215 
FXUS63 KLMK 170733
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
333 AM EDT Tue Aug 17 2021

.Short Term...(Today and tonight)
Issued at 315 AM EDT Tue Aug 16 2021

...Another Day Of Locally Heavy Rainfall Potential For Some...

Things are dry across the CWA at this hour, and the only initial 
concern lies with patchy dense fog in areas that saw rain Monday and 
are currently seeing clearer skies. Will monitor through the pre-
dawn hours and may issue a Special Weather Statement if needed.

The pattern still continues to feature weak troughing over the upper 
Midwest into the mid Mississippi River Valley, with mid Atlantic 
ridging to our east, and TS Fred working its way northward from the 
Gulf coast. We'll continue to have a high PWAT airmass with values 
in the 1.7"-2.0" range, and as we combine the moisture with diurnal 
heating and perhaps some mid level deformation we'll initiate 
scattered to numerous showers (and a rumbles of thunder) later 
today. Messaging of locally heavy rainfall will continue to be a 
good call as efficient rainfall rates and slow storm movement allow 
for some locally enhanced totals. Have the best coverage of 
afternoon/evening showers/storms across the western and northern 
half of the CWA where the mid level deformation and perhaps some 
differential heating due to less cloud cover will be noted. Wouldn't 
be surprised if we end up with some minor flooding concerns in spots 
if the storms stay oriented along a focused axis with little 
movement as you see with deformation axis'. Expect between 1000-2000 
J/KG of instability in that area. Much like yesterday, that 
instability will be oriented throughout a classic tall/skinny CAPE 
profile and is the main reason for the continue efficient rainfall 
rates.

SE of a Bowling Green to Elizabethtown to Frankfort line, expect 
less coverage today as this area lacks instability and will be 
removed from any notable triggers. There will still be ample deep 
moisture especially as the remnants of Fred move closer, but it may 
be tough to fire too much coverage off. This will be good as that 
area has been hit pretty hard with heavy rain the past couple of 
days and some recovery in FFG values would be nice. We'll see fairly 
notable temp gradient from W to E with mid 80s west and around 80 
east under heavy cloud cover.

Convection should diminish in the evening with the loss of heating 
and the overnight should be pretty quiet as the remnant of Fred move 
well to SE of our CWA.

&&

.Long Term...(Wednesday through Monday)
Issued at 334 AM EDT Tue Aug 17 2021

Wednesday-Friday

Upper level ridge centered off the Carolina coast will begin to 
retrograde westward over the Gulf Coast as the trough over the Upper 
Midwest slides eastward across the Great Lakes and over Lake Erie by 
the end of the week. This will continue to keep us unsettled with a 
moist southwest to eventual west-southwesterly flow. We should also 
see a couple of embedded shortwaves rotate through the flow Wednesday 
night and Thursday night. The combination of shortwaves and 
afternoon diurnal heating will keep the continued chance of 
scattered showers and isolated storms through the end of the week. 
Highs will range from the low to mid 80s during the day with 
overnight lows in the upper 60s to near 70. With PWAT values 
remaining between 1.75 to as high as 2.00 inches, heavy rains and 
localized flooding remains the main concern. 

Saturday-Sunday

Upper ridge centered over Ark-La-Tex expands and strengthen over the 
weekend as a series of upper level troughs slide across the Northern 
Plains and into the Upper Great Lakes. This will push a cold front 
through the Ohio Valley Saturday into Sunday. While the 
deterministic models agree on timing, they continue to show 
differences on how far south the front will go by Sunday. With good 
moisture pooling ahead of the front Saturday, expect to see 
scattered showers/storms for the afternoon and evening with just 
widely scattered to isolated showers/storms on Sunday. Temperatures 
will remain in the mid/upper 80s through the weekend.

Monday-Tuesday

Secondary front looks to move into the region Monday and Tuesday but 
stall just north across central Indiana. Temperatures should return 
to more seasonal norms in the upper 80s to near 90 with isolated to 
widely scattered showers/storms in the afternoon.

&&

.Aviation...(06Z TAF Issuance)
Issued at 200 AM EDT Tue Aug 17 2021

IMPACTS:

-Patchy Fog possible early this morning
-Low stratus possible at KLEX this morning
-Isolated to widely scattered heavy showers & storms later today

DISCUSSION:

Some patchy fog will be possible at KHNB and perhaps KLEX. Toward 
dawn, there is a signal that low cigs will set in around or just 
after sunrise. Any MVFR ceilings should be pretty short-lived as VFR 
cigs would likely return by midday into early afternoon. Look for 
isolated to widely scattered showers and storms again later this 
afternoon/evening, with brief heavy rainfall.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Short Term...BJS
Long Term...BTN
Aviation...BJS