Frankfort, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

214
FXUS63 KLMK 130218
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1018 PM EDT Mon May 12 2025

.KEY MESSAGES...

*  Scattered showers and thunderstorms are expected this afternoon
   and evening, as well as on Tuesday and Wednesday. Heavy rainfall,
   lightning, and gusty winds are the main threats.

*  A warming trend is expected later in the week, with highs well
   into the 80s Thursday and Friday. The potential for waves of
   strong, possibly severe storms Thursday through Friday night is
   increasing.

&&

.UPDATE...
Issued at 1011 PM EDT Mon May 12 2025

A very mild and somewhat muggy air mass, at least for this early in
the warm season, remains in place over central Kentucky and southern
Indiana. The more robust moisture feed is just to our west, fueling
a cluster of showers with a few embedded thunderstorms lifting
northward through the Pennyrile, while we just see a few stray
showers try to move into south-central and east-central Kentucky.
Believe this activity will mainly dissipate in the next couple hours
as any residual instability is lost, and most areas will be dry
overnight. These trends are handled well in the previous forecast,
so changes will be limited to minor tweaks of hourly trends in the
hi-res products.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 353 PM EDT Mon May 12 2025

This afternoon, a stacked low pressure system continues to spin over
the Mississippi Delta as an occluded surface front extends across
Tennessee to the northeast of the center of the low. A plume of deep
moisture extends from the Carolina coast across the Appalachians and
into southwest Ohio as bands of scattered showers and thunderstorms
stream from south to north. The Bluegrass region remains on the
western edge of this moisture plume at this time, though this should
gradually push off to the east later this afternoon. Farther to the
west, an area of slightly drier mid-level air has resulted in
partial clearing, although a cu field has quickly filled in thanks
to plentiful low-level moisture.

As we head through the rest of the afternoon, hi-res guidance
suggests that a band of showers and thunderstorms should be focused
where there is enhanced convergence in the vicinity of the sfc
occluded front, with much more isolated convection elsewhere. This
should primarily be along and west of a line from Tell City, IN to
Tompkinsville, KY. Soundings show around 1000 J/kg of MLCAPE with
around 20 kt of deep-layer shear, so mainly garden-variety storms
are expected, though one or two stronger storms with gusty winds
cannot be ruled out. While storms should be moving around 20 mph,
any training of storms could lead to localized heavy rainfall
amounts and minor flooding.

Tonight, coverage of showers and storms should begin to decrease
after sunset and will continue to dwindle after midnight. As the
diurnal cu field subsides, if there is enough clearing, winds within
the boundary layer may be light enough for some patchy valley fog to
develop, although confidence in this is low. With the humid air mass
remaining in place, temperatures should remain mild tonight, only
falling into the upper 50s in rural areas and the low-to-mid 60s in
urban areas.

Tuesday, the upper low is expected to pivot from northern MS toward
the Ohio Valley. While moisture in the vicinity of the low will not
be as plentiful as the plume to the east of the region today, it
should still be more than sufficient for scattered showers and
thunderstorms to develop once convective temperatures are reached.
With the upper low centered overhead, storm motions should be quite
slow tomorrow afternoon, generally around 10 mph. Winds aloft should
be even weaker, so organized/severe convection is even less likely
tomorrow afternoon. As a result, localized heavy rainfall and minor
flooding would be the main threat with showers and storms.
Temperatures should be fairly similar to today, with highs topping
out between 75 and 80 in most locations.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 353 PM EDT Mon May 12 2025

Tuesday night into Wednesday, the upper low is expected to continue
to lift to the north as it begins to interact with a trough
descending across the western CONUS. In its wake, low-amplitude
ridging will begin to build into the Mississippi and lower Ohio
Valleys. At the surface, lee troughing will set up over the high
Plains, allowing for low-level return flow across the Ozarks and
into the lower Ohio Valley on Wednesday. There should be enough
residual moisture and forcing from the departing upper low on
Wednesday for scattered showers and storms to develop Wednesday
afternoon, particularly east of Interstate 65. Temperatures will
begin a warming trend on Wednesday, rising into the upper 70s and
lower 80s Wednesday afternoon.

A return to an active weather pattern is expected for the end of
this week as the trough over the western CONUS ejects across the
northern Plains Wednesday into Thursday. The leading sfc low
pressure system is expected to occlude over the upper Midwest on
Thursday, with the associated cold front pushing toward the Ohio
Valley Thursday afternoon and evening. Ahead of the front,
temperatures will surge into the mid-to-upper 80s across the area.
While NBM probabilities of temperatures at or above 90 degrees are
fairly high (50-70%), think we will struggle to realize full warming
potential given elevated soil moisture conditions. Dewpoints in the
upper 60s and lower 70s will make things feel quite muggy Thursday
afternoon, with heat indices currently forecast to rise into the
upper 80s and lower 90s.

With plentiful low-level moisture in place and incoming height falls
from the approaching trough, instability will surge on Thursday.
While raw model soundings show SBCAPE exceeding 4000 J/kg, this is
likely overdone and MLCAPE progs around 2500-3000 J/kg seem to be
more realistic. Still, this is more than sufficient for severe
convection, and wind shear will begin to increase as faster mid- and
upper-level flow arrives ahead of the approaching trough. The
limiting factor for severe storms Thursday/Thursday Night looks to
be a warm mid-level capping layer and lack of a triggering
mechanism. If storms were to fire upstream, then strong-to-severe
storms could continue across the area from west to east Thursday
night.

The upper trough will evolve into a closed low over the Great Lakes
on Friday, with a zonally-oriented jet expected to be located over
the region. Depending on how much convection is realized Thursday
and Thursday night, there may be additional potential for severe
convection on Friday with a similar parameter space for instability
and shear. While the GEFS/Colorado State machine learning models are
keying on Thursday as the primary severe threat, the ECMWF-based AI
models indicate the greatest potential Friday into Friday night. It
is also possible that multiple waves of strong/severe convection
could occur depending on the evolution of convection and the
positioning of the cold front later this week. The setup would
suggest damaging winds would be the primary hazard type later this
week, though the shear/instability parameter space would suggest all
hazards are possible.

This weekend, forecast confidence decreases and will be dependent on
how far south the cold front makes it earlier in the week. The GFS
continues to suggest that the front may stall across southern KY,
resulting in additional rounds of showers and storms over the
weekend. On the other hand, the ECMWF clears the front through the
region, resulting in drier weather over the weekend. Stay tuned for
updates later this week on the potential for severe weather Thursday
through Friday night.

&&

.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 741 PM EDT Mon May 12 2025

Prevailing VFR expected through the night with mainly mid-level
cigs, but RGA is the exception with a current MVFR cig below 2000
feet. Showers seem to be splitting BWG and could affect SDF and HNB
late this evening, but probabilities of a direct impact are low and
if it does happen, would not expect conditions to drop below IFR.

There`s a window for MVFR stratus on Tuesday morning, but the only
site we take below 2000 feet will be RGA, where a low cloud deck
could stay in place until late morning. Next disturbance to pinwheel
around the low will have its main impact Tue afternoon, but cig/vis
should be VFR if only just barely so. Forecast confidence regarding
showers and storms is fairly low, no better than medium. Confidence
is higher that we`ll have mainly cloudy skies and light E-SE winds.

&&

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

&&

$$

UPDATE...RAS
SHORT TERM...CSG
LONG TERM...CSG
AVIATION...RAS