352
FXUS63 KLMK 091711
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
111 PM EDT Sun Jun 9 2024

.KEY MESSAGES...

*   Scattered showers and isolated thunderstorms today in south
    central Kentucky. Severe weather is not expected.

*   Below normal temperatures and humidity Monday and Tuesday,
    followed by a warming trend with hot and dry conditions likely
    for late this week into next weekend.

&&

.UPDATE...
Issued at 1004 AM EDT Sun Jun 9 2024

Cold front now just south of Interstate 64 and continuing to make
slow but steady southward progress. Dewpoints behind the front are
dropping into the upper 50s, and any showers incoming from the west
are being deflected well south into south-central Kentucky. Think
precip chances for the balance of the day will be limited to south
of the Parkways, with isolated to scattered coverage at best.
Diurnal temp curve will be a bit delayed, but still believe we can
get to forecast max temps this afternoon. Changes to the going
forecast will be more in the hourly details, but the update will be
on the way shortly.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 305 AM EDT Sun Jun 9 2024

At 06Z a surface boundary stretched from central Ohio through
southern Indiana to southeast Missouri. This will push southward
across Kentucky this morning, possibly accompanied by scattered
showers south of Interstate 64. Lapse rates will be weak and
soundings don`t indicate much in the way of instability, with debris
clouds streaming in from robust convection to our west helping to
further hamper destabilization. Still could hear some thunder, but
it should be isolated. Better chances for storms and any severe
weather will be to our south this afternoon ahead of the front,
especially from Arkansas into west TN/MS/AL. Highs this afternoon
will be around 80.

Tonight high pressure will build from the Prairie Provinces into the
upper Mississippi Valley, ridging southward to the Ozarks. This will
provide the Ohio Valley with clearing skies and a light northwest
breeze. The air mass should be dry enough to prevent much fog from
forming, though there could still be some sheltered river valley fog
by dawn. Lows will generally be in the lower and middle 50s, 4 to 8
degrees cooler than normal, though HREF grand ensemble
(HRRR/HRW/NAM) indicates a 10-20% chance of briefly dipping into the
upper 40s in rural, low-lying parts of southern Indiana.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 305 AM EDT Sun Jun 9 2024

The extended forecast period will feature quite a bit of change
across the Ohio and Tennessee valleys as the pattern across the
central and eastern CONUS transitions from one favoring mild and dry
weather to a more typical hot summertime regime. Model guidance is
fairly consistent in the pattern evolution through much of the
upcoming week, with some discrepancies noted in the finer details.

On Monday, an abnormally amplified pattern for mid June will be
present across much of North America, with deep troughing extending
from SE Canada down into the eastern US. A mid-level shortwave
disturbance will swing through the Ohio Valley during the daytime
hours, although it should bring little more than extra cloud cover
for the afternoon hours. This cloud cover, combined with cool N/NW
flow, should keep temperatures below normal on Monday. Ensemble
confidence in below normal temperatures Monday afternoon is
relatively good, as indicated by the ECMWF MaxT EFI, which is around
-0.7 in our region. Below normal temperatures are expected to
continue into Monday night and Tuesday, with EFI values continuing
to indicate medium to high confidence in below normal temperatures.
In addition to below normal temps, there is also high confidence in
anomalously dry air Monday night into Tuesday. The NAEFS and EPS
mean PWAT values are both below the 5th percentile of model climo,
with ensemble mean values around 0.50" Tuesday morning. The
combination of cool and dry air should help temperatures fall into
the low-to-mid 50s in most locations Tuesday morning, with a few
upper 40s possible in the typical cool spots.

Late Tuesday into Wednesday will be the transition period as
troughing lifts into the North Atlantic and positive height
anomalies over the desert southwest begin to spread eastward. Sfc
high pressure will remain close to the region, with continued dry
air overhead and subsidence aloft negating precipitation chances. By
Thursday, ensemble mean 850 mb temperatures are progged to be around
15 degrees warmer than on Monday, with warmer temperatures aloft
translating down to the surface as many locations across central KY
and southern IN approach 90 degrees for highs. Dewpoints and PWAT
values should still be fairly modest (Td low-to-mid 60s), so while
temperatures will be hot, it will be more akin to an oven than a
sauna, keeping expected heat indices in check. An upper level wave
is expected to slide through the upper Great Lakes and the northeast
US during the late week, with an associated sfc cold front washing
up near the Ohio Valley Friday into Saturday. While this could
provide a trigger for showers and storms, moisture and kinematics
look to be lacking at this time, so we`ll keep PoPs largely dry. The
hot pattern looks to continue into next weekend, though we`ll have
to keep an eye to the Gulf of Mexico as some long range guidance
brings tropical moisture into our area during the June 16th-18th
time frame.

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 110 PM EDT Sun Jun 9 2024

Cold front draped across or just south of RGA, and about to move
through BWG this afternoon, with northerly flow getting better
established at SDF, LEX, and HNB. Rain shield coming out of western
Kentucky with MVFR conditions into BWG, possibly dropping into IFR
at times in the heaviest precip. Just a few lightning strikes so
will mention VCTS/CB there, but keep that activity far enough south
that VCSH should cover RGA. Could also see some MVFR cigs there, but
will be an issuance time decision.

VFR conditions in place at SDF and LEX will get into all terminals
this evening as the cold front pushes south of the area. Even with
light winds and clearing skies, minimal fog concerns overnight as
low-level dry air should win out over radiational processes. For
Monday expect NNW winds to pick up just shy of 10 kt as mixing
deepens, with just enough cold pool influence for a healthy diurnal
Cu field around 5K feet.

&&

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

&&

$$

UPDATE...RAS
SHORT TERM...13
LONG TERM...CSG
AVIATION...RAS