311
FXUS63 KLMK 141054
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
654 AM EDT Mon Apr 14 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Severe thunderstorms will be possible this afternoon across the
  Bluegrass region of central Kentucky.

* The primary severe weather threats will be large hail, damaging
  winds, and a risk of isolated tornadoes.

* Cooler and dry conditions are expected for the middle of the week
  before warmer temperatures returns late this week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 312 AM EDT Mon Apr 14 2025

Conditions across the region were partly cloudy this morning.  A
gradient of temperature was noted in observations.  Temperatures
ranged from the lower 70s over far western KY to the low 60s in the
I-65 corridor.  OUt east of the I-75 corridor, temperatures were
more of a ridge/valley split with the ridges in the upper 50s/lower
60s and valleys in the lower 40s.  Breezy southerly winds will
continue overnight, but no significant weather is expected through
sunrise.

After sunrise, daytime mixing will begin in earnest.  Surface winds
are expected to pick up through the mid-late morning with winds
becoming gusty by lunchtime and continuing through the afternoon.
Have gone a little higher with temps given the strong southerly wind
flow.  Plan on going with mid-upper 70s across southern Indiana and
much of the northern half of Kentucky with upper 70s and lower 80s
across southern Kentucky.

During the afternoon hours, attention will turn to convective
development ahead of an approaching cold front.  Southerly flow
across the area today will transport low-level moisture into the
region and allow this moisture to pool across much of central and
eastern KY.  By late afternoon, a mid-level jet streak will approach
from the west and much of our region will be within the left exit
region of this 80-90kt jet.  The combination of the synoptic scale
lift with the jet and the cold front should result in scattered to
numerous convection firing across portions of the region.

For the past several days, the convective signal has been there in
the data, with the main concern on whether convection would be able
to break through some mid-level capping.  The last several runs of
the CAMs have been trending stronger with the forcing and weakening
this cap, especially in areas east of I-65.  Model soundings across
the region show rather straight and elongated hodographs with 0-6km
shear values in the 55-65 kt range.  MLCAPE values increase across
the area to 1500-2000 J/kg during the afternoon with the highest
values, mainly east of I-65. Lapse rates in the 700-500 mb layer are
impressive as well with values of 7-8 C/km.

Current thinking is that we`ll see the cap break between 3-5 PM this
afternoon, in a zone roughly from Campbellsville northeast to
Ashland.  Given the thermodynamic and kinematic parameters, multi-
cellular and supercells are expected favoring large hail and
damaging winds.  Depending on updraft strength and localized
instability hot spots, some of the strongest cores could produce
very large hail.  By late afternoon, the low-level jet flow will
increase in the I-75 corridor and points east resulting in a low-
level flow more prone for tornado production.  Eventual upscale
growth of convection into linear bow like structures is expected
with a damaging wind threat being possible.  The highest threat of
severe is across the eastern half of our area, roughly east of a
line from Louisville to Campbellsville.  The current slight risk
area from SPC looks good, though I could see some extension of this
risk further south and southwest in later outlooks.

Convection from the late afternoon should continue to move off to
the southeast and weaken with time as the sun sets.  Convection many
linger over our southern and southeastern sections into mid-evening
before dying out.  Cooler and somewhat drier air will push into the
region tonight with lows falling back into the middle 40s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 312 AM EDT Mon Apr 14 2025

Mid-level trough axis will swing through central and eastern KY
during the day on Tuesday. This will keep the Ohio Valley under
cyclonic northwest flow and allow for cooler air to advect in over
the region. A few clouds may build in over the parts of southeast
IN, and the Bluegrass during the afternoon with daytime highs below
seasonal normals by nearly 10 degrees in the mid/upper 50s across
most of our CWA with near 60 along the KY/TN border. Sfc high
pressure coming out of the central plains will move over MS/AL on
Wednesday as the upper ridge to the west slowly works over the Ohio
Valley. This will keep skies clear and allow for increased heights
over the region, which will result in slightly warmer temperatures
for the middle of the week. Lows Wednesday morning will be chilly,
in the upper 30s to near 40 with afternoon highs warming into the
low 60s, which are still around 5 degrees below normal for mid
April.

By the end of the week, sfc high will move off to the east as the
upper ridge builds over the eastern half of the CONUS. A lee-side
sfc low develops over the Rocky Mountain Front Thursday and then
towards the eastern Great Lakes by Friday. A warm front will lift
northward during the day on Thursday, mainly over our northwestern
CWA. This could result in a couple of showers/thunderstorms across
southern IN. Winds will become more southerly advecting in warm
moist air from the south. By Friday, as the sfc low works into the
Great Lakes, our precipitation chances will depend on where the
associated cold front stalls in relationship to the Ohio Valley and
southern IN/central KY. Models are trending more westerly with this
feature keeping just slight chance of showers/storms along the Ohio
River and north into southern IN. It will become much warmer for the
end of the week as highs will be in the mid/upper 60s on Thursday
with upper 70s and even a few isolated 80s on Friday.

Rain showers and a couple of thunderstorms could be around heading
into the weekend depending on where the advancing cold front to our
west stalls over the region. A second storm system take shape over
the TX Panhandle by the end of the weekend and takes a similar path
into the Great Lakes by Monday. This would lift the stalled boundary
back northward as a warm front and bring another chance of showers
to the region. At this point, we are still to far out to get any
real details on this scenario. Forecast continues to keep rainfall
totals low, (around a half an inch or less), with warm temperatures
remaining in the mid 70s.

&&

.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 654 AM EDT Mon Apr 14 2025

LLWS will diminish but surface winds will pick up out of the
west-southwest. Wind gusts of 20-25kts will be common through the
afternoon. Convection is likely to fire across portions of the
region in the afternoon.  Convection is most likely to affect our
eastern terminals (KLEX/KRGA).  However, will continue to keep a
PROB30 in at KSDF/KBWG for this forecast.  Convection will wane
rapidly after sunset with northwest breezes and VFR conditions
expected for the remainder of the period.

&&

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

&&

$$

SHORT TERM...MJ
LONG TERM...BTN
AVIATION...BTN