JKL issues Area Forecast Discussion (AFD) at Sep 30, 9:56 PM EDT310
FXUS63 KJKL 010156
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
956 PM EDT Mon Sep 30 2024
.KEY MESSAGES...
- Showers will affect the area at times until a cold front passes
on Tuesday night.
- Behind Tuesday night's cold front, dry weather will arrive on
Wednesday and last at least into the weekend.
&&
.UPDATE...
Issued at 956 PM EDT MON SEP 30 2024
Not many wholesale changes made to the forecast grids as they've
been largely on track through the evening. Made a few little
touch-ups based on local obs. Went ahead and issued an SPS for fog
development overnight. Ensemble probs and guidance suggested that
widespread fog will be likely; therefore, jumped on issuing the
SPS. Lastly, updated text and radio products to reflect the
changes. Grids have been saved and sent.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 505 PM EDT MON SEP 30 2024
The lingering mid/upper level low which has been around for days
has finally had its center shift to our east. However, we are
still seeing its influence with shower boiling up with some
heating occurring today. As expected, the shower have been capped
in the mid levels and have not grown tall/cold enough for any
lightning in our area as of late afternoon. With peak heating
having arrive, that should carry over into the evening as
instability wanes and showers decrease.
The upper low will continue to weaken and move away on Tuesday.
However, a large but progressive upper trough crossing the Great
Lakes will support a cold front which will approach us from the
northwest. Will look for more showers to develop ahead of this
front on Tuesday into Tuesday night. Forecast soundings in the NAM
(not the GFS) now look marginally supportive of thunder. However,
there still is a mid level warm layer indicated, which convection
will would need to punch through, and above that the atmosphere
will be extremely dry. Not certain that tall convection will be
able to sustain itself in that environment. To maintain
continuity, have only mention showers and not thunder ahead of the
cold front. However, later shifts will monitor the potential in
subsequent model runs. With the front passing on Tuesday night,
precip will eventually taper off.
There is also fog potential both nights. The extent of fog will
be dependent on the degree of clearing. The amount of precip
heading into Tuesday night will also be a factor.
.LONG TERM...(Wednesday through Monday)
Issued at 603 PM EDT Mon Sep 30 2024
This particular long term forecast package is characterized by a
much quieter, classic fall weather pattern here in Eastern KY. The
period opens on Wednesday with surface high pressure building into
the area behind a departing frontal boundary. Expect a clearing
trend throughout the day as drier air filters into the area, with
slightly cooler afternoon highs in the low 70s. The sun should
remain out through the end of the work week in most places, and
rising 500mb heights will support a return to near 80 degree MaxTs
on Thursday and Friday afternoons. The mostly clear skies and upper
level ridging will foster the return of our classic quiet weather
caveats in Eastern Kentucky: ridge-valley temperature splits and
patchy AM valley fog. In the immediate wake of the aforementioned
front, a few locations may dip down into the upper 40s. The
modification of this airmass as the week progresses, however, will
keep most locations' MinTs in between the lower 50s (valleys) and
mid 50s (ridges).
For Friday evening and beyond, the attention will shift towards a
more amplified upper atmospheric pattern to the north. A second cold
front, nestled within longwave troughing over the Great Lakes, may
produce a few showers, but the lack of potent moisture return
beforehand will relegate both their intensity and coverage. PoPs
peak around 20% immediately ahead of frontal passage, and we will
return to dry conditions for most of the weekend. The primary
sensible weather impact from this second frontal passage will be the
reinforcement of seasonably appropriate fall temperatures. Saturday
and Sunday's highs will be in the mid 70s, with lows just above 50
degrees on ridgetops and in the upper 40s in the most sheltered
valleys. Any rain that falls into Friday evening may locally enhance
fog potential on Saturday morning, so trends in higher-resolution
forecast visibility guidance will need to be monitored closely as
the time approaches. While the forecast guidance suite is in
agreement in the forecast for Wednesday through Sunday mornings,
models resolve a second upper level trough differently at the end of
the forecast period. Confidence is thus lower at the end of the long
term forecast period than it is at the beginning. If the trough digs
deep enough into the Ohio River Valley, next week could begin with
some rain in the forecast. The model blend used to populate the
grids was slightly more aggressive with the related PoPs on Sunday
night than it was for the same period yesterday (they went from 20%
to around 30%), and it will be interesting to see if that trend
continues in future forecast issuances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 730 PM EDT MON SEP 30 2024
At TAF issuance, showers are decreasing in coverage and terminals
are beginning to improve to VFR. Overnight, widespread fog is
expected to develop which will cause terminals to fall into
categorical IFR/MVFR through early Tuesday morning. Once fog burns
off, terminals will slowly recover but due to expected shower
activity, terminals are expected to fluctuate between MVFR and VFR
through the remainder of the period. An approaching cold front
will bring increased shower chances for the end of the period.
Shower activity could cause CIGs and VIS to drop into IFR before
recovering. Light and variable winds will persist through the TAF
period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...VORST
SHORT TERM...HAL
LONG TERM...MARCUS
AVIATION...VORST
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 30, 9:56 PM EDT---------------
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