Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

031
FXUS63 KJKL 260031 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
831 PM EDT Thu Jun 25 2026

.KEY MESSAGES...

- Unsettled weather returns to end the week and into the weekend,
  with rounds of showers and storms possibly producing heavy rain
  and a flood threat.

- An extended period of hot temperatures begins Monday, with high
  temperatures reaching into the low to mid 90s and heat indices
  nearing or exceeding 100 degrees by Tuesday.

&&

.UPDATE...
Issued at 818 PM EDT THU JUN 25 2026

Some adjustments were made to increase sky over a bit over the
next few hours with extensive high cloud/cirrus debris from
upstream convection. Otherwise, hourly temperatures and dewpoints
were fine-tuned based on recent observations. Valley fog formation
is still problem around or after midnight, but at this time it is
expected to not have as significant reductions in visibility as
compared to Thursday morning.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 454 PM EDT Thu Jun 25 2026

Afternoon surface analysis reveals that the forecast area remains
under the influence of a broad ridge of high pressure over the SE
CONUS. A slow-moving surface frontal boundary is currently analyzed
to the north of the Ohio River. That front currently lacks well-
defined support aloft, as the forecast guidance suite currently
resolves a regime of quasi-zonal WNW flow at 700mb and above. A
series of shortwave disturbances will navigate through this regime
and pass over the Ohio River Valley in the coming days. The
progression of these impulses will allow the aforementioned boundary
to oscillate south/north through the end of the long term forecast
period before a stronger system approaches the area on Friday night
into Saturday. Thus, these shower and thunderstorm chances are
contained to the Bluegrass in the initial stages of the period, then
spread back east across the CWA tomorrow afternoon and night.

This afternoon, efficient diurnal processes have led to widespread
temperatures in the mid 80s and the development of a scattered field
of cumulus clouds. The lingering influence of the ridge has left an
unfavorable environment for these clouds to develop into full-
fledged showers in our CWA this afternoon, although we will be
closely monitoring the evolution of upstream activity associated
with the first shortwave disturbance. After sunset, expect our
sheltered and shaded eastern valleys/hollows to decouple.
Temperatures there should quickly cool into the 60s after sunset and
allow for patchy river valley fog to develop. These ridge/valley
splits are most likely in SE KY, as they are contingent on there
being less cloud cover tonight in accordance with those diurnal
processes. Further to the NW, in the Bluegrass, rain showers and
perhaps a general, sub-severe thunderstorm cannot be ruled out, and
lingering cloud cover streaming off stronger upstream convection
could be enough to block the terrain-based thermal decoupling.

Tonight`s rain chances are on the lower end of the probability
spectrum, and diverging model solutions preclude there from being
much forecast confidence in their formation. The best synoptic
forcing will remain displaced from our CWA, as the boundary is not
progged to make it south of the Ohio River tonight. Furthermore, the
CWA is positioned in the right rear exit region of an upper level
jet streak. That positioning is not favorable for large-scale
ascent, and widespread severe weather or heavy rainfall is not
expected in the JKL CWA tonight. Any rain that does fall from the
weak isolated to scattered convective activity north of I-64 tonight
would serve as an appetizer for the more active weather tomorrow
though.

Above-normal overnight lows in the 60s will give tomorrow`s
temperatures a head start, and breezy southwesterly low level flow
should advect a relatively warmer and wetter airmass into the
region. The quasi-stationary boundary nudges back north of the Ohio
River as a warm front while a better-defined and deeper shortwave
trough approaches the commonwealth. This leads to upstream surface
cyclogenesis and a tightening pressure gradient, which, in turn,
points towards more effective low-level advection. Highs are
accordingly forecast to climb into the mid to upper 80s alongside
afternoon dewpoints in the upper 60s/lower 70s. This sets up more
favorable thermodynamic profiles for tomorrow afternoon`s cumulus
clouds to produce precipitation, but the 1000+ J/kg of CAPE contour
remains confined to counties west of the Pottsville Escarpment
tomorrow. Locales to the west of I-75 and along/north of the I-64
corridor have the greatest rain chances tomorrow. An isolated
stronger storm cannot be ruled out, but widespread severe weather is
not probable in the JKL CWA tomorrow. The evolution of Friday`s
daytime activity will need to be monitored closely though,
especially given the chances for multiple rounds of activity in the
north.

As the low pressure system deepens and propagates northeast and the
parent shortwave disturbance approaches on Friday night, a 30-40
knot west-southwesterly low level jet will pump deeper moisture into
the column over Eastern Kentucky. Additional bands of showers and
storms are progged to develop within the warm sector to the east and
southeast of the low pressure center. The related cloud cover will
insulate Friday night`s low temperatures to the upper 60s/lower 70s,
leaving enough instability in place for additional thunderstorms.
Friday night`s activity will have more synoptic support than the
previous rounds, which may have left wet grounds in place across
northern portions of the forecast area. As such, WPC has outlined a
Slight (2/4) Risk for Excessive Rainfall across most of Kentucky
through 8AM Saturday. The risk for flash flooding will be highest in
areas that experience multiple rounds of convective activity with
high rainfall rates. In the short term forecast period, this is most
likely along the I-64 corridor, but the risk spreads southeast
headed into the short term forecast period on Saturday morning.

