Paoli Peaks

000
FXUS63 KLMK 011045
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
645 AM EDT Sat Aug 1 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Several waves of showers and thunderstorms are expected today. 
  Strong to severe storms will be possible this afternoon and 
  evening, especially east of I-65. Damaging winds are the main 
  threat, and a few spin-up tornadoes are possible.

* Isolated rainfall amounts of 2-4+" could lead to flash flooding 
  today. The greatest probability of heavier rainfall amounts will 
  be east of I-65.

* More scattered shower/storm activity possible through the middle 
  of next week, mainly in the afternoon and evening hours.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 247 AM EDT Sat Aug 1 2026

Early this morning, a robust line of showers and thunderstorms is 
moving into western KY and southwest IN. Along and just ahead of 
this corridor of heavy rain, a strengthening 850 mb jet is priming 
the atmosphere from west to east across the area this morning, with 
a corridor of 2+" PW values expected to move across the area during 
the morning hours. All of the moisture advection is occurring within 
the warm conveyor belt of an approaching low pressure system which 
is nearly vertically stacked over eastern IA as of 06Z. As this low 
pressure system drifts to the southeast later today, multiple bands 
of showers and thunderstorms are expected to move across the area 
from west to east.

The first wave of showers and storms to move through the area this 
morning is expected to have a very low severe threat with it as 
lingering stability near the surface should keep convection mainly 
elevated through mid-morning. Still, with an axis of 1000+ J/kg 
MUCAPE expected to make it to the I-65 corridor by around sunrise, 
embedded thunderstorms are likely across most if not all of the area 
with the first wave of precipitation. Some 6-hr HREF/REFS localized 
prob-matched mean swaths of 1-3" are associated with the morning 
convection, so a low, but non-zero flooding threat will also be 
possible.

Later this morning into the afternoon hours, a 45-50 kt 500 mb jet 
will swing around the base of the upper low across western KY. This 
will place our area into a region of diffluence aloft and broad 
rising motion in the low-to-mid levels. Combine this with an 
anomalously moist environment (PW 2-2.25") and building instability 
with daytime heating, and several ingredients for additional rounds 
of showers and thunderstorms will be in place this afternoon and 
evening. The last of those three ingredients may be the most 
uncertain, as some 00Z high-res model guidance shows fairly 
persistent convective development through the late morning and early 
afternoon hours. If this scenario plays out, it would lessen the 
destabilization this afternoon (at least for a portion of the area), 
which would lessen the potential for strong to severe thunderstorms. 

Nevertheless, if there are breaks in the clouds/precipitation during 
the late morning and afternoon hours, this will allow pockets of 
1000-2000 J/kg MLCAPE to develop, with the largest probabilities of 
higher instability (>1500 J/kg) expected between I-65 and I-75 and 
south of I-64. Along and north of I-64, there is more uncertainty 
whether instability will be sufficient for strong updrafts to 
develop. While weakening mid- and upper-level flow will keep bulk 
shear values around 25-30 knots, a significant component of the bulk 
shear vector should be perpendicular to the low-level forcing 
boundary (i.e., the sfc cold front), increasing the likelihood of 
cellular convection initially. Low-level shear is abnormally strong 
for August, with hodographs showing a decent amount of curvature in 
the lowest 1-2 km ahead of the cold front. As a result, while 
damaging winds will be the most likely severe threat this afternoon, 
a few spin-up tornadoes will be possible. 00Z HREF guidance does 
show a couple swaths of 2-5 km Updraft Helicity in excess of 75 
m2/s2 mainly east of I-65, highlighting the potential for rotating 
updrafts. It should be noted that the parameter space is much less 
supportive for significant severe weather than on July 21st, so long 
track tornadoes and higher-end damaging wind gusts (70+ mph) are 
very unlikely.

In addition to the severe weather potential, any training of 
thunderstorms this afternoon and evening could lead to a localized 
flash flooding threat. As mentioned above, the atmosphere will be 
quite saturated ahead of the sfc cold front, and deep warm cloud 
depths should support some increase in the rainfall efficiency. The 
00Z HREF/REFS both show a few swaths of 2-4+" in 6 hours, with a 
stronger signal along and east of US 127. However, given the 
relatively isolated coverage of these heavier swaths and a general 
progressive nature to the storms, decided to hold off on any flood 
watch at this time.

The main timing for the severe threat looks to be between 18Z and 
01Z, though a few stronger storms could linger east of US 127 as 
late as 02-03Z. After sunset, the loss of diurnal heating should 
lead to a downward trend in convective intensity, with isolated 
showers expected after midnight tonight. For the late evening and 
early morning hours on Sunday, isolated showers should continue, 
with the best chances expected across southern IN and northwest KY, 
which will be closer to the center of the low. Temperatures should 
fall into the upper 60s and low 70s Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 247 AM EDT Sat Aug 1 2026

Sunday - Tuesday Night...

From Sunday through the first half of the upcoming week, an upper 
low will continue to spin over the Ohio Valley. Most ensemble 500 mb 
progs have the low starting to pull out of the region Tuesday 
evening into Wednesday morning as it gets absorbed into an 
approaching synoptic trough over central Canada. During the time 
period that the low is still overhead, above normal PW values will 
persist, with LREF mean PW values gradually stepping down from 1.75-
1.9" Sunday to 1.5-1.7" by Tuesday. The elevated moisture levels 
should lead to greater cloud cover and continued scattered shower 
and thunderstorm chances mainly in the afternoon and early evening 
hours. Weak mid-level flow in the vicinity of the trough/low will 
result in deep-layer shear of only 10-15 knots, so any storms which 
form should be disorganized with strong/severe storms unlikely. 
Temperatures should be below normal for early August due to the 
elevated moisture/cloud coverage, with highs in the upper 70s and 
low-to-mid 80s and lows in the mid-to-upper 60s.

Wednesday - Friday Night...

As the upper low pulls out of the area mid-week, PW values should 
return to more seasonable levels, and without a defined triggering 
mechanism, precipitation coverage/chances should decrease Wednesday 
into Thursday. For the second half of the week, a transition to a 
more zonal pattern is favored. Positive upper height anomalies over 
the western US should spread into the southern Plains, with broad 
troughing spreading across the northern CONUS and Canada. While 
we'll have to watch for any smaller-scale waves within the broader 
zonal/NW flow pattern that could bring enhanced chances for showers 
and storms, at this time, most guidance keeps the better rain 
chances to the north and west of the region. Temperatures are 
expected to creep up toward climo normals by the end of the week, 
with highs returning to the upper 80s and low 90s.

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 644 AM EDT Sat Aug 1 2026

A round of showers and a few storms currently moving through the 
area. Cigs are falling to MVFR/IFR due to lowered ceilings with 
these initial showers. Ceilings will begin to drop more widespread 
below 3kft in BWG around 12z and continue to build in eastward into 
all sites. A secondary line of showers and storms will move through 
this afternoon and evening. Gusty winds of at least 20kts are likely 
to accompany these storms. Lowered vis can also be expected 
throughout the forecast period as storms move through. Ceilings will 
potentially improve to VFR for LEX/BWG/SDF after the rain moves 
through, however another low cloud deck may build back in late 
tonight. PROB30s were put in for SDF/HNB/LEX/RGA to cover the 
possibility for lingering rain showers tomorrow morning.

&&

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

&&

$$

SHORT TERM...CSG
LONG TERM...CSG
AVIATION...CAL