543 
FXUS63 KLMK 190528
AFDLMK

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

...Updated Aviation Discussion...

.Forecast Update...
Issued at 935 PM EDT Mon Oct 18 2021

Another beautiful night in the region...with temperatures expected 
to fall within a few degrees of seasonal lows. Ongoing forecast 
right in the middle of guidance for lows, so see no good reason to 
change, especially given persistence from previous couple of nights. 
Only slight tweak was to add in some river fog...as a few models are 
hinting at some potential there. Updated the point and click 
forecast for this change, but otherwise no updates needed.

&&

.Short Term...(This evening through Tuesday)
Issued at 245 PM EDT Mon Oct 18 2021

Sfc high pressure will move east to the Appalachians tonight with an 
upper ridge working in from the west. This will result in continued 
quiet weather with seasonal temperatures. Looking at cross over temp 
analysis, some light patchy valley fog may be possible late tonight 
into Tues morning.  Low temperatures should reach the lower 40s 
tonight with some isolated cold spots in the upper 30s possible.

For Tuesday, expect plenty of sunshine though some upper level 
clouds look to enter the region by Tues afternoon/evening.  High 
temperatures should be similar to today or slightly warmer with 
highs in the upper 60s/lower 70s.

.Long Term...(Tuesday night through Monday)
Issued at 330 PM EDT Mon Oct 18 2021

Upper level ridge axis will slowly move over the region Tuesday 
Night into Wednesday as sfc high pressures moves into the US 
southeast. Sfc wave moving through the Upper Midwest Wednesday will 
tighten the pressure gradient over the area resulting in strong 
southerly flow and gusts of 10-15mph. WAA on the backside of the 
southeast US High will warm daytime highs into the low/mid 70s. 

Wednesday night into Thursday, sfc wave moves into the lower Great 
Lakes dragging a cold front across the area. PoPs increase out ahead 
of the front late Wednesday night/early Thursday morning with the 
bulk of the rain falling during the first half of the day. Model 
soundings shows a shallow moisture level below 700mb and limited 
instability. CAPE values will be between 300-500J/kg but isolated 
thunder could still occur as a 30-40kt LLJ moves across the Ohio 
Valley ahead of the boundary. Winds will remain breezy as the front 
works across central KY/southern IN during the day with wind gusts 
between 15-25mph. 

Surface high pressure builds in behind the front Thursday night into 
Saturday as a zonal flow aloft sets up over the region. While we 
expect to stay dry Friday into Saturday, an upper level closed low 
over the Hudson Bay will work southward towards the Great Lakes 
pushing a few embedded shortwaves across the Ohio Valley keeping us 
under mostly cloudy skies. 

Rain chances increase Sunday into Monday thanks to weak isentropic 
lift that sets up along a weak quasi-stationary boundary that 
stretches across the Ozarks into the Ohio Valley. Temperatures 
Friday through the weekend will be cooler than normal with highs in 
the low/mid 60s and lows in the mid/upper 40s.

&&

.Aviation...(06Z TAF Issuance)
Issued at 655 PM EDT Mon Oct 18 2021

IMPACTS: VFR conditions expected. Brief light fog possible BWG 
around daybreak Tuesday.

DISCUSSION:  High pressure at the surface and increasing ridging 
aloft will result in VFR conditions for this TAF period.  Light and 
variable winds tonight will be more southerly for tomorrow 
afternoon...as that high center gets farther east of the region.

CONFIDENCE: High confidence on all elements.

&&

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

$$

Update...RJS
Short Term...AMS
Long Term...BTN
Aviation...BJS