JKL issues Area Forecast Discussion (AFD) at Aug 7, 7:40 AM EDT072
FXUS63 KJKL 071140 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
740 AM EDT Wed Aug 7 2024
.KEY MESSAGES...
- Temperatures and humidity will peak today, with afternoon heat
indices reaching 95 to 100 degrees in a few locations.
- Just a small chance of showers and storms around this afternoon.
- The impacts of Tropical Storm Debby on eastern Kentucky are
becoming more clear now with most likely just some convection
around on Thursday and Friday - but primarily contained to the
far eastern parts of the state.
&&
.UPDATE...
Issued at 720 AM EDT WED AUG 7 2024
No significant changes to the forecast with just the inclusion of
the latest obs and trends for the T/Td/Sky grids with this update.
These minor adjustments have been sent to the NDFD and web
servers.
&&
.SHORT TERM...(Today through Thursday)
Issued at 435 AM EDT WED AUG 7 2024
08Z sfc analysis shows a weak area of low pressure over central
Kentucky well north of the current center of Tropical Storm Debby
which is currently spinning off the coast of Georgia/South
Carolina. The nearby low was able to generate a cluster of storms
last evening that mainly stayed northwest of the JKL CWA but has
brought a deck of high clouds over the area early this morning.
This appears to be mitigating the valley fog formation at this
point, though some patches likely exist under the clouds - clouds
that will be dissipating through dawn. These clouds, and the high
moisture content in the air, are also keeping temperatures fairly
uniform in the upper 60s and lower 70s across the area currently
along with only the barest hint of a terrain based split.
Dewpoints similarly are fairly uniform, not far from 70 degrees,
amid light and variable winds.
The models, and their individual ensemble suites, are now in
better agreement aloft through most of the short term portion of
the forecast especially with respect to the core of Debby. They
all depict a bit of a lull at 500mb over Kentucky between faster
westerly flow in the northern Ohio Valley and Debby's slow
approach to our southeast through Thursday evening. This will keep
a quiet mid-level flow pattern in place with little in the way of
energy nearby - aside from Debby's swirl that does get close to
far east Kentucky by 00Z Friday. Given the better agreement and
smaller model spread through Thursday have gone with the NBM as
the starting point for the forecast grids with little adjustment
needed aside from some incorporation of the latest CAMs guidance
for PoPs this afternoon and again on Thursday.
Sensible weather features another very warm and humid couple of
days with small chances for mainly afternoon thunderstorms. The
convection of today will be from a stalling area of low pressure
over this part of the state - with the CAMs favoring our western
counties more than the rest of the area. On Thursday, the shower
and limited storm chances will be mainly confined to the far east
as that part of the state will start to be impinged upon by
Debby's circulation as she starts to move past to the east. The
extra clouds and convection around each afternoon during the short
term portion of the forecast should be enough to cap the heat
index to just below 100 degrees for nearly all spots. For tonight
we will see enough clouds around to likely limit temperature
differences - keeping them mild near 70 degrees for lows, and also
hindering valley fog development into dawn Thursday.
The main changes to the NBM starting point consisted of adding in
PoPs details from the CAMs this afternoon and again on Thursday.
Only made minor changes to temperatures from the NBM tonight for
scant terrain distinctions.
.LONG TERM...(Thursday night through Tuesday)
Issued at 407 AM EDT WED AUG 7 2024
The upper flow pattern in the extended will start off with the
remnants of Debby in place over the southeastern CONUS, along with a
vigorous shortwave that will be moving through the northern Great
Lakes and then stalling there to end the week and into the upcoming
weekend. As this shortwave begins to move eastward toward New
England, it will draw whats left of Debby northward, and will
eventually absorb it. This hybrid system will bring extensive
rainfall to the Great Lakes, New England, and parts of the eastern
Seaboard Friday through Monday. Further west, we will have weak
ridging aloft in place over the western CONUS, with weak low
pressure in place over the southwestern US and desert southwest.
Eastern Kentucky will see rain chances at times Thursday night
through Friday night, as Debby and the northern stream shortwave
interact. Our best chance for showers and storms looks to be during
the day on Friday, as Debby makes a slight westward jog as it is
ingested by the northern shortwave. The last few showers and storms
should exit our area early Friday night. Any precipitation we
receive from Debby should remain confined to our most eastern
counties along the Virginia and West Virginia borders Thursday night
into Friday morning, before spreading further west Friday afternoon.
After that, it appears that a ridge of high pressure will move into
the area behind the departed northern trough. This ridge will bring
a whole new air mass to the area that should provide mostly clear
skies, light winds, and below normal temperatures. With the ridging
forecast to remain overhead for at least few days and nights,
conditions will be primed for nightly ridge valley temperature
splits, especially Saturday night and Sunday, when the lowest valley
temperatures are expected. After several days of nice weather, a
southern stream system could push a few showers and storms into our
southern counties Monday night through Tuesday night.
Temperatures should be normal to slightly above normal on Friday,
with highs in the mid to upper 80s forecast for that day. After
that, we should see below normal temperatures in the lower 80s for
most locations, with nightly lows in the 50s Friday night through
Sunday night. There are no significant weather hazards to speak of
in the extended, but everyone should remain aware that any
thunderstorms that we see Thursday night and Friday could produce
dangerous cloud to ground lightning.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 740 AM EDT WED AUG 7 2024
VFR conditions will prevail for the most of the period at all TAF
sites. Increased moisture, courtesy of T.S. Debby, will keep some
valley fog around through about 13Z before dissipating. With most
models initiating isolated showers and thunderstorms across
eastern Kentucky later this morning and into the afternoon have
included an extended period of VCTS in the TAFs. Light and
variable winds will persist through the period, though erratic
wind gusts can be expected with any showers or storms later today.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 7, 7:40 AM EDT---------------
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