JKL issues Area Forecast Discussion (AFD) at Sep 2, 4:35 AM EDT579
FXUS63 KJKL 020835
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
435 AM EDT Mon Sep 2 2024
.KEY MESSAGES...
- Lingering areas of dense fog will clear out in the far south
towards dawn.
- Pleasant and comfortable weather this Labor Day will continue
well into the new work week.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 435 AM EDT MON SEP 2 2024
08Z sfc analysis shows a distinct cold front sweeping south
through eastern Kentucky. Ahead of this boundary a brief period
of dense fog remains in southeast parts of the CWA but that front
brings drier air and northerly breezes that are clearing the fog
as it drops south. A dense fog advisory remains in effect until 5
am EDT for our southern tier of counties. Otherwise, a band of mid
level clouds trail the boundary with mostly clear skies elsewhere
- along with low stratus in the far southeast with the fog.
Temperatures now vary from the mid 60s north to near 70 in the far
south. Meanwhile dewpoints range from the drier upper 50s north
to the upper 60s south. Winds behind the front are generally from
the north to northeast at 5 to 10 mph but light and calm ahead of
it.
The models, and their individual ensemble suites, are in
excellent agreement aloft through the short term portion of the
forecast. They all depict eastern Kentucky on the southwestern
edge of a departing large 5h trough to the northeast to start the
forecast. This will mean slowly rebounding heights at that level
- even as a small shortwave slips through in the trough's wake
tonight. After its passage, the flow pattern at mid levels will
stay benign reflecting neither troughing nor ridging for this part
of the country. On account of the still small model spread
through Tuesday, have again gone with the NBM as the starting
point for the forecast grids with little adjustment needed aside
from incorporating some more terrain details in the temperatures
for tonight into Tuesday morning.
Sensible weather features a spectacular day - once the limited
early morning fog in the south clears towards dawn. While low
clouds linger in the south through noon, the rest of the area will
enjoy full sunshine, a nice northeast breeze and cooler
temperatures along with pleasant humidity through this holiday. A
cool and clear night is on tap after dark with radiational and
advective cooling combining for readings 10 to 15 colder than this
morning for many spots. Still could see some mainly river valley
fog accompanying the small ridge to valley temperature difference
that sets up after sunset. Tuesday will be equally pleasant as
the drier air settles over the region and temperatures tick up
closer toward normal for the start of September.
The main changes to the NBM starting point consisted of adding in
more terrain distinctions for temperatures tonight. PoPs will be
near nil through the period in line with all guidance.
.LONG TERM...(Tuesday night through Sunday)
Issued at 413 AM EDT MON SEP 2 2024
The long-term period will kickoff Tuesday evening with a trough axis
to our east, extending from Davis Strait to Bermuda, while ridging
with embedded shortwave disturbance is situated to our west over the
Midwest and Plains states. Further upstream, a potent southern
stream Pacific disturbance is crossing the Northern Rockies as
another northern stream trough is diving southward into Alberta
and Saskatchewan. At the surface, high pressure is centered over
the Mid-Atlantic.
As that high pressure shifts east, the ridging to our west will
break down and the previously embedded upper level disturbance
will drift across the Tennessee/Lower Ohio valleys later
Wednesday and Thursday. Showers are possible with this
disturbance on Thursday, though limited moisture return (PWATs
recover to between 1.1 and 1.3 inches) warrants only low-end PoPs
in the 10 to 30 percent range. Meanwhile, the northern stream
trough and Pacific disturbance will merge and drop toward the Ohio
Valley this weekend bringing a potent cold front with it. With
moisture remaining limited, only slight chance to chance PoPs are
forecast with the frontal passage on Friday and Saturday. Chilly
Canadian high pressure builds across the Lower Ohio Valley behind
the front this weekend, bringing 850mb temperatures down to 5 to
8C over east Kentucky. This will set the stage for the coldest
thermometer readings of the autumn season thus far.
Temperatures start the long-term period with highs in the lower 80s
on Wednesday but fall back to the lower and middle 70s by Sunday.
Meanwhile, nighttime lows starting in the 50s to lower 60s Tuesday
night fall back into the 40s by Saturday night. A few of the
coldest locations may drop back to near or just below 40 on Sunday
night.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 200 AM EDT MON SEP 2 2024
LIFR and IFR conditions are noted at several of the TAF terminals
at issuance due to dense fog, low stratus or both. However a
stronger cold front will push south between 07 and 11Z likely
bringing enough mixing to allow for fog to lift to low stratus,
but with IFR CIG conditions in place for a time. Have kept MVFR
cigs in the TAFs (except KSYM) into the daytime hours. However,
all stratus should be burned off or lifted by 18Z with VFR
conditions holding thereafter.
Winds will initially be light to begin the period. However,
northerly breezes will increase as the aforementioned cold front
moves into the area early this morning, becoming more
northeasterly with time through the remainder of the overnight and
into the morning hours. Winds will generally be in the 5 to 8 kt
range during the morning hours today before becoming lighter into
the afternoon.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 5 AM EDT early this morning for KYZ079-
080-083>088-110-113-115>118-120.
&&
$$
SHORT TERM...GREIF
LONG TERM...GEERTSON
AVIATION...GEERTSON/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 2, 4:35 AM EDT---------------
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