208
FXUS63 KLMK 111657
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1257 PM EDT Tue Mar 11 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Warm and dry weather continues for Tuesday-Wednesday time frame.
  Above normal temperatures expected all week.

* Gusty winds and heavy rain possible Friday night through Saturday
  night as a strong low pressure system is expected to track through
  the central US. Strong to severe storms may also accompany this
  system.

&&

.UPDATE...
Issued at 1050 AM EDT Tue Mar 11 2025

After an impressive ridge/valley split this morning, temperatures
have recovered nicely into the mid-upper 50s as of late morning.
Satellite imagery shows clear skies across the much of the eastern
US.  Overall, the forecast remains on track this morning and into
this afternoon.  We should see temperatures average about 6-8
degrees above what we saw yesterday with highs in the low-mid 70s.
Expecting another good day of afternoon mixing which will allow
dewpoints to fall in the afternoon.  Our winds will be a little
higher this afternoon which could result in some local fire hot spots
to pop up outside of ongoing prescribed burns that are in progress.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 352 AM EDT Tue Mar 11 2025

A quiet weather pattern is in place with zonal flow aloft and
surface high pressure centered to our south. There will be a weak
surface cool front trailing from an eastern Canada low pressure that
sinks into our northern CWA tonight, however this will only bring
variable winds. Expect sunny/clear skies through the period outside
of a few thin cirrus later this evening.

Temperatures will be the main story with another day of temperatures
trending milder. 1000-850 mb thickness rises suggest a 6 to 7 degree
warm up, plus we`ll get a slight warm advection component ahead of
that frontal boundary sinking toward the Ohio River. As a result,
went above guidance once again which will put highs in the low to
mid 70s. Do expect a steady pressure gradient with some gusts up
around 20 mph this afternoon. Soundings show fairly deep mixing once
again, which will tap into the hydrolapse. As a result, expecting
another dry air mix down this afternoon, and went 5th percentile NBM
for dew points to account for that. Given the combo of some decent
surface winds, mild temps, and low RH values we could start to have
a few hot spots across the region. Small fuels have steadily become
more receptive so will be something to watch for. Expect to see
another night of ridge/valley splits for low temperatures. Surface
winds may stay up just enough to not decouple, however sheltered
areas will certainly decouple and tank like we are seeing early this
morning. Most lows will be in the 40s, however may hang onto some
lows around 50 for the typically milder spots.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 352 AM EDT Tue Mar 11 2025

Wednesday - Thursday Night...

The prevailing theme of warm and dry weather will continue into the
day on Wednesday as a zonal mid- and upper-level flow pattern sits
atop flat ridging over the Gulf states. A washed out sfc front will
be located over central Indiana during the day on Wednesday; this
should allow for southwesterly breezes across our area. While the
flow just above the boundary layer will not be particularly strong
(20-25 kt), this setup would support deep mixing, depending on how
prevalent upper sky cover is. Will follow the previous forecaster`s
thinking of increasing T and winds and lowering Td during the day on
Wednesday, resulting in highs in the mid-to-upper 70s, and SW winds
of 10-15 mph with gusts to around 20 mph.

A beleaguered upper shortwave will slide across the Ozarks Wednesday
night, entering the lower Ohio and Mississippi valleys for the day
on Thursday. While there should be some low-level moisture return
ahead of this system, it is still expected that this system will
struggle to produce much in the way of precipitation. Scattered
light rain showers will be possible, especially across south central
KY; however, precipitation amounts should be less than 0.10" in most
areas. Daytime temperatures will remain well above normal, but may
be tempered somewhat by additional cloud cover. Nighttime
temperatures will be quite mild Wednesday and Thursday night, with
lows only falling into the upper 40s and lower 50s.

Friday - Saturday Night...

A transition to a more amplified and active weather pattern is
expected for the end of the week and the weekend as troughing along
the west coast ejects eastward, crossing the Rockies Friday morning
before approaching the Mississippi Valley Friday night into
Saturday. A lead shortwave is expected to race ahead of the longwave
trough axis on Friday, moving from the southern Plains up into the
upper Mississippi Valley by Saturday morning. As this wave passes
just west of our region, a strengthening pressure/height gradient
will lead to increasing S/SW flow. This is a favorable pattern for
overachieving with temperatures on Friday, especially if cloud cover
is limited. Near-sfc moisture should be fairly slow to recover given
the track of this lead system, so would expect any diurnal cu to be
fairly limited. If everything comes together, temperatures could
approach records Friday afternoon, though we`ll keep this forecast a
few degrees below (75-79 across the CWA) given lingering uncertainty.

