JKL issues Area Forecast Discussion (AFD) at Jul 10, 4:22 PM EDT194
FXUS63 KJKL 102022
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
422 PM EDT Thu Jul 10 2025
.KEY MESSAGES...
- Locally dense fog is expected to form overnight, especially in
valleys, potentially impacting visibility for the Friday morning
commute.
- High temperatures will be near normal through the week though
they may trend above normal over the weekend and early next
week.
- Chances for showers and storms persist through the upcoming
weekend and into week, mainly during each afternoon and
evening. These chances peak Sunday to Monday.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 330 PM EDT THU JUL 10 2025
Widely scattered showers and thunderstorms (often referred to as
garden variety for their disorganized nature) continue across
parts of central/eastern Kentucky at mid-afternoon. This activity
is occurring as a dampening upper-level trough, extending
southward from Quebec, crosses the Central Appalachians. This
convection is also generally ahead of the last associated weak
mid-upper level vorticity max, which is passing over Central
Kentucky. Meanwhile, there is little in the way of discernible
features in the surface pressure field as it remains dominated by
mesoscale diurnal and convective effects. A stalled frontal
boundary well north of the Ohio River has little direct impact on
our sensible weather. PWATs have dropped sharply since yesterday
and now range from 1.4 to 1.6 inches while flow in the 850-300 mb
layer favors cell motions to the east at about 10 to 15 kts,
limiting hydrologic concerns to very isolated poor-drainage/urban
ponding and elevated small stream flows in locations affected by
the most persistent convection. MLCAPE is modest around 1,000 to
1,500 J/kg and shear is minimal, minimizing the severe weather
concern. Temperatures are seasonable, ranging from the mid 70s in
areas recently affected by convection to the mid 80s where
sunshine has been more prevalent.
As the trough and its associated vorticity energy slowly slide
eastward, low to mid-level heights will begin to rise as weak
subsidence leads to a mid-level capping. This will cause showers
and thunderstorm coverage to gradually wane through the remainder
of the afternoon and evening and actually allow a weak tongue of
high pressure to build along the Central and Southern Appalachian
Mountains tonight. The combination of clearing skies, light winds,
and ample lingering low-level moisture will set the stage for
efficient radiation fog formation. Locally dense fog is not out of
the question as nighttime minimum temperatures are forecast to
fall 2+ degrees below crossover temperatures in many areas. On
Friday, heights continue to rise (aside from a weak upper level
perturbation in the afternoon) while surface ridging slides a
little further east ahead of the next weak upper level trough
approaching from the Central Plains. Limited deep convection is
possible again on Friday afternoon/early evening with the passing
disturbance and differential heating. However, lean CAPE profiles
and minimal shear will keep any activity sporadic and weak. After
bottoming out between 1.2 and 1.4 inches tonight/early Friday,
PWATs will again creep higher amidst southwesterly return flow,
likely exceeding 1.5 inches toward dawn on Saturday.
In sensible terms, look for leftover showers and thunderstorms to
dissipate heading through the evening. Partly cloudy skies yield
to areas of fog overnight. Some of that fog could become locally
dense, especially in valleys. Low temperatures are forecast to be
in the mid to upper 60s. On Friday, mostly sunny skies might be
interrupted in some locations by isolated to scattered showers and
thunderstorms. Otherwise, it will be seasonably hot with highs
from 85 to 90 degrees. Friday night is shaping up similar to the
prior night with any late-day convection giving way to mostly
clear skies and areas of fog overnight. The fog is likely to be
more confined to the river valleys than tonight. Look for Friday
Night temperatures to settle back into the mid 60s to near 70
degrees.
.LONG TERM...(Saturday through Thursday)
Issued at 415 PM EDT THU JUL 10 2025
The period is expected to begin with upper level ridging centered
near the souther FL vicinity and extending west into the Gulf as
well as northeast to near Bermuda and further into the Atlantic.
Some guidance, particularly GFS has a weak disturbance/shortwave over
Southern Appalachians with another shortwave moving off the eastern
seaboard. An upper level low is expected to be moving from Manitoba
into Ontario at that point with troughing south into portions of the
Central Conus with another center of upper level ridging off the
coast of southern CA. Another trough in the Gulf of AK vicinity to
off the coast of BC should be in place at that time as well. At the
surface, high pressure is expected to initially be centered over the
Appalachians with a wavy frontal zone to its north from the mid
Atlantic coast into upstate NY and the eastern Great Lakes west to a
sfc low pressure system preceding the troughing over the Central
Conus.
