Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 281431
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1031 AM EDT Thu Mar 28 2024

.KEY MESSAGES...

* Near or below freezing temperatures this morning could damage
  sensitive vegetation due to frost.

* Stormy pattern setting up for Sunday through Tuesday. Most likely
  timing for strong to severe storms appears to be Monday/Monday
  night, but confidence in timing is low.

* After temperatures generally reaching into the 70s Saturday
  through Monday, a cool down is expected by late next week with
  temperatures potentially dipping down into the 30s by Thursday
  morning

&&

.UPDATE...
Issued at 1030 AM EDT Thu Mar 28 2024

High pressure over the region is leading to clear skies and light
winds. Low temps this morning fell into the upper 20s and have
already warmed into the mid 40s, so we are on track for the upper
50s and low 60s by this afternoon. The previous forecast remains on
track.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 323 AM EDT Thu Mar 28 2024

Synopsis...Dry weather with slowly warming temperatures. East CONUS
upper-level longwave trough will slowly eject to the east during the
short term period as ridging starts to build across the Central US.
Meanwhile, low- to mid-level shortwave energy moving out of the
Rockies will ride atop the low-level anticyclone/ridge over the
Southeast US, promoting warm air advection over the forecast area.

Today...Current satellite imagery shows scattered mid/upper cloud
deck moving across the Cumberland/Bluegrass regions with overall
minor influence on temperatures where clouds are thickest.
Elsewhere, the combination of clear skies, light winds, and
subsidence aloft is promoting efficient radiational cooling with
lows this morning expected to be near or below freezing. As a
result, frost continues to be a concern for susceptible vegetation
through 13 or 14Z when temperatures start raising above the 40
degree mark. Rest of the day will feature sunny conditions with
highs warmer than yesterday but still a few degrees below average
for this time of the year. Winds, on the other hand, will be light
and variable in the morning and acquiring a westerly component in
the afternoon/evening as surface high pressures moves south of the
Ohio Valley.

Tonight...Winds will steadily blow from the southwest between 5-10
knots which will put a cap to the radiational cooling effect during
the overnight hours. Therefore, lows will most likely stay in the
upper 30s to low 40s limiting mention of impactful frost formation.
In addition, increasing warm air advection pattern aloft and weak
isentropic lifting will yield scattered low- to mid-level clouds
over southern Indiana and northern Kentucky (on the southern edge
of a NW-to-SE oriented LLJ), favoring the upward trend of
temperatures.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 323 AM EDT Thu Mar 28 2024

We will enter into an active pattern for the Long Term, with
multiple chances of showers and storms. The feel of spring will be
further enhanced by very warm temperatures for the first half of
next week, before cooling back down later in the week. Though the
warm and wet conditions of the first few days of the Long Term will
encourage plant growth and development, we may not be done with the
threat of frost this season quite yet.

The Long Term does start off quiet, though, with shortwave ridging
overhead, dry low levels, and an east-west surface boundary just to
our north. Afternoon temperatures will peak around 70 under a partly
cloudy sky.

A weak upper trough behind Friday`s ridge, and surface low pressure
crossing lower Michigan along the boundary to our north, may bring a
few showers and thunderstorms to southern Indiana and the Kentucky
Blue Grass by afternoon as the mercury climbs a few degrees above
convective temperatures. That being said, the trend of the
deterministic GFS over it past several runs has been to decrease
QPF Saturday, and GEFS plumes show little if any rain on Saturday.
So, will keep PoPs low. The surface boundary is expected to sag
southward Saturday night, however, bringing increased chances of
convection to the entire region. There will be enough weak
instability to support a few rumbles of thunder.

The upper flow will become increasingly amplified this weekend and
into early next week as an upper low currently over the Gulf of
Alaska digs aggressively into the Desert Southwest. As it slowly
spreads eastward into the Plains a Canadian upper trough may slide
east southeastward into the Great Lakes and Northeast. How much
these two systems phase is still a question. Cluster MME progs
suggest that the base of the Rockies/Plains trough will remain over
the Southwest while the Canadian trough slips eastward ahead of it,
with only weak phasing. There is greater uncertainty with the
smaller Canadian disturbance than with the much more significant
Rockies trough. This should become better resolved in the coming
days.

Waves of Gulf moisture will stream northward this weekend into early
next week, interacting with packets of energy ejecting out of the
Southwest trough and riding up an over a Southeast ridge. Sunday-
Sunday night the surface boundary that sank southward into the Ohio
Valley will remain in the region. Instability will increase on
Sunday, compared to Saturday, along with strong deep layer shear.
Can`t rule out a few stronger storms Sunday afternoon and evening
before instability weakens and a stable surface layer develops
Sunday night.

Moving into Monday-Tuesday, deepening surface low pressure will
advance across the central Plains and Midwest/Great Lakes. The
surface boundary that had been in our region will lift north as a
warm front, and the trailing cold front may not pass through the
area until Tuesday evening. That will put us in the warm sector for
at least Monday and possibly Tuesday, with shower and thunderstorms
in the forecast. Instability will increase further from Sunday into
Monday with strong shear continuing. EC EFI is showing slightly
unusual shear and CAPE-Shear Monday through Monday night. Surface
dew points will be in the 60s with afternoon highs in the mid and
upper 70s...possibly 80 in southern Kentucky. SPC chiclets have been
consistent showing a severe weather threat Monday-Monday night, and
this is supported by CSU-MLP, though CIPS analogs keep the greatest
threat off to our west. Due to aforementioned uncertainties in the
evolution of the complex upper pattern, and questions surrounding
the future of the surface features, confidence is appropriately low
for the Day 5-6 forecast. Nevertheless, as of this writing, it
appears that Monday-Monday night may be our most likely time period
for strong or severe storms. Stay tuned.

Record warm low temperatures may be in jeopardy April 1, with
currently forecast calendar day lows within a degree or two of the
records, in or near the lower 60s.

Additional strong storms could be on tap for Tuesday, depending on
the timing of the cold frontal passage. Scattered post-frontal
showers may then linger into Wednesday.

After all this warm and wet weather, a cool-down looks possible
behind the departing storm system later next week. Temperatures may
dip into the 30s, especially by next Thursday morning.

&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 639 AM EDT Thu Mar 28 2024

Discussion...Continuing VFR conditions through the current TAF
period. Influence of surface high pressure will account for dry and
stable weather as winds remain light and variable this morning with
a weak westerly component later this afternoon and evening. The
presence of the southern edge of a LLJ over southern Indiana and
northern KY could yield a brief period of LLWS, but confidence
remains low in this scenario.

&&

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

&&

$$

UPDATE...SRM
SHORT TERM...ALL
LONG TERM...13
AVIATION...ALL


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