Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

130
FXUS63 KJKL 021402
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1002 AM EDT Wed Apr 2 2025

.KEY MESSAGES...

- Temperatures return to above normal levels today through this
  upcoming weekend.

- At least northwest parts of eastern Kentucky are favored to see
  another round of strong to severe storms tonight, with better
  chances over most if not all of eastern Kentucky on Thursday
  into Thursday night.

- We are looking for repeated rounds of heavy rain and
  thunderstorms to affect eastern Kentucky through Sunday -
  especially northwest parts of the forecast area where between 3
  and 6 inches of rain will be possible over those several days.
  This area remains in a Flood Watch from this evening through
  Sunday morning.

&&

.UPDATE...
Issued at 1002 AM EDT WED APR 2 2025

Showers associated with elevated instability have not materialized
in the JKL area and remain to our north. It`s looking more likely
that we will stay capped during the day, and the POP has been
lower below the 20% threshold for forecast inclusion area wide.
Have also lowered sky cover in the very near term based on
satellite obs. Latest temps have been blended into the forecast.

&&

.SHORT TERM...(Today through Thursday)
Issued at 519 AM EDT WED APR 2 2025

Thermometers have dipped into the mid 30s in the coolest
northeastern hollow this morning but range up to the mid 50s to
low 60s in the vicinity of Lake Cumberland and on southern thermal
belt ridges. High clouds are streaming in from the west southwest
while winds are slowly picking up out of the southeast,
especially over the higher terrain and in open areas, due to a
tightening surface pressure gradient. The broader regional
analysis shows a quasi-stationary front extending from South
Carolina westward through the Lower Tennessee Valley and then
northwestward as warm front to an ~988mb elongated low over the
Kansas and Oklahoma. Looking aloft, a broad 500H trough is in
place over the Western CONUS while broad ridging prevails over the
East.

The upper-level wave pattern will become more amplified through the
short-term but with little overall propagation to the east. The
aforementioned surface low will continue to occlude as its parent
500H shortwave ejects out of the western trough and races
northeast to over Lake Superior late tonight and onward into
Quebec on Thursday. The system`s associated warm front will lift
through eastern Kentucky later this morning with limited moisture
and only a low chance of a shower or thunderstorm toward the I-64
corridor. Behind the boundary, deepening mixing under partial sun
will promote momentum transfer to the surface from the system`s
warm conveyor belt jet. GFS BUFKIT mixed layer momentum transfer
was sufficient (34+kts at times) over our western counties to
warrant issuance of a Wind Advisory from 10 AM to 8 PM EDT,
coincident with mix-out through peak afternoon/early evening
heating. Winds will be gusty during that time further east, but
the weaker wind field is not likely to support widespread wind
advisory criteria gusts (40 to 57 mph) there. Gulf moisture will
surge to well above climatological norms by later this evening/
tonight as the southerly flow pulls a juicy air mass northward
from the Gulf (HREF PWATs rise to between 1.2 and 1.5 inches by
late tonight). Meanwhile, a convectively-reinforced cold front
trailing behind the surface low will race southeastward into the
Ohio Valley late tonight before stalling over the Commonwealth on
Thursday as the cold pool-driven convection outruns the better
upper level support. The boundary`s theta-e gradient becomes
nearly parallel with the deep, moist southwesterly flow for much
of the day, supportive of training convection along the boundary.

Considerable spread is noted in the 00 and 06z model suites as to
the eventual location of the boundary by 18z Thursday, whether it be
just south of the Ohio River or further southeast into the
Tennessee Valley/southeastern Kentucky. A more southeasterly
position of the boundary should favor weaker synoptic scale
ascent as it would be more displaced from the better jet/vorticity
dynamics aloft. With that being said, the air mass feeding into
the boundary from the Gulf will be extremely moist (approaching
climatological maximums according to the NAEFS and ECWMF ENS),
which combined with relatively skinny CAPE and efficient warm
layer rain processes could easily lead to locally heavy rainfall.
Given relatively low antecedent streamflows and soil moisture,
rainfall on Wednesday night and Thursday along this southeastward
sagging boundary should be largely a priming type of event with
most hydro issues being limited to poor drainage/urban
flooding/ponding and minor stream flooding. WPC has placed most of
eastern Kentucky under a Marginal Risk of excessive rainfall late
tonight into early Thursday with this initial round of rainfall.
A Slight Risk for excessive rainfall is in place for locations
along/northwest of a Paintsville-to-Jackson-to-London line on
Thursday and Thursday night, roughly corresponding to the
footprint of the current Flood Watch. This is the area which is
currently expected to see the more persistent southwest-northeast
training convection on Thursday into Thursday evening and is
favored to receive a widespread 0.75 to 1.50 inches of rain, as
per the 02/00z HREF PMM precipitation. In more extreme high-end
training scenarios, localized swaths of up to 4 inches could occur
in the Flood Watch area through 00z Friday. It is important to
note that there is a very sharp cutoff in rainfall amounts south
of the boundary and should the boundary stall further north than
expected, very little rainfall would occur in the JKL CWA in the
short-term. Conversely, those amounts could creep a little
further south and east if the front makes a more aggressive push
south of the Ohio River and into the blocking ridge. Those with
interests vulnerable to flooding in the watch area are advised to
have a plan for what they will do if flooding occurs and
individuals southeast of the present Flood Watch are encouraged to
monitor later forecast updates for any potential southeastward
shifts in the heavier rainfall amounts. Model guidance is in good
agreement that a new wave of low pressure will ride the baroclinic
zone across the Ohio Valley just beyond the end of the short-term
period, temporarily lifting the stalled boundary and its
associated rainfall back to the north beginning Thursday evening.

