JKL issues Area Forecast Discussion (AFD) at Aug 3, 2:27 PM EDT132
FXUS63 KJKL 031827 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
227 PM EDT Sat Aug 3 2024
.KEY MESSAGES...
- Thunderstorms are possible at times through today but should be
less organized and generally weaker.
- Heat and humidity will be in place on Tuesday, with afternoon
heat indices near 100 degrees in a few locations.
&&
.UPDATE...
Issued at 227 PM EDT SAT AUG 3 2024
The forecast generally remains on track. Will continue to stick
with the current forecast highs, as only a few hours of heating is
resulting in a quick return to the lower 80s, before passing
shower activity knocks readings back into the mid 70s at a given
location. Lightning has also been absent thus far across the
forecast area, with the deeper cores currently restricted to
portions of Virginia and Tennessee. This should change through the
next few hours, as we approach peak heating, with at least
isolated to widely scattered thunderstorms expected.
UPDATE Issued at 1118 AM EDT SAT AUG 3 2024
An upper level trough is overhead currently, with light shower
activity on the rise. The latest higher resolution model guidance
continues to suggest the better coverage of precipitation should
consolidate and become focused more across southeastern Kentucky
through this afternoon. The current forecast has all of this well
in hand, and have merely made some minor grid adjustments,
incorporating the latest trends in the observations. Updates have
been sent.
UPDATE Issued at 730 AM EDT SAT AUG 3 2024
No significant changes to the forecast - just the inclusion of
the latest obs and trends for the T/Td/Sky grids. These minor
adjustments have been sent to the NDFD and web servers.
&&
.SHORT TERM...(Today through Sunday)
Issued at 450 AM EDT SAT AUG 3 2024
08Z sfc analysis shows low pressure off to the northeast of
Kentucky with its cold front easing out of eastern parts of the
state. This helped to clear out the earlier showers and
thunderstorms last evening with just a few stray showers and
sprinkles around early this morning. Skies are partly to mostly
cloudy with low clouds and fog filling in any breaks in the sky
cover. Currently, temperatures and dewpoints continue to be mild
and quite humid in the upper 60s and lower 70s, amid light winds.
The models, and their individual ensemble suites, continue to be
in great agreement aloft through the the short term portion of the
forecast. They all depict rising 5h heights through the weekend
as troughing over the Ohio Valley retreats to the northeast
tonight. Before it departs, though, enough mid level energy will
drag over eastern Kentucky this afternoon and evening to support
one last round of convection - but likely less organized than
those of the past few days. The energy and cyclonic flow skirts
off to the east of the JKL CWA on Sunday with 5h heights becoming
more ridge-like by that evening along with a dearth of mid level
energy. Given the still small model spread have gone with the NBM
as the starting point for the forecast grids with little
adjustment needed aside from some incorporation of the latest CAMs
guidance for PoPs through the evening.
Sensible weather features one last day of scattered to numerous
showers and storms around with humid conditions. The best chances
for these additional storms will be in the eastern portion of the
JKL CWA - peaking in the late afternoon. The storm chances fall
off later tonight as sfc high pressure builds in from the west.
This will again support some, mostly valley, fog tonight with a
return of a small ridge to valley temperature difference -
mitigated by still elevated dewpoints and some low clouds around
through dawn, Sunday. Sunday proper will be a warmer day with more
sunshine for most areas allowing temperatures to approach 90
degrees in a few spots. The exception may be in the far southeast
nearer the Virginia border where a stray shower cannot be ruled
out at peak heating during the afternoon.
The main changes to the NBM starting point consisted of adding in
PoPs details from the CAMs through this evening while limiting
the higher values for our western parts. Only made some minor
changes to temperatures from the NBM tonight for slightly more
terrain distinctions.
.LONG TERM...(Sunday night through Friday)
Issued at 450 AM EDT SAT AUG 3 2024
The 03/00z model suite 500H analysis beginning Sunday evening shows
ridging, centered around an ~596 dam high over the Four Corners
region, across much of the CONUS west of the Mississippi and
south of the Canadian border states. This ridge is connected, via
a col over the Southern Appalachians/Carolinas, to another ~597
dam high over the Central Atlantic. North of the col, troughing
persists over the Northeast US around its parent ~542 dam low
over Quebec. (Eastern Kentucky remains on the eastern periphery of
the ridging as the upper level trough axis remains off to our
east.) South of the col, an ~583 dam low (the upper level
reflection of what is currently Tropical Depression 4), is coming
ashore the Eastern Gulf Coast. Dropping down the surface, we find
a potential tropical storm nearing or making landfall in the
vicinity of Florida's Big Bend/Nature Coast. A sprawling area of
high pressure is steadfast ahead of that tropical system over the
Western Atlantic Ocean/Mid-Atlantic States and Ohio Valley. Far
to the north an ~997 mb low is rotating over northern Quebec while
its cold front arcs east and south to along the Labrador coast to
Newfoundland and then westward as a stalled boundary through the
St. Lawrence Valley over the Great Lakes and out onto the Northern
Plains.
This long-term period starts off partially through a dry, three-
day warming trend (Sunday - Tuesday). During this time, the
tropical low makes only slow northeastward progress to roughly
along/off the South Carolina coast while a shortwave trough rides
southeastward between the western ridging and northeastern
troughing, scooting the formerly stationary boundary southward as
a cold front. In between the cold front and tropical low, high
pressure and a moderating air mass overhead set the stage for
fair skies and strong diurnal temperature cycles over eastern
Kentucky through Tuesday. Look for highs in the vicinity of 90F on
Monday and in the lower 90s on Tuesday while nighttime lows fall
back into the mid and upper 60s (a few lower 60s cannot be ruled
out in the coolest hollows on early Monday morning).
The cold front arrives on Kentucky's doorstep early Wednesday,
starved of moisture and lacking notable forcing. Model guidance
favors the boundary fully crossing eastern Kentucky on Wednesday
with little chance for rainfall before stalling south and east of
the Appalachians. Meanwhile, the anticipated tropical storm,
makes only very slow northward or northeastward up the Atlantic
Seaboard/Piedmont. Beyond Wednesday, disagreement grows on how far
inland the tropical system is able to push before ejecting
northeastward along the frontal boundary. For right now, only our
southeastern counties, those adjacent to the Virginia-Kentucky
state line , have more than a 20 percent chance of a shower or
thunderstorm on Wednesday and Thursday. By Friday evening, the
model spread on the location of the tropical low is marked,
ranging from over South Carolina in the ECMWF to off the New
Jersey coast in the GFS. The former solution could bring better
chances of rain to at least portions of the forecast area while
something like the latter solution would bring somewhat cooler and
dry conditions. For slight to low chance PoPs have been included
for Friday across locations east of the Escarpment on Friday. The
second part of the long-term period will also feature slightly
cooler temperatures, probably mid 80s for highs and in the lower
to mid 60s for lows.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 227 PM EDT SAT AUG 3 2024
Scattered to numerous showers will affect the area through late
this afternoon, before activity diminishes this evening. A few
thunderstorms are also possible, but given the more isolated-
nature of these, have left out a mention at the terminals. Any
passing shower could bring temporary MVFR and possibly IFR
conditions to a terminal, otherwise VFR conditions will generally
prevail. As clouds break up tonight, fog will likely set in, with
dense fog looking more likely at the TAF sites between 08 and 13z.
The fog will burn off by 14z, with a return to VFR conditions.
Winds will average around 5 kts or less through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...GREIF
LONG TERM...GEERTSON
AVIATION...GEOGERIAN
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 3, 2:27 PM EDT---------------
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