JKL issues Area Forecast Discussion (AFD) at Aug 26, 5:17 PM EDT129
FXUS63 KJKL 262117
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
517 PM EDT Mon Aug 26 2024
.KEY MESSAGES...
- Hot weather is forecast for several days, with near record
temperatures Tuesday through Friday.
- A modest cool-down is expected for the weekend.
- Our greatest potential for rain is Friday into the weekend.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 517 PM EDT MON AUG 26 2024
The latest upper level map features a stagnant ridge centered
over the Midwest, with a short wave trough rotating over the
central/northern Rockies, while a deeper closed low churns over
the northern portion of Hudson Bay. At the surface, moderate high
pressure remains sprawled from New England through the southern
Appalachians, Deep South, and into the lower Mississippi Valley.
A few weaker surface troughs are noted in the relatively weaker
areas of high pressure, more so over New England. Mostly sunny
skies and an increasingly warmer air mass has allowed for highs
mostly in the upper 80s to lower 90s across eastern Kentucky today.
The models are in excellent agreement through the short term, with
the center of the ridge gradually curling east southeast through
the period, dampening with time, as passing short wave energy on
the northern periphery of the ridge flattens it. At the surface,
high pressure will remain anchored across the southeastern CONUS,
while a surface cold front stalls near the Great Lakes/Ohio
Valley. For eastern Kentucky, mostly clear skies, along with
building heat will be on tap.
Tonight, clearing skies, patchy valley fog, and probably the last
night of any typically colder eastern valleys dipping to below 60
degrees will occur. Tuesday, temperatures will rebound into the
lower 90s at most locations, with a few mid 90s possible. Still
relatively lower dew points in the low to mid 60s will continue
to keep heat indices in check. Given the proximity of the ridge
center, have leaned closer to the 50th percentile of the blended
guidance for the highs, despite readings being closer to the 25th
percentile lately. Tuesday night will be a few more degrees warmer
compared to tonight, with lows in the 60s in the valleys, while
ridges stay up around 70 degrees.
.LONG TERM...(Wednesday through Monday)
Issued at 405 PM EDT MON AUG 26 2024
While the highlight of this long term forecast package is the
potential for record-breaking heat, the passage of a couple of upper
level disturbances will reintroduce rain chances to the forecast in
the second half of this week. On Wednesday, ridging remains parked
over Eastern Kentucky both aloft and at the surface, albeit slightly
further south and east than in days prior. Further north, a
shortwave trough and its associated surface low/frontal boundaries
will move from the Great Lakes into the Ohio River Valley and become
fairly diffuse. Upstream development of Mesoscale Convective Systems
associated with these features appears possible. Any activity that
is able to sustain itself for extended periods of time may traverse
into northern portions of the forecast area on Wednesday, but become
displaced from the best forcing and shear mechanisms as it does so.
The Storm Prediction Center has introduced a marginal (level 1/5)
severe weather risk along and north of the Mountain Parkway on
Wednesday to account for this slight chance of storms, but
uncertainty regarding the evolution of these mesoscale features
limits confidence this far out. Stay tuned to future forecast
updates as these features are resolved in higher-resolution forecast
guidance and near-term mesoscale analyses.
Confidence is much higher in the potential for warmer-than normal
temperatures in the second half of the workweek. The continued
presence of high pressure should produce mostly clear skies and
foster strong diurnal mixing/a potent diurnal temperature curve.
This yields afternoon highs in the mid to upper 90s and overnight
lows around 65 (valleys) to near 70 (ridges) degree range through
Friday. Record highs at KJKL are pretty paltry during this period
of time (93 on Wednesday, 94 on Thursday, and 95 on Friday), so
this heat has the potential to be record-breaking. The
aforementioned, yet subtle, southeastward shift of the parent
synoptic features will gradually facilitate moisture return
through the column as time goes on. Heat indices accordingly climb
above the 100 degree mark on Wednesday afternoon across much of
the area, maximize around 103 on Thursday afternoon, and remain
elevated around 100 on Friday. While this is technically just
below heat advisory criteria, heat-related impacts are certainly
possible, especially in communities with enhanced levels of
exposure and vulnerability to heat hazards. Be sure to stay
hydrated and take breaks if spending time outside this week.
It is worth mentioning that if we see any MCS activity or associated
convective cloud debris in our forecast area on Wednesday or
Thursday, temperatures could under-perform the current forecasts. In
a similar manner, it is plausible that forecast guidance is slightly
overdoing MaxTs. Lower-percentile NBM guidance has been closer to
observed temperatures both upstream and in our area as of late.
Probabilistic DESI guidance still depicts the potential for MaxTs
greater than 97 degrees in a crescent-shaped corridor along and
north/west of the Mountain Parkway and I-75 corridors, but
forecast highs greater than this value appear unlikely. After
coordinating with neighboring offices, the forecast MaxT grids in
the coming days were adjusted slightly downwards from base NBM
output. Ridge-valley temperature splits were added during the
overnight hours as well.
Heading into Labor Day Weekend, another cold front will approach the
area on Friday and pass through on Saturday, this time with better
upper level support and more moisture to work with. Chance PoPs re-
enter the forecast on Friday and then upgrade to likely categorical
PoPs on Saturday with better frontal forcing available. Organized
severe thunderstorm potential still looks low with this second
system, but there should still be enough instability to support
general thunderstorms. The boundary responsible for these storm
chances will stall out over the area this weekend, keeping shower
and storm chances in the forecast through Monday. This lingering
activity should peak each afternoon in accordance with diurnal
heating, although temperatures will be much closer to climatological
norms (highs in the 80s and lows in the 60s) in the post-FROPA
airmass.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 201 PM EDT MON AUG 26 2024
VFR conditions will continue to prevail through the majority of
the time, as high pressure remains in place. Isolated to
scattered cumulus, ranging from 4-5k feet agl, will diminish by
dusk. IFR or lower valley fog will develop once again overnight.
Some spotty MVFR may affect KSME and KSYM between 10 and 12z, but
there is not enough confidence to include a mention at this time.
Winds will remain light and variable through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEOGERIAN
LONG TERM...MARCUS
AVIATION...GEOGERIAN
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 26, 5:17 PM EDT---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
