JKL issues Area Forecast Discussion (AFD) at Aug 19, 1:21 PM EDT840
FXUS63 KJKL 191721 CCA
AFDJKL
AREA FORECAST DISCUSSION...CORRECTED
National Weather Service Jackson KY
121 PM 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.
&&
.UPDATE...
Issued at 1226 PM EDT MON AUG 19 2024
This update was focused on making some adjustments to PoPs given
the radar trends. Overall minor changes, but did add in around a
15-20 PoP a little further north than we had previously. Outside
this, there were very few changes made for this update.
UPDATE Issued at 1027 AM EDT MON AUG 19 2024
We are continuing to see influence from a robust upper level
trough axis starting to exit to the east. This will keep a few
showers and perhaps a thunderstorm or two this afternoon in the
forecast for areas mainly south of the I-64 corridor. Overall
forecasts grids look on target for this resulting in little if
any changes to the forecast database.
UPDATE Issued at 744 AM EDT MON AUG 19 2024
Isolated to scattered showers have filled in near the I-64
corridor early this morning. Have adjusted the PoPs higher per
the latest radar and latest higher resolution model trends through
this morning. Otherwise, mainly freshened up the hourly
temperatures and dew points, accounting for the latest trends in
the observations. This resulted in slower diurnal rise through
noon, given the prevalent cloud cover.
&&
.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 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 116 PM EDT MON AUG 19 2024
We are finally starting to see MVFR Cigs lift to the VFR level at
all the sites this afternoon. We are seeing a few showers and
perhaps you will see an isolated storm at times through the
afternoon. These might lead to some brief lowering of vis at
times down toward the MVFR level, but these will be quick and
should be limited at most TAF sites. We will see skies clear out
tonight and this could lead to mainly river valley fog. However,
there is still some signal for LOZ and SME to see a little touch
of fog late tonight and lift around 13Z Tuesday. Then expect VFR
conditions to prevail the remainder of the period. The winds will
generally remain in the 5-10 knot range out of the northwest
mainly in the afternoon under the influence of peak heating and
then become more light and variable in the evening and overnight.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...GEOGERIAN
LONG TERM...MARCUS
AVIATION...DJ
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 19, 1:21 PM EDT---------------
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