JKL issues Area Forecast Discussion (AFD) at Nov 16, 12:38 PM EST785
FXUS63 KJKL 161738
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1238 PM EST Sat Nov 16 2024
.KEY MESSAGES...
- Temperatures will be near normal through Saturday, before
warming to around 10 degrees above normal for the first half of
next week.
- Rain chances return late Monday night into Tuesday and continue
through the rest of the work week.
- A colder pattern arrives Wednesday afternoon and night.
&&
.UPDATE...
Issued at 1016 AM EST SAT NOV 16 2024
The morning surface analysis shows high pressure has settled
across the Great Lakes and extends southward into the Ohio Valley.
This coupled with ridging aloft has kept some pesky moisture in
the form of stratus clouds locked underneath a strong inversion
aloft. This will be the main weather challenge today is how much
this will mix out through the afternoon. Right now, it looks like
areas south of the Hal Rogers Parkway and KY80 have the best shot
of seeing some clear through the late morning and afternoon.
However, the clearing we have seen across parts of southcentral
Kentucky has started filling in with stratocumulus clouds. This
will have to be watch through the rest of the morning to see how
this trends. Outside this only minor changes were made for this
update to handle the latest obs and trends.
UPDATE Issued at 741 AM EST SAT NOV 16 2024
Satellite imagery shows southern edge of low cloud deck just south
of the Kentucky-Tennessee border at 1240z. Still expect the cloud
deck to gradually erode from south to north through the day as
low-level flow veers easterly to southerly. Given proximity of
cloud deck edge to our southern counties, nudged high
temperatures up a couple degrees near the Tennessee border.
&&
.SHORT TERM...(Today through Sunday)
Issued at 433 AM EST SAT NOV 16 2024
Widespread low cloud cover is found across eastern Kentucky early
this morning along with temperatures ranging through the 40s (except
in the upper 30s above ~3,000 feet). The latest surface analysis
shows high pressure passing through the Great Lakes/Lower Ohio
Valley, feeding low-level moisture on a weak north-northeasterly
flow into eastern Kentucky. Looking aloft, a 500H longwave ridge
extends from just east of the Mississippi River Delta to Northern
Ontario. A longwave 500H trough is found further upstream from
the Western Canadian Arctic to off of the Baja California.
Sinking air east of the ridge axis will keep a low-level
subsidence inversion in place over eastern Kentucky today. This
inversion will help to hold the low-level moisture in place until
the surface high has shifted far enough east in the Upper Ohio
Valley for the low-level winds to veer around to the
east/southeast. At that point, expect dry air to spill over the
Central/Southern Appalachians and gradual erode the low-level
moisture from generally south-to-north this afternoon and
evening. A shortwave disturbance aloft ejecting out of the deep
trough to our west will try to suppress the 500H ridge aloft
tonight and Sunday but will ultimately fail. However, a cold front
associated with the trough will approach the mid-Mississippi
Valley leading to some tightening of the surface pressure gradient
across the Lower Ohio Valley.
In sensible terms, look for low clouds to linger through the morning
before gradually eroding from south-to-north this afternoon and
evening. Today's temperatures hinge on how quickly the clearing
occurs. A slower clearing would favor highs mainly in the low/mid
50s, whereas a quicker clearing could help temperatures flirt
with or even exceed 60F in the southern counties. Partial high
clouds return tonight as moisture streams into the upper levels
of the troposphere ahead of 500H trough to our west. Even so,
expect decent radiational cooling with lows ranging from the lower
30s/mid 30s in the sheltered valleys to the upper 30s on ridges.
Fog is likely to develop along the main stem rivers and larger
tributaries. A mix of sun and high clouds is expected for Sunday
with highs in the mid to upper 60s. A mild light southwesterly
breeze could gust up to around 10 mph in the afternoon.
.LONG TERM...(Sunday night through Friday)
Issued at 441 AM EST SAT NOV 16 2024
The forecast period begins with upper-level ridging over the area.
At the surface, high pressure will be dominate over much of the
southeastern CONUS. As a result of surface high pressure being in
place, temperatures Monday will climb into the mid to upper-60s with
a few places climbing into the low-70s. However, to the north of the
forecast area, an upper-level trough is pivoting through the Upper
Great Lakes. At the surface, a weak cold front is forecast to extend
back toward the Central Plains but will remain north of the Ohio
River and transition into a stationary boundary that the next next
feature will ride along for Tuesday. While all this is occurring, an
upper-level trough is forecast to eject out of the Baja California
region into the southern Plains. This trough will quickly eject
through the Central Plains and be over the Great Lakes by Monday
night. At the surface, southwesterly flow ahead of the cold front
will bring temperatures up to the upper-60s to low-70s. However,
with the speed of the system, increasing showers are expected to
move into the JKL CWA by early Tuesday morning and persist through
the day Tuesday into Wednesday. The Tuesday system is forecast to
largely stall out and get wrapped up in another approaching system
that's quickly moving across the CONUS through the day Tuesday. The
third shortwave is expected to be the strongest of the active
pattern and will get stronger as it approaches the Commonwealth for
Wednesday. This third surface low will push the stalled cold front
through the forecast area as it pivots to the northeast toward the
Ohio Valley and Great Lakes. A brief lull in precipitation is
expected overnight Wednesday but as the comma head pivots back into
the region, PoP chances will increase again for Thursday and persist
through the remainder of the week. This increase in PoP for Thursday
has become a little more interesting compared to yesterday's model
suite. Guidance has come in colder compared to this time yesterday
and both deterministic and their associated ensembles are beginning
to hint at the first possible snow flakes across eastern Kentucky as
those backside showers will occur in an environment that's largely
cold enough to support snow. However, there's still some ensemble
members out there that think this will be rain but deterministic
soundings and colder trends lean toward possible rain-snow mix
Thursday before it warms up above freezing. The best chances for
snow does appear to be the high terrain along the Virginia border
where low-level temperatures will be supportive of snow for the
duration of the event. PoP chances will continue through the day
Friday with more rain-snow mix showers being possible before warming
back above freezing. Through the day Friday into overnight hours,
showers will begin to dissipate from southwest to northeast as the
system moves off to the northeast and high pressure builds back into
the region.
Overall the forecast period will be highlighted by a pattern change
that's largely climatologically expected for this time of year.
Before this system arrives, high pressure will exist with above
average temperatures. However, the aforementioned pattern shift will
bring rain showers through the remainder of the week. Showers are
expected mainly for the lower elevations but as mid to low level
temperatures fall, rain may switch to snow on the high elevation of
the southeastern mountains. Temperatures will fall from above
average highs to more seasonal levels for the remainder of the
forecast period.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1238 PM EST SAT NOV 16 2024
Most sites are starting the period MVFR, with a pesky stratus
deck that has been stuck underneath an inversion for quite
sometime now. The good news is we are seeing this erode at SME and
LOZ at this afternoon hour and expect this to continue to erode
through the remainder of the afternoon and early evening. This
will take all sites back to VFR this afternoon and evening. We
could see mostly river valley fog tonight given the diurnally
limited day for most. That said, this is not expected to affect
the TAF sites at this time. We are seeing variable winds at less
than 5 knots and this would mix out through the afternoon out of
the east in most cases.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...GEERTSON
LONG TERM...VORST
AVIATION...DJ
Source:
JKL issues Area Forecast Discussion (AFD) at Nov 16, 12:38 PM EST---------------
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