896
FXUS63 KJKL 211215 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
815 AM EDT Tue Jul 21 2026

.KEY MESSAGES...

- A strong cold front could produce multiple rounds of thunderstorms
today into tonight.

- There is a Slight to Enhanced Risk for severe storms today,
including damaging winds, large hail, and isolated tornadoes.

- Torrential rainfall from persistent thunderstorms could lead to
flash flooding this afternoon into tonight.

- Mainly dry weather is expected from Wednesday night to Friday,
with temperatures averaging about 5 degrees below normal.

&&

.UPDATE...
Issued at 755 AM EDT TUE JUL 21 2026

Hourly grids have been freshened up based on recent radar and
convective allowing model trends. With little upstream convection
at this doing or over the area and passing cloud cover, lowered
pops a bit through midday or early afternoon. Otherwise, other than
freshening up temps based on observations, no additional changes
were made at this point.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 600 AM EDT TUE JUL 21 2026

Early this morning, a upper level low was centered over Ontario
between Lake Superior and James Bay with a trailing shortwave
trough into the western Great Lakes to mid MS Valley within an
mean trough from eastern Canada into the eastern Conus. Further
west, an upper level ridge was centered in the Rockies/CO vicinity
and extended into parts of the Central and Southern Plains while
Bertha was over northeastern sections of the Gulf. At the surface,
an area of low pressure was also centered in Ontario with a warm
front southeast to the eastern Great Lakes to mid Atlantic states
and a cold front trailing into the Central Great Lakes to mid MS
valley to Central Plains. Temperatures were mild in the warm
sector, mainly in the low to mid 70s with a few upper 60s in a
couple of spots. Dewpoints were in the upper 60s to low to in some
cases mid 70s. PW is currently analyzed in the 1.45 northeast to
near 1.9 near Lake Cumberland. A few stray showers have crossed
the area overnight, but most locations have remained dry with a
bit of fog and low clouds in parts of the upper Cumberland near
the VA border.

Today and tonight, the upper low in Canada should meander to the
Ontario and Quebec border with the trailing shortwave trough
rotating across the Central and into the eastern Great Lakes and
across sections of the Lower and middle OH Valley. Further south,
Bertha should meander west in the northern Gulf while the upper
ridge currently in the rockies becomes centered in the Southern
Plains. West to northwest flow should prevail during the period
across eastern KY. Meanwhile, the surface low in Canada should
reach portions of Quebec by Wednesday morning, with the trailing
cold front extending into the Mid Atlantic to eastern KY to the
Red River Valley near the TX and OK border. On Wednesday, the axis
of the upper level/500 mb trough should enter the Great Lakes to
to mid OH Valley to Southern Appalachians by evening. Further
west, the upper ridge should remain centered in the Southern
Plains on Wednesday while Bertha continues moving slowly west in
the northern Gulf. Locally the cold front will gradually move into
VA and TN by mid to late afternoon.

For today, ahead of the front, moisture will be transported into
eastern KY with PW reaching roughly the 93rd to 97th percentile
range, or about 1.75 to 2.1 inch range. Meanwhile, MLCAPE may
reach as high as the 1750 to 2750 J/kg range with effective shear
peaking in roughly the 35 to 45KT range per the RAP. Effective SRH
per the RAP may reach as high as 100 to 175 to 200 m2/s2, with
the highest values in the north and northeast. MUCAPE should peak
roughly in the 2000 to 3150 J/kg range though mid level lapse
rates should only average near 6C/km with low level lapse rates
peaking around 7 to 8C/km. Ahead of the front, a few discrete
cells/supercells may occur though eventually more linear
convection dropping south/southeast is generally favored by the
evening. Any discrete cells/supercells that could develop would
pose some risk of all hazards with damaging winds and lower end
severe sized hail in the quarter to half dollar size and
torrential downpours most favored. A tornado would also be
possible if it could interact with an outflow or if there is a
storm merger. With the more linear convection in the late
afternoon/ evening, winds will be the primary threat along with
torrential downpours. If the line could become optimally aligned
with 0-3km shear vector a brief spin-up could not be completely
ruled out.

Many of the past few HRRR runs are not initializing the
convection over northeastern IN and into OH with earlier runs
prior to 06Z possibly having a better handle on it. The 06Z NAM
may have initialized that convection a bit better and has some
higher rainfall amounts in the south. Nevertheless, confidence in
coverage and timing strong to severe storms if and where any heavy
rain may occur remains on the low side.

