JKL issues Area Forecast Discussion (AFD) at Aug 18, 4:42 PM EDT559
FXUS63 KJKL 182042
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
442 PM EDT Mon Aug 18 2025
.KEY MESSAGES...
- Areas of fog may become locally dense in the valleys overnight.
- Following low end rain chances Tuesday, chances will peak on
Wednesday and also linger into the weekend.
- Expect temperatures to return to near normal Wednesday, with
even cooler temperatures in store by early next week.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 253 PM EDT MON AUG 18 2025
Current satellite shows a mid level cumulus field that has
developed across eastern Kentucky. These clouds are expected to
dissipate heading into the evening. Dry conditions will continue
this afternoon and overnight, with a ridge of high pressure
remaining over the area. Temperatures have risen into the mid to
upper 80s across much of the area, with the warmest areas
currently around 90, in Wayne county. Temperatures may warm
another degree or two, but should generally remain in the upper
80s to low 90s. This evening, clearing skies and fairly light
winds will favor river valley fog formation across far eastern
Kentucky and Southeastern Kentucky, such as the Cumberland area.
ridge top locations, across the Big Sandy area remain elevated,
and may mitigate fog potential some. Temperatures will cool into
the mid to upper 60s.
Tuesday, the ridge of high pressure weakens some, as a strong
upper level low, and associated trough axis and cold front, begin
to push encroach on the Upper Great Lakes Region and The Ohio
River Valley. Temperatures are expected to be slightly cooler
than previous days, though the NBM continue to push a warm bias.
With model 850-mb temperatures around 20C and the unlikelihood of
mixing that air down dry adiabatically, we've adjusted
temperatures down some, to fall more in line with the 50th
percentile of guidance, generally around 90 tomorrow, with a few
warmer spots getting into the low 90s. With the ridge weakening,
there may be enough forcing to kick off some isolated to
scattered showers or storms across the southern part of the CWA.
Most models do not hint at this, with the HRRR hinting at some
activity in the afternoon, especially over the high terrain of
Harlan county, and the TN/KY boarder. While this alone isn't
enough to make this kind of adjustment to the forecast, a
consistent issue that has been noted while using forecast models
across Eastern Kentucky has been the underdone dew points. Models
continually under-does available moisture which in turn causes
underdone modeled storm activity. Felt better adding a low end
shower and storm chance across the Cumberland area than leaving
zero chance of rain.
.LONG TERM...(Wednesday through Monday)
Issued at 440 PM EDT MON AUG 18 2025
The period is expected to begin with an upper level ridge centered
near the vicinity of the Four Corners region and extending into
the Plains. An upper level low is expected to be over BC with a
trough into the Pacific Northwest. Meanwhile, further to the
east, upper troughing is expected to extend from Ontario to the
eastern Great Lakes to OH Valley to TX with Erin east of the GA
and SC coastal area. At the surface, an area of low pressure is
expected to be over eastern OH with a cold front into the middle
to Lower OH Valley region to Plains with this front separating a
ridge of sfc high pressure in the southwest and a stronger area of
low pressure over Ontario to the upper MS Valley region.
Wednesday to Wednesday night, the northern portion of upper
troughing from Canada into the eastern Conus is expected to move
more quickly east across the Northeast to mid Atlantic states than
the southwestern portion that gradually sags into the Appalachians
to eastern TX and the western portion of the Gulf of Mexico. At
the same time, Erin should continue north and begin to turn to the
northeast east of the coast of the Carolinas. The upper ridge
centered near the Four Corners region should build to western
Great Lakes to mid MS Valley regions while an upper level trough
moved east from BC to Alberta. At the surface, the surface wave
should track into the mid Atlantic states and weaken with the
front sagging southeast across eastern KY through Wednesday and
Wednesday evening and then south and southeast of the area
overnight. However, with the axis of the 500 mb trough lingering
to the west, a sfc inverted trough may develop from AL into the
Commonwealth and portions of the OH Valley. At the same time, the
sfc system preceding the troughing in western Canada should reach
the Northern plains to portions of the Great Basin.
Chances for convection should peak near and in advance of this
boundary on Wednesday to Wednesday evening and guidance has some
spread as far as timing and coverage. Scattered pops still appear
in order at this time. With an increase in moisture near and in
advance of the boundary, 12Z HREF and LREF means bring PW to the
1.5 to 1.9 inch range, there remains some chance for locally
heavy rain for any areas that pick up multiple storms. WPC has
maintained a marginal ERO. Temperatures should be nearer to normal
with anticipated clouds and convection across the area.
Thursday to Friday night, the axis of upper troughing should shift
gradually to the south and southeast to over or just south and
southeast of eastern KY while Erin tracks between Bermuda and the
mid Atlantic and Northeast Conus. Upper troughing should continue
east across Canada and the Northern Plains to Quebec to the upper
MS Valley and western Great Lakes downstream of the upper ridging
into the western Conus that is still progged to build into
sections of the Great Basin to Pacific Northwest. With the upper
trough near or over eastern KY into early Friday, the sfc inverted
trough may remain from AL into eastern KY. Near and southeaster
of this inverted trough location, convection will be most probable
on Thursday afternoon to early evening with chances also on
Friday afternoon into Friday evening, mainly over the more
southern and southeastern portions of the JKL CWA. Temperatures
are expected to remain near normal for Thursday to the start of
the weekend.
Saturday to Saturday night, upper troughing is expected to evolve
from Ontario across the Great Lakes to the OH Valley and parts of
the Southeast downstream of upper the ridging over the western
Conus to Southern Plains. As this trough begins to take shape, a
cold front should gradually work across the eastern Great Lakes to
Lower OH Valley to the Arklatex region. As the front approaches
and mid level heights begin to fall, scattered convection is
possible generally peaking Saturday afternoon though chances
linger through Saturday night.
Sunday and Monday, the axis of upper troughing should move to
Quebec to the OH valley to Southeast downstream of ridging over
the western Conus. The surface cold front meanwhile should cross
the area Sunday to Sunday evening with sfc high pressure building
to the Lower OH Valley from the Plains and Central Conus. Chances
for convection will linger near and in advance of the front Sunday
to early Sunday evening, with drier weather to end the period. The
high building in behind the front is expected to usher in colder
air with below normal temperatures forecast to end the period.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 212 PM EDT MON AUG 18 2025
A scattered CU field currently exists across much of the area
which should dissipate heading into the evening. VFR conditions
will prevail through the TAF period for most sites. Some areas of
river valley fog are expected to develop again tonight for parts
of the Cumberland, where KLOZ and KSME visibility could drop down
to IFR conditions after 09Z. Elsewhere, winds remain to elevated
aloft in model soundings to support the same vis reductions at
KSJS. Fog development remains less likely at KSYM with afternoon
dew points in the low 60s, and forecasted lows in the mid to upper
60s.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GINNICK
LONG TERM...JP
AVIATION...GINNICK
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 18, 4:42 PM EDT---------------
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