JKL issues Area Forecast Discussion (AFD) at Aug 5, 11:33 PM EDT972
FXUS63 KJKL 060333
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1133 PM EDT Mon Aug 5 2024
.KEY MESSAGES...
- Hot temperatures and humidity will peak on Tuesday and Wednesday,
with afternoon heat indices near 100 degrees in some locations.
- Still quite a bit of uncertainty as to how the remnants of
Tropical Storm Debby will impact eastern Kentucky late in the
forecast period.
&&
.UPDATE...
Issued at 1133 PM EDT MON AUG 5 2024
The forecast is generally on track. Valley fog has already
developed over much of the Upper Kentucky River Valley, as well as
parts of the other river valleys to the northeast and southwest.
The latest hourly observations were used to initialize the
forecast.
UPDATE Issued at 748 PM EDT MON AUG 5 2024
There are no significant changes to the forecast with the early
evening update.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 315 PM EDT MON AUG 5 2024
Early afternoon surface analysis has the area under surface high
pressure. To the south, Tropical Storm Debby is moving over the
panhandle of Florida and to the north, a frontal boundary is
triggering severe thunderstorms across the Great Lakes into New
England. Locally, low-level moisture is allowing for a widespread
deck of cumulus clouds with temperatures climbing into the upper-80s
to low-90s.
The entire short-term period will be highlighted by two main
features. First, upper-level flow will continue to remain rather
stagnate as the main jetstreak is located well to the north of the
CWA. Within the mean main flow, a shortwave trough is dragging the
aforementioned cold front through the Great Lakes into New England.
At the surface, this boundary will remain to the north of the area
but as upper-level perturbations move through the main shortwave,
surface impulses will develop and travel along the stationary
boundary. These impulses will remain north of the area but can't
rule out a stray showers or thunderstorm working south into the
Bluegrass/I-64 corridor. Second, Tropical Storm Debby, while
expected to remain well south of the area through the short-term,
will begin to bring high cirrus clouds to the area. Mainly along the
far southeastern portions of the CWA.
Locally, in eastern Kentucky, high pressure will remain dominate.
This will allow for hotter and drier weather to exist across the
area. However, not expecting any PoP through the period, can't rule
out the possibility of a stray shower or storm sneaking into the
Bluegrass thus mostly dry. Also, temperatures will climb into the
upper-80s to low-90s today and Tuesday. Increased moisture will
allow for heat indices to approach 100 degrees in a few locations.
Overnight lows will be relatively warmer (upper-60s to low-70s) as
well but with mostly clear skies or high cirrus clouds, due to T.S.
Debby, valley fog will likely develop each night and then burn off
each morning by 13Z. Overall, a largely quiet short-term forecast
period is expected.
.LONG TERM...(Wednesday through Monday)
Issued at 447 PM EDT MON AUG 5 2024
Tropical Storm Debby will be the story of the extended, although
impacts continue to trend minimal. The center of the low pressure
system will have migrated very little by Wednesday morning, with all
models showing it just off the southeastern Georgia coastline. It
should remain here over the next few days, while farther to the
north, a boundary drops into KY and stalls, unable to move farther
southward due to the tropical system. This system will be fairly
weak and moisture starved, but could result in a few diurnally
driven afternoon convection, especially in the far east.
It's not until Thursday night into Friday that the tropical system
begins to shift northward and towards the spine of Appalachia. It's
also at this point that models start to lose as lot of agreement in
the timing and placement of the low pressure center, though they all
do at least pull it far enough north that eastern KY will find
itself on the NW flow side with some possible wrap-around moisture
during the afternoon Friday. The latest NBM is very pessimistic with
the impact of this precip, only showing low end chances during the
peak afternoon heating, quickly dissipating again by nightfall.
After this point, it's really up in the air. The ECWMF is much more
progressive with only minimal impacts to the far east part of the
state, while the GFS is slower and brings precip chances across the
entire state for Friday night into Saturday. Decided to keep with
NBM given the uncertainty, which is definitely favoring a more
eastward and progressive trend, keeping eastern KY mostly dry once
more. At least everyone agrees that by Sunday, this system should be
well out of the region, and everyone will be dry.
The one nice thing about this system is that it will, nonetheless,
bring more northerly flow to the region (and perhaps some cloud
cover), which will hamper temperatures during the day. While
Wednesday and Thursday are expected to top out in the upper 80s and
lower 90s (hottest on Wednesday), with increased humidity making it
feel several degrees warmer, models have temperatures cooling back
into the low to mid 80s by the weekend. That being said, the NBM is
trying to take the average of some of these models in the extended
which are currently expressing very different solutions. So there is
a good chance that depending on which model the conditions continue
to trend, could mean a trend towards cooler and wetter, or warmer
and drier. It's a wait and see how it starts to play out kind of
forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 713 PM EDT MON AUG 5 2024
VFR conditions will prevail across all TAF sites through a bulk
of the TAF period. Clear skies will develop overnight and allow
for valley fog after 06Z through 13Z. Terminals could drop into
categorical IFR/MVFR through that time period. Terminals will
improve to VFR and remain VFR through the end of the period. Light
and variable winds are expected through the TAF period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...VORST
LONG TERM...JMW
AVIATION...CMC
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 5, 11:33 PM EDT---------------
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