Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

813
FXUS63 KJKL 112331
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
731 PM EDT Mon May 11 2026

.KEY MESSAGES...

- Isolated instances of frost are possible late tonight into
  Tuesday morning in deeper rural valleys and hollows - mainly
  away from mainstem rivers.

- There is a greater concern for frost formation late Thursday
  night into Friday morning, especially in sheltered rural valleys
  and hollows away from mainstem rivers.

- A cold front is expected to bring chances for showers and
  perhaps a few thunderstorms for Wednesday.

- Additional shower and thunderstorm chances arrive this weekend
  accompanied by a trend of increasingly warmer temperatures into
  early next week.


&&

.UPDATE...
Issued at 731 PM EDT MON MAY 11 2026

Added the latest surface observations and interpolated through the
rest of the evening. Grids have been saved and sent.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 228 PM EDT MON MAY 11 2026

An upper disturbance that brought widespread rain to southeastern
Kentucky this morning will track east of the area by this evening,
with northwesterly cyclonic flow gradually becoming neutral by
Tuesday morning, weakly anticyclonic during the day Tuesday with
passing shortwave ridging, and then increasingly cyclonic again as a
disturbance and surface cold front approach the area from the
northwest Tuesday night into Wednesday morning.

Below normal low temperatures are expected tonight under clear to
mostly clear skies and light winds. Given this morning`s rainfall
combined with good radiational cooling conditions, expect widespread
lows in the upper 30s to mid 40s, with fog in most if not all river
valleys, with just the slightest chance of frost in some of the
outlying valleys and hollows.

With shortwave ridging and just a bit of low-level warm advection
Tuesday, highs will climb to near normal for this time of the
year in the mid- 70s under mostly clear skies.

Warm advection slowly increases through the Tuesday night period,
and chance PoPs are introduced from the northwest toward morning as
a cold front moves toward the area. Given very limited instability
indicated in the models, any activity arriving before 12z Wednesday
would be in the form of showers. Before the arrival of clouds and
potential showers, good radiational cooling during the first half of
the overnight, despite increasing warm advection, would support a
fairly robust ridge-valley splits in temperatures as well as the
likely formation of fog in the more protected river valleys.

.LONG TERM...(Wednesday through Monday)
Issued at 339 PM EDT MON MAY 11 2026

The long-term period begins daybreak Wednesday with the next round of
unsettled weather developing from the northwest with an approaching
cold front. Aloft, a potent high amplitude 500 hPa trough axis will
extend from Northern Ontario southward across the Ohio and Tennessee
Valleys. Meanwhile, a similarly high amplitude ridge extends from New
Mexico NNW along the Rocky Mountains all the way to over the Brooks
Range of Alaska. In between this unusually strong upper level
ridge and trough, surface high pressure resides from the Plains
north and westward into the Canadian Arctic.

The aforementioned cold front seems to be moving through more quickly
in recent guidance and should initially be on our northwestern
doorstep mid-morning on Wednesday before quickly marching southeast
across the forecast area and departing into southwestern Virginia by
early to mid-afternoon. The early timing of the frontal passage will
limit destabilization and overall thunderstorm potential, especially
across the northwestern half of the CWA. Over the southeastern half
of the CWA, the late morning and early afternoon frontal arrival may
give sufficient time for more substantial destabilization (MLCAPE
might reach 500 to 1000 J/kg). If sufficient destabilization occurs,
effective shear should be greater than 30 kts and could favor
some organization of the cells. However, the recent forecast
trends for a quicker frontal passage leave some doubt on this
potential. Overall PoPs for the frontal passage are highest over
the Big Sandy Basin where 80 to 90 percent probabilities of
measurable rainfall are common, but those quickly decrease with
southwestward extent, only ranging in to the 10 to 30 percent
probability range in the drought-stricken areas around Lake
Cumberland. Rainfall amounts generally appear light, mainly under
0.10 inch outside of thunderstorms. Also, 850 hPa temperatures
near 10C and good mixing should support temperatures on Wednesday
at similar levels compared to Tuesday, ranging in the 70s.

