486
FXUS63 KLMK 061016
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
616 AM EDT Sun Apr 6 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Areal flooding will slowly diminish today but river flooding will
  continue into the second half of April.

* Patchy frost will be possible early tomorrow morning in southern
  Indiana.

* A hard freeze is expected for Monday night and again Tuesday
  night, with many locations dropping into the middle and upper 20s.
  A Freeze Watch has been issued for Monday night. Tuesday night may
  also require one in future forecasts.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 310 AM EDT Sun Apr 6 2025

The surface boundary that has been plaguing us recently has slipped
to the southeast, but not by much, and waves of low pressure will be
riding northeastward along the boundary today. As a result, clouds
and showers will continue. Instability will be meager, with just a
few rumbles of thunder possible in the Lake Cumberland and Blue
Grass regions. Rainfall totals will be light, around a third of an
inch or less after 12Z...though a few spots in the Blue Grass could
approach half an inch. Because of the light QPF, and because we`re
past the "watch" phase of this flood event, will let the Flood Watch
expire on time this morning and will let the already established
flooding be covered by areal and river Flood Warnings.

The rain will end (!) this evening, followed by partially clearing
skies and light winds overnight. Temperatures will fall into the 30s
by morning. There may be just enough clearing skies and light winds
to lead to some patchy frost formation in southern Indiana.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 310 AM EDT Sun Apr 6 2025

Monday - Tuesday

Strong Canadian high pressure will push a cold front ahead of it as
the high drops SSE from Saskatchewan to the Great Lakes. Fropa in
the Ohio Valley will occur Monday evening, and will likely be dry,
though there is a very small chance of an isolated shower or two,
especially in the Blue Grass, a couple hours either side of sunset.
After highs in the 50s on Monday, the front will usher in much
colder air. By Tuesday morning the mercury will have tumbled into
the middle and upper 20s for most...lower 30s in the Bowling Green
region. This will bring many locations a hard freeze, and the
coldest readings since at least March 21. Confidence in a freeze is
fairly high due to model consistency over the past several runs,
progged temps well below freezing, and ECMWF EFI showing a signal
for unusual cold. So, after coordinating with neighbors, will go
ahead and hoist a 4th period Freeze Watch for Monday night.

Tuesday will be chilly but mostly sunny as the high sinks farther to
the south. Afternoon temperatures will range from the upper 40s to
middle 50s, which is about 15 degrees below normal. This will be
followed by another chilly night, though a couple degrees warmer
than Monday night as the high moves off to our east and clouds begin
to increase from the northwest as the next system approaches. Still,
most locations will see another freeze Tuesday night.

Wednesday - Thursday

A clipper type low will quickly cruise from around Omaha Wednesday
morning to near Cleveland by Thursday evening pulling its trailing
cold front through the Ohio Valley. This system will bring a period
of showers to the region Wednesday night through Thursday night.
There should be enough instability and deep layer shear for
organized convection Thursday afternoon ahead of the cold front,
though so far severe storms look unlikely. QPF for this system is on
the order of half an inch over 24-48 hours so no impact on river
flooding is expected.

Friday - Saturday

Confidence decreases quite a bit for the end of the week as models
diverge. In general it looks like the 5H trough that brought us the
showery weather Thursday will push to the East Coast by Saturday as
ridging moves into the Plains.

&&

.AVIATION /12Z TAFS THROUGH 18Z MONDAY/...
Issued at 615 AM EDT Sun Apr 6 2025

High RH trapped under a strong low level inversion will keep post-
frontal stratus across the entire region for much of this TAF
period. Showers ahead of broad upper troughing from Hudson Bay to
the Big Bend will keep showers in the forecast especially during the
daylight hours, tapering off tonight from west to east. A surface
pattern featuring waves of low pressure crossing the Southeast and
weak high pressure ridging from the Plains to the Great Lakes will
result in a steady NNE breeze.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch until 8 AM EDT /7 AM CDT/ this morning for
     KYZ023>043-045>049-053>057-061>067-070>078-081-082.
     Freeze Watch from late Monday night through Tuesday morning
     for KYZ023>043-045>049-053>057-061>067-070>078-081-082.
IN...Flood Watch until 8 AM EDT /7 AM CDT/ this morning for
     INZ076>079-083-084-089>092.
     Freeze Watch from late Monday night through Tuesday morning
     for INZ076>079-083-084-089>092.

&&

$$

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