JKL issues Area Forecast Discussion (AFD) at Aug 19, 4:08 AM EDT740
FXUS63 KJKL 190808
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
408 AM EDT Mon Aug 19 2024
.KEY MESSAGES...
- Below normal temperatures are expected through Wednesday.
- Isolated to scattered showers and thunderstorms will remain in
the forecast today, with dry weather then taking hold for the
rest of the week.
- Above normal temperatures return into the weekend.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 408 AM EDT MON AUG 19 2024
The latest upper level map features troughing stretched north to
south across the majority of the eastern portion of North
America. High pressure remains anchored over the southern Plains
and Four Corners region, with ridging extending northward near the
Continental Divide. At the surface, high pressure is centered
just southwest of Hudson Bay, with an exiting cold front arced
from the Mid-Atlantic region through the Carolinas, Deep South,
and into the southern Plains. A secondary surface trough is
positioned southwest across the Ohio Valley. A few showers are
still popping up across far eastern Kentucky at this time, thanks
to the nearby surface and upper level troughs. Temperatures
currently range from the mid to upper 60s.
The models are in good agreement through the short term, with the
upper level pattern remaining quite amplified. The trough in the
East will get reinforced by migrating short wave energy dropping
south out of northwestern Quebec. This short wave will cut off
over southwest Quebec by tonight, with the low continuing to
spiral south, reaching Lake Ontario by late Tuesday. Meanwhile,
the western ridge axis will pivot eastward with time, aligning
from Hudson Bay through the northern High Plains, and then the
central and southern Rockies by Tuesday. At the surface, high
pressure will expand southeast into the Great Lakes and eventually
Ohio Valley with time, allowing for a more fall-like air mass to
invade the Commonwealth.
Low clouds will likely expand across the area through dawn, with
a gradual raising of these expected by late this morning. As we
heat up, isolated to scattered shower activity will redevelop,
with a few thunderstorms possible as well, thanks to the nearby
trough. These will be more confined more across our south and
southeast, towards the better lingering low level moisture, as
well as orographic help. Highs today will be a shade cooler
compared to yesterday, with mainly upper 70s, and perhaps a few
sites squeaking out an 80 degree reading. Have stayed closer to
the 25th percentile for the highs, as temperatures came in cooler
yesterday towards these numbers, with even some locations nearer
the 10th percentile. Skies will clear out tonight, as drier air
advects into the region. Fog will likely be seen in the river
valleys overnight. Lows will be in the low to mid 50s, with the
northern valleys seeing the colder readings, closer to the surface
high. Tuesday will feature mostly sunny skies following the
dissipation of the valley fog. Temperatures will top out in the
mid 70s, with dew points mixing down into the upper 40s for most
locations in the afternoon.
.LONG TERM...(Tuesday night through Sunday)
Issued at 408 AM EDT MON AUG 19 2024
This long term forecast package contains the first hints of fall
this year in Eastern Kentucky, with climatologically cool
temperatures and clear skies likely through midweek. Synoptically,
these autumn-esque conditions are supported by a surface high
pressure system settling into the Great Lakes region and
northwesterly flow wrapping around the backside of a upper level low
centered over New England. Such a setup favors mostly clear skies,
efficient diurnal mixing processes, and pronounced ridge-valley
temperature splits in our area, and all are present in this week's
forecast. In deep valleys, overnight lows could drop into the 40s
for the first time this season on Tuesday and Wednesday nights.
Ridgetops will remain warmer at around the 50 degree mark. The
development of valley fog, especially in valleys with nearby water
sources, appears likely each morning, but any fog should burn off
after sunrise as diurnal warming takes effect. Afternoon high temps
will remain in the 70s on Wednesday, but the second half of the long
term forecast is characterized by changing conditions.
The above synoptic features begin to shift on Thursday. The surface
high pressure system will move further to the south and then the
east, which will veer our winds towards the south. Aloft, ridging
builds into the Ohio River Valley as the Northeastern low finally
ejects, leading to height rises and subsidence in our forecast area.
Thus, a noticeable warming trend begins on Thursday and continues
through the end of the long term forecast period. Afternoon high
temperatures will incrementally step through the 80s in the latter
half of the work week, and MaxTs should cross the 90 degree
threshold on Saturday and Sunday. Overnight lows mirror this trend
and increase by 3-5 degrees each night through the end of the
period, where they top out at 65 degrees.
While the temperatures might be trending warmer, this new weather
pattern still favors the dominance of drier air in our forecast
area. Thus, heat indices will be similar to the forecast afternoon
highs, and it will not feel nearly as humid outside as it felt
earlier this summer. The lack of deep moisture throughout the column
will limit cloud coverage throughout the period, although afternoon
cumulus clouds could develop later in the period when temperatures
peak. The general dryness, combined with the absence of any real
synoptic forcing mechanisms, precludes PoPs from rising above 10
percent at any point in the extended forecast. Clear nighttime skies
under this new pattern will continue to foster fog formation
overnight in valleys. Therefore, the weather will remain quiet in
Eastern Kentucky for the foreseeable future, with only patchy fog in
the weather grids.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 156 AM EDT MON AUG 19 2024
A mix of VFR and MVFR conditions in fog will generally trend lower
overnight, as a stratus deck likely develops over the area,
bringing IFR ceilings, and/or visibilities at times between 08 and
14z. This stratus deck will raise up by the late morning hours,
with VFR conditions returning in the afternoon. Isolated to
scattered showers will also redevelop; however, will only include
a 3 to 5 hour window of VCSH at the terminals for now, with the
better coverage generally favored toward a line from KSJS to K1A6.
Skies will clear out by dusk or just thereafter. Light and
variable winds will become northwest to north northwest through
the afternoon, peaking at 5 to 10 kts, before diminishing by
sunset.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEOGERIAN
LONG TERM...MARCUS
AVIATION...GEOGERIAN
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 19, 4:08 AM EDT---------------
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