Saturday to Saturday night, the shortwave trough should rotate
across Ontario to Quebec and the Great Lakes and into the Lower OH
Valley with a secondary shortwave moving across the Northern Plains
to the upper MS Valley and nearing the western Great Lakes. The
first shortwave trough should cross eastern KY on Sunday with the
secondary shortwave approaching from the west late Sunday to Sunday
night. Over the weekend upper level ridging should strengthen and
build further into the western Conus while upper ridging is expected
to also build over the Gulf into the Southeastern Conus. The
previously mentioned secondary shortwave should cross the area Monday
to Monday evening with upper ridging building building north into
the mid MS Valley and Lower OH Valley. The two shortwaves tracking
across the area over the weekend into early next week should allow
for a cold front to gradually move across the Great Lakes and into
the OH Valley and eventually south of the OH River by Sun night to
Monday. This frontal zone should cross eastern KY Monday to Monday
evening.
Daytime heating over the weekend and into early next week should
allow for a general diurnal peak in convection each day. Coverage on
Saturday with only slight height falls or neutral height tendencies
at 500 mb should generally be near climatology and less than the
Sunday to Monday period. With the shortwave troughs and then the
frontal zone to move across eastern KY, convection at night is
also probable Saturday night and Sunday night and Monday evening
into Monday night. Of the three days, Saturday should be the
warmest with highs forecast slightly above normal. A few of the
deeper eastern valleys should reach the low 90s with JKL and LOZ
probable to fall a degree or two short of the 90 degree mark. A
stronger storm or two with a wind threat can be ruled out over
the weekend or Monday and typical of July, storms should contain
torrential downpours. Pending the degree of clearing, valley fog
should be a fixture in several locations each night to early
morning.
Tuesday to Tuesday night, recent guidance generally has narrow upper
level ridging building north and northeast across parts of the OH
Valley and Appalachians with the axis of upper ridging remaining
from the Arklatex region across eastern KY toward the mid Atlantic
states into Wednesday. Recent GFS runs have an upper low/trough
moving west into parts of the Southeast Coast and eastern Gulf of
Mexico from Tuesday to Wednesday while the ECMWF holds onto higher
heights from parts of the Southeast into the TN and OH Valleys
including eastern KY. During the Tuesday to Wednesday timeframe,
upper level ridging is progged to remain centered to the south and
southeast of Bermuda with another upper ridge extending into
southwestern Conus and parts of the Pacific. Guidance continues to
have an upper level low rotating across the northern portions of
Hudson Bay during the Tuesday to Wednesday period with an associated
shortwave trough rotating across parts of the Canadian Prairies and
Northern to Central Plains and into the Upper MS Valley from Tuesday
to Wednesday night. This shortwave trough per the consensus of
guidance should rotate into the Great Lakes to end the period. In
advance of this shortwave trough, a weaker shortwave may also pass
to the north and northwest of the OH Valley from parts of the
Central Plains to the Great Lakes. As noted earlier the axis of
upper level ridging should be over or west of eastern KY for Tuesday
to Thursday with the axis shifting east and southeast of eastern KY
as the period end with a trend of falling heights as well. Sfc high
pressure should also be in place from the Appalachians to the
southeast during this timeframe with a boundary that will have moved
south of eastern KY to begin the week becoming diffuse. A cold front
in advance of the 500 mb shortwave that approaches late in the
period is expected to approach the OH Valley to end the period as
well.
For Tuesday to Thursday timeframe, temperatures should climb a few
degrees above normal for Tuesday into Wednesday with Wednesday
currently expected to be the warmer of the two days, before slightly
lower Max T for Thursday. Ridging for Tuesday to Wednesday should
limit coverage of convection at an extent with some degree of
capping. However, isolated to lower end scattered pops near
climatology from the NBM seem reasonable at this time though one or
both days could be dry in all areas pending the degree of capping.
Height falls and the approaching front should promote greater
coverage of convection to end the period on Thursday. Following
anticipated rain earlier in the week, valley fog is anticipated each
night to early morning.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 158 PM EDT THU JUL 10 2025
Generally VFR conditions are noted at TAF issuance, though
briefly worse conditions are occurring under scattered diurnally-
driven pop-up convection. Once that convection dissipates this
evening, expect good clearing tonight which will allow for areas
of BR/FG to develop, likely dropping to IFR/LIFR visibility or
worse at valley terminals, though significant reductions will be
possible at the TAF sites as well. Winds will generally be under
10 kts through the period, except locally stronger and erratic
near thunderstorms.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...JP
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 10, 4:22 PM EDT---------------
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