Low-level CAA behind the front will send 850 hPa temperatures falling
later in the day on Wednesday and throughout Wednesday night. The
11/00z LREF mean supported 850 hPa temperatures falling to 2 to 4C by
12Z Thursday, with the colder end of the guidance suite near 0C. The
northwesterly flow through Wednesday night does diminish from 20
to 25 kts at 925 hPa in the evening to 10 to 20 kts by daybreak,
but should keep low-level mixing going for most of the night and
thus keep temperatures from radiating very efficiently. Thus,
anticipate widespread lows in the 40s early Thursday morning. A
dry, cool Canadian air mass will then reside over the Commonwealth
for Thursday with minimal change in the overall air mass temperature.
Given the 00z LREF mean 850 hPa temperatures of 3 to 5C, widespread
highs in the lower to middle 60s seems reasonable for Thursday
afternoon given deep mixing, but if the actual air mass is closer
to the colder end of guidance, then many places could struggle to
reach 60F. Given the spread in the guidance suite regarding the
true dryness and modification of this air mass, there is currently
moderate confidence in Thursday`s high temperatures.

This will all be in place as high pressure shifts east and crests
directly over eastern Kentucky Thursday night, providing nearly
optimal conditions for radiative cooling. If dew points remain mainly
above 32F on Thursday afternoon, there will likely be a competition
between fog and frost Thursday night, especially in the sheltered
valleys and hollows. Those locales prone to fog along the mainstem
rivers and larger tributaries are likely to fog, whereas those
hollows and rural valley/low-lying areas not prone to fog are
more likely to pick up on a late season frost. COOP MOS suggests
lows in the mid 30s by early Friday morning for the cooler hollows
and valleys and in the upper 30s in those locations prone to fog.
Those with cold-sensitive agricultural interests are encouraged
to monitor later forecasts for the late Thursday night and early
Friday morning timeframe, as a Frost Advisory may eventually be
needed for some of our sheltered eastern valleys. For perspective,
the 30-year normal lows (1991-2020 computational period) for May
15th range from 49F in the colder northeastern hollows to 56F in
the vicinity of Lake Cumberland, while daytime highs range from
74F to 76F across the lower elevations. Furthermore, the average
last frost dates (temperatures 36F or less) for the colder
northeastern hollows generally fall in the May 5th to May 18th
timeframe.

For the colder hollows, this could be the latest frost in 5 to 10
years. Most of the mainstem river valleys should fog and be
protected from frost concerns. After this cold night, May 15th
will mark the pivot to a significant pattern change heading into
late May. Heights aloft will rapidly rebound as the upper level
ridging presses eastward, replacing the troughing, though the
ridge will be flattened by a Pacific trough that rides along the
US and Canadian border late week. Locally, a mild southwesterly
return flow develops behind the departing surface high while a
cold front associated with the Pacific trough approaches the Ohio
Valley. However, that front will lose its upper level forcing as a
new upstream trough digs deeply into the western CONUS late week
and early next week. Specific details on the overall rainfall
threat with the approaching front remain obscure due to increased
model spread, but agreement is good that rising heights and very
warm temperatures aloft will send thermometers soaring past normal
levels by Saturday and potentially nearing record highs (close to
90F) by Monday.

For area gardeners, the outlook for the remainder of the month,
once we get past Friday morning`s chill, does not favor any
additional cold snaps sufficiently cool for frost, even in the
colder sheltered hollows. However, a few cold fronts could still
bring cool mornings (probably 40s to near 50F).

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 731 PM EDT MON MAY 11 2026

VFR conditions are expected to prevail through the TAF period for
KJKL, KSJS, KSYM and KIOB but MVFR to IFR conditions are possible
as river valley fog is forecast to develop and impact KLOZ and
KSME. Once the fog burns off, all sites will return to VFR and
stay there. Light and variable winds are likely through the TAF
window.

&&

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

&&

$$

UPDATE...VORST
SHORT TERM...CMC
LONG TERM...GEERTSON
AVIATION...VORST