951
FXUS63 KLMK 141720
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
120 PM EDT Tue May 14 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Active pattern with 2 storm systems bringing chances of showers
    and storms through Saturday.

*   Scattered showers and storms, especially during the afternoon
    Tuesday and Wednesday.

*   Main impacts from this activity will be gusty winds, small hail
    and heavy rain that could result in localized minor flooding.

*   Another similar system arrives for the end of the week and into
    the weekend with a chance of showers and a few embedded storms.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 324 AM EDT Tue May 14 2024

A stacked low pressure center will drift from southeast Missouri
this morning into western Kentucky tonight, with a weak warm
frontal structure developing eastward along the length of Kentucky
this afternoon. Though the best moisture will remain well to our
south along the Gulf and southeast Atlantic coasts, there will still
be plenty enough of a supply this far north to support widespread
clouds and showers ahead of the advancing low. Instability this
afternoon will be kept in check due to the clouds and rain, but
models do suggest moderate lapse rates, 1000-1500 J/kg of SBCAPE
with 25-30kt of deep layer shear, and 25-30kt mid level winds
supporting loosely organized convection. The lack of strong synoptic
scale wind energy and DCAPE progged below 800 J/kg suggest mostly
sub-severe wind gusts, with any stronger gusts likely associated
with the heaviest downpours. WBZ heights indicate marginally severe
hail may be possible in the strongest updrafts. Slightly backed
surface winds ahead of the low will contribute to low level shear
and may facilitate a non-zero chance of an isolated, brief tornado
(STP < 1 all day), especially in the vicinity of the warm front. The
best chance of any severe storms will be from mid afternoon into
early evening south of Interstate 64.

Precipitation amounts will vary from one location to the next due to
the convective nature of the rainfall, but half an inch to an inch
is a good ballpark number for southern Indiana and central Kentucky
today through tonight.

Though we`ll have a warm start this morning around 60 degrees,
clouds and rain should prevent temperatures from warming much past
the lower and middle 70s this afternoon. Lows tonight will again be
around 60.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 324 AM EDT Tue May 14 2024

Wednesday morning, the low pressure system bringing showers and
storms during the short-term will be directly over the CWA. The
pooled moisture with the system will have precipitable water values
reaching into the 1.3-1.5" range over southern Indiana and central
Kentucky, and even though the system will quickly get pushed east of
the Washington D.C. area by 0z Thursday, its moisture over the CWA
won`t have the same urgency to leave. Model soundings show deep
layer moisture with modest instability, around 500-1,000 J/kg of
MLCAPE, during the afternoon and evening hours. Shear will remain
low with 0-6km values less than 20 knots, so it will likely be a
overall wet drizzly, sprinkly kind of day. There could be some
isolated to scattered heavier showers with a few thunderstorms
before things taper off in the evening/early Wednesday night.

Wednesday night will see the arrival of upper ridging and a sliver
of surface high pressure stretching south over the Great Lakes down
into the Mississippi Valley. Expect clearing skies over the CWA into
Thursday which will help boost temperatures from the mid 70s on
Wednesday to the upper 70s to low 80s Thursday afternoon/evening.

Thursday night through the weekend is where the forecast has been a
little messy the last few days due to model variation. The forecast
has carried precipitation chances through this time not because
there is really a chance of ongoing rain showers for several days,
but it`s the uncertainty during the period. Both the deterministic
models and ensembles have had this issue. For the last two nights,
there appears to be a better signal to move the precipitation in
earlier, beginning Thursday night or Friday. This earlier trend was
picked up first by the GFS, last night the Euro jumped on board, and
now that the NAM is in focus, it`s even earlier. Thursday night and
Friday look to be the best chance for heavier rain showers and
thunderstorms. A lower chance of precipitation could remain during
the weekend, but believe the trend is drier. Most of the data keeps
any showers and/or storms on Friday sub-severe. There could be some
instability which would make thunderstorms more likely, but limited
shear would limit storm development. If the NAM is correct, it
brings more impressive instability and shear Thursday night ahead of
the line of convection, but by the time the line would arrive in the
CWA, it would be elevated, which again would limit the severe
threat. For now, the weekend looks mostly sunny with highs in the
80s.

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 120 PM EDT Tue May 14 2024

Surface low pressure system moving into western KY will bring
showers and scattered thunderstorms through tonight.  Periods of
MVFR/VFR ceilings are likely, perhaps even brief (low confidence)
IFR conditions at times for area terminals. A brief break in
precipitation chances overnight will give way to another round of
scattered showers and thunderstorms after 12z Wednesday with MVFR
ceilings/visibilities.

&&

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

&&

$$

SHORT TERM...13
LONG TERM...KDW
AVIATION...MK