JKL issues Area Forecast Discussion (AFD) at Aug 19, 3:00 PM EDT889
FXUS63 KJKL 191900
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
300 PM EDT Mon Aug 19 2024
.KEY MESSAGES...
- Below normal temperatures are expected through Wednesday.
- Dry weather will take hol today through late next week.
- Above normal temperatures return into the weekend.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 300 PM EDT MON AUG 19 2024
There is good agreement in the guidance that the upper level trough
axis will continue to pull east tonight and high pressure at the
surface will push toward the Great Lakes and Ohio Valley. That said,
the major ensembles only have about a 1 mb difference in the MSLP
between the 25th and 75th percentile through the period. The showers
and perhaps a rumble of thunder will diminish this evening and skies
will clear tonight. Given the high pressure crests to the north will
keep the overall ridge/valley temperature splits to a minimum. This
will lead to low to mid 50s in the valleys and mid to upper 50s on
the ridges. The valleys will come in closer to the 10th percentile
of the NBM.
We will continue to see a cold air advection pattern set up across
the area, as 850mb temperatures hit around 10 celsius Tuesday
morning. This as high pressure to the north continues to usher in
northerly flow at the surface Tuesday. Even under ample sunshine
Tuesday, the afternoon highs will remain around 10 degrees below
normal for this time of year in the low to mid 70s and will give us
a fall feel given the dewpoints will mix out in the upper 40s to
lower 50s.
This will set the stage for a cool fall like night Tuesday night
with high pressure remaining nearby and clear skies being the story.
The only concern is how much will fog affect the valley lows and
there is some uncertainty on this. However, the NBM is showing
around a 60 percent chance of valleys lows equal or below 50s
degrees. Given this opted to blend the valley overnight lows toward
the 10th percentile of the NBM to better capture this potential.
This will lead to upper 40s to low 50s in the ridges and mid to
upper 40s in the valleys. This will be the first time we have seen
valley temperatures in the 40s since around the middle of June.
.LONG TERM...(Wednesday through Monday)
Issued at 300 PM EDT MON AUG 19 2024
The forecast period begins with an upper-level trough digging toward
the forecast area. At the surface, high pressure will remain
present; however, with upper-level flow out of the north-northwest,
below average temperatures will be advected into the region.
Confidence in these forecast below average temperatures is high as
ensembles such the ECMWF's EFI has 80% to 90% of its members are
presenting a very good chance of these cold temperatures occurring.
Highs for the first part of the forecast period are forecast to be
in the low to mid-70s with overnight lows in the upper-40s to low-
50s. With forecast clear skies in place, the more sheltered valleys of
eastern Kentucky could experience overnight lows in the mid-40s.
As the trough ejects to the northeast, height rises, from a building
ridge over much of the southern U.S., will continue to keep dry
weather over the area but temperatures will begin to warm back to
more seasonal normals. Staring Friday and persisting through the
remainder of the period; highs will climb into the mid-80s on Friday
to low-90s by Sunday. Also, overnight lows are forecast to climb on
this scale as well with overnight lows topping out in the upper-50s
to low-60s by Saturday night into Sunday. Since the air mass that's
building is a drier airmass, heat indices will be fairly close to
the forecast highs.
Otherwise, a quiet forecast period is expected as high pressure will
be dominate. Temperatures will start below average but will climb
back to seasonal normals. Valley fog is expected each night but will
burn off by mid-morning and the area will return to full sunshine
and dry weather.
&&
.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.
&&
$$
SHORT TERM...DJ
LONG TERM...VORST
AVIATION...DJ
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 19, 3:00 PM EDT---------------
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