Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 240147

Area Forecast Discussion
National Weather Service Louisville KY
947 PM EDT Mon Apr 23 2018

.Forecast Update...
Issued at 945 PM EDT Mon Apr 23 2018

Convection over the southwest sections of the CWA diminished as
earlier CAMs suggested.  Redevelopment has now shifted over to the
east in the Lake Cumberland region.  A steady stream of showers with
some embedded thunder will move from east-central TN northward into
east-central KY through the overnight hours.  In general, the best
chances of precipitation overnight will be mostly confined to areas
east of the I-65 corridor.

QPF amounts from the latest CAMs suggest anywhere from a quarter to
one inch of rainfall over the next 12-18 hours.  Flash flood
guidance is much higher than that with 1.5-2 inch amounts over 6
hours and generally 2.5+ inches over 12 hours.  Certainly not out of
the question that we could have some minor hydro issues overnight
with ditches and small streams filling up leading to some minor
flood issues with poor drainage areas.

Have gone ahead and bumped up PoPs over our eastern half for the
overnight period and backed off PoPs a bit in areas west of I-65.
Plenty of cloud cover overnight will keep lows in the lower-mid 50s

Issued at 610 PM EDT Mon Apr 23 2018

Made a few updates to the forecast in the very near term.  Watching
a band of arcing convection that is streaming northward across
Logan, Simpson, Warren, Butler, and Ohio counties this evening.
Moderate to heavy rain is occurring in this area.  Rainfall amounts
since midnight over this region have been in the one half to one
inch range per the KY Mesonet.  This agrees well with MRMS QPE with
gauge bias correction.  Current flash flood guidance in this area
are running around 1-2in for one hour QPF. Current indications are
that we could see about half that over the next several hours as
this convection trains northward.  As of right now, we are handling
this with a flood advisory, but are closely monitoring conditions
for flash flooding.

Latest CAMs guidance suggests that this activity will wane around
23Z and then shift off to the east.  This seems reasonable as we
have quite a bit of convection moving northward out of the TN
plateau and this will impact areas from Glasgow and eastward toward
Somerset through the evening.

In terms of forecast changes, simply have increased PoPs over our SW
to be within line with obs and radar presentations.  Have allowed
some higher PoPs across southern KY this evening and into the
overnight hours.  Also did a quick refresh of hourly temps and


.Short Term...(This evening through Tuesday night)
Issued at 229 PM EDT Mon Apr 23 2018

The upper low spinning over the mid Mississippi Valley this
afternoon will proceed across Tennessee on its way to Virginia
during the short term. As a result, clouds and showers will continue
tonight and tomorrow before decreasing significantly in coverage
tomorrow night. Though mid-level lapse rates won`t be quite as steep
as they are in western Kentucky today, a few thunderstorms will be
possible Tuesday afternoon just ahead of the low, especially east of
I-65 and south of the Blue Grass Parkway. A few storms could produce
some small hail, particularly in the Lake Cumberland region.

The clouds and rain will keep diurnal temperature ranges limited,
with readings in the 50s tonight and tomorrow night and highs in the
60s on Tuesday.

.Long Term...(Wednesday through Monday)
Issued at 237 PM EDT Mon Apr 23 2018

Wednesday should be quieter as we sit between the upper low moving
off to the east and an upper trough approaching from the west. The
best chance of any shower activity on Wednesday will be east of I-65
closer to the low, but even there not much is expected.

After weakening high pressure slips in for Thursday, a cold front
will sweep through the district on Friday. Right now it looks like
moisture and instability will be lacking, and the stronger flow
aloft will be to our north. Nevertheless, showers and a few
thunderstorms will accompany the system.

Saturday through Monday look dry and warm as upper ridging builds
over the eastern United States and surface high pressure expands
from the Ohio Valley to the East Coast. By Monday we`ll see
afternoon temperatures well into the 70s...possibly approaching 80.


.Aviation...(00Z TAF Issuance)
Issued at 718 PM EDT Mon Apr 23 2018

Arcing band of showers will move northward across central Kentucky
this evening and into the overnight hours.  Initially, VFR ceilings
will give way to MVFR ceilings that should be predominant during the
overnight hours.  Visibilities will start off as VFR, but will also
likely drop into the MVFR range.  Some temporary periods of high IFR
ceilings will be possible after 24/06Z at the terminals.  Winds will
remain out of the east/southeast at 8-10kts.




Short Term...13
Long Term....13
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