JKL issues Area Forecast Discussion (AFD) at Sep 3, 1:48 PM EDT433
FXUS63 KJKL 031748
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
148 PM EDT Tue Sep 3 2024
.KEY MESSAGES...
- Pleasant and comfortable weather conditions deep remain over
eastern Kentucky for much of the week.
&&
.UPDATE...
Issued at 148 PM EDT TUE SEP 3 2024
Current forecast is in good shape. Adjustments were made to the
hourly grids to incorporate the latest hourly observations. Not
seeing any significant increases in returns from the regional
radar mosaic. Therefore will continue with just sprinkles across
our south. Updated suite of products have been issued. No update
to the zones was required.
UPDATE Issued at 1027 AM EDT TUE SEP 3 2024
Forecast is generally on track this morning. Updated hourly T/Td
and sky grids based on recent obs and trends. Radar is showing
some light echoes tracking into our forecast area, north of the
KY/TN state line. Consequently expanded sprinkles to include a few
more counties over our southern zones. 12Z CAMs are suggesting
more robust convection may be possible across our south by this
afternoon. For now will stay with sprinkles, but will be watching
trends in case more substantial PoPs become necessary. Removed
morning fog as well from the zones. No other changes to the
forecast package at this time.
UPDATE Issued at 730 AM EDT TUE SEP 3 2024
No significant changes to the forecast with 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.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 425 AM EDT TUE SEP 3 2024
08Z sfc analysis shows a large area of high pressure to the north
of Kentucky and that is providing for a cooler, drier, and mostly
clear night. Winds are staying stirred from the northeast on
account of the high's position over the Great Lakes. These
conditions have been favorable for the development of a small
ridge to valley temperature difference along with some fog in the
deeper river valleys of the southeast parts of the area.
Currently, temperatures generally vary from the upper 50s on the
hills to the upper 40s and lower 50s in the more sheltered low
spots - especially northeast. Meanwhile, the northeast winds of
around 5 mph continue to bring in lower dewpoints with values
ranging from the upper 40s north to the mid 50s in the far south.
The models, and their individual ensemble suites, are still in
very good agreement aloft through the short term portion of the
forecast. They all depict weak northwest mid level flow on the
back side of a departing 5h trough to the northeast. This flow is
carrying just a hint of energy along with it today. Much of this
energy then gets left behind tonight into Wednesday creating a
dirtiness to the ridge slowly building east from the Plains. As
such, by Wednesday evening, a shortwave forms over southern
Kentucky at the 5h level with a pooling of energy quite evident by
00Z Thursday. Due to the continued small model spread through the
short term portion of the forecast, have again favored the NBM as
the starting point for the grids with little adjustment needed
aside from incorporating some more terrain details in the
temperatures for early this morning and again tonight.
Sensible weather features the pleasant late summer temperatures
and comfortable humidity levels continuing through mid week. While
the overall forecast is for dry conditions, there is a small
potential for a light shower or a couple of sprinkles in the
southwestern parts of the JKL CWA this morning, on account of a
weak inverted trough helping to consolidate low level moisture
mainly to the southwest of Lake Cumberland. This will dry out by
the afternoon as its focus retrogrades more to the west for
tonight and Wednesday. There will be another cool night on tap
following sunset along with a decent ridge to valley split holding
into Wednesday morning and probably a bit more in the way of fog
in the river valleys. Wednesday will also be dry, comfortable and
just a tad warmer - but still seasonably cool.
The main changes to the NBM starting point consisted of adding in
terrain distinctions for temperatures early this morning and
moreso tonight. PoPs were only touched up this morning in the
southwest parts of the area where there is some model support for
a light shower around, but probably just some sprinkles.
.LONG TERM...(Wednesday night through Monday)
Issued at 445 AM EDT Tue Sep 3 2024
This long term forecast package is defined by a significant pattern
shift, which will bring about much cooler temperatures for the first
full weekend of meteorological fall. On Wednesday night, upper level
ridging begins to overtake the inverted trough responsible for the
short term forecast's clouds. As it does so, skies should
correspondingly clear. Thursday thus looks to be the warmest day in
the extended forecast, with efficient diurnal warming processes
producing afternoon highs in the mid 80s and overnight lows in the
mid (upper) 50s in valleys (ridges). However, the synoptic features
responsible for this fair weather shift out of the area by Friday.
Forecast guidance generally agrees that a well-defined upper level
trough will dig into the Great Lakes on Friday and Saturday. An
associated surface cold front will sweep across Eastern Kentucky at
some point during this time frame, triggering scattered showers and
perhaps some isolated thunderstorms. Severe weather potential
appears quite low at the moment, with limited moisture return and
the presence of a southern stream system over the Gulf Coast states
keeping the best thermodynamics away from KY. The greatest rain
chances currently look to be during the overnight hours on Friday
into Saturday morning, progressing from NW to SE across the area as
the boundary passes through. Increasing cloud coverage will relegate
highs to the lower 80s on Friday and keep overnight lows near the 60
degree mark, with less pronounced ridge-valley splits. Once the
boundary moves through and the trough axis aloft shifts east on
Saturday, northerly to northwesterly flow throughout the column will
advect a much drier and cooler airmass into Eastern Kentucky. This
modified continental polar airmass will yield afternoon MaxTs in the
low 70s this weekend. As skies clear amidst building surface high
pressure, ridge-valley thermal splits become more likely. This will
allow some sheltered valleys to approach the low 40s on Saturday and
Sunday nights, but a warming trend begins on Monday in accordance
with the plentiful sunshine.
In short, after some some beneficial rainfall to start the
weekend on Friday night and Saturday morning, expect clear skies and
seasonably cold temperatures. Record low temperatures at the Jackson
and London climate sites could potentially be broken or tied on
Saturday and Sunday nights, so stay tuned to future forecast updates
to see if that comes to fruition!
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 148 PM EDT TUE SEP 3 2024
VFR conditions will prevail through the period. Valley fog will
develop late tonight - again likely not affecting any TAF sites.
Winds will remain predominantly out of the northeast at around 5
kts through the afternoon, but thereafter will become more
variable with time.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...RAY
SHORT TERM...GREIF
LONG TERM...MARCUS
AVIATION...RAY
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 3, 1:48 PM EDT---------------
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