729
FXUS63 KLMK 221941
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
341 PM EDT Wed May 22 2024

.KEY MESSAGES...

*   Strong/severe storms possible region wide this afternoon with
    damaging winds, hail, and very heavy rainfall being the main
    threats.

*   Stormy pattern with a risk for localized flooding Thursday
    through Tuesday with strong/severe storms possible Sunday.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 341 PM EDT Wed May 22 2024

Forecast is still on track to see scattered clusters of strong to
severe thunderstorms this afternoon into the evening hour. Sfc cold
front remains oriented northeast to southwest stretching from around
Ft. Wayne, IN, to around Bloomington, IN curving towards Vincennes,
IN and along the borders of far western KY and southern IL. Current
afternoon mesoanalysis shows Td mainly in the upper 60s to even a
few low 70s southern IN and most of KY. SBCAPE ranging from 1500-
3000 J/kg, with the lowest values mostly to the east/southeast where
shower/storm activity has been persistent most of the afternoon.
Visible satellite imagery shows partly to mostly clear skies along
the Ohio River into southern IN with mostly cloudy conditions across
our southern counties. Area WSR-88D continues to show a linear
cluster of showers/storms along a prefrontal boundary stretching
from the Bluegrass then southward along the KY/TN border. This
convection stretches back into far western TN. SPC continues to keep
all of central KY in a slight risk for severe storms with gusty
damaging winds being the main threat as DCAPE values along and ahead
of the sfc boundary across southern IN and along the OH River range
from 1100-800 J/Kg. Large hail can`t be ruled out given the ample
amount of instability especially seen in the hail growth zone on
model soundings for later this afternoon and evening. While the
tornado threat is relatively low, shear still looks to be between 30-
40kts. Hi-res CAMS like to lift the cluster of convection currently
over far western TN northeastward into our southern CWA later this
afternoon and evening. Feel the main focus and highest probability
of strong to severe storms will be across our southern CWA along the
KY/TN border but any outflow associated with these storms working
into the higher instability to the north and interacting with the
slow approaching sfc boundary would likely initiate additional
convection north of the Parkways towards the Ohio River with the
potential for some supercells and even linear development later this
evening. While activity continues to along the KY/TN border, our
best chance remains between 5pm EDT this evening to around 10pm EDT
with the bulk of the activity pushing out between 11pm/Midnight EDT.

While focus is on severe potential the other impact will be the
potential for heavy rain and localized flooding. PWAT axis on
mesoanalysis stretching from Memphis TN where we have a bullseye of
2.00" into the Bluegrass where we have 1.60" is where we are seeing
the main focus of activity so far this afternoon. Any storms will
produce very heavy rainfall and if storms train over an area
localized flash flooding is a possibility. The one positive here is
that the dry weather the last couple of day has allowed current 1hr
FFG to range from around 1.75" at the lowest to as high as 3.00"
over our CWA.

Once activity pushes off and out of the area overnight we will be in
a bit of a lull but a second shortwave pulse will work across the
Ohio Valley overnight into tomorrow morning. This could produce
another cluster of showers and storms working from the Bootheel of
MO through KY and southern IN during the morning hours.  Sfc
boundary looks to stall out over the Ohio River for tomorrow with
more scattered showers/storms possible especially during the
afternoon. It`s possible we could see a lull in the activity briefly
during late morning into early afternoon. The threat of severe
appears to be lower but remains as SPC has the southern half of our
CWA in a marginal risk (1 out of 5) for the potential for strong to
severe storms.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 340 AM EDT Wed May 22 2024

Thursday through Wednesday...

A cold front will stall over the Ohio Valley, and coupled with
multiple shortwave troughs of low pressures and continued
southwesterly jetstream flow, will lead to increased chances for
showers and storms through Tuesday. Temperatures will warm each day
from near normal to slightly above normal. Dew points will also
remain in the mid-upper 60s, which will lead to warm and muggy
conditions through Tuesday.

Strong to severe storms are possible, however, this will likely be
determined on a day-by-day basis to assess mesoscale evolution and
recovery for convective initiation. Moisture is present through the
weekend and instability recovery looks possible each day, however,
shear remains weak-marginal. In this scenario, main hazards would be
locally gusty to damaging winds with heavy downbursts and lightning.

Sunday continues to trend as the best convectively organized day. A
low pressure system will likely move thorugh the mid-Mississippi
Valley and into the Ohio Valley, promoting stronger deep-layer
dynamics for strong storms organization. Model forecast soundings
suggest a very moist and unstable environment, with ample deep-layer
shear. Coupled with dynamic triggers at the surface and aloft will
likely allow for strong to severe storms. ECMWF EFI shows a signal
of 0.75-0.85 and a shift of tails of 1 on Sunday, which is a
generally significant signal given that most of M climate is within
severe weather season. CSU probabilities also shows a signal over
the region for Sunday. Over the next few forecast periods, trends
will be monitored closely.

Given multiple days of rain and possible training of cells, flooding
and flash flooding is possible. Current QPF for this timeframe is 2
to 4 inches, with locally higher amounts possible in the strongest
thunderstorms.

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1259 PM EDT Wed May 22 2024

Active weather expected in the near term with multiple rounds of
showers and storms likely to impact most TAF sites today. Most
shower and storm activity is south of a line from Madison County
(KY) to Simpson County (KY) and is gradually pushing east.
Additional showers and storms will develop to the west and southwest
later today and move into the region. Some of this activity will
likely clip TAF sites and result in briefly reduced cigs/vis.

We should see a lull in activity overnight, but more showers and
storms could develop toward dawn tomorrow and overspread much of the
region.

&&

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

&&

$$

SHORT TERM...BTN
LONG TERM...SRM
AVIATION...DM