578
FXUS63 KLMK 150519
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
119 AM EDT Sat Jun 15 2024

.KEY MESSAGES...

*   Above normal temperatures expected Sunday into next week. Spotty
    showers and storms possible next week as well, particularly on
    Monday, though confidence in their development remains low.

&&

.UPDATE...
Issued at 933 PM EDT Fri Jun 14 2024

A dew point front has drifted south to the Ohio River this evening,
with dew points in the lower 70s ahead of the boundary in central
Kentucky, and in the 50s behind the boundary in central Indiana.
This boundary will continue to sink south into central Kentucky
tonight, pushed forward by high pressure strengthening and expanding
over the Great Lakes. A light north breeze and the drier air coming
in will limit fog formation, but some patchy fog in sheltered
eastern valleys will be possible around dawn, especially in spots
that got rain right before sunset today. Low temperatures tonight
will generally be in the lower and middle 60s.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 231 PM EDT Fri Jun 14 2024

Weak frontal boundary is pushing through our southern Indiana
counties and is nearing the Ohio River at this hour (1830z). As is
typical with June `cold` fronts, there is a minimal temperature
gradient but lower dewpoints (50s) have been observed in central
Illinois. Models still indicate we could see some very isolated
convection develop this afternoon near the frontal boundary, and a
cu-field has recently developed as the low levels have destabilized.
AMDAR soundings from SDF reveal a weak capping inversion near 850mb
that has steadily eroded through the day, and once this erodes a bit
more, we should start to see the potential for isolated
showers/storms increase. A quick environmental analysis shows
marginal deep layer shear (20-30kts) co-located with modest MLCAPE
(1000-1500 J/KG), but very high DCAPE (1000-1400 J/KG). If we are
able to get a storm with a modest core aloft, given the high DCAPEs,
it would have the potential to produce very gusty winds along with
heavy rainfall.

Shower/Storm chances should taper off this evening with the setting
sun and an increasing nocturnal inversion. Drier air will filter in
from the northwest behind the front, and we`ll stay dry and mostly
clear going into tomorrow. Temperatures behind the front won`t
change much as we`re expecting another warm day Saturday (highs in
the mid/upper 80s), but dewpoints should steadily decrease into the
50s for most spots to help make the warmer temperatures a bit more
bearable.

&&

.LONG TERM /TONIGHT THROUGH FRIDAY/...
Issued at 231 PM EDT Fri Jun 14 2024

Saturday night - Sunday night...

Upper level ridging centered over the Southeast US slowly builds
eastward late in the weekend. At 850 mb, southwesterly low-level
flow develops by late Saturday night into Sunday as ridging slips
east across the Appalachians. Warmer air is advected northward into
the region, and 1000-850 mb thicknesses rise quite a bit relative to
Saturday. With a dry airmass in place, temperatures will likely end
up several degrees warmer with afternoon highs in the low to mid
90s.

Sunday morning lows are forecast to be in the low to mid 60s, fairly
typical for this time of year. Increasing low-level moisture via
steady southerly return flow late Sunday into Monday will result in
a warmer night with Monday morning lows in the lower 70s in most
places.

Monday - Tuesday...

Upper level ridging amplifies over the eastern United States next
week and will be very slow to progress eastward. Southerly low-level
flow will continue to bring a stream of moisture up the Mississippi
River Valley and into the Lower OH Valley. PW values push past 1.5
inches, around 1 SD above normal. LREF members do show a notable
uptick in SBCAPE Monday afternoon and evening with median values
above 1000 J/kg. However, there isn`t really any forcing of note
other than pure convection. Isolated pulse showers/storms will be
possible, which could briefly knock back the heat and humidity.
However, precip coverage should remain fairly limited.

Given the increased low-level moisture on Monday and potential for
an expanding diurnal cumulus field, confidence in afternoon high
temperatures is a bit lower. Still think we could see low to mid 90s
once again, but this forecast is toward the upper end of the model
distribution. These values would yield heat indices near 100 Monday
afternoon and early evening.

Tuesday still looks mainly dry and hot with highs in the low to mid
90s.

Tuesday night - Thursday...

Strong ridging aloft will expand its influence over our region
through the middle of next week, even as it becomes centered further
northeast. Dry weather appears likely at this time with our heat
wave continuing. Highs in the 90s are likely each day with morning
lows in the upper 60s and lower 70s.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 107 AM EDT Sat Jun 15 2024

Diffuse cold front is draped just south of the Ohio River, with
lower dewpoints filtering into SDF but moisture pooling still noted
at LEX and BWG. Expect the front to drop just far enough south to
return LEX to VFR by 08Z, with lower confidence at BWG. Light
N-NE winds behind the front will veer to ENE and increase to
just shy of 10 kt shortly after daybreak as high pressure over
the Great Lakes asserts its influence.

&&

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

&&

$$

UPDATE...13
SHORT TERM...DM
LONG TERM...EBW
AVIATION...RAS