454
FXUS63 KLMK 051315
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
915 AM EDT Fri Jul 5 2024

.KEY MESSAGES...

*   Scattered thunderstorms will move east across central KY and
    southern IN this morning into early afternoon. Some stronger
    storms could produce isolated damaging winds, torrential
    downpours, and frequent lightning. Localized flooding is
    possible.

*   Drier and less humid conditions are expected for the weekend.

*   Remnants of tropical cyclone Beryl may affect the Ohio Valley by
    late week.

&&

.UPDATE...
Issued at 915 AM EDT Fri Jul 5 2024

Watching a couple of areas of more intense storm activity this hour,
one approaching the Louisville metro and another crossing south
central KY. The northern one appears to be fading as it heads into a
more stable low-level environment, even one with some patches of fog
earlier this morning. Cannot rule out some reinvigoration as it gets
into the metro , so cannot give up on it yet.  The southern storms
are maintaining themselves well, per latest satellite imagery and
continued lightning activity. So far no reports of stronger wind
gusts...again per the diurnal minima in instability. SPC
mesoanalysist does show more these storms into a better surface-
based environment over the next hour or two. KY Mesonet showing
temperatures around 80 in the Lake Cumberland vicinity with
dewpoints in the mid 70s. PW`s are high areawide, so these will be
some heavier rains falling, and have had to issue a couple of flood
advisories where elements have trained a little longer than the
otherwise fairly progressive flow of the storms.

Will update the gridded forecast towards latest radar trends as well
as hi-res models for this afternoon.  Thinking we will see a break
by late morning/early afternoon, and then perhaps some isolated to
widely scattered showers/storms by late afternoon.

Issued at 535 AM EDT Fri Jul 5 2024

Showers and thunderstorms are now advancing east across southern IL
and western portions of KY/TN. This wave of active weather is still
expected to impact southern IN and central KY from roughly 7 AM
through early afternoon. In the near-term, MLCAPE is roughly 1000
J/kg but low-level lapse rates are meager given the time of day.
Furthermore, the convection in western KY appears to be sub-severe
as of this writing. However, we are seeing brief upticks in
convective intensity along the leading edge. Still cannot rule out
localized wind damage, but would expect winds of 30-40 mph to be a
lot more common with this activity as it approaches our southwestern
CWA. Torrential rainfall and localized flooding will also be of some
concern, especially if any training occurs. Expect heavy rainfall to
reduce visibility and cause ponding of water on the roads this
morning.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 305 AM EDT Fri Jul 5 2024

A low pressure system is spinning across the Upper Midwest early
this morning. A mid/upper level trough is forecast to swing across
the Great Lakes today, spreading moderate WSW flow aloft as far
south as the Ohio Valley and central Appalachians. At the surface,
low pressure will move from southern Wisconsin across Michigan and
drag a cold front southeast through central Kentucky and southern
Indiana this afternoon and evening.

A moist airmass remains in place across the Lower OH Valley with sfc
dewpoints in the low to mid 70s. Moisture convergence and low-level
moisture transport is forecast to briefly surge once again this
morning ahead of the cold front and convection currently moving
through Southeast Missouri. Recent SPC RAP mesoanalysis data shows
1500 J/kg MLCAPE present across much of central KY, though notable
low-level CIN will naturally linger through sunrise. As the
mid/upper trough draws slightly closer, effective deep-layer shear
will be as high as 35-40 kts this morning.

One or more storm clusters or line segments appear likely to move
ENE across southern IN and central KY from 7-8 AM through 1-2 PM.
These storms will be capable of isolated damaging winds, heavy
downpours, and intense lightning. Areas east of I-65, especially the
Bluegrass Region, will have slightly more time for the airmass to
destabilize and low-level lapse rates to steepen. But anywhere will
be fair game for locally gusty winds and heavy rainfall. PW values
are forecast to surge to 2.0-2.2 inches with this early day wave, so
very heavy rainfall rates could result in localized flooding issues.
While the storms should be fairly progressive overall, cannot rule
out isolated flash flooding.

Precip coverage will diminish for the second half of the day. A few
isolated showers/storms will still be possible as the actual cold
front sweeps through, but it looks to be pretty spotty. Winds will
veer westerly this afternoon and increase to 10-15 mph. Temperatures
will top out in the mid/upper 80s.

Skies will begin clearing from west to east late in the day. Drier
air will continue to advect into the region tonight behind the cold
front. It will be a dry night with lows in the low to mid 60s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 305 AM EDT Fri Jul 5 2024

Saturday through Monday Night...

Surface cold front is forecast to south and east of the region by
Saturday morning with high pressure building in from the west.
Mostly sunny skies are expected on Saturday with much less humidity.
Afternoon temps will warm into the 85-90 degree range while dewpoints
remain in the lower 60s.  Quiet conditions will continue into
Saturday night with lows dipping into the lower 60s.  A few of the
typical cooler spots will probably dip into the upper 50s.  Quiet
weather will continue into Sunday with slightly warmer temperatures.
Mid-level heights will rise slightly during the day and afternoon
temps look to warm into the upper 80s with a few spots hitting the
lower 90s.  Temperatures Sunday night will fall back into the mid-
upper 60s.

Moving into the new work week, the global deterministic and
ensemble solutions continue to show strong ridging developing across
the western US with a downstream trough axis in the Plains.  This
will place the Ohio Valley within a broad southwest flow aloft. This
southwest flow will also bring an increase in low-level moisture to
the region and some diurnally driven convection will be possible
during the afternoon/evening.  Highs Monday will again warm into the
upper 80s and lower 90s with lows Monday night dropping back into
the upper 60s/lower 70s.

Tuesday through Thursday...

By Tuesday, the central Plains trough is expected to move through
the Ohio Valley bringing a higher chance of showers/storms to the
region.  This trough axis quickly moves off to the east by Wednesday
with a somewhat quick transition to zonal flow aloft.  By mid-late
week, the remnants of tropical cyclone Beryl are forecast to lift
northward through Texas with the residual moisture plume moving
northeast through the Ozarks and then into the Ohio Valley toward
the end of the period.

For this forecast, will continue to run the highest chance of PoPs
in the Tuesday time frame with the initial upper trough passage.
PoPs will be kept near climatology for Wed/Thu with 20-30% coverage.
Higher PoPs will likely be needed for the late Thu/Friday period as
the remnants of Beryl track through the region.  Highs through the
period will be close to seasonal with mid-upper 80s for highs and
overnight lows in the upper 60s to the lower 70s.

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 657 AM EDT Fri Jul 5 2024

Strong TSRA will push west to east across central KY and southern IN
in the first six hours of this TAF period. Brief IFR/MVFR ceilings
and visibilities will be likely within TSRA and areas of heavier
rainfall. Locally gusty winds of 30-40 kts will also be possible in
stronger thunderstorms. Most likely timing of TSRA is reflected in
each TAF.

Outside of storms, light southwesterly winds this morning will veer
westerly and increase this afternoon and evening with the passage of
the cold front. Winds diminish tonight as skies clear and drier air
advects into the region.

&&

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

&&

$$

UPDATE...EBW/RJS
SHORT TERM...EBW
LONG TERM...MJ
AVIATION...EBW