Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

865
FXUS63 KJKL 121115 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
715 AM EDT Tue May 12 2026

.KEY MESSAGES...

- There is another 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 Wednesday.

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

&&

.UPDATE...
Issued at 715 AM EDT TUE MAY 12 2026

No significant changes were made to the forecast with mainly just
the inclusion of the latest obs and trends for the T/Td/Sky grids.
These minor adjustments have been sent to the NDFD and web servers
along with a freshening of the zones.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 420 AM EDT TUE MAY 12 2026

07Z sfc analysis shows a weak area of low pressure and its frontal
structure working through northern Kentucky early this morning.
Even so, skies have remained mostly clear through the night with
just light winds. These conditions have led to some patchy valley
fog developing - especially for the southeast parts of the JKL
CWA. Temperatures currently vary from around 50 degrees on the
ridges to the lower 40s in the sheltered valleys. Meanwhile,
dewpoints are generally running in the low to mid 40s.

The models, and their individual ensemble suites, are in pretty
good agreement aloft through the short term portion of the
forecast. They all depict general troughiness at 5h through the
eastern portion of the nation to start the period. Currently, to
the northeast, one trough is departing to the east while another
is poised to enter the Upper Midwest. This latter trough will
further deepen as it descends into the Great Lakes and northern
Ohio Valley tonight. It then parks itself over the region by
Wednesday afternoon with ample energy at mid levels sweeping
through the northern half of Kentucky - along with some distinct
height falls at 5h. Given the excellent agreement among the
models, the NBM was used as the starting point for the grids. The
main adjustments made to this initialization were to include PoP
and thunder details from the latest CAMs guidance for Wednesday.

Sensible weather features a dry day with temperatures near normal
under mostly sunny skies. For tonight, look for clouds to spread
in from the northwest with time, ahead of an approaching cold
front. This boundary will help to keep temperatures fairly
uniform overnight into Wednesday morning, but also bring a chance
of showers and possible thunderstorms to the area by dawn. As this
front slowly settles into the area, the showers and storm chances
will peak early Wednesday before departing to the southeast that
afternoon. In its wake, high pressure will build into the area by
evening along with a drier and cooler air mass.

The changes to the NBM starting point mainly consisted of tweaking
the hourly temperatures for some terrain distinctions early this
morning. As for PoPs, did include some details from the latest
CAMs guidance for the pcpn potential late tonight through early
Wednesday evening.

.LONG TERM...(Wednesday night through Monday)
Issued at 330 AM EDT TUE MAY 12 2026

The main change to the extended forecast from the NBM this
morning was to add more terrain distinction to hourly and low
temperatures Wednesday and Thursday nights. We appear to be on
track for some anomalous cold temperatures and a potential for
frost Thursday night into Friday morning in our most sheltered
valleys. Following this, a significant warm up looks to affect the
area over the weekend and into the start of the next work week.

The previous long term discussion follows:

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 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 700 AM EDT TUE MAY 12 2026

VFR conditions will prevail through the bulk of the TAF period
for all sites. There is a small chance for showers to develop and
impact northwest terminals before 12Z Wednesday as a cold front
approaches. Light and variable winds will be the rule through the
TAF window.

&&

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

&&

$$

UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...GEERTSON/GREIF
AVIATION...GREIF