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396
FXUS63 KLMK 060721
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
321 AM EDT Thu Jun 6 2024

.KEY MESSAGES...

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*   One more warm and muggy day today before a reinforcing shot of
    cooler and drier air arrives tonight. An isolated rain shower
    will be possible late this afternoon and into the evening.

*   Scattered light rain showers will be possible Saturday afternoon
    through Sunday morning.
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&&

.SHORT TERM /THROUGH TONIGHT/...
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Issued at 320 AM EDT Thu Jun 6 2024

Now through Late Morning...

At this hour, a band of light to moderate rain showers extends from
near Bowling Green to Richmond and up into northeastern KY ahead of
a cold front which is losing sharpness as it crosses the region.
Latest SPC mesoanalysis suggests that the back edge of this area of
rain is co-located with a sharp gradient in precipitable water, with
values decreasing from 1.6-1.7" along and south of the Parkways to
less than 1" west of the Interstate 69 corridor. While encroaching
drier air in the mid- and upper-levels of the atmosphere should help
to clear the rain showers off to the south and east over the next
several hours, stubborn low-level moisture will result in lingering
low stratus, with some patchy fog also possible where near-sfc winds
slacken. At this time, while sites like FRH, HNB, and BMG are
experiencing some fog, would expect there to be just enough wind for
stratus to be predominant, though we`ll monitor trends in obs in
case a headline for fog is needed later this morning. By mid-
morning, low-level moisture should scatter out as diurnal heating
helps to mix drier air aloft down to the surface. Sunshine should
increase from NW to SE later this morning, allowing temps to warm
quickly later this morning.

This Afternoon and Tonight...

A secondary frontal boundary will drop through the region this
afternoon and evening. Ahead of the front, 10-15 mph WSW winds will
not allow for much in the way of cold advection, and temperatures
are expected to surge into the low-to-mid 80s once again this
afternoon. As the front approaches and moves through, there should
be enough lingering moisture in the sfc-700 mb layer combined with
steep low-level lapse rates and lifting associated with the front
for isolated showers to develop. A layer of warm air above 700 mb
associated with mid-level subsidence should effectively cap
convection within a fairly narrow layer, and it appears unlikely
that convection will be deep enough for thunderstorms to develop.
The best chances (20-30%) for showers this afternoon are expected
across the KY Bluegrass, though a brief sprinkle or light rain
shower cannot completely be ruled out in any portion of the CWA.

Once the second front crosses the region tonight, a fetch of much
drier air will move overhead, with dewpoints falling from the low-to-
mid 60s to the upper 40s and lower 50s by Friday morning. Cooler air
will also arrive behind this secondary FROPA as winds veer from WSW
to WNW. This drier air combined with steady winds overnight Thursday
night should limit fog potential Friday morning, with no significant
weather expected through the remainder of the short term forecast
period once showers move east of the region this evening.
Temperatures Friday morning should feel quite refreshing, with lows
expected to fall into the mid-to-upper 50s in most locations outside
of Louisville.
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&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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Issued at 320 AM EDT Thu Jun 6 2024

High pressure sliding from the Ozarks to the Tennessee Valley and a
mostly dry atmosphere will provide us with pleasant weather Friday
into Friday night. Friday afternoon should see high temperatures
peak around 80 with scattered fair weather cu. Fairly dry low levels
are showing up on sounding progs so went slightly below NBM for
afternoon dew points (though only by a couple of degrees, given
evapotranspiration from the very green, healthy vegetation), with RH
falling into the 35-45% range. Good sleeping weather Friday night
with lows in the middle and upper 50s.

This weekend a cold front will approach from the northwest and push
through the region overnight Saturday night into early Sunday
morning. Surface dew points will generally be in the 50s with only
slightly greater than normal precipitable water values. The
atmosphere will be strongly capped Saturday and Saturday night, with
very limited instability all weekend. So, just expecting some
scattered light rain showers and an isolated rumble of thunder,
especially late Saturday night into Sunday morning with the front.
Highs both days will be in the middle and upper 70s.

Dry weather will return for at least Monday and Tuesday next week as
a long north-south ridge of high pressure from Hudson Bay to the
lower Mississippi Valley crosses the eastern United States. While
high temperatures on Monday will once again be in the middle and
upper 70s, readings will moderate to around 80 on Tuesday as the
high exits to the east.

By Wednesday a 5H shortwave trough may pass overhead, but at this
time it looks like there won`t be much moisture available so will
keep the forecast dry for now. CPC 6-10 day outlook calls for odds
leaning towards drier than normal conditions for the June 11-15
period (next Tuesday through Saturday).
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&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 116 AM EDT Thu Jun 6 2024

A cold front is located over the region early this morning, with a
disorganized line of showers and one or two rumbles of thunder
extending along a BWG-LEX line at this time. This area of rain along
the front will gradually push to the east later this morning,
clearing BWG and LEX within the next 2-3 hours, and clearing RGA by
10-11Z. Occasional visibility reductions will be possible in any
heavier shower, with temporary IFR/MVFR conditions possible at BWG,
LEX, and RGA over the next few hours.

Across all sites, there is potential for reduced visibilities and/or
reduced ceilings later this morning. At LEX/BWG/RGA, would lean
toward low stratus given persistent light low-level breeze
overnight. At SDF, it is quite a challenging forecast through 12Z
this morning as the deeper moisture and stratus should make it just
southeast before settling into MVFR levels; however, the back edge
of the low clouds will be close enough that brief MVFR CIGs are
still possible. At HNB, while deeper moisture should be far enough
to the southeast to limit low stratus, fog potential will be present
due to weaker winds. Would expect most if not all sites (with the
possible exception of SDF) to bounce between VFR/MVFR/IFR between 08-
13Z this morning, and the forecast is low confidence between now and
then.

Later this morning, confidence increases in a return to VFR
conditions as drier air aloft starts to work in behind the cold
front. Winds will increase out of the west later today, with
sustained winds around 10 kt and gusts to around 20 kt during the
late morning and afternoon hours. A secondary front dropping through
the area will bring an increase in mid-level clouds this afternoon
as well as a few showers; however, substantial impacts from
clouds/showers are not expected at this time. After sunset tonight,
clearing skies and light westerly winds are expected through the end
of the current forecast period.

&&

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

&&

$$

SHORT TERM...CSG
LONG TERM...13
AVIATION...CSG