Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

123
FXUS63 KJKL 030555
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
155 AM EDT Thu Apr 3 2025

.KEY MESSAGES...

- At least northwest parts of eastern Kentucky are favored to see
  another round of strong to severe storms tonight, with
  additional 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.

- Temperatures will be warmer than normal into the weekend
  followed by a sharp cool down to start the new work week.

&&

.SHORT TERM...(Today through Friday)
Issued at 125 AM EDT THU APR 3 2025

Extremely mild temperatures are in place across eastern Kentucky
early this morning. Thermometer readings range from the mid to upper
70s across all but the higher elevations. South to southwest wind
winds remain gusty to between 20 and 35 mph. Dew points have
risen into the lower/mid 60s west of I-75 and over much of the
Bluegrass while dew points remain in the mid/upper 50s at most
locations further east. Looking upstream, a potent squall line
responsible for many severe thunderstorm and tornado-warned
storms over the last several hours stretches from Wilmington, OH
southwestward through Frankfort, KY to Bowling Green and beyond.
This line of intense thunderstorms is racing out ahead a cold
front extending southward from an ~992 mb low over Lake Superior
southward across Lake Michigan through the Mid-Mississippi Valley.
This boundary lies between a 500H trough over the western CONUS
and a ridge over the eastern CONUS. An extremely moist air mass
(near to exceeding climatological maximums) is feeding into the
Commonwealth on a 60-70 kt 850mb warm conveyor belt jet. Though
the line is outrunning its upper level support, it has generated a
robust cold pool which will continue to propel the the QLCS into
eastern Kentucky through sunrise. Compared to locations further to
our south west, analyzed instability is more marginal early this
morning, approximately 200 to 600 J/kg of MLCAPE (northeast to
southwest) and that is offset by 75 to 200 J/kg of MLCIN (north to
south). While the instability fields are marginal, effective
shear upwards of 55 kts should help the line maintain better than
the instability alone would typically suggest. Strong to damaging
straight-line winds with bowing line segments appear the main
threat, with DCAPE values of 700 to 1,000 J/kg ahead. A brief
spinup tornado is also possible with the greatest chance for that
in the recently issued Tornado Watch.

The weakening QLCS outflow is expected to sink through southeast
Kentucky to near the Kentucky/Virginia border by or shortly after
12z. Additional showers and storms are likely to develop along the
remnant outflow boundary throughout the daylight hours and could
train repeatedly over the same locations. HREF LPMM continues to
support a widespread 0.5 to 2.0 inches of rain over most of the
watch area through 8 PM this evening; however, localized swaths of
rainfall nearing 4 inches are depicted in high-end scenarios. The
higher end amounts would be sufficient to cause minor and poor
drainage flooding and substantial rises on larger creeks, streams,
and rivers. In addition the the growing threat for flooding, there
will continue to be a threat of severe thunderstorms, primarily in
the form of supercells (potentially tornadic) that could develop and
ride the remnant outflow boundary from southwest to northeast. The
eventual position of the stalled outflow boundary is favored to
generally be along or just north of the Hal Rogers Parkway/KY-80
corridor. South of the boundary, temperatures are expected to
warm in the lower and middle 80s. North of the outflow boundary,
afternoon temperatures are forecast to be much cooler, mainly in
the upper 60s to lower 70s.

For tonight and Friday, anticipate that the trough over the western
CONUS will continue to amplify with a compensatory strengthening
over the ridge over the eastern CONUS. As a result, the boundary
over eastern Kentucky will gradually retreat back toward the Ohio
River, causing rain chances to wane slowly from south-to-north.
Locations near and north of the Mountain Parkway are most favored
to receive additional heavy rainfall, where an another widespread
1 to 2 inches of rainfall is likely. Further localized rainfall
amounts of 4 inches cannot be ruled out. Tonight`s minimum
temperatures are forecast to range from the mid 50s near/north of
I-64 up the mid 60s near/south of the Hal Rogers Pkwy/KY-80
corridor. Greater amounts of sunshine are anticipated for most
locations on Friday with high temperatures forecast to range from
the mid 70s north of I-64 to the mid and upper 80s south of the
Mountain Parkway.

