JKL issues Area Forecast Discussion (AFD) at Jul 30, 7:22 AM EDT293
FXUS63 KJKL 301122
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
722 AM EDT Tue Jul 30 2024
.KEY MESSAGES...
- There is a potential for severe thunderstorms in the early
morning hours today with damaging wind gusts the main threat
favoring locations along and west of I-75.
- There is a threat for excessive rainfall from multiple rounds
of showers and thunderstorms through most of the week, which may
lead to localized flooding at times.
- Temperatures climb and humidity builds for Thursday afternoon
when heat indices could reach between 100 and 105 degrees for
many locations.
&&
.UPDATE...
Issued at 721 AM EDT TUE JUL 30 2024
QLCS has crossed eastern Kentucky early this morning and is now
exiting into Virginia and Tennessee. Fortunately, other than the
severe wind gust at the Fleming Mason Airport as the line moved
in, observed wind gusts have remained under 40 mph. Behind the
line, a trailing stratiform rain shield and any subsequent spotty
showers should generally diminish over the next couple of hours.
Forecast grids has been blended with latest observations and
recent CAM data. Updates have been sent and published.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 423 AM EDT TUE JUL 30 2024
The regional radar mosaic shows a semi-organized line extending from
Carter Caves State Park to Stanton to just north of
Campbellsville at 815z. Ahead of this activity, weather is quiet
with exception of a storm over western Morgan and southwest
Elliott counties. At the moment, temperatures are holding in the
lower to middle 70s. Some fog is also noted in the deep, sheltered
valleys particularly close the Virginia border. The surface
weather map analysis suggests a warm front extending northward
from Southern Appalachians to an ~1007 mb low over the Lower
Peninsula of Michigan, while a cold front trails back to the
southwest across the Lower Ohio valley and then back across the
Midwest, and then into the Northern Plains as a quasi-
stationary/warm front. Looking aloft, mean 500H ridging is found
over the Plains, while broad troughing is found over the Ohio
Valley/Great Lakes/Northeast US. Multiple vorticity maxes are
passing over the ridge and into the troughing. The first of these
vort maxes is dropping through Lower Ohio Valley this morning and
is supporting a line of showers and thunderstorms dropping
southeastward across the Commonwealth. Ahead of this line, the
parameter space meets all of the requirements for sustaining
healthy convection west of I-75, whereas the instability is
somewhat wanting further east. Analysis suggests moderate
instability (MUCAPE values of ~1,000 J/kg east of US-23 to ~2,000
J/kg west of I-75) atop weak surface-based CIN). A sharp DCAPE
gradient is also noted across the forecast area ranging from
~900J/kg near the West Virginia border up to ~1,400J/kg near Lake
Cumberland. EBWD (20-30kts) and 0-6km mean winds (20kts or a
little higher) are also sufficient for cold-pool driven QLCS
maintenance. While the QLCS has been slow to organize, a recent
gust to 61 mph at Flemingsburg Mason Airport was evidence that at
least portions of the line have strengthened to severe limits and
warranted a severe thunderstorm warning for much of Fleming and
portions of Rowan County.
Expect the QLCS to generally press southeast and cross the entire
forecast area through 12z. While strong to severe elements, mainly
capable of producing damaging wind gusts, are possible anywhere
along the line, the parameter space is most favorable for
sustaining robust convection for locations near and west of I-75.
However, light rain ahead of that portion of the line may dampen
the severe potential even there. At any rate, once the QLCS clears
the JKL CWA after 12z, isolated to widely scattered convection is
possible this afternoon with the combination of daytime heating,
another passing subtle perturbation aloft, and a weak cold front
sagging in from the north. Today's forecast highs are in the mid
80s to around 90, though the humidity will make it feel more like
95 to 100 for most locations. Some of the CAMs suggest another
MCS forming this evening over southcentral Kentucky ahead of the
cold front and impacting portions of the Lake Cumberland area,
though confidence in this occurring is low. Additional
perturbations aloft may trigger another MCS riding the frontal
boundary overnight, but much of the guidance suggests that the
better parameter space will remain just to our southwest, thus the
MCS is more likely just to graze the Lake Cumberland vicinity
late in the night. Temperatures are forecast to bottom out in the
upper 60s to lower 70s.
Looking ahead to Wednesday, look for another day of similarly hot
temperatures with the highest heat and humidity near Lake Cumberland
where the cold frontal boundary will have stalled. Another MCS may
develop and track along the stalled boundary bringing another
opportunity for organized thunderstorms, best chances southwest of
US-421. In general this pattern will favor the potential for strong
to severe thunderstorms as each of these systems pass. The risk for
excessive rainfall is also greatest in those counties along and
southwest of US-421 where localized 36-hour amounts of 3 to 4 inches
cannot be ruled out, though amounts of 1/2 to 1 inch should be most
common.
.LONG TERM...(Wednesday through Monday)
Issued at 313 PM EDT MON JUL 29 2024
The extended period will begin with an upper level flow pattern
that features a series of shortwaves moving through Great Lakes
and Ohio and Tennessee Valley regions through the weekend and into
the upcoming work week. Hot and muggy air will be in place as the
short waves move through, which will lead to repeated rounds of
showers and thunderstorms across eastern Kentucky. The convective
activity will occur primarily during the afternoon and early
evening hours each day, and should be generally scattered in
nature. The threat for excessive rainfall has decreased a bit due
to the scattered nature of any showers and storms, but there is
still a marginal(10% chance)risk for excessive rain Wednesday
through Friday night, that could lead to flooding around the
forecast area.
Temperatures will likely max out each afternoon in the upper 80s
to lower 90s. Nightly lows will also be a bit balmy, with min
readings in the upper 60s and lower 70s on tap.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 721 AM EDT TUE JUL 30 2024
At TAF issuance, variable flight categories were observed across
eastern Kentucky as a line of convection exits southeast. A
period of generally MVFR is anticipated this morning behind the
rain before ceilings rise and break allowing for improvement to
VFR area-wide by around midday. Additional convection may
redevelop late this afternoon or evening, especially southwest of
US-421; but confidence in timing was too low to mention more than
VCTS at SME and LOZ at this time. Another round of convection is
possible late tonight and would be favored to impact the same
areas. IFR or worse conditions will be possible at any terminal
which experience a direct impact from a thunderstorm. Winds could
also be strong and erratic near thunderstorms. Winds will be
southwest at less than 10 kts today away from any storms.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEERTSON
SHORT TERM...GEERTSON
LONG TERM...AR
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 30, 7:22 AM EDT---------------
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