072 
FXUS63 KLMK 041737
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
137 PM EDT Wed May 4 2022

.Forecast Update...
Issued at 1105 AM EDT Wed May 4 2022

Low stratus under a subsidence inversion has produced pockets of 
light drizzle and even reports of light rain from the Blue Grass 
Airport. These observations have also been verified by observations 
and area web cameras. Expect these patchy pockets of light drizzle 
and sprinkles to continue for the rest of the afternoon. Went ahead 
and updated forecast grids to include the mention of light drizzle. 
Rest of the forecast looks on track with no additional changes.

&&

.Short Term...(Today and tonight)
Issued at 215 AM EDT Wed May 4 2022

Upper ridging underneath a sfc high over the Great Lakes will allow 
for dry conditions today, though low level moisture trapped 
underneath a subsidence inversion will keep us mostly cloudy 
throughout the day. Additionally, post-frontal northwest winds will 
become northerly this afternoon, and will help limit temps to remain 
below climate normals. Forecast highs range from the mid to upper 
60s. Some breaks in the cloud cover across south-central KY may be 
possible this afternoon, and if so, would help raise temps closer to 
70 across that area of the CWA. 

For tonight, dry and quiet weather expected to continue. Light NE 
winds with temps cooling into the low 50s overnight.

.Long Term...(Thursday through Tuesday)
Issued at 312 AM EDT Wed May 4 2022

===================================
Synoptic Overview
===================================

The last in a series of Pacific systems is expected to move from the 
Plains on Thursday and into the Ohio Valley for Friday and into 
Saturday.  This feature will bring yet another round of unsettled 
weather to the region as we head into the weekend.  For the later 
half of the weekend and into next week, the pattern over the Ohio 
Valley is forecast to relax a bit as large troughs will be found on 
the western US coast and off the southeastern US coast.  A SW-NE 
oriented ridge axis is forecast to set up which should result in 
drier and much warmer weather for our region.

===================================
Meteorological Discussion and
Sensible Weather Threats
===================================

The last in a series of systems of Pacific origin is expected to be 
located out in the Plains at the start of the period.  Overall 
progression of this system to the east has trended a bit slower in 
the latest guidance.  For Thursday, the day should start off fairly 
dry across the region.  A frontal boundary to the south is then 
forecast to lift northward as a warm front and should push through 
the region during the day on Thursday.  We'll likely see a 
temperature gradient across the region on Thursday with highs in the 
lower 70s in southern Indiana with mid-upper 70s across much of 
Kentucky and a shot of lower 80s down along the KY/TN border.  By 
late Thursday, precipitation chances will likely increase as we 
should start to see some warm advection showers/storms develop along 
the front. For Thursday night, there is a signal in the data that we 
could see some sort of MCS move through the region ahead of the main 
trough axis and cold front which will still be out west.  Overnight 
lows look to remain mild with lower 60s expected.

On Friday, nearly stacked upper level low and surface low should be 
located out across MO and this feature will move northeastward 
through Indiana during the day.  Attendant cold front is forecast to 
then push through the region in the afternoon and evening.  Model 
soundings show a bit of instability developing during the day, 
however, there is considerable uncertainty among the models on how 
much instability will be able to develop.  This is due to lingering 
clouds/precip from early Friday morning convection.  Should 
instability develop, strong to severe storms will be a possibility 
again.  Highs Friday should be slightly cooler with readings in the 
mid to perhaps the upper 70s.  Behind the frontal boundary, look for 
temperatures Friday night to cool back into the mid-upper 50s.

For Saturday, upper level low should be in the vicinity of SE OH and 
WV with a large amount of wrap around moisture remaining in place 
across the region.  Widespread showers should be in progress early 
Saturday with the activity diminishing in coverage throughout the 
day.  Cloud cover will likely keep temperatures down a bit with 
highs in the middle 60s expected.  Drier conditions along with 
clearing is expected for Saturday night with lows dipping into the 
lower 50s.

For Sunday, upper level low is forecast to move off the US east 
coast with decent mid-level height rises occurring over the Ohio 
Valley.  With surface high pressure in control, mostly sunny skies 
and mild conditions are expected.  Highs of 75-80 are likely across 
the region.  Lows Sunday night will cool back into the upper 50s to 
the lower 60s.

For Monday-Tuesday, aforementioned upper level pattern change will 
lead to upper troughs situated out across the western CONUS with 
another trough likely off the eastern US coast.  Across the Ohio 
Valley, upper level ridging is expected with a warm southwest flow 
pattern through the lower atmosphere.  Dry and increasingly milder 
conditions are expected.  Highs on Monday should solidly warm int 
the 80-85 degree range with overnight lows cooling into the lower-
mid 60s.  Milder temperatures are expected on Tuesday with highs 
pushing into the mid-upper 80s.  Strong ridging should persist into 
Wednesday with highs warming even further with widespread readings 
in the mid-upper 80s.

===================================
Forecast Confidence
===================================

Forecast confidence for the Thursday-Saturday period is generally 
medium overall.  We have high confidence that we'll see rainfall in 
the Thursday-Saturday time frame.  However, there is low confidence 
on the strength of convection in the Thursday night-Friday night 
time frame.  Forecast confidence increases markedly for Sunday-
Wednesday given the good model agreement in the extended period.

&&

.Aviation...(18Z TAF Issuance)
Issued at 130 PM EDT Wed May 4 2022

IMPACTS: Low stratus will keep MVFR conditions through the afternoon 
into the evening, especially for HNB-SDF-LEX with BWG improving 
before 00z. 

DISCUSSION: Thanks to a subsidence inversion locking low-level 
moisture in over the Ohio Valley, low stratus will continue to keep 
MVFR CIG through at least early evening. Satellite imagery seems to 
be showing places where clouds are breaking but current models are 
too quick in my opinion to break/lift the cloud deck. 

There will be a period after 00z where CIG will lift above MVFR and 
become BKN to SCT. Still challenging so confidence on when this will 
happen remains fairly low. Winds have generally been light and 
mostly variable today. Winds will remain fairly light but expect a 
wind shift from NE to more easterly overnight into tomorrow.

&&

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

$$

Update...BTN
Short Term...CJP
Long Term...MJ
Aviation...BTN