JKL issues Area Forecast Discussion (AFD) at Aug 9, 5:37 AM EDT416
FXUS63 KJKL 090937
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
537 AM EDT Sat Aug 9 2025
.KEY MESSAGES...
-The weekend looks great, with mostly dry conditions and hot
temperatures expected for both Saturday and Sunday, making it
great for outdoor plans.
-A significant pattern change arrives for the new work week,
bringing a more humid pattern with daily chances for scattered
afternoon and evening thunderstorms starting Monday.
-Localized torrential downpours and strong, gusty winds are
possible with thunderstorms next week.
&&
.SHORT TERM...(Today through Sunday)
Issued at 338 AM EDT SAT AUG 9 2025
A few high clouds are drifting across eastern Kentucky early this
morning as fog thickens and expands through the mainstem river
valleys. Temperatures are seasonably mild, ranging in the mid to
upper 60s. The quiet weather is courtesy of an elongated ~1026 mb
surface high pressure centered southeast of Nova Scotia with a
pronounced surface ridge extending southwest along the spine of
the Appalachians. Aloft, a 595 dam high is centered over southwest
New Mexico with ridging extending northeast into the Ohio Valley
and then northward toward the James Bay. A weakness in the ridge
is noted from the Lower Mississippi Valley to the Mid-Atlantic
with stronger ridging east of the Bahamas. Northwest of the ridge,
an ~561 dam low is passing just north of the US/Canadian border
and is centered over the Saskatchewan prairies. An associated
occluding surface low is passing over southern Manitoba while its
cold front extends down into Minnesota and then southwest into
Colorado and westward through the Central Rockies.
Heights over Eastern Kentucky will remain nearly steady today and
tonight as the upper level ridge axis shifts eastward into New
England. On Sunday, heights rise slightly over the Commonwealth as
the high center over the Desert Southwest dissipates and is
replaced by a loosely defined upper level high centered south of
Bermuda. The upper level low to our northwest opens into a broader
trough with its associated energy ejecting toward the Hudson Bay.
The systems associated cold front only makes slow southeastward
progress, dozens to a few hundred miles, through the short-term
period. Over eastern Kentucky, abundant mid-level dry air and weak
lapse rates will largely keep a lid on the thunderstorm threat
for today and tomorrow. With that being the case, model soundings
still suggest that towering cumulus could reach sufficient depth,
generally southwest of US-421, for isolated sprinkles or pin-prick
showers this afternoon and evening. Forcing is meager with subtle
500mb positive vorticity advection in this area. Little in the
way of cloud cover tonight will once again favor fog formation in
the typical river valley locales. On Sunday, small height rises
will further strengthen and lower the cap, perhaps sufficiently
strong to preclude any shower/sprinkle activity at all.
In more sensible terms, look for any river valley fog to
lift/dissipate by 9 to 10 AM with mostly sunny skies through the
remainder of the day. A stray shower or sprinkle (under 20 percent
chance) is in the forecast for locations near/southwest of
US-421, but a vast majority of the area will remain rain-free. It
will be hot with high temperatures in the upper 80s to near 90F at
most locations. Mostly clear skies follow for tonight with some
fog in the favored valley spots. Temperatures will be very
comfortable, dipping back into the mid 60s, except low 60s in the
coolest hollows. On Sunday, look for mostly sunny skies and
temperatures rebounding to between 87F and 91F.
.LONG TERM...(Sunday night through Friday)
Issued at 523 AM EDT SAT AUG 9 2025
The long-term period opens Sunday night with a 500 hPa ridge
extending from the Canadian Maritime Provinces, southwestward
along the Appalachians, with a stronger high off the Southeast US
coast. A positively-tilted trough is found upstream, stretching
from Hudson Bay southwestward to New Mexico. At the surface, a
ridge of high pressure is departing off the Atlantic Seaboard
while a cold front extends from an ~1003 mb surface low near James
Bay down through the Upper Great Lakes and southwestward into the
Texas Panhandle.
The ridging over the eastern CONUS will break down on
Monday/Tuesday as the trough presses eastward and fills, leaving a
quasi-zonal flow over the Ohio Valley. Any significant forcing
from the trough/former upper low passes far to our north, leaving
the cold front abandoned and stalling out northwest of the Ohio
River. Early in the period, the low-level flow will veer
south/southwesterly and advect a tropical air mass back north
across the Commonwealth on Monday (the LREF shows PWATs surging
back above 1.5 inches by the afternoon). This increasing moisture
combined with a weak perturbation aloft will favor a rising threat
of deep convection from south to north Monday afternoon. Upper-
level ridging over the Atlantic does build/retrograde westward
along the Gulf Coast mid to late week, but multiple disturbances
riding over the ridge will pass directly over Eastern Kentucky,
almost certainly sparking additional diurnally-driven deep
convection through the remainder of the long-term. The modeled
environment still does not favor any organized, strong to severe
convection at the synoptic scale. However, moderate to high SBCAPE
values and high PWATs (1.6 to 1.9 inches) could set the stage for
downburst wind gusts and torrential downpours.
In sensible terms, look for humidity levels to climb back to
muggy levels for the entire work week while the daily threat of
showers and thunderstorms returns, especially during the afternoon
and evening hours. Daily high temperatures reach the upper 80s to
lower 90s on Monday and Tuesday before retreating into the mid
and upper 80s for Wednesday and Thursday. Slightly hotter daytime
temperatures may return for the end of the week. Meanwhile,
nighttime low temperatures moderate to around 70F by Monday night
and remain in that vicinity through the remainder of the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 141 AM EDT SAT AUG 9 2025
Valley fog is forecast through mid-morning Saturday, with
localized IFR or worse conditions. However, TAF locations are
likely to evade. Otherwise, VFR conditions are expected through
the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...GEERTSON
AVIATION...GEERTSON/HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 9, 5:37 AM EDT---------------
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