Aside from the strong environmental wind and flooding threats,
there is a Slight Risk of severe thunderstorms tonight over the
northwestern half of the forecast area as the line of convection
initially settles southeast and then across all of eastern
Kentucky on Thursday as the boundary most likely stalls for a time
over our forecast area. Damaging wind gusts (15 to 30% chance
within 25 miles of a point) will be the primary hazard with
stronger storms riding along the frontal boundary. However
isolated instances of hail and a brief spinup tornado cannot be
ruled out (though probabilities are lower) as the air mass feeding
into the frontal boundary will be support of supportive of
transient supercellular structures embedded along the edge of the
frontal line.

In sensible terms, look for a much warmer and increasingly windy
Wednesday with a mixture of sun and clouds. Expect winds to become
southerly and increase to between 10 and 20 mph with gusts of 30 to
45 mph from later morning through early evening. The strongest gusts
are expected to occur near and west of the Pottsville Escarpment
(roughly Rowan down to Whitley Counties and westward). It will also
be much warmer than recent days with widespread afternoon high
temperatures in the lower to middle 80s. There is a small chance
of a shower or thunderstorm late this morning and early afternoon
near/north of the Mountain Parkway but most locations should
remain dry. Mild and breezy conditions follow for tonight with a
line of showers and thunderstorms settling in from the northwest
overnight. Tentatively expect the line to reach the I-64 corridor
by 1 to 4 AM EDT and sink to near the Hal Roger/KY-80 corridor by
around sunrise. That line then wavers on Thursday before gradually
lifting back to the north later in the day. Some locations near
the Virginia border could see little or no rainfall, whereas
locations further northwest could receive multiple inches of rain
and experience instances of high water. There could also be strong
to severe thunderstorms along the leading edge of this line.
Temperatures tonight are expected range in the 60s. On Thursday,
forecast highs range from the upper 60s where showers and storms
persist up the lower and middle 80s over far southeastern counties
where sunshine is prevalent.

.LONG TERM...(Thursday night through Tuesday)
Issued at 453 AM EDT WED APR 2 2025

To summarize what is forecast to happen before the start of the
forecast period, a surface low will move out of the Central Plains
through the Great Lakes and into Canada. The cyclone will then
abandon its surface cold front which is forecast to be draped over
much of the mid-Mississippi Valley and Ohio River Valley. At the
start of the forecast period, this baroclinic zone will be aligned
from southwest to northeast through the Commonwealth primarily
centered from Little Rock, Arkansas to Columbus, Ohio. Several
rounds of showers and storms will move along this area of
baroclinicity leading to widespread hydrologic issues. As for the
JKL CWA, areas along and northwest of an imaginary line of
Johnson County to Wayne County will likely see the highest
impacts from this abandoned cold front. However, any shift in
where the boundary stalls out will play a role in precipitation
totals across the CWA. As a result of this heavy rain and flooding
potential, the WPC has that highlighted area, mentioned above, in
a Day 2 (Friday) Slight to Marginal Risk for Excessive Rainfall.

By late Friday into early Saturday, a surface low is progged to
develop in Texas and eject northeast toward the Ohio Valley. As the
system lifts northeast, the stationary boundary will lift north into
the Ohio Valley as a warm front and bring decreasing PoP chances for
Saturday but as the system continues to lift toward New England,
the trailing cold front will cross through the CWA for Sunday into
Monday. With the front, showers and storms will begin to increase
in coverage overnight Saturday and are forecast to continue
through early Monday afternoon before tapering off. With this cold
FROPA, the WPC has reintroduced another Slight to Marginal
Excessive Rainfall risk as heavy rainfall is once again expected
with this frontal passage. Surface high pressure will quickly
follow in behind the departing cold front and remain in place
through the end of the period. Lastly, with CAA and clearing
skies, there`s potential for widespread frost Tuesday morning and
again Wednesday morning.

Overall, the forecast period will feature several rounds of showers
and storms due to a stalled boundary. This will lead to several days
of heavy rainfall which could result in increased threats for
widespread hydrologic issues through the weekend before drying
out for early next week. Lastly, the period will feature above
average temperatures as daytime highs, through much of the period,
will be in the upper-70s to mid-80s with overnight lows in the
low to mid-60s. The cold front for Monday will usher in below
average temperatures for Tuesday before another subtle warm-up
arrives for Wednesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 749 AM EDT WED APR 2 2025

VFR conditions are in place at TAF issuance and will largely
prevail during the period. Any stray shower activity with a warm
frontal passage this morning will likely not affect the TAF sites.
Surface winds will pick up quickly through late morning as
daytime mixing commences and gusts of 20 to 35 kts can be expected
from the south through the afternoon. A cold front will approach
from the northwest late tonight with a rising threat of showers
and thunderstorms along with the potential MVFR or worse flight
conditions.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 8 PM EDT this evening for KYZ044-050>052-
058>060-068-069-079-080-083>085-106-108-111.

Flood Watch from 8 PM EDT this evening through Sunday morning
for KYZ044-050>052-058>060-068-069-079-080-083-084-104-106>109-
111-112-114.

&&

$$

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