By late in the evening, following the anticipated pre frontal
convection, the chances for severe weather should diminish though
the threat of heavy rain may linger a bit longer. Drier air will
begin to arrive in the north ahead of the boundary by late
tonight, though chances for showers will linger in the south and
southeast through the night. A bit of an increase in coverage of
convection may occur on Wednesday in the south ahead of the front.
That convection could still produce some heavier/torrential
downpours near the VA and TN border, but drier air moving in will
lead to decreasing chances by late afternoon to early evening.

.LONG TERM...(Wednesday night through Monday)
Issued at 525 AM EDT TUE JUL 21 2026

The models remain in generally good agreement with an amplified
and stagnant long wave pattern to rule over the CONUS through
early next week. The center of a seasonably strong upper level
ridge will meander/retrograde northwest from the southern Plains
to the Four Corners region and building into parts of the Central
Plains to Lower MS Valley at times, while broader troughing
modulates east of the Mississippi River with it`s axis aligned
from near the Ontario and Quebec border to the mid Atlantic coast
to east of the southeast US coast. This will result in a reprieve
from the humidity across the Ohio and Tennessee valleys at midweek
into early Friday. However, humidity will be on the increase once
again across the region by Friday afternoon and into early next
week.

By Wednesday evening, a surface cold front should have pushed
well into VA to the Smokes to the Lower MS Valley, and high
pressure building into the Lower OH Valley form the Upper MS
Valley. Wednesday night, welcomed northeasterly low level winds
ushering in much lower dew points than has been experienced this
month. Some fog will likely on Wednesday night into early Thursday
morning and some of this could be dense in some more southern
locales. However, although the pressure gradient/mixiness may
limit this coverage. Drier and cooler weather will be in full
swing on Thursday, with valley fog favored with high pressure
dominating on Thursday night.

As troughing sharpens back up over the Ohio Valley Friday to
Saturday, shortwaves moving southeast within the established
northwesterly flow aloft between the trough axis to the east and
northeast and the ridging in the western to south-central Conus.
Model details regarding timing remain lower confidence this far
out, but rain chances will return as some moderate moisture
advection occurs in the low levels, with LREF mean PWATs of 1.4 to
1.5 inches nosing back into southeastern portions of the
Commonwealth by Friday. PoPs look to peak Friday night into
Saturday, with somewhat better model agreement on increased mid
and upper level forcing in place from one of the shortwaves. For
the rest of the weekend and early next week, despite the favorable
stormier track that northwest flow can mean aloft, mean PWATS
right now remain in the 50th to 75th percentile, so only slight to
chance PoPs are in the forecast for Sunday through Monday.

Highs will remain cooler than normal by about 5 degrees on
Thursday, before gradually warming to the mid to upper 80s by
SUnday Monday. Overnight lows will moderate from the upper 50s
and low 60s Wednesday and Thursday nights, to the upper 60s and
around 70 by early next week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 805 AM EDT TUE JUL 21 2026

At issuance time, VFR was occurring from the TAF sites north with
a bit of lingering fog and low ceilings near the VA border. The
low clouds and IFR or lower ceilings and/or vis near the VA border
in the K1A6 and KI35 vicinity should lift and dissipate by 14Z
and for a time give way to prevailing VFR ahead of an approaching
cold front. Showers and thunderstorms should affect the region
along and ahead of it, mainly after 18Z. The greatest coverage of
activity is anticipated between about 20Z and 04Z. For a few hours
during that time have included thunder on station at the TAF
sites with PROB30 groups a few hours either side of that window
for thunder. When thunder occurs on station, it could be severe
with peak wind gusts of 40KT or higher possible with a period of
IFR or worse conditions. Winds should generally increase to 7 to
15KT range from the southwest after 15Z as the front nears with
some gusts as high as 20 to 25KT. Stronger winds and gusts are
expected in storms as already noted. Winds should trend more west
to northwest late, generally slackening behind the leading edge of
a strong to severe line of storms.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 1 PM EDT this afternoon through late tonight
for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.

&&

$$

UPDATE...JP
SHORT TERM...JP
LONG TERM...JKL/JP
AVIATION...JP