346
FXUS63 KLMK 131606
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1206 PM EDT Mon May 13 2024

.KEY MESSAGES...

*   Active pattern with 2 storm systems bringing chances of showers
    and storms through Saturday. Best chance for a dry day will be
    Wednesday afternoon and Thursday. Severe weather is not expected.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 1205 PM EDT Mon May 13 2024

Conditions remain dry early this afternoon with a few light showers
noted across western KY, SE MO, and TN. A nearly vertically-stacked
low pressure system is approaching Kansas City, with troughing
extending south across TX. This slow-moving low closes off as it
meanders eastward across Missouri this evening. Southerly to
southwesterly flow in the low to mid-levels will pull Gulf moisture
northward ahead of the low. Lingering dry air up through the mid-
levels will keep us mainly dry into the afternoon hours. A few
isolated light showers will be possible across the southern and
western parts of the forecast area by late afternoon and early
evening. Otherwise, expect a relatively quiet afternoon with
thickening clouds and temperatures topping out in the mid 70s to
near 80 degrees.

Tonight, moisture and lift deepen as the low rotates east across
Missouri. Moderate low-level moisture transport develops along a 25
kt LLJ. PW increases to 1.3+ inches with forecast soundings showing
a moist profile with limited instability. Scattered showers are
likely, and there is a slight chance (10-20%) for an isolated rumble
of thunder. Precipitation will be somewhat spotty, with more
widespread activity arriving Tuesday. Expect mild morning lows in
the upper 50s to lower 60s.

Numerous showers with scattered storms are expected Tuesday as the
low moves over the Lower Ohio Valley. While broad ascent is noted
along with deep, rich moisture, instability will be kept in check by
clouds and moist adiabatic lapse rates. Tall, thin SBCAPE developing
by the afternoon will support scattered storms capable of locally
heavy downpours, gusty winds up to 40 mph, and perhaps isolated
small hail. Deep-layer shear is only 20-25 kt, with stronger mid-
level winds remaining to our south across the Gulf Coast states.
This will significantly limit convective organization, and severe
weather is not expected. Rainfall amounts of 0.50-1.25" inches are
possible, with some locally convectively-enhanced totals not out of
the question. With a wet ground and above normal streamflow, might
result in some ponding and minor flooding issues in low-lying or
flood-prone areas. Temperatures will top out in the 70s Tuesday
afternoon.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 312 AM EDT Mon May 13 2024

Tuesday - Wednesday...

Well...a very slow meandering closed low pressure will go from Show
Me State and eventually thru the Ohio Valley. This low will pass
thru the LMK CWA with plenty of deep lift and moisture. Time
sections show deep tropospheric moisture along with omega fields and
deep layer isentropic lift.  This portends a rainy day (hyetal
pattern).

Moisture/clouds will keep instability in check and deep-layer shear
will remain weak, so expecting no severe weather. However...thin
long CAPE, PWATS of 1.4" and WBZ around 10K bring a few shra/tsra
with graupel and some 30-40 mph gusty showers. Rainfall amounts of
0.60-1" inch are possible through Wednesday, with some locally
convectively-enhanced totals not out of the question. With a wet
ground and streams above normal flow...might result in some ponding
and minor flooding issues in low-lying or flood-prone areas.

Rain chances linger into Wednesday with moisture wrapping around the
slow-moving system, with Bluegrass stuck in low clouds and sct shra.
Meanwhile clouds will be trying to thin and clear out from the the
west heading towards I 65 corridor.

Area west of I 65 should see some later afternoon peaks of sun and
perhaps some crepuscular rays. Areas of east of I 65 and especially
east of US 127 will be stuck in the clouds til sunset. Temps west of
I 65 should see mid 70s. Towards the Bluegrass region, soundings and
time sections show 850 moisture stuck in east of I 65,
consequently temps might struggle to get to 70F.

Wednesday night - Thursday Night...

Shortwave ridging building east over the Ohio Valley will bring dry
weather Wednesday night through Thursday. Look for mostly clear to
partly cloudy skies with lows in the 50s and highs in the upper 70s
to low 80s. Behind this front and with the transitory high pressure
with winds switching from northerly 5-10 mph to the south 5-10 mph
during the afternoon.

Friday...

Two pieces of energy, a distinct southern stream over ARKLATX and
one from Great Lakes with cold front into MO/IL.  Will they phase or
be separate will determine Fri.  The GFS combines them and the ECM
does not. Deterministic GFS shows an all day rain but there is quite
a spread in GFS ensemble data.  WRT the northern stream the ECM has
the low at 18z Fri w over Lake Winnipeg with trough across E ND/E SD
to Lincoln NE. The GFS is much further east over Gitchee Gumee to N
IL.

Friday night and Saturday...

A cold front will be taking over Friday night with what should be
plenty of lift and abundant moisture. Some thunderstorms will be
possible, with marginal instability for convection. Another 0.50-1
inch is possible with this wave.

Major differences in GFS and ECM (old 12Z) for Sat with ECM showing
closed low over Ohio Valley and IL/OH, and GFS showing hints of
ridging moving in.  Now I see why NBM has sct precip for this
coming weekend.  The 12z ECM would result in cloudy, intermittent
rain and temps well blo normal. The new ECM has sped things up and
will opine, still significant differences in the data.

Weather Factoid...

May 14 1995...Widespread severe weather event. Fort Knox gusted to
104 mph...baseball hail caused 5 million in Marion County, Bullitt
County F2 downed trees, Franklin County tornado touched down near
Frankfort, and in Nelson County, house struck and destroyed by
lightning, and 17 year old boy was struck and injured by lightning.

&&

.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 1205 PM EDT Mon May 13 2024

Mid-level ceilings will steadily lower this afternoon and evening as
moisture deepens ahead of lower pressure near Kansas City. This
stacked low pressure system will rotate slowly across Missouri
tonight, with scattered showers and MVFR ceilings developing
downstream across central KY and southern IN. Brief vis reductions
in a moderate shower cannot be ruled out, but this won`t be the
prevailing condition.

Numerous showers expected Tue along with scattered TSRA as the low
drifts east over the Lower Ohio Valley. Expect slow ceiling
improvement into the afternoon hours, but occasional ceiling/vis
reductions possible in heavier showers. Some storms could produce
locally gusty winds (up to 40 mph) as well.

&&

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

&&

$$

SHORT TERM...EBW
LONG TERM...JDG
AVIATION...EBW