JKL issues Area Forecast Discussion (AFD) at Jul 5, 12:46 PM EDT077
FXUS63 KJKL 051646 AAB
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1246 PM EDT Fri Jul 5 2024
.KEY MESSAGES...
- A few thunderstorms this afternoon to early evening could
produce locally heavy rainfall and strong to damaging wind
gusts.
- Somewhat cooler and less humid weather arrives behind a cold
front over the weekend.
- Warmer and more humid conditions will make a noticeable comeback
on Monday and continue into next week, along with a potential
for more thunderstorms.
&&
.UPDATE...
Issued at 1245 PM EDT FRI JUL 5 2024
Heating of a humid airmass across eastern KY has occurred east of
a line of showers and thunderstorms that have moved into eastern
KY from Central KY. Some wind damage reports have been received
from areas nearer to Interstate 75. East of this line, MLCAPE is
forecast in the 1000 to 2000 J/kg range with effective shear
around 30 to 40KT. Mid level lapse rates in more southern areas
should be near 6C/km while lapse rates east of the line are
expected near or in excess of 7C/km. This should be favorable for
a few areas of damaging wind gusts along the line as it moves
deeper into eastern KY over the next couple or hours and a Severe
Thunderstorm Watch is in effect into early in the evening for
this scenario.
UPDATE Issued at 700 AM EDT FRI JUL 5 2024
No significant changes to the forecast - 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 Saturday)
Issued at 445 AM EDT FRI JUL 5 2024
08Z sfc analysis shows low pressure dropping into the northern
Ohio Valley early this morning dragging a cold front into the
region as it arrives. Ahead of this, skies are mostly clear over
this part of the state allowing for a very small ridge to valley
temperature split along with areas of valley fog. Currently,
readings are quite warm running in the low to mid 70s across
eastern Kentucky - a few degrees cooler in the sheltered valleys
than the ridges. Meanwhile, amid light to calm winds, dewpoints
are also high - in the low to mid 70s - creating a floor to the
potential temperature drop through dawn. A few showers are noted
trying to develop to the west and south of the Cumberland
Valley which the CAMs suggest could slip in the southwest around
dawn.
The models, and their individual ensemble suites, are in very
good agreement aloft through the short term portion of the
forecast. They all depict a shortwave trough moving southeast from
the Upper Midwest and entering the northern Ohio Valley today into
tonight. This brings substantive height falls and a brush-by of
mid level energy to eastern Kentucky through 12Z Saturday.
Thereafter, the pattern loosens a bit through Saturday evening
with broad southwest flow at mid levels and weak energy streaming
past the state. The model spread through the short term is
relatively small so the NBM was used as the starting point for the
grids through Saturday afternoon with little deviation needed
aside from the incorporation of the latest CAMs details for the
PoPs today and tonight.
Sensible weather features another hot and humid day with heat
indices in a few places reaching near 100 degrees. The heat will
fuel, and be mitigated in a few places, by scattered to numerous
showers and storms developing through mid afternoon. The latest
CAMs suggest that a convective line will move southeast into the
the area towards noon with a potential for organized convection
with damaging wind gusts as the main threat. Decent instability
will sustain these storms through the afternoon with CAPE progged
to be over 2000 J/Kg while high PWs - over 2 inches - will make
heavy rain a threat with these storms and a potential for
localized flooding will exist with any repeated cell training. The
storm threat will diminish after dark but remain a concern well
into the night. The synoptic cold front settles through the bulk
of the area late tonight, but may not quite clear the JKL CWA
through the day, Saturday. This will keep a small chance for a
shower in the forecast along the border with Virginia to start the
weekend. The front should also bring in some drier air and make
for a less oppressive day, with respect to the heat and humidity,
than we face today.
The main changes to the NBM starting point consisted of tweaking
the temperatures in order to better reflect some very limited
terrain details early this morning. PoPs were adjusted more
significantly today into tonight per the latest guidance from the
CAMS.
.LONG TERM...(Saturday night through Thursday)
Issued at 400 AM EDT FRI JUL 5 2024
Surface high pressure will continue to nudge into the region for the
start of the forecast period. With surface high pressure in place,
temperatures will be back on the rise with highs climbing into the
upper-80s to low-90s for Sunday. Surface high pressure will nudge
off to the east on Monday with enhanced southwesterly flow ahead of
an approaching shortwave. Temperatures on Monday are forecast to be
warmer as highs are forecast to be in the low to mid-90s, coupled
with warm, moist southwesterly flow, heat indices will be
approaching 100 degrees to over 100 in isolated locations.
Models have come into better agreement with a positively tilted
trough approaching the area. At the surface, a surface low will be
tracking through the Upper Great Lakes. Along and ahead of the
front, increasing showers and thunderstorms are likely. As the low
tracks through the Great Lakes, the front will dive southeast
through the CWA. Forecast soundings, sampled ahead of the front show
a marginally severe atmosphere. Can't rule out a severe storm or two
but overall, pre-FROPA environment appears to be a poor supportive
environment for severe storms. Models continue to remain in very
good agreement post-frontal Wednesday as deterministic runs keep PoP
chances through the end of the forecast period and even possibly
bring the remnants of Hurricane Beryl to the forecast area for the
end of the forecast period.
Overall, the period will highlighted with periods of showers and
thunderstorms that'll bring much needed rain to the area. Also,
temperatures will return to more seasonal ranges as daytime highs in
the mid-80s to low-90s and overnight lows ranging from the upper-50s
to upper-60s.
&&
.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 725 AM EDT FRI JUL 5 2024
Just a scant chance for a stray shower or thunderstorm through mid
morning. Any valley fog will clear out shortly with no impact on
the terminals. Look for a lower CIG (but still likely VFR) to
develop by late morning for most of eastern Kentucky with some
convection likely impacting each of the TAF sites. For now have
tried to time the window of highest impact via tempos. Winds will
average 10 kts or less, outside of any convection, generally from
the south to southwest.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GREIF
LONG TERM...VORST
AVIATION...GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 5, 12:46 PM EDT---------------
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