777
FXUS63 KLMK 262328
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
728 PM EDT Fri Jul 26 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Scattered showers/storms possible across southern KY today.

*   Precipitation chances increase slightly on Saturday and increase
    still further Sunday into mid week.

*   By Tuesday and Wednesday heat index readings will be reaching
    100 degrees in parts of the area, especially along and west of
    Interstate 65.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 342 PM EDT Fri Jul 26 2024

Sfc front is currently very near the Kentucky/Tennessee border, and
starting to show signs of wavering back to the north as a warm
front, especially out toward western Kentucky. Sfc high pressure
over Lake Huron is funneling a drying NE wind which has pushed upper
50s/lower 60s dewpoints into southern Indiana and north-central
Kentucky, but moisture pooling near the front has kept dewpoints in
the lower 70s in south central Kentucky. The front and increased
moisture, coinciding with a saddle point in the upper ridge, will
support a few isolated/scattered showers or thunderstorms during the
next few hrs over south central Kentucky. Weak wind fields will not
allow any storms to move anywhere fast, but with PWATs barely at 1.5
inches even the flooding threat is limited today.

Convection will die out an hour or two after sunset, with some
breaks in the cirrus ceilings overnight. Light winds and decreasing
cloud cover will support decent radiational cooling, but not ideal,
so mins will be generally in the 60s.

By Saturday the upper ridge starts to retreat toward eastern
Kentucky, with a weak southerly component through a deep layer. Best
moisture feed will run up the Mississippi Valley, so POPs will
increase from the south and west.  Look for a 20-30 percent chance
focused mainly SW of Interstate 165 and south of the Cumberland
Parkway. Storms on Sat afternoon will again be slow movers, with a
bit more heavy rain potential as PWATs creep up toward 2 inches. No
severe threat otherwise given the lacking wind fields.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 342 PM EDT Fri Jul 26 2024

Heading into Saturday night and Sunday, the relatively narrow upper
ridge over the Ohio Valley will begin to get pushed out of the way
by a strong shortwave associated with an upper trough, and while
this is going on, moisture at all levels will be flowing northward
across the CWA. Precipitable water values will climb to above 2" all
the way up into the Great Lakes region, and when PWATs get over 2"
in our region, it`s time to dig a little deeper into the data due to
heavy rainfall and flooding concerns.

Model soundings show deep layer saturation and "long skinny" CAPE.
Deep layer (0-6 km) shear is fairly weak around 25 knots where it
has remained for most of this past week. Storm motion looks to be
around 15 knots, and with temperatures expected to be in the 80s
which should make for a deep warm layer. All of this supports a risk
of showers and thunderstorms that could produce heavy rainfall and
localized flooding, so in coordination with WPC and surrounding
forecast offices, WPC is placing most of the CWA in the Slight risk
area of their Excessive Rainfall Outlook for Sunday.

Looking past Sunday, an upper high parks over Texas and will stretch
over most of the southern US, setting up an ugly northwest flow type
pattern from the Northern Plains into the Lower Ohio Valley.
Multiple shortwaves will work towards the CWA along this flow. Some
of these waves will push their own moisture which will meet up with
moisture already over the CWA, causing precipitable water values
over the CWA to bounce between 1.5" to just over 2" through the end
of the workweek. Nothing looks severe as the typical summer time
shear remains weak, but isolated to scattered showers and
thunderstorms will continue. High temperatures are expected to
increase a little each day until reaching into the low to mid 90s on
Thursday.

Beyond Thursday, the GFS has a cold front moving through on Friday,
but the Euro parks a surface low nearby, continuing rain chances.
So, confidence remains low for the late week period.

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 727 PM EDT Fri Jul 26 2024

Precip activity from earlier has just about diminished across the
KBWG region. As we go into tonight, expect dry conditions across the
area, but calm winds and saturated grounds from recent showers will
support the potential for fog development near KBWG. It`s possible
that vis will drop to MVFR for a few hours before sunrise.

Elsewhere, light winds overnight will mainly be from the NNE. For
tomorrow, expect light SE winds, VFR conditions, and upper-level
cloud cover. A few isolated pop-ups may be possible near KBWG
tomorrow afternoon.

&&

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

&&

$$

SHORT TERM...RAS
LONG TERM...KDW
AVIATION...CJP/LMP