As height falls continue to our west Friday afternoon into Friday
night, a strong LLJ is expected to develop near the area. The ECMWF
and its ensembles are more bullish with this jet, showing 60+ kt of
flow at 850 mb. The GFS is a bit more modest; however, it still has
a swath of 50+ kt. Since the peak of this jet is expected to move
across the region between 06-12Z Saturday, the high-end wind gust
potential may be modified somewhat by nocturnal stability; however,
BUFKIT momentum transfer still shows periodic 40-45 kt just off the
surface Friday night. Using the 20% reduction mentioned by the
previous forecaster, this still gets us right around wind advisory
criteria, so wind headlines continue to look possible for Friday
into Saturday.

The strong flow aloft also introduces the potential for strong to
severe storms Friday night into Saturday. Wind shear Friday night
continues to look impressive, with around 60 kt of 0-6 km Bulk Shear
depicted in sample soundings. The main limiting factor appears to be
instability, as low-level moisture return may be insufficient to
overcome a warm/capping layer in the mid-levels. While this would
limit convective initiation, what is more likely is that convection
will be ongoing to our west Friday evening and will run into a
progressively more unfavorable environment as it pushes east. This
could still yield severe weather, particularly west of I-65 as
enhanced DCAPE values aid strong winds aloft in making it down to
the surface within outflow-dominant convection.

A strong/severe storm potential also exists on Saturday for portions
of the area, though there are also uncertainties with this setup.
The main upper trough will encroach from the west, with brief
coupled jet structure and mid-level vort advection supporting sfc
cyclogenesis from the Gulf states into the Tennessee valley. This
should allow another wave of precipitation to move across the region
Saturday afternoon into Saturday night, with the focus of this wave
being farther east than the Friday night wave. Longer residence time
for low-level moisture advection should increase instability;
however, it is uncertain whether the wind field will be as
supportive for organized/severe storms. If the sfc cold front is
able to make more eastward progression late Friday night, this could
shove the warm sector to the southeast of the region, transitioning
our area into more of a heavy rain threat for Saturday and Saturday
night. A slower progression of the front will support a second
chance at strong or severe storms Saturday afternoon into Saturday
evening.

Speaking of heavy rain, still thinking a widespread swath of 1-3"
from Friday night through Saturday night, with locally heavier
amounts where training of convective complexes occurs. While
antecedent dry weather will help abate much of the flooding concern,
brief heavier rates could lead to localized flash flooding and minor
river flooding, particularly on the Green/Cumberland basins.

Sunday - Monday Night...

The upper trough axis will push through the Ohio Valley Sunday into
early Monday morning, with lingering low-level moisture likely
leading to lingering showers and breezy west winds for the day on
Sunday. While cooler temperatures are expected for Sunday into the
first part of next week, the air mass which will follow the
weekend`s system will be dominated by Pacific sources, so
temperatures should only fall to near normal for mid-March. High
pressure should settle into the western Gulf by Monday afternoon,
with dry weather expected to return for the first few days of next
week. Any cool-down will be short-lived, as there is a consistent
signal for a return to deep SW flow next Tuesday and Wednesday.
There is a fairly consistent signal in deterministic guidance for
another impactful system around next Thursday; however, confidence
in specifics is very low at this time.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1257 PM EDT Tue Mar 11 2025

VFR conditions are expected through the upcoming TAF cycle.  Look
for clear skies this afternoon with southwesterly breezes of 8-12kts
and gusts to 20kts or so.  Winds will slacken by 11/22Z.  For
tonight, some light cirrus will build into the region from the west
with a light southwest wind continuing.  VFR conditions are expected
overnight and again on Wednesday.

&&

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

&&

$$

UPDATE.......MJ
SHORT TERM...BJS
LONG TERM....CSG
AVIATION.....MJ