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000
FXUS63 KLMK 240517
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
117 AM EDT Wed Apr 24 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Rain showers tonight, with a quarter to half inch of
    precipitation over southern Indiana and lesser amounts farther
    south in Kentucky.

*   Lows in the upper 30s Wednesday night from southern Indiana into
    the northern Bluegrass region, and typical cold spots.

*   Active weather Friday through the weekend, but plenty of
    uncertainty in timing of any intervals of showers and
    thunderstorms.

*   Weekend will feature temperatures in the 80s and breezy
    southerly winds.

&&

.UPDATE...
Issued at 905 PM EDT Tue Apr 23 2024

The forecast is mostly on track this evening as widespread light
rain currently works across our northern CWA. Seeing some deeper
moisture transport (PWATs above 1") funneling into our area with the
aid of a 30-40 knot low level jet, and just ahead of the shortwave
trough axis noted nicely on water vapor imagery. As a result,
looking for categorical pops (80-90%) across our northern CWA, with
pops tapering to likely across southern and central KY later tonight
as the LLJ weakens. Precipitation is having to overcome some pretty
dry lower levels, so wouldn`t be surprised to see some amounts fall
short of the .25" to .5" amounts north of I-64. HNB has only seen
.07" as of 9 PM EDT, and with rain about done it appears they will
fall short of forecast totals. Still like the high pops, but amounts
might end up more in the .1" to .25" range across our north. A tenth
of an inch or less still looks good across the south.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 337 PM EDT Tue Apr 23 2024

Upper shortwave trof is diving SE through the Upper Midwest, with a
sfc cold front and associated rain band pushing across Illinois and
Indiana. Look for this front to be just north of the Ohio River by
sunset, after which it will make slower progress through Kentucky.
Expect rain showers for most if not all locations in southern
Indiana this evening, with a quarter to half inch of QPF. Rainfall
amounts will taper from north to south across Kentucky, with less
than a tenth of an inch in south central Kentucky as the slower
moving front is left behind by the east-moving upper wave.

Precip shield departs in the pre-dawn hours Wednesday, giving us a
dry and slightly cooler day as Canadian high pressure builds
southward through the Great Lakes. Temps will run a few degrees
below normal, with light north winds.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 337 PM EDT Tue Apr 23 2024

Sfc high pressure over the Great Lakes Wednesday night will slowly
work eastward towards the northeastern US by the end of the week as
upper ridging over the central US builds eastward over the Ohio
Valley. This will result in quiet weather over the area through
Friday morning. Northwest flow aloft along with northrly sfc winds
and mostly clear skies will translate into a chilly Thursday
morning. With winds remaining near or even slightly above 5 mph, the
frost threat looks very low but wouldn`t rule out spotty frost
development, especially across the Bluegrass where lows could drop
into the upper 30s while the rest see lows near 40. As heights
increase aloft due to upper ridging, temperatures will be just shy
of seasonal norms in the upper 60s to low 70s Thursday afternoon.

Through the end of the week and into the weekend the overall pattern
begins to shift and turn more active. A series of storm systems will
develop over the Central Plains and then work to the northeast into
the Upper Midwest along the western peripheral of the upper ride
that will be over the eastern half of the CONUS. The first of these
systems will start to take shape Thursday night into Friday as an
upper low over the Baja gets picked up and opens up into a shortwave
trough over the Central Plains. As this system tracks to the
northeast it will lift a warm front across the Ohio Valley during
the day on Friday. Showers and a few embedded thunderstorms are
possible but model sounding show meager instability with shear
increasing behind the boundary as a stout LLJ works into the Ohio
Valley. Our highest PoP chances will be during the day on Friday and
work from the southwest to the northeast during the day.

We will be squarely in the warm sector for the weekend thanks to
strong southerly flow advecting in warm moist air into the area.
Highs will be about 10 degrees above normal warming into the low 80s
each day and overnight lows in the 60s. With the main storm track to
our west, the bulk of the weekend looks relatively dry. Saturday
places southern IN and central KY in a weak area of shortwave
ridging and strong sfc high off the Mid-Atlantic coast. While there
will be plenty of instability on Saturday along with a strong LLJ,
there continues to lack any trigger to fire off any activity.
Current forecast keeps isolated to scattered chances in mainly
across southern IN and along the Ohio River. Thanks to the strong
winds aloft and a tightening pressure gradient, the potential
impacts this weekend could be gusty winds. Confidence is growing of
gust of around 30-35 mph with a few isolated 40 mph not out of the
question. Winds will remain gusty for Sunday between 25 to 30 mph as
the next storm system develops over the central US and take a
similar track to the northeast into the Upper Midwest by Monday.
Shower and storm chances look similar to Sunday but extending a
little further to the south and southeast. Scattered to isolated
showers are possible along and west of the I-65 corridor.

The aforementioned sfc low and shortwave trough will work a cold
front across the area on Monday with a chance of showers and
thunderstorms. Temperatures will remain warm in the 70s for the
start of next week

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 117 AM EDT Wed Apr 24 2024

Areas of light rain from a VFR ceiling associated with a nearby cold
front will taper off during the pre-dawn hours as the front pushes
through.

An area of low stratus and patchy fog has developed from southern
Illinois to central Ohio. The future of this area of fog and cloud
is uncertain. Recent satellite trends show little if any southward
progression of the clouds, though some new cloud development has
taken place over south central Indiana in the last hour. Right now
confidence is not high enough to introduce a sub-2k` ceiling into
the TAFs, but will include SCT low clouds in an effort to take a
tentative step in that direction, and to account for the scattered
low clouds that have recently popped up between IND and SDF.
Northwest breezes should stay up enough to reduce chances of fog at
the 06Z TAF sites, but will be something to keep an eye on.

High pressure building into the region from the Great Lakes today
and tonight will otherwise provide quiet weather with NNW breezes
and partly cloudy skies for the bulk of the daylight hours, and
mostly clear skies with light NNE breezes tonight. There may be some
river valley fog by sunrise Thursday but SDF will stay VFR.

&&

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

&&

$$

UPDATE...BJS
SHORT TERM...RAS
LONG TERM...BTN
AVIATION...13