.LONG TERM...(Friday through Wednesday)
Issued at 515 PM EDT WED APR 2 2025

The models, and their individual ensemble suites, are still in
surprisingly good agreement aloft through the bulk of the long
term forecast before some differences of note start to show up
concerning a late period trough dropping into the Ohio Valley from
the north. They all depict a deep Southwestern trough anchoring
the 5h pattern through the rest of the week only slowly grinding
east through Saturday while a strong ridge holds firm in the
Southeast. This continues to depict a stagnant pattern aloft for
most of the country into the first part of the weekend locking in
an extended period of fast southwest mid-level flow into Kentucky.
This will be able to scour ample moisture northeast from a wide
open western Gulf of America for a near continuous flux of
moisture into the region. Within the flow, several impulses of
concern will ride past eastern Kentucky. One of these, in a series
of them, passes through early Friday before another slides by to
the north that night into Saturday morning, while a third then
crosses towards that evening. By early Sunday, though, a
substantial portion of the Southwestern trough finally works
east into the Mid-Mississippi Valley helping to shove the blocking
Southeast ridge further away from Kentucky. This will allow the
pattern to start moving again for our area and also helps to pull
a large trough southward from eastern Canada sending 5h height
falls through this part of the state during the day, Sunday. Then,
with the pattern finally on the move, a stream of energy will
settle into the Ohio Valley and press south into the JKL CWA later
Monday. This energy swath lingers overhead through early Tuesday
before the large northern trough`s axis at 5h will finally sweep
east of the Ohio Valley - now faster and more dampened in the
ECMWF cluster compared to the GFS solutions. This change will turn
the mid-level flow more sharply to the northwest bringing a
pattern more conducive for drying and colder conditions.

The still rather small model spread aloft through Saturday
supported using the NBM as the starting point for the forecast
grids into the weekend then have decided to used it split the
difference between the still shifting cluster solutions of the
various long range model systems into the first part of next week.
Again made some adjustments mainly to add more terrain distinction
to the temperatures in the southeast parts of the area each night
through Saturday morning.

Sensible weather features a warm end to the week for most with
the models now depicting the concerning boundary lying across
northern parts of the JKL CWA to start the day, Friday. Model
consensus has this boundary shifting north on Friday as the next
sfc wave consolidates to the southwest of the state. This process
looks on track to spare much of eastern Kentucky the heavy rains
and stronger storms through the afternoon and into the night.
However, this boundary will start to return southeast later
Saturday with more strong to possibly severe storms arriving, for
at least northwest portions of the area by evening, while the
southeast looks to stay dry and very warm. The caveat through
Saturday evening is that while the models are in decent agreement
that the boundary stays west and north of the bulk of southeast
Kentucky, mesoscale dynamics and outflow boundaries could help to
push it further south than the models indicate so caution is
urged, especially in the Flood Watch areas. Eventually, this
system and the frontal structure push through the entire area
mainly Sunday morning with a final incident of heavy rain before
it departs. We will probably have to consider extending the Flood
Watch through the day Sunday if the ECMWF trends holds in having a
lingering sfc wave move along the front on Sunday and holding it
up by perhaps another 12 hours.

Sharply colder weather follows behind the system into Monday and
through the start of the next work week. This will bring an air
mass change on northerly winds. The coldest air is indicated to
arrive later Monday into Tuesday such that scattered frost and
some sub freezing temperatures are anticipated for Monday and
Tuesday night. The high pressure that moves into the area in the
wake of the weekend system will start to shift east on Wednesday
but serve to keep the weather dry and cool.

Despite the extremeness and climatological rareness of this
stalled pattern, most of eastern Kentucky is expected to miss out
of the higher impacts owing to the heaviest rains forecasted to
stay north of the headwaters of our rivers. Even so, we need to
stay vigilant for a possible shift southeast in the heavy rain
axis and not let our guard down. However, as it stands now, it
seems increasing likely that the western part of the state and
confluence region of the Ohio and Mississippi rivers will see the
historic impacts from the repeated heavy rains of such extreme
durations. Meanwhile many of us here, especially those outside of
the flood watch, will mostly note just an unseasonably warm
stretch of weather for early April interrupted occasionally by a
bout of mainly nocturnal showers and storms.

The changes to the NBM starting point consisted primarily of
adjusting the PoPs for hourly temporal resolution. Did also
include more terrain distinction to the low temperatures through
Saturday morning and again for Tuesday night.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 155 AM EDT THU APR 3 2025

VFR conditions at TAF issuance will deteriorate from northwest to
southeast through the remainder of the early morning hours as a
weakening line of showers and thunderstorms drops in from the
northwest, potentially reaching the Kentucky/Virginia border
around or after 12z. This storm line will bring the threat of high
winds and potentially a brief spinup tornado. The stronger storms
along the line will likely bring at least MVFR/IFR conditions,
but could be briefly worse. The line of storms is expected to
waver over the area on Thursday before slowly lifting back to the
north later in the evening into Thursday night. Periods of MVFR
conditions are likely with stronger rounds of convection. Some
IFR conditions are possible, but confidence in timing and
occurrence is too low to include in the TAFs.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday morning for KYZ044-050>052-058>060-
068-069-079-080-083-084-104-106>109-111-112-114.

&&

$$

SHORT TERM...GEERTSON
LONG TERM...GREIF
AVIATION...GEERTSON