934
FXUS63 KLMK 052307
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
707 PM EDT Sat Apr 5 2025

.KEY MESSAGES...

* Extremely dangerous flooding will continue tonight and through the
  weekend. Heed any flood warnings issued as this will be a life
  threatening flood event across much of Kentucky and southern
  Indiana.

* A few severe storms will be possible this afternoon, mainly south
  of a line from roughly Bowling Green to just south of Lexington.
  Gusty winds and isolated tornadoes are possible. Trees, especially
  those that have leafed out, will be particularly vulnerable to
  winds given the water-logged soils.

* Heavy rain today and tonight will exacerbate flooding and renew
  flooding in areas where water has receded. Amounts of 2-5" are in
  the forecast from this morning through sunrise Sunday from the
  Blue Grass through the Bowling Green/Mammoth Cave region.

* A hard freeze is expected for Monday night and again Tuesday
  night, with many locations dropping into the middle and upper 20s.

* Much drier conditions expected next week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 324 PM EDT Sat Apr 5 2025

Afternoon satellite imagery show mostly cloudy skies over southern
IN and much of western KY.  Clearing skies were noted over portions
of southeastern KY.  Temperatures were in the low-mid 60s in the
clouds with upper 60s and lower 70s in the sun across the Lake
Cumberland region. The cold front was entering western KY where
temps west of a Henderson to Paducah line were down in the upper 40s
to the lower 50s.

For this afternoon, we`ll be watching the southern half of Kentucky
for another round of severe weather.  A strong bow echo is working
across the MS river into western TN.  Out ahead of that bow, we have
a few scattered supercells.  There is a quasi-stationary boundary
draped near the I-40 corridor.  It appears that these cells and bow
echo will move along this boundary, which may drift a little more to
the north this afternoon.  There is potential for some of these
cells and for the northern edge of the bow to impact our southern KY
counties.  Confidence on how far north the severe threat will get is
somewhat in question given how far north the front could go. Current
thinking is that a line of storms will move across our southern
counties, mainly south of a line from Bowling Green to Richmond.

South of that line, modest instability and ample wind shear will
remain in place and would support the possibility of severe storms
producing a damaging wind and isolated tornado threat.  Given the
bow echo movement and isolated supercells out ahead of it, SPC has
proactively issued a tornado watch for portions of southern KY for
the afternoon/evening.

For areas north of the Bowling Green to Richmond line, light to
moderate rainfall will continue, but will get heavier this afternoon
and evening.  Model soundings do not show much in the way of surface
based instability, but we do have some elevated instability over the
residual cool layer near the surface.  So rumbles of thunder with
locally heavier rainfall rates will be possible, especially in areas
along and south of the Ohio River.

For tonight, the cold frontal boundary to the west will move
eastward while a wave of low pressure moves through the region.
Moderate to heavy rainfall is expected to move across the region
resulting in additional flooding issues.  Latest HREF PMM suggests a
swath of 2-4 inches of rainfall roughly along the WK/BG Parkway
corridor.  Localized 5+ inch amounts will be possible.  This
rainfall will be falling on the same area that has seen 6-12 inches
of rainfall in the last 4 days.  This will lead to additional life-
threatening flash flooding and areal flooding across much of the
forecast area.  Lows tonight will cool into the middle 40s across
southern IN and northern KY with mid-upper 50s across the southern
and southeast sections.

For Sunday, we may see relative lull in the activity Sunday morning
as the overnight activity pushes into eastern KY.  However, as the
upper level trough axis moves across the region, widespread light to
moderate showers will move across the area.  Instability and wind
shear will be much weaker, so the threat of severe weather will be
greatly diminished compared to what we`ve seen in the last 3-4 days.
Highs will range from the upper 40s to around 50 across southern IN
and northern KY with upper 50s to around 60 in the Lake Cumberland
region.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 324 PM EDT Sat Apr 5 2025

===== Sunday Night - Wednesday =====

Weather will be trending drier by Sunday night as the frontal
boundary finally shifts a bit more to the east. With the positively
tilted trough still over the eastern third of the country, cloud
cover will linger into Monday, but at least we`ll have a dry
forecast heading into Monday. CAA will increase Sunday night, which
will likely result in temps near freezing for southern Indiana
counties.

The cloud deck is expected to shift est through Monday morning. With
sfc high pressure setting up over the High Plains, CAA regime will
remain in place, leading to temps in the upper 50s. Guidance
continues to pick up on a subtle secondary shortwave riding through
the main flow Monday night, though a lack of moisture will keep a
dry forecast going. Could see a narrow cloud deck slide overhead
Monday evening and night though. Temps appear even cooler for Monday
night and into Tuesday morning, with lows as cold as the mid 20s for
souther Indiana and most of central Kentucky. Freeze headlines still
look like a good probability when the time comes.

Canadian high pressure will slide into the Ohio Valley for Tuesday
and Wednesday, which will promote continued dry weather for the mid-
week. Temps will be below quite cool for this time of year on
Tuesday, with highs struggling to hit 50 for many locations. We`ll
still be below normal for Wednesday, though slightly closer with
highs in the upper 50s and near 60.


Wednesday Night - Friday...

Sfc high pressure slides east of Wednesday night as a shortwave
pivots across the Great Lakes and Ohio Valley. As the associated sfc
low tracks across Missouri and Illinois, it will extend a warm front
to the east. Isentropic lift will promote a return of showers by
Wednesday night and Thursday morning. With temps rising into the
60s, showers and some storms will be possible throughout Thursday.
Sfc dewpoints could struggle to get into the 50s, and model
soundings indicate meager instability parameters but high shear.
QPF around 1" is forecast, which won`t be too bad, but could
definitely delay some of the river falls a bit.

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 657 PM EDT Sat Apr 5 2025

A stationary front across central Kentucky will combine with a
large upper level storm system and great moisture convergence to
continue a long lived rain event in the region that will last
through pretty much the entire time period. With the pockets of
heavier rain and thunderstorms we could see surface visibilities
between 2-4 SM between 00-04Z and then as the system transitions
to more steady light to moderate rainfall surface visibilities
will be in the 4-6 SM range. Overall severe weather will be
limited to early in the TAF between 00-02 and mainly for SDF,
LEX and RGA as the leading edge of the squall line could lead to
wind gusts up to 25-30 kts. With the slow movement of the
frontal boundary and the overall storm system...expect generally
IFR flight category for all terminals at least through 03Z
Monday. We could begin to see ceiling rises for HNB and SDF
after 03Z. While IFR is the highest probability of flight
category there could be times of MVFR or LIFR flight category
based on when the heaviest rains move through and when there is
times of lighter rain. After 03Z we should see a slow exit of
the system where the rain subsides from north to south and
clearing skies after 06Z Monday.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch through Sunday morning for KYZ023>043-045>049-
     053>057-061>067-070>078-081-082.
IN...Flood Watch through Sunday morning for INZ076>079-083-084-
     089>092.

&&

$$

SHORT TERM...MJ
LONG TERM...CJP
AVIATION...WFO DDC