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000
FXUS63 KLMK 131519
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1119 AM EDT Sat Apr 13 2024

.KEY MESSAGES...

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

*   Stormy weather Tue night through Wednesday evening with showers
    and thunderstorms. Wednesday looks to be the most concerning for
    strong to severe storms.

*   Significant cool-down appears increasingly likely next
    weekend (April 19-21). This may mean highs only in the 50s
    for a few days and lows possibly falling into the 30s.

&&

.UPDATE...
Issued at 1119 AM EDT Sat Apr 13 2024

Sunny skies are present across all of central Kentucky and southern
Indiana this morning as latest visible satellite imagery shows
mostly clear skies across the Ohio and Tennessee valleys. 15Z
surface pressure analysis shows the high pressure ridge axis
extending from Alabama up along the I-65 corridor toward Lake
Michigan, which has led to light westerly winds across the area so
far this morning. Temperatures have quickly risen with the help of
insolation into the upper 50s and low-to-mid 60s as of 15Z, and
we`ll expect to add another 10 degrees before reaching highs in the
upper 60s and low-to-mid 70s this afternoon.

The current forecast is on track, with only minor changes made to
near term temperature and dewpoint trends.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 258 AM EDT Sat Apr 13 2024

After a fairly long stretch of wet weather, we`re finally turning
the corner and returning to warm and dry conditions to kick off the
weekend. A surface ridge of high pressure extending from the Gulf
Coast into the Midwest will steadily slide over and east of the
region today, resulting in westerly to southwesterly flow under
mostly clear skies. There will be a little bit of a temperature
gradient with highs today, as the warmer low level temps/thicknesses
will be on the western end of the surface ridge. Highs should top
out in the low/mid 70s west of I-65, while east of I-65 should see
highs in the upper 60s to low 70s.

Temperatures will be a bit more mild overnight compared to this
morning as a modest 40-50kt 850mb LLJ ramps up and keeps the lower
atmosphere mixed while also providing low level moisture and warm
air advection. Some CAMs hint at light reflectivity echoes
developing overnight on the nose of the LLJ, but forecast soundings
reveal quite a bit of dry air in the mid/low atmosphere that
wouldn`t be ideal for precipitation development, so will continue
with a dry forecast for time being.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 258 AM EDT Sat Apr 13 2024

Sunday - Friday...

Well...several waves of potential precip, and Tue-Wed could be
stormy and bares watching for strong/svr wx.

Sun...

Expect a mostly dry day, with a warm front passing thru in the
morning, allowing temps to heat up into the upper 70s and possibly
overachieve into very low 80s. With warm front passing through there
is a stout llvl inversion at 800 mb. There should be more cloud
cover than Sat, but more of a mix of clouds and sun. The NBM
continues to generate some slight PoPs across mainly across N 1/3rd
of the CWA which seemed reasonable.

Sun Night...

Sfc Low over Lake Huron/Ontario will swing towards the Ohio Valley.
Moisture return is fairly limited, but may be enough in combination
of the front and weak H5 s/wv in the evening to generate some slgt
chc activity. The best lift associated with the surface low and
frontal boundary remain well NNE over Buckeye State.

Mon...

Decent agreement in the models on weakly defined frontal boundary
becoming qstnry near I 64 corridor. Soundings show some weak aftn
elevated MUCAPE, but not much of a trigger. Will keep low PoPs in
afternoon and evening, with best chances in the eastern CWA. The
Massie Rose 1000-850 mb thickness support highs in the low 80s.

Mon Night...

Front starts moving back north as a warm front in response to
cyclogenesis over central KS/NE (in response to bowling ball 549 dm
low moving into DDC). Will keep slgt chc PoPS for lgt shra
(especially north of the parkways), however the confidence in timing
placement/ amounts quite low. SE winds of 5 to 10 will keep temps in
low to mid 60s in bigger cities.

Tue-Thu...

As the warm front becomes positioned from IND to CVG, the only isol
convection should be in Nrn CWA. Rest of the CWA should be dry
awaiting for the deep convection over Srn Plains to move east. In
response the low level jet starts to bring in some decent glfmex
moisture bringing dew pt temps into the upper 50s Tue aftn. WAA
continues to bring highs into the low 80s. Probabilistic 25th
percentile has BWG and SDF at 84 Tue.

Deep convection over the MO River Valley will be pushing east, with
shra and tsra approaching Wrn CWA by sunset Tue. It appears the
instability will be in the weakening phase overnight. However...GFS
redevelops the convection ahead of the cold front (with increasing
CAPE) on Wed. This could be very problematic with strong jet energy
and classic diffluence aloft with deep low with a negative tilt. The
hodographs are right turning with increasing speed.

Scattered severe weather looks like a distinct possibility across
portions of the Ohio Valley. There is alot of uncertainty and
mesoscale details are too far out and will come into focus over the
next several days, but this system bares watching. Once the cold
front passes Wed evening the strong instability gets shunted south
of the CWA.

Looks like a drier period from 06z to 18z Thu before secondary front
pushes through bringing more rain to CWA. With little instability,
main concern will be with rainfall and possible flooding.

Total QPF will be 1-2 inches, but depending on the Tue-Wed front
forward speed and how many rounds of convection, that number could
be higher as depicted by some of the ensemble members on the LREF.
Some minor river flooding is possible.

Fri... The CWA appears to be in a post frontal phase, with MVFR to
low VFR Cigs and brisk WNW winds of 15 to 25 with gusts to 30 mph +.
LLVL thicknesses support highs 57-62 F, which is will be the coolest
day of the work week.  Winds will slacken late in the day as
Canadian High pressure builds into the region.

Next weekend...

Data suggest a significant cool down with H8 temps below 0 C. This
translates to highs in the mid 50s and lows into the 30s. Well below
normal temps!

Weather Tidbit...

April 16 1998...A TN/KY Tornado Outbreak...with 3 tornadoes in
Davidison County (Nashville, including a F3, killing 1 and injuring
60).  23 Tornadoes hit TN, including the F5 that hit Lawrence
County, on the ground for over 60 miles. This forecaster published a
paper Titled "The Forgotten F5" on this nasty supercell.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 633 AM EDT Sat Apr 13 2024

VFR conditions expected through the forecast period. Winds will pick
up in strength late this morning and into the afternoon as the
boundary layer mixes out. Gusts near 20kts will be possible at
times. Winds will slacken some this evening but steadily climb up as
a modest LLJ moves in. This will result in LLWS issues for all TAF
sites late tonight and continue through Sunday morning.

&&

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

&&

$$

UPDATE...CSG
SHORT TERM...DM
LONG TERM...JDG
AVIATION...DM