JKL issues Area Forecast Discussion (AFD) at Aug 4, 12:53 PM EDT834
FXUS63 KJKL 041653
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1253 PM EDT Sun Aug 4 2024
.KEY MESSAGES...
- Areas of dense fog, widespread in the southeast, will impact the
area early this morning.
- Hot temperatures and humidity will peak on Tuesday and
Wednesday, with afternoon heat indices near 100 degrees in a
few locations.
&&
.UPDATE...
Issued at 1252 PM EDT SUN AUG 4 2024
Did another update to load in the latest observations, making sure
the near-term forecast was on track with the current conditions.
The northern CWA which saw less fog/cloud cover this morning is
heating up a bit faster than originally forecast, while areas
under the slow-to-dissipate llvl stratus deck are still trying to
catch up. Ultimately, still think the high temperature forecast is
on track, so also update the trend from the current conditions to
the ongoing forecast in the next few hours. In addition, a
diurnally driven CU deck has developed across much of the region.
Went ahead and increased the sky grids across the entire CWA
throughout the afternoon to account for about 25 to 30% sky cover.
These should quickly dissipate by the evening hours. All updates
have been published and sent to NDFD/web. These changes likely did
not impact the ongoing forecast packages.
UPDATE Issued at 1100 AM EDT SUN AUG 4 2024
Valley fog slowly dissipated into the 10am hour, however the
large area of low stratus/mid-level fog is taking a bit longer.
Went ahead and let the dense fog advisory expire given that much
of this llvl stratus deck is sitting above the valley floor where
most the population is, and it was starting to dissipate. Now by
the end of the 10am hour, it's shrunk down to almost half of what
it was an hour ago. Otherwise, forecast is in pretty good shape.
The lingering status deck did hamper the rising of temperatures
thus far, so made sure that the forecast was in line with the
current observations. Expect these to make a quick recovery as the
fog/stratus continues to erode. All updates have been published
and sent to NDFD/web. Also sent out new forecast package to remove
the dense fog advisory and morning fog wording.
UPDATE Issued at 645 AM EDT SUN AUG 4 2024
With the densest of the fog working northeast went ahead and
upgraded the entire area to a Dense Fog Advisory through 10 am.
Did also include the latest obs and trends for the T/Td/Sky grids.
These adjustments have been sent to the NDFD and web servers
along with a freshening of the zones, HWO, and SAFs.
&&
.SHORT TERM...(Today through Monday)
Issued at 445 AM EDT SUN AUG 4 2024
08Z sfc analysis shows weak high pressure building into Kentucky
while a cold front is well off to the southeast. The last of the
showers and thunderstorms drifted out of Wayne County just after
midnight with its associated deeper clouds dissipating shortly
after. The clearing skies allowed for radiational cooling to kick
in and the development of dense fog starting in the valleys of
the southeast. The extent of the fog prompted the issuance of a
Dense Fog Advisory for the southeast 2/3rds of the JKL CWA with
an SPS for areas of dense fog elsewhere. Temperatures are
currently varying from the mid 60s in some of the deeper valleys
to near 70 on a few of the southern ridges. Amid light to calm
winds, dewpoints remain rather elevated - generally in the upper
60s.
The models, and their individual ensemble suites, remain in
excellent agreement aloft through the the short term portion of
the forecast. They all depict the earlier trough weakening and
pulling further away to the northeast from eastern Kentucky. This
happens as 5h ridging stretches east from the Rockies and High
Plains into Kentucky. This ridge will be key in blocking, at least
for a while, the tropical system from impacting the area through
the start of the new work week. It will also keep any mid level
energy to a minimum, locally, through Monday. Given the very
small model spread have gone with the NBM as the starting point
for the forecast grids with the main adjustment needed being to
include more terrain details at night.
Sensible weather features a chance to dry out through the start of
the new work week as high pressure holds in place. With the
return of sunshine (once the fog clears early this morning)
temperatures will be on the rise - reaching near 90 in many places
this afternoon and even warmer on Monday. The humidity will be
generally decreasing each afternoon, though, and this will keep
the heat index similar to air temperatures during the short term
portion of the forecast. At night, we will again see a decent
ridge to valley temperature split develop along with mainly valley
fog formation - likely becoming locally dense into Monday morning.
The main changes to the NBM starting point consisted of adding in
terrain details early this morning and again more extensively
tonight. PoPs were kept to a minimum similar to the NBM values
with only a small threat (less than 10 percent) near the Virginia
border this afternoon and again on Monday afternoon.
.LONG TERM...(Monday night through Saturday)
Issued at 350 AM EDT SUN AUG 4 2024
The period will begin with mid-level height rises peaking on
Tuesday. This will be the warmer day of the period, with afternoon
highs in the lower to mid 90s and isolated locations seeing near
100 degree peak heat index values. However, based on the ensembles
best chances (60-80 percent) of seeing greater than 95 degree heat
index values will be out in parts of western and central
Kentucky. Some guidance is starting to show the potential for a
mid-level wave by mid-week and this seems to be affecting more of
the area north of the Ohio River right now. Overall looks like we
see each day through at least Thursday the potential for mainly
afternoon showers and thunderstorms (15-30 percent chance of rain)
near the high terrain near the Virginia border.
The end of the week remains a bit of a wild card, as deterministic
and ensemble solutions struggle to resolve what happens with
currently Tropical Storm Debby. The various ensemble solutions show
quite a bit of spread as we move toward Friday and Saturday, with
some solutions retrograding the remnants of this tropical system
west or northwest. If this was to happen it would lead to more
impacts across parts of Kentucky. Right now the NBM peaks the
chance of rain on Friday at around 20 to nearly 40 percent. This
seems reasonable given the large amount of spread among the
various solutions on where the low pressure will in fact track,
with some solutions showing as little as a quarter of an inch and
some showing greater than an inch of rainfall through Saturday. So
all this said, we will just have to track this storm over the
next week to see how trends change. The good news is the extra
cloud cover and chances of rain will end up leading to afternoon
high temperatures in the low to mid 80s, which is near normal for
this time of year.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
ISSUED AT 720 AM EDT SUN AUG 4 2024
Dense fog and low CIGs will be the main concern through mid
morning, as skies are clear and winds near calm with high humidity
in place. Will continue the VLIFR conditions at all the terminals
through 13Z, before the fog and stratus starts to lift and
dissipates toward 14Z - followed by a return to VFR conditions.
Winds will average around 5 kts or less through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...GREIF
LONG TERM...DJ
AVIATION...GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 4, 12:53 PM EDT---------------
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