LMK issues Area Forecast Discussion (AFD) at Jun 13, 6:56 AM EDT ...Updated Aviation Discussion...986
FXUS63 KLMK 131056
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
656 AM EDT Fri Jun 13 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
* Waves of showers and thunderstorms are expected today. Heavy
rainfall and localized flooding is the main concern, though
isolated gusty winds and small hail are also possible.
* Additional rounds of showers and storms are expected over the
weekend. The potential for severe storms is low, but additional
waves of heavy rain may increase the potential for flash flooding.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 337 AM EDT Fri Jun 13 2025
The main weather-maker across the Ohio and Tennessee valleys over
the next few days is a cutoff upper low which will meander from MO
into southern IL today into tonight. Downstream from the center of
the upper low, moderate to somewhat elevated 500 mb SW flow on the
order of 20 to 30 knots will continue over the region. Deep-layer
southerly and southwesterly flow will continue to advect a tropical
air mass into the region, with PW values expected to range from 1.75
to near 2". This will all condition the atmosphere for multiple
waves of showers and thunderstorms starting today and continuing
over the weekend.
This morning, a decaying band of showers and storms has lifted into
western KY on the leading edge of an 850 mb jet. Later this morning,
a secondary LLJ is expected to push across western TN and KY,
helping to spark additional waves of showers and storms for the late
morning and afternoon. As these waves of showers and storms push
into central KY and southern IN, dewpoint temperatures are expected
to rise into the upper 60s and lower 70s, with air temperatures
rising with daytime heating later this morning. Exactly how much
heating occurs is uncertain, and will be limited by increasing low-
and mid-level cloud cover, especially west of I-65. As a result,
temperatures should be a few degrees cooler in most locations today,
with highs expected to range from near 80 west of I-65 to the mid
80s along the I-75 corridor.
The combination of ingredients for thunderstorms this afternoon is
modest. Instability progs show between 1400-1800 J/kg MLCAPE, though
poor (~5 C/km) mid-level lapse rates will result in a "tall, skinny
CAPE" profile which is less favorable for explosive updrafts.
Effective bulk shear values are expected to be around 20-25 kt, so
one or two organized clusters of storms is possible. Low-level shear
is weak, so rotating updrafts are unlikely with today's storms,
although it should be noted that a subtle sfc boundary is expected
to lift through the area today, with backed winds likely in the
vicinity of this boundary. All in all, the severe potential appears
to be limited, though isolated instances of strong wind gusts and
small hail is certainly possible. Heavy rainfall and isolated
flooding will be of greater concern, and the 00Z HREF localized
probability-matched mean QPF field does show a few swaths of 2-4"
across the area this afternoon.
As instability wanes this evening into tonight, the coverage of
showers and storms will diminish. With that being said, continued
warm/moist advection within 20-25 kt of SW flow at 850 mb should
support at least isolated to scattered showers overnight. The
saturated air mass will limit cooling, with low temperatures
Saturday morning only expected in the upper 60s and lower 70s.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 337 AM EDT Fri Jun 13 2025
This Weekend...
Unsettled weather is expected to continue over the weekend as the
upper low gradually weakens and moves across the Ohio Valley. With
no significant changes in the synoptic flow patterns, the tropical
air mass should remain in place, with PW values remaining between
1.8-2". Although there will be plenty of near-sfc moisture, elevated
moisture content through the troposphere and continued poor lapse
rates will limit instability. As the upper low moves nearly
overhead, deep-layer shear and mean winds will weaken, further
reducing the potential for organized/severe storms while increasing
the potential for slow moving/heavy rainfall amounts. Fortunately,
the lack of organization will keep shower/storm development fairly
random, though any locations which receive multiple waves of storms
over the weekend could see flash flooding. Diurnal temperatures will
be suppressed by increased cloud cover and the muggy air mass, with
highs expected in the low-to-mid 80s and lows in the upper 60s and
lower 70s.
Next Week...
There is growing consensus in a decrease in shower/storm activity
for Sunday night into Monday as the remnant energy from this
weekend's system dissipates and lifts to the northeast. The
continued humid air mass will still keep a chance for afternoon
showers and storms on Monday, but coverage should be more isolated
than over the weekend.
For the middle and latter portions of next week, split upper-level
flow will develop across much of the CONUS downstream of the Pacific
jet which will extend into the northwestern US Monday into Tuesday.
This will allow a couple shortwaves to slide across the northern
half of the US within the broader zonal flow pattern. As these waves
pass by just to the north of the region, they should fire off
additional waves of showers and thunderstorms. While there should be
considerable gaps between waves of showers and storms, confidence in
timing these waves is only low-medium at this point, so we'll have
to keep an ongoing elevated PoP in the forecast for much of next
week. Stronger signals for showers and storms are present Tuesday
afternoon and evening and again on Thursday, though this may change
as additional guidance comes in over coming days. Each of these
waves of storms would carry a potential for stronger wind gusts
given a pattern which is somewhat favorable for MCS development;
however, confidence in this is also low. Temperatures will gradually
warm next week, although the current forecast is only a few degrees
above normal for mid June.
&&
.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 656 AM EDT Fri Jun 13 2025
There is fairly low forecast confidence beyond the first few hours
as multiple waves of showers and thunderstorms are expected to move
across area terminals later today. Outside of showers and
thunderstorms, VFR conditions should be prevalent, though IFR/MVFR
ceilings and visibilities will be possible with heavier showers and
thunderstorms. Generally speaking, the greatest concentration of
showers and storms should be between 17-00Z, with coverage
decreasing after sunset tonight. Winds will be light out of the
south today, backing to the southeast later this afternoon and into
the evening. Tonight, VFR conditions are expected to continue,
though model guidance hints at falling ceilings from north to south
during the early morning hours on Saturday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...CSG
LONG TERM...CSG
AVIATION...CSG
Source:
LMK issues Area Forecast Discussion (AFD) at Jun 13, 6:56 AM EDT ...Updated Aviation Discussion...---------------
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