038
FXUS63 KLMK 240037
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
737 PM EST Mon Dec 23 2024

.KEY MESSAGES...

* A few light showers along and north of the Parkways tonight.

* Above normal temperatures Tuesday through the end of the week.
  Multiple disturbances to bring rain chances most days.

&&

.UPDATE...
Issued at 737 PM EST Mon Dec 23 2024

Well...

Current forecast is humming along nicely with a weak front
approaching ORD-STL.  Ahead of this is a 30kt llvl jet, but is
running into significant llvl dry layer.

The moisture transport will interact with right entrance region of
an H3 jet. Ceilings have been dropping from 12K when swing shift
took over at 4 pm est (Cigs currently around 5 K). T/Td Spreads have
decreased from 30 degrees to 20-25 degrees). So expect some 20-30%
coverage of shra over night mainly over S IN and Nrn Bluegrass.

Winds go from Sw 5-10 and as front approaches go light and variable
from E-SE and could be very patchy fog around daybreak.

Tue looks like a bunch of llvl clouds.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 342 PM EST Mon Dec 23 2024

Mild conditions are in place across our region as plenty of sunshine
and steady, to occasionally gusty, SSW winds are adding a warm
advection component. Highs are peaking in the lower 50s this
afternoon, however don`t expect much of a diurnal drop into tonight
as heavy cloud cover and steady winds keep temps up a bit. Look for
lows mostly in the upper 30s and lower 40s. Our SE could dip into
the lower 30s where clouds take the longest to set in.

Currently seeing some blips on the radar across southern IN, and
these are associated with a weak isentropic lift component, and
perhaps some mid level frontogenesis. This will continue into the
evening and overnight as a 30 know low level jet lingers ahead of an
approaching frontal boundary, and we stay situated beneath the right
entrance region of an upper jet. So, have chances for a measurable
shower later this evening through the overnight mainly along and
north of the parkways. Also, precipitation will be falling out of a
mid deck of clouds, so included some buffer with sprinkle mention.

The front reaches our northern CWA tomorrow, however it will stall
and briefly wash out. As a result, calling for a mostly dry day
outside of a very small chance for a shower across southern IN
tomorrow afternoon. We will keep the heavy cloud cover around, so
not expecting it to be as mild as today. Still, temps will be above
normal with highs mostly in the mid to upper 40s. Some low 50s are
possible down along the KY/TN border.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 342 PM EST Mon Dec 23 2024

Tuesday night, an upper trough in the lower stream of a split upper
jet will push a dying surface low east across northeast Texas. Mid
and upper level flow around this circulation will help to push deep
layer moisture north into the Mississippi River Valley and towards
the Lower Ohio Valley, but the trend of drier weather for central
Kentucky continues. Southern Indiana will likely see some sprinkles
with some drizzle and fog mixed in.

Wednesday, as the low pressure system approaches the Mississippi
River Valley, the system could expand light rain from southern
Indiana into parts of central Kentucky, but as with Tuesday night,
believe the NBM is being too bullish with rain chances. This is
being driven by the Euro as most other models keep the dry levels
too dry to see too much in the way of rain. Under cloudy skies and
with east winds in place high temperatures are expected to push into
the mid 40s to mid 50s.

Friday, the main system for the week will arrive. Another upper
trough in the southern stream will push a surface low through the
Ozarks early Friday morning. This will cause strong deep layer
moisture advection, including a 50 knot low level jet. Strong
isentropic lift will cause widespread rain over the CWA. Model
soundings look stable, keeping this an all rain event. The majority
of the rain should push through the area by early Friday night. The
CWA gets a short break before a large cold front moves through the
CWA Saturday night/ Sunday morning. This system should end up with a
little lightning, but currently looks like mostly rain.

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 631 PM EST Mon Dec 23 2024

Impacts...

- MVFR CIGS developing overnight at HNB & Tue AM at SDF

Well...upper trough pushing towards the area with extensive mid deck
clouds producing virga and some sprinkles.  With such a strong
Temp/Dew Point Spread most of the precip north of the river will be
very light until more wet bulbing takes place.

Short range CAMS indicating enough wet bulbing to saturate the lower
levels this evening. This will bring some slgt chc to chc -shra at
HNB/SDF and perhaps to near LEX late tonight. All light pcpn should
be gone sunrise.

With wet bulbing...the boundary layer will saturate and together
with a subsidence inversions means stratocumulus. The SC will lower
from 5 to 6K downward to MVFR at HNB by 9z, SDF by 12z, & LEX by
15z. RGA will eventually go blo 3K Tue aftn and BWG will stay VFR.

Light south winds will go light and variable late in the period.

&&

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

&&

$$

UPDATE...JDG
SHORT TERM...BJS
LONG TERM...KDW
AVIATION...JDG