878
FXUS63 KLMK 010146
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
946 PM EDT Sun Jun 30 2024

.KEY MESSAGES...

*   Unseasonably cool temperatures tonight, with lows in the 50s for
    most.

*   Unsettled weather Wednesday afternoon through Friday Afternoon
    with daily chances of showers and storms. Rain chances on
    Independence Day 70-80%.

*   Heat index Wednesday afternoon may surpass 100 degrees,
    especially west of the Natcher Parkway (I-165).

&&

.UPDATE...
Issued at 945 PM EDT Sun Jun 30 2024

A drier air mass continues to work across central Kentucky and
southern Indiana from north to south at this hour, with surface
dewpoints ranging from the mid 50s across southern Indiana to the
low 70s in the vicinity of Lake Cumberland. Divergent northerly low-
level flow away from high pressure centered over Wisconsin will
supply increasingly dry air through the overnight hours tonight,
allowing lower dewpoints to spread across southern Kentucky by
daybreak tomorrow. Latest nighttime microphysics satellite imagery
shows scattered low-level clouds continuing to linger across south
central KY, with one or two light showers still showing up over the
Cumberland Plateau in TN at this hour. These clouds should dissipate
over the next few hours, with mostly clear skies expected across the
region overnight.

The current forecast remains in good shape, with temperatures
expected to drop into the 50s and lower 60s by sunrise Monday.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 305 PM EDT Sun Jun 30 2024

Currently, the cold front that will bring more comfortable weather
to the region is trudging south through Kentucky. May areas north of
the front have already seen winds veer towards the northwest under
mostly clear skies. Even some areas south of the front have seen a
decent amount of sun this afternoon, but with precipitable water
values up to 2" still as far north as the Ohio River, there is still
lots of moisture for convection to take advantage of in the unstable
environment. Showers and thunderstorms are south of the Kentucky
parkways and have a history of heavy rainfall, lots of lightning,
and gusty winds, resulting in reports of tree damage in Nelson and
Marion Counties. These storms are moving with the front following
the instability and will continue moving off to the southeast
through the rest of the evening. Drier air behind the front will
drop south across Indiana as dew points drop from the low to mid 70s
into the upper 50s to mid 60s by 0z (8 PM EDT) this evening.
Precipitable water values drop to less than an inch near the Ohio
River.

Tonight, an upper ridge, centered over the Plains, will push a
surface high from the Midwest towards the Great Lakes. It`s this
circulation around this surface high that is generating our
northerly winds behind the front, and as the high gets pushed
eastward, winds will veer towards the northeast. Clear skies and
light winds will help drop low temperatures that were above normal
this morning to below normal tonight into early tomorrow morning
with lows ranging from near 50 to 60 across the CWA. Normal lows for
this time of year range from the mid 60s to 70.

Tomorrow, the surface high to our north slides by to the east while
our winds remain out of the northeast. Dry air will continue to
advect into the Lower Ohio Valley as dew points drop into the upper
40s to low to mid 50s. Clear skies with lots of sunshine will help
warm area temperatures into the upper 70s to low 80s. It`s going to
feel a lot better around here as heat indices only reach into the
upper 70s to near 80.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 305 PM EDT Sun Jun 30 2024

Monday Night through Wednesday Night...

High pressure at the surface and aloft will be in control of our
weather pattern at the start of the period.  Mostly sunny days and
mostly clear nights are expected from Monday night through Tuesday
night.  Another crisp night of temps is expected Monday night as
temperatures drop back into the low-mid 50s.  Still an outside
chance that a few of our valley locations and good radiational
cooling spots could dip into the upper 40s.  By Tuesday, we`ll get
into a more robust southwest flow which will allow temps to spike
back into the upper 80s to around 90.  Dewpoints will increase here
as well with values getting back into the mid-upper 60s.

Wednesday looks to start off dry within a broad southwest flow.
Highs will probably top out in the lower 90s in most spots.  By
Wednesday afternoon, a slow moving frontal boundary will creep into
the region from the north/northwest and may spark off scattered
afternoon/evening showers/storms.  Some of the storms could be on the
strong side given moderate instability, but the overall shear profile
looks to be pretty weak.  PWATs will jump back up over 2 inches by
this time, so torrential rainfall will be possible with any storms
Wednesday afternoon/eve.  Lows Wednesday night will only drop into
the upper 60s to the lower 70s.

Thursday through Sunday...

As we move into the 4th of July holiday period, upper trough axis
across the northern Plains will move eastward into the Great Lakes.
This will flatten the 500 mb ridge to our south placing the Ohio
Valley on the northern periphery of the ridge.  Slow moving cold
front from the earlier time period will likely continue to move
slowly south and stall out as it becomes parallel to the upper level
flow. This front will likely get a push southward by late Friday as
a secondary upper level trough axis pushes into the Midwest.  If
this scenario, as suggested by the Euro pans out, drier weather will
be possible across our region for the Saturday/Sunday period.

With the slow moving front in the vicinity on Thursday/Friday, will
keep high chance PoPs going in the forecast.  Longer range GFS and
Euro show a decent plume of moisture streaming across the region.
While instability may be locally high each afternoon due to heating,
bulk shear is forecast to be rather marginal (20-25kts).  Widespread
organized severe weather does not look likely given the set up.
However, can`t rule out some MCS activity which may result in some
localized periods of higher severe storm risk.  Given the
instability/high moisture set up, torrential rainfall and gusty winds
would be the main weather hazards for Thursday and Friday.

Highs Thursday and Friday will be dependent on cloud cover and
possible precipitation in the area.  For now will go with mainly
upper 80s for highs with overnight lows in the upper 60s/lower 70s.
If we can get the front pushed through for the weekend, highs
Sat/Sun will be near normal with upper 80s to around 90 for highs
and lows in the upper 60s to the lower 70s.

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 719 PM EDT Sun Jun 30 2024

VFR conditions are expected through the current forecast period.

Now that the cold front and lingering showers and storms have
cleared the region, clearing skies and occasionally gusty northerly
winds are expected over the next few hours. As we head later into
the overnight hours tonight, winds will gradually weaken, though a
persistent 6-10 kt N/NE breeze should continue through much of the
night, especially at SDF and LEX. Tomorrow, mostly clear skies
should continue with high pressure sinking closer to the region.
Winds will gradually veer more northeasterly tomorrow, with
sustained winds around 10 kt and gusts of 15-20 kt expected during
the daytime hours on Monday.

&&

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

&&

$$

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