Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

835
FXUS63 KJKL 190007
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
807 PM EDT Thu Jun 18 2026

.KEY MESSAGES...

- Showers and thunderstorms will affect many locations into
  tonight, but will mostly taper off during the night. Dry weather
  then lasts at least until near the finish of the weekend

- Some thunderstorms may bring locally heavy rainfall into
  tonight, especially in south central and southeast Kentucky.

- Somewhat less humid air will arrive behind a cold front tonight
  and allow for cooler morning lows through the weekend.

&&

.UPDATE...
Issued at 807 PM EDT THU JUN 18 2026

Have updated for a cooler start to the evening and a faster
tapering of precip in our northwest counties.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 653 PM EDT THU JUN 18 2026

A broad upper level trough is over the north central and northeast
CONUS late today, and is supporting a surface cold front entering
KY from the northwest. Clouds and precip ahead of the front have
held temperatures down considerably over northern and central
portions of the area today, and new convection after diurnal
heating/destabilization has cooled temperatures in the southern
portion of the area late this afternoon. That being the case,
instability is now limited and is also limiting the severe wx
potential. However, precipitable water is still near 2" over
south central and southeast KY and is supportive of heavy rainers.
With a Flood Watch already in place and ongoing
showers/thunderstorms, it is being left to run into the evening.

The aforementioned cold front will move southeast through the
forecast area tonight and precipitation will taper off. High
pressure building in behind the front will give us a somewhat
drier air mass lasting into the weekend. This will allow for
cooler low temperatures.

There is fog potential tonight, with moist ground, decreasing
clouds, and light winds favoring development. Cool/dry advection
behind the front and resulting steep low level lapse rates will
fight against fog. The factors favoring fog tend to win out more
often than not, and fog is in the forecast. However, the degree of
clearing is questionable, especially in southeast KY, and fog has
not been hit as hard there.

.LONG TERM...(Saturday through Thursday)
Issued at 627 PM EDT THU JUN 18 2026

The long term period will open with broad 500 mb troughing over
the Northeastern CONUS and Midwest, with ridging over the Mountain
West and High Plains. Farther west, a secondary, more compact
trough will be located over the Pacific Coast. At the surface,
high pressure will persist over Kentucky, and pleasant weather is
expected throughout the day on Saturday. Highs will remain
relatively mild (in the upper 70s to low 80s in most of the
forecast area), and winds are expected to remain light, with good
model consensus regarding a weak pressure gradient over our area.
Some model discrepancy still exists regarding the exact location
of this surface high during the day on Saturday, owing to
differences in the eastward progression of this feature. This
positioning will have implications on the magnitude of moisture
return; a quicker eastward translation of this high would allow
for enhanced moisture advection via southwesterly winds on
Saturday, whereas a slower surface high would delay this moisture
return. Regardless, skies should remain mostly clear on Saturday
night into early Sunday morning, and with high pressure overhead,
a modest ridge-valley temperature split is expected, with the
floor for low temperatures remaining dependent on dewpoints going
into Saturday night. MOS guidance suggests that low temperatures
could fall into the mid 50s in our sheltered hollows, but given
uncertainty regarding dewpoints going into the overnight hours,
these hollows were generally kept in the upper 50s for now, with
ridges seeing minTs in the low to mid 60s. This will also allow
for typical fog formation overnight in mainstem river valleys.

On Sunday, a shortwave rotating around the base of the broad
eastern CONUS trough will travel across the Plains, taking on a
negative tilt as it approaches the Ohio Valley by Sunday evening.
Meanwhile, the associated surface low will translate northeastward
into the Midwest, and a warm front extending from this low is
expected to lift northward into our area on Sunday as high
pressure fully exits our area. Accordingly, rain chances are
expected to return as early as Sunday afternoon. Instability will
be modest Sunday evening (with mean ensemble CAPE well below 1000
J/kg across the forecast area), but will be adequate for some
thunderstorms in our area. More notably, rich moisture is expected
to be in place late Sunday into Monday, with anomalously high
PWATs likely; LREF guidance shows mean PW values ranging from 1.7
to 1.9 inches across eastern Kentucky, indicating column moisture
generally in the 95th percentile or higher compared to
climatology. Accordingly, WPC has placed eastern Kentucky in a Day
4 and Day 5 Marginal Risk for Excessive Rainfall (Level 1/4),
indicating an environment conducive to flash flooding on both
Sunday and Monday. However, great uncertainty still remains with
this pattern.

Rain chances will continue through at least Monday, although
guidance diverges significantly at this point. Generally, multiple
shortwaves could impact the area, leading to repeated shower and
storm chances through at least Monday; after this, uncertainty
compounds. At the surface, the original low is expected to
generally continue to translate eastward along with an associated
cold front, although there is presently low confidence regarding
the progression of this front. Some models (such as the GFS) hint
that the front may stall near our area, bringing repeated rounds
of rain and storms to the Commonwealth. In this scenario, the
flooding risk would increase, particularly given such rich
preexisting moisture. Alternatively, other models (such as the
ECMWF) favor a relatively progressive system, with the cold front
clearing our area Monday night. With this discrepancy in mind, the
spread for instability is quite large on Monday
afternoon/evening; in a more progressive scenario, a combination
of frontal forcing and relatively higher instability could allow
for a low end risk for severe weather, with some machine learning
guidance hinting at this possibility. However, uncertainty remains
very high with this setup. Looking beyond Monday, confidence
remains low as sensible weather impacts will remain dependent on
the progression of embedded shortwaves within general troughing.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 807 PM EDT THU JUN 18 2026

Showers and thunderstorms were affecting portions of the area at
the start of the period, mainly south of a line from KSME-KJKL-
KSJS. They were bringing localized IFR or worse conditions.
Away from the precipitation, conditions were largely VFR. During
the course of the night, a cold front will move southeast through
the area and with it the remainder of the precipitation will
taper off from northwest to southeast. Even though rain will
diminish, the moist ground and decreasing clouds will favor
eventual fog/low cloud development. Cooler and drier air arriving
behind the front will fight against fog/low cloud development, but
probably not prevent it. This leaves uncertainty to the extent.
Any fog or low clouds should dissipate on Friday morning and leave
VFR conditions to finish the period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 2 AM EDT Friday for KYZ058>060-068-069-079-080-
083>088-104-106>120.

&&

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...GEERTSON
AVIATION...HAL