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000
FXUS63 KLMK 141731
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
131 PM EDT Sun Apr 14 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Warm period tonday through Wednesday, with highs ranging from
    the upper 70s to lower 80s.

*   Stormy weather Tuesday night through Wednesday evening. Some
    potential for a couple of waves of strong to severe storms.

*   Significant cool-down appears increasingly likely next weekend.
    This may mean highs around 60 and lows falling into the 40s.

*   The Ohio River will run high this week but stay below flood
    stage at Louisville through at least mid-week. How much rain we
    get Tuesday night through Wednesday evening, and where the
    heaviest rain falls, will be a significant factor for river
    levels next weekend.

&&

.UPDATE...
Issued at 1041 AM EDT Sun Apr 14 2024

A sunny, breezy, and warm afternoon is still on tap for southern
Indiana and central Kentucky. In a fairly tight surface pressure
gradient between high pressure over Florida and a cold front
reaching from low pressure over Michigan west southwestward across
the Midwest, winds will gust 25-30 mph this afternoon. 12Z balloon
out of OHX, model soundings, and atmospheric cross-sections show
plenty of dry air in the column, other than a bit of moisture
showing up in the 500-400mb layer and seen as a few mid and high
clouds on satellite and Kentucky Mesonet cameras. The mid-April
sunshine and WAA will pull temperatures into the upper 70s and lower
80s today as supported by the 50th, 75th, and 90th NBM percentiles
for MaxT this afternoon.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 248 AM EDT Sun Apr 14 2024

A modest LLJ over the region this morning has helped to keep the low
level somewhat mixy and temperatures at the surface fairly mild (50s
to low 60s) early this AM. Temperatures likely won`t fall too much
more, save for locations in very sheltered valleys where winds have
gone light/calm.

Shortly after sunrise, we should see the boundary layer begin to
slowly mix out and surface winds pick up and remain steady/gusty
through the late morning and afternoon hours. Forecast soundings
reveal a warm air advection regime with southwesterly surface flow,
and we tend to `overachieve` on temps in this type of setup so have
hit the higher end of guidance for highs today. This should result
in most locations getting into the low 80s. A strong capping
inversion between 800-700mb will keep shower/storm chances near 0%.

A frontal boundary will slowly sag southward from northern IL/IN/OH
late this afternoon into the overnight hours. Low level CIN/capping
is weakest from Ohio points eastward, which is where the majority of
guidance fire off convection. A very small minority of guidance
hints at convection developing in IN/IL and drifting to the
southeast, though even in those models much of the activity weakens
or dissipates before it reaches our CWA. Odds of a stray shower are
too low to warrant mention in the grids, so will run with a dry
forecast for time being.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 248 AM EDT Sun Apr 14 2024

Fairly high confidence in movement of large scale features for the
first half of the week. Deterministic and Ensemble suites all point
to ridging across the Southern Plains Monday morning steadily
shifting eastward as a close low, currently featured just off the
central California coast, moves from the Four Corners area to the
Central Plains and then the Great Lakes by midweek. By that time,
the pattern over the Ohio Valley will be zonal, sandwiched between
the two larger features. The gradient may amplify by the end of the
week to allow another quick-moving disturbance to bring light precip
chances.

As for sensible weather, Monday into early Tuesday, we could see
some light precip form along a east/west band. The GFS/GEFS seems
too aggressive with it`s precip field here, given somewhat higher
heights over the area. A quick look at forecast soundings from the
NAM and CMCreg show a nice warm nose around 800mb coming and capping
our area, whereas the GFS is cooler with a much weaker cap. It
should be noted however that the HRRR also has a thin band of precip
stretched out east/west across our area, so carrying at least the
NBM 20 pop forecast seems a safe bet at this time.

We should be more solidly into the warm sector Tuesday during the
day. Still increasing moisture coming in from the south and
southwest may lead to a brief light rain shower at any point in the
day...mainly over the I-64 and north corridor, closer to a warm
front. By Tuesday night, we should have a better/more-focused line
of storms coming in from the west, ahead of the main cold front.
Timing of this feature is key to severe potential for our area. A
slower path gets until a better instability environment during the
day Wednesday, but then we may also have new showers develop ahead
of the line that could sap energy from that system. A faster
solution brings in the always difficult high-shear/low-instability
environment where you have to watch for stronger parts of any squall
lines to drop a quick spin-up tornado. Then there`s the solution
that allows for both waves. So there is some risk for severe weather
during this time period.

That cold front looks to push in and lay out east/west across the
region Wednesday and Wednesday night. Even outside of storms
Wednesday, it should be fairly breezy, as the pressure gradient
tightens with the associated surface low traveling across the
Midwest.

For Thursday-Saturday, given that zonal flow aloft, any quick-moving
disturbances could activate some shower activity along that frontal
boundary. Have somewhat lower confidence in how far south that front
gets, which means keeping in some rain chances each day.

Temperatures should be above normal most of the period, though later
in the week the exact location of the stationary front could bring
our northern zones below normal.

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 131 PM EDT Sun Apr 14 2024

This afternoon will continue to be mostly sunny with gusty southwest
winds. Winds should relax some with sunset this evening.

A cold front will approach slowly from the north tonight. Though no
precipitation is expected, 925-850mb moisture will pool ahead of the
boundary and manifest itself in an increase in low clouds. How
widespread and low these clouds will be remains uncertain -- for now
introduced some scattered VFR clouds, but future TAF issuances may
need to include sub-VFR ceilings by Monday morning.

Winds just off the surface will increase slightly this evening but
then weaken a bit overnight. Borderline LLWS may briefly be
attained, but kept it out of the TAFs with this package. Will re-
evaluate for the 00Z issuance.

Tomorrow the front to our north will budge only slightly southward
towards the Ohio River. Isolated thunderstorms will be possible as
the atmosphere destabilizes in the afternoon, though at this time
coverage looks too sparse to include in the outer periods of the SDF
TAF.

&&

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

&&

$$

UPDATE...13
SHORT TERM...DM
LONG TERM...RJS
AVIATION...13