659 
FXUS63 KLMK 191137
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
737 AM EDT Tue Oct 19 2021

.Short Term...(Today and tonight)
Issued at 300 AM EDT Tue Oct 19 2021

The nighttime microphysics satellite channel is currently showing 
fog starting to fill some of our river valleys early this morning. 
Expect the fog to mainly stay confined to those areas, however can't 
rule out a few patches of shallow fog elsewhere. Will keep an eye on 
satellite/obs/webcams through the morning.

High pressure at the surface and aloft will control the area for the 
short term period. We'll start the day with plenty of sunshine, 
however we will see a transient period of upper sky cover this 
afternoon. Would have gone just a bit more aggressive with highs if 
not for this upper sky cover, but still going at or just above 
values we saw yesterday. This should put most everyone in the 69 to 
74 degree range. The surface high shifts a bit to the east later 
tonight, which will allow for a light southerly flow in the 
unsheltered areas. This will keep things a bit more mixy and mild 
for many in the mid 40s to around 50. Sheltered locations and 
valleys will still decouple, so fully expect some lower 40s in those 
typical cool spots.

.Long Term...(Wednesday through Monday)
Issued at 345 AM EDT Tue Oct 19 2021

Wednesday...Surface high pressure over the Appalachians slides 
towards the Atlantic allowing the wind to veer to a southerly 
component. This wind shift facilitates WAA into our area and as a 
result highs on Wednesday will climb to the mid 70's. As the high 
pressure departs our area, a cold front and attendant upper-level 
trough will slowly progress from the Midwest to the Ohio Valley. A 
weak pressure gradient favors a gentle breeze starting Wednesday, 
but otherwise expect dry conditions to prevail.

Thursday...Precipitation chances increase as the cold front moves 
through our CWA on Thursday. At this moment there is no flooding 
concerns with this event since the pattern seems fairly progressive 
and PW values barely reach 1.20 inches. This is also reflected by 
WPC's 24-hour PQPF having less than 5 percent chance of 0.5 inches. 
Overall, the boundary layer will not recover fast enough to support 
widespread surface-based convection since the dewpoints will be in 
the high 50's at the time of FROPA, plus some low-level capping 
inversions and weak lapse rates. The best chance for lightning 
appears to be linked to elevated convection.  

Friday...Cooler air mass and surface ridging will be in place over 
central Kentucky and southern Indiana. Winds will shift to a 
northwesterly direction behind the front while low clouds will hover 
around during the first part of the day before mixing out by 
afternoon. Shortwave energy propagating around the upper trough will 
result in a slight chance of showers, mainly across southern Indiana 
and into the Bluegrass, but drier air and weak lapse rates will 
likely keep most dry.  

Saturday and beyond...Models really begin to diverge at this point, 
especially with the placement of upper level synoptic features. 
Overall, it appears that high pressure will dominate much of the 
eastern US with deep troughing over the west. Our position on the 
western flank of the aforementioned high pressure will result in 
southerly flow with warm and moist air advection over the region. 
Weak isentropic upglide near a weak quasi-stationary boundary 
extending into the lower OH Valley could result in light rain 
chances from Sunday into the beginning of next week.

&&

.Aviation...(12Z TAF Issuance)
Issued at 637 AM EDT Tue Oct 19 2021

IMPACTS: Brief light ground fog possible for low lying terminals,
especially those near streams.

DISCUSSION: Outside of the brief morning ground fog potential, 
high pressure at the surface and aloft will result in VFR 
conditions for the next 24 hours. Light and variable or calm 
winds early this morning will be more south-southwesterly later 
this afternoon.

CONFIDENCE: High confidence on all elements.

&&

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

$$

Short Term...BJS
Long Term...ALL/CG
Aviation...BJS/MK