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FXUS63 KJKL 250838
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
438 AM EDT Sun Aug 25 2019

.SHORT TERM...(Today through Monday)
Issued at 430 AM EDT SUN AUG 25 2019

Early this morning, the axis of an upper level ridge extended from
the Southeast into the Great Lakes with a secondary center of the
ridge located north of the OH River. Further west, a trough
extended south through the Plains with a couple of weaker lead
shortwaves nearing the Lower OH and the Mid South regions.
Meanwhile, high pressure was centered over the St Lawrence Valley
and Northeast with ridging extending south along the eastern
seaboard and west across the Great lakes into parts of the MS
Valley. In between an inverted trough extended into southeastern
KY from the TN Valley. CLouds at low and mid levels have gradually
been increasing near this feature through the night across
southern portions of the area while skies have remained mostly
clear to clear further north and east with just cirrus passing
overhead. Valley fog has developed in these more northern and
eastern locations per satellite imagery. Temperatures have also
dropped off into the mid and upper 50s in mainly valley locations
in these areas.

After initial valley fog lifts and dissipates early this morning,
the axis of the upper level ridge will move further east with
gradual advection of moisture into the OH Valley including eastern
KY. The low level flow will become more southeast and downslope
as the sfc high moves further northeast away from the area and the
inverted trough becomes located further northwest. An initial
weak shortwave will move toward the area today with some
associated isentropic lift over a sfc boundary located well south
of the area. Clouds will increase as moisture advection continues
and the moisture should become deep enough by the afternoon fro
scattered to numerous showers and perhaps a stray storm to move
into the Lake Cumberland area and possibly reach as far east as I
75 by sunset. Areas further northeast and east should receive the
most sunshine today along with the airmass drier with eastward
extent. These locations should be the warmest today reaching the
low to perhaps mid 80s while areas nearer to Lake Cumberland could
not get out of the 70s.

Tonight and Monday, the axis of the upper level ridge will move
futher east while additional weak shortwaves in advance of a more
significant trough cross the area tonight. The axis of the more
significant trough will reach near the MS River late tonight and
then begin to move across the Commonwealth on Monday. Falling
heights and continued moisture advection should result in shower
chances spreading east across the entire area by the end of the
period.

Persistent cloud cover, meager low and mid level lapse rates, and
model CAPE/instability appear very meager on Monday and thus
thunder chances also appear to be very minimal as a result.
Elevated instability or omega with the passing wave may be
sufficient for a bit of elevated embedded thunder across western
and northwestern locations but confidence in this is very low.
The cloud cover may also be rather extensive on Monday and given
the colder MOS numbers holding in the 60s in some cases and colder
CONSRAW guidance it seems NBM numbers well into the 70s seem too
high at least wherever clouds and showers are most persistent. In
general, have trended highs down for Monday from NBM/previous
forecast, especially for northern and central portions of the
CWA. Accordingly, it is appearing more probable that some portions
of the are may struggle to get above 70. With the shortwave
trough moving through the area, confidence is increasing for
measurable precipitation from showers on Monday. The affect of
downsloping should keep QPF lower in the east, especially the far
southeastern sections.

.LONG TERM...(Monday night through Saturday)
Issued at 255 AM EDT SUN AUG 25 2019

The shortwave trough will continue to advance east across the
area Monday evening, likely keeping scattered to numerous showers
going through much of the night. With southeast flow continuing,
rainfall amounts should generally be light, but measureable,
nonetheless. May need to go higher on pops for Monday night given
the deeper moisture and lift present. Still looks like a break
from precipitation early on Tuesday as we get some subsidence
behind the departing wave and ahead of the cold front pushing east
across the Ohio river valley. However, the approaching boundary
with some weak daytime instability may be enough to allow for some
shower and storm development Tuesday afternoon. The better chance
of rain will accompany the cold front as it pushes across the
area Tuesday evening. Shear and instability are lacking with the
cold frontal passage and thus, severe threat continues to look
very low. Showers will wind down from northwest to southeast as we
head through Tuesday night and early Wednesday morning. Much
drier air will surge into the area behind the departing front.

High pressure will build across the area from late Wednesday
through the beginning of next weekend, providing a very pleasant
stretch of weather. Dewpoints may get as low as the lower 50s
Thursday and Friday afternoons with morning lows well into the
50s. A few upper 40s cannot be ruled out Thursday and Friday
mornings. The ridge could begin to break down by late next
weekend, but for now the forecast will remain dry.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 200 AM EDT SUN AUG 25 2019

Surface high pressure will continue to prevail across the region
overnight, though clouds will increase in the low and mid level
range across the south and southwest during the first 6 hours of
the period. An approaching shortwave trough will lead to some
convection generally after 18Z for locations nearer to and west
of I 75. By the end of the period isolated shra cannot be ruled
out as far east as an SYM to LOZ line. SME will have the best
chance for any convection late in the period. River valley fog
with IFR and MVFR reductions in eastern sections should persist
and become more extensive through sunset before lifting and
dissipating through 14Z. This will not affect any of the TAF
sites, however. Winds initially out of the northeast and east
will shifting toward the southeast between 12Z and 18Z as high
pressure departs. Speeds should be 10 kt or less through the
period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...JP
LONG TERM...KAS
AVIATION...JP
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