.LONG TERM...(Saturday through Thursday)
Issued at 346 PM EDT THU JUN 25 2026

A significant pattern change to much hotter weather is still
anticipated as we close out the month of June and turn the
calendar to July. When the long-term period opens at 12Z Saturday,
the models are in good agreement showing shortwave troughing
aloft over the Ohio Valley to Eastern Great Lakes while a
developing ridge extends northward across the Plains from a broad
upper-level high extending from Bermuda to Northern Mexico. An ~550
dam closed low will also be diving into the Pacific Northwest
from the Gulf of Alaska. At the surface, a weak area of low
pressure will be situated near/over the Bay of Fundy with a cold
front extending southwest from the low to a weak area of low
pressure over southern Indiana and then west to a lee trough along
the eastern slopes of the Colorado Rockies. Convection is likely
to be ongoing across eastern Kentucky after daybreak Saturday
within the warm sector of the low, amidst a high PWAT air mass
(nearing 2.00 inches) and weak skinny instability (750-1250 J/kg
of MLCAPE).

While guidance varies on overall speed, the surface low will scoot
north of the JKL CWA during the day on Saturday with the trailing
cold front sagging to along or south of the Lower Ohio River, though
overall progress across the Commonwealth is uncertain due to
guidance spread. With morning convection and categorical PoPs,
sufficient destabilization for severe weather ahead of the cold
front remains an open question. Of greater confidence will be the
deep warm cloud layer, PWATs near or exceeding 2 inches and skinny
CAPE with high RH to the stratosphere, all of which will be
supportive of torrential downpours. Where rainfall is most
persistent, isolated instances of flash flooding remain a legitimate
concern and so most locations south of I-64 are in a Day 3 WPC
ERO Slight Risk.

By Sunday, troughing over the Western CONUS will continue to deepen
while the downstream ridging builds over the Central CONUS and a
closed high takes shape over the Lower Mississippi Valley. In
response, the frontal boundary will lift back to the north and
east with a generally lower probability of showers and thunderstorms
(mostly chance PoPs) on Sunday afternoon. The boundary continues
to progressively lift northeast through the new work week as the
center of the upper-level high drifts up into the Mid-
Mississippi and Lower Ohio Valleys. This will keep high humidity
in place from Monday through Thursday, but the rising heights
will tend to lead to some mid-level capping. LREF mean PWATs are
in the 1.5 to 1.6 inch range during this period. High humidity
values at the low-levels will support robust instability (2,500
to 3,500 J/kg of MUCAPE) formation each afternoon but it will
remain largely trapped by the capping inversion. However,
differential heating over the rugged Coalfield topography may be
sufficient to break the cap and yield isolated afternoon and
evening pulse thunderstorms. With weak flow and mid-level dry air
in place, it does appear that there is a risk for a few of the
most robust cores to produce strong to severe microburst winds as
they collapse. Temperatures will also be very hot with LREF mean
850 hPa temperatures reaching 20 to 21C on Monday, around 22C on
Tuesday, 22 to 23C on Wednesday, and around 23C on Thursday.
Probabilities for temperatures exceeding 90F across the lower
elevations are in the 50 to 70 percent range on Monday, 70 to 90
percent range on Tuesday, 80 to 100 percent on Wednesday, and 90
to 100 percent on Thursday. The high temperatures combined with
dew points in the low to mid 70s should support heat indices
nearing and in many locations exceeding 100F, especially by mid-
week.

In sensible weather terms, look for occasional rounds of showers and
thunderstorms, some of which could produce heavy rainfall and
instances of flooding on Saturday, becoming less numerous on Sunday.
It will be mild and muggy with highs in the low to mid 80s on
Saturday, warming into the 85 to 90F range for Sunday, while
nighttime lows range within several degrees of 70F. Thereafter, it
will be hot and steamy with temperatures soaring into the upper 80s
to lower 90s on Monday, and low to mid 90s each subsequent
afternoon. Nighttime lows stay mostly in the 70s. Heat indices
will reach new highs each afternoon with most places eclipsing the
100F mark by Thursday. Isolated showers and thunderstorms will be
possible each afternoon and may bring localized relief for some.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 831 PM EDT THU JUN 25 2026

VFR conditions should prevail for the majority of the forecast
period, with a couple of caveats. Upstream convection could affect
locations generally north of the Mtn Parkway tonight and some
brief reductions to MVFR are possible. A PROB30 group was used for
a couple of hours at KSYM. Otherwise, valley fog formation is
anticipated in SE KY again tonight, with reductions to MVFR or
IFR though this again should not affect the terminals. Mid to high
level clouds, debris from upstream convection, will likely linger
for much of the last 12 hours of the period. Cumulus should again
develop during the 14Z to 17Z period, which should eventually
yield convective chances during the last 6 hours of the period as
a cold front sags toward the OH Valley. Light and variable winds
are expected through about 14Z, giving way to south to southwest
winds at 5 to 10KT.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...JP
SHORT TERM...MARCUS
LONG TERM...GEERTSON
AVIATION...JP