreement that following the exit of this low pressure area, a
couple of short waves and/or upper lows will follow. One is expected
to move through the Great Lakes or northern OH valley and another
one is forecast to move from the plains through the southeast U.S.
It appears we will be between the two systems, with only a small
chance for showers in the far south on Thursday afternoon. By Friday
a cold front will be approaching, but again the impact of this looks
to be minimal, with shower chances so low that they will not even
appear in the forecast for most areas. After this frontal passage
rain chances continue to decrease, with dry weather for the weekend
and into early next week.

Temperatures will generally be below normal for the first part of
the forecast period, but will trend warmer by early next week as
ridging builds into the area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 730 PM EDT MON APR 23 2018

Storm system over the mid Mississippi Valley will meander
eastward very slowly through the forecast period, moving from
to roughly Knoxville by this time Tuesday. Surface low will move
eastward along with the upper level feature. This will keep the
threat of rain in the forecast, but with a relative lull through
the overnight period as activity becomes a bit more scattered in
nature. However, rain returns by Tuesday morning as the storm
system moves ever closer to our area. In addition to the rain we
can expect to see deteriorating flight conditions through MVFR and
eventually down into IFR territory for much of the area by
Tuesday morning. Still cannot rule out some isolated thunder in
our south and southwest this evening and most places on Tuesday
afternoon, but at present the threat does not look high enough to
warrant a mention in the TAFs. East to southeast winds at around
10 kts - with higher gusts in the elevated terrain of far eastern
Kentucky - will decrease through the evening hours settling
between 5 and 10 kts and continuing at that rate into Tuesday.
Some LLWS will still be possible in the far east (SJS) for a good
part of the night and accordingly this has been included in its
TAF.

&&

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

$$

UPDATE...GREIF
SHORT TERM...RAY
LONG TERM...SBH
AVIATION...RAY/GREIF



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