972
FXUS63 KLMK 080731
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
331 AM EDT Sat Jun 8 2024

.KEY MESSAGES...

*   Showers and a few thunderstorms this weekend, with extended
    breaks in the rain expected. Locally heavy downpours possible
    late Saturday night into early Sunday morning across western and
    southern Kentucky.

*   Temperatures will begin a warming trend Tuesday, with 90 degrees
    a possibility by late week, especially Friday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 330 AM EDT Sat Jun 8 2024

Across the region early this morning, mostly clear skies are
observed on latest nighttime microphysics satellite imagery, with
the first few convective debris clouds from an ongoing MCS over
eastern KS and western MO reaching our area at this time. As we head
toward dawn, additional clouds will begin to move toward the region
as the convective system moves eastward. This system should weaken
considerably as it loses its source of instability; however, an area
of light to moderate rain showers will approach areas west of I-65
by the mid-to-late morning hours.

Since the pre-existing air mass over our area is abnormally dry,
would expect initial radar returns to struggle to make it to the
ground later this morning. While current analysis and short range
progs do show increasing PWAT values later today, inspection of the
moisture profile via hi-res soundings reveals that much of this
moisture increase will take place above 700 mb, with the lowest 10
kft being slow to saturate. Accordingly, have lowered PoPs from NBM
guidance, though this still leaves chance PoPs across much of the
area later today. PoPs generally decrease the farther south and east
you go, given that the remnants of the MCS should be falling apart
as they move east across central KY and southern IN.

With the additional mid- and upper-level moisture present, mostly
cloudy skies are expected for much of the day today. Clouds are
expected to keep temperatures in the mid-to-upper 70s outside of
southern KY, though there is a low confidence possibility that brief
breaks in the clouds later this afternoon could allow temperatures
to quickly surge up into the 80s (10-20% likelihood). With the sfc
high pressure axis shifting to the southeast U.S. later today, SW
winds on the order of 5-10 mph are expected during the daytime hours.

This evening into tonight, an upper-level shortwave moving through
the upper Midwest will help to push a sfc cold front into the region
from the north. To the west of the region, waves of convection are
expected to initiate over central MO as convergence and lift in the
vicinity of the aforementioned front combines with a quite unstable
air mass over the Ozarks. Once this convection fires up, it should
move to the ESE along with deep-layer flow, taking it into the lower
Ohio and Tennessee valleys. Early Sunday morning, rain showers and
embedded thunderstorms should begin to move into the region, with
latest guidance generally favoring a track into southern KY and TN.
These convective complexes should be weakening as they move east of
the greatest instability; however, these showers and storms could
still produce areas of heavy rainfall, though exact positioning is
somewhat uncertain. 00Z HREF rainfall LPMM has swaths of greater
than 1" QPF over portions of southern KY, though this does appear to
be driven largely by one (HRRR) solution. Farther to the north,
light to moderate rain showers will be possible late tonight, with
rain chances falling off precipitously as you get north of I-64.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 330 AM EDT Sat Jun 8 2024

Sunday...

Cold frontal passage from north to south will take place on Sunday,
accompanied by showers and a few thunderstorms. QPF is highest over
southern Kentucky where there will be the longest residence time of
shower activity ahead of the front, and where there could be some
locally heavy downpours in rich PWAT air.

Rest of the week...

On Monday an upper trough reaching from the Canadian Maritimes to
the Ohio Valley will pass overhead. There should be very little
moisture for this system to work with and a strong mid-level cap
will be in place, so right now the forecast calls for partly cloudy
skies and no more than perhaps a stray low-topped light rain shower
along/east of I-75.

Tuesday through Thursday continue to look dry as high pressure
translates from the Midwest to off the mid-Atlantic coast and the
main storm track is well to our north along the Canadian border.
Temperatures will moderate from highs Tuesday in the middle and
upper 70s to the middle and upper 80s Thursday as we get into return
flow behind the departing surface high along with increasing 1000-
500mb thicknesses.

A cold front may approach by Thursday night or Friday, but
uncertainty is great this far out in the forecast and most ensembles
and operational runs keep us dry with the main sources of available
moisture to our south over the Gulf and our north over the Great
Lakes, so will stick with a dry forecast here for now.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 141 AM EDT Sat Jun 8 2024

High clouds from a convective system over the central Plains will
begin to move across the region over the next few hours, with winds
remaining light and generally out of the SW through sunrise. Later
this morning, the remnants of the convective system are expected to
move across the region as a weakening band of light rain showers.
Little to no impacts are expected from these showers, and due to
coverage and timing uncertainty, we`ll only go with VCSH mention for
now.

A light SW breeze should pick up after sunrise this morning,
with wind speeds of 5-10 kt expected through the daytime hours
today. Cloud bases will gradually build downward through the day,
though there is high confidence in VFR conditions continuing through
at least the late evening hours tonight. Toward the end of the
current forecast period, a cold front dropping in from the north
will bring an increase of moisture below 10 kft. At this time, we`ll
keep VFR CIGs going through the forecast, although the probability
of MVFR or lower CIGs will increase between 06-12Z Sunday.
Additionally, a second round of rain (and possibly a few storms) may
impact sites early Sunday morning; however, confidence is too low to
mention in the current forecast.

&&

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

&&

$$

SHORT TERM...CSG
LONG TERM...13
AVIATION...CSG