Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 211604

National Weather Service Jackson KY
1204 PM EDT Mon May 21 2018

Issued at 1204 PM EDT MON MAY 21 2018

Beginning to see a few showers and storms fire across southeast
Kentucky as temperatures have warmed to near 80 degrees. Agitated
cumulus will continue to develop across the higher terrain,
eventually spreading farther northward into the Bluegrass region.
Given anemic shear profiles, do not expect long-lived
organization to any storms that develop. Rather, brief upticks in
updraft strength will be possible as cells merge, thus leading to
brief periods of heavy rainfall and cloud to ground lightning.

UPDATE Issued at 659 AM EDT MON MAY 21 2018

Issued an update to the forecast to input the latest observations
into the forecast and trend through the mid morning hours.
Slightly adjusted the amount of fog in the valleys. A new zfp will
not be needed for this update.


.SHORT TERM...(Today through Tuesday)
Issued at 440 AM EDT MON MAY 21 2018

Current conditions across the area feature mid and upper level
cloud cover beginning to filter into the area. While some fog has
indeed formed in the river valleys and some of the deeper
valleys, this cloud cover may begin to hinder the development. The
overall pattern continues to display a return flow situation with
southerly flow assisted by high pressure just off the southeast
coast. This as an impulse will track east today through the
Midwest. The mentioned ridging in the southeast will hinder the
approach of the from into the OH Valley. Nonetheless, with plenty
of instability across the area today, showers and thunderstorms
will develop by noon across eastern Kentucky and continue into the
evening hours. Model soundings are hinting at PWATs between 1.50
and 1.75 today some storms will the potential to produce heavy
rainfall will certainly be possible heading into this afternoon
and evening. Tonight, despite the front pushing southeast
thunderstorms will eventually diminish overnight giving way to
showers. Valley fog will begin to develop, especially with the
ample moisture in place.

For Tuesday, the front will continue to slowly push southeast
through the area. With ongoing convection, expect some of the
boundary to wash out. Despite the boundary, activity will still
take on a diurnal like trend in activity. Daytime heating for
Tuesday afternoon will allow for additional thunderstorm
development lasting into Tuesday evening. The summer like pattern
will continue to be in place for the short term.

.LONG TERM...(Tuesday night through Sunday)
Issued at 415 AM EDT MON MAY 21 2018

The axis of a broad low amplitude upper trough and an associated
weak surface cold front will be crossing the area Tuesday night and
Wednesday morning. Convective precip should peak on Tuesday
afternoon before the long term period starts, with a diurnal decline
underway as the period starts. A few showers could still occur in
southeast KY through mid day Wednesday before the cold front clears
to our south.

A slightly drier air mass will arrive behind the front, followed
shortly thereafter by upper level ridging building in from the west.
This combination will result in a period of warm and dry weather
late in the week. Models then depict another upper level trough
moving across the Great Lakes during the weekend, with a much weaker
trough extension southward over the southeast CONUS. The developing
deep layer flow pulls tropical moisture northward, and gives us a
return of showers and thunderstorms in a diurnal pattern.

A wildcard in the mix is the potential for development of a tropical
system in the Gulf of Mexico or off the southeast Atlantic coast.
Models have been showing this for several days, but can`t come to
any agreement on where and to what extent. Obviously, this could
affect the flow of moisture and overall pattern, so there is a


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)

Some IFR and below conditions are present across the area due to
some fog this morning. This fog will quickly burn off in the next
few hours. An approaching wave and the heating of the day will
allow showers and thunderstorms to develop across the area and
continue across the area into tonight. Will expect vis and cigs to
drop in thunderstorms. Fog will develop again tonight, especially
locations that received heavy rainfall. Winds are expected to
remain light outside of thunderstorms.




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