Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 220739

Area Forecast Discussion
National Weather Service Jackson KY
339 AM EDT MON AUG 22 2016

.SHORT TERM...(Today through Tuesday)
Issued at 339 AM EDT MON AUG 22 2016

Early this morning, a mid level trough continues to depart to the
east of the area with mid level height rises as a mid level ridge
is building into the area. At the surface, high pressure is
building into the Great Lakes and Lower OH Valley Region from the
mid MS Valley. The height rises are expected to continue on
average into the day on Tuesday, before the axis of the ridge
approaches and begins to shift east of the area late in the
period. The surface high will continue building across the OH
Valley today with the center of the high settling across the Mid
Atlantic States by late tonight. The axis of this high should move
to the Eastern Seaboard by the end of the period.

Fog should persist through sunrise, dense in some of the valley
locations, particularly the deeper valleys, before lifting and
dissipating by 2 to 3 hours after sunrise today. The dense valley
fog this morning will remain the primary weather concern in the
short term as high pressure will remain dominant. The fog is
already highlighted in the HWO and a Graphical Nowcast and plan to
highlight in an SPS for the morning commute.

Otherwise, the relatively cooler and drier airmass will bring a
reprieve from the warm and humid weather that has prevailed for
much of this month. Highs today will average around 5 degrees
below normal and this combined with dewpoints in the mid to upper
50s will make it feel more like early September. Lows tonight
should fall into the mid to upper 50s, especially in the valleys
while some ridgetops may not fall below 60 as the surface high
remains dominant, but begins to shift east leading to the small to
moderate ridge/valley temperature split. This pattern will favor
fog formation again, but this should be confined to the
climatologically favored spots for fog such as the deeper and more
sheltered valleys near the larger creeks, streams and area rivers.

The airmass will begin to moderate on Tuesday as the surface high
moves east. 850 mb temps are expected to be about 3 degrees C
warmer than today so highs should return to closer to normal with
mid 80s for highs common outside of the high terrain. However, the
break from the heat and humidity that has been prevalent this
month will continue as afternoon dewpoints should be in the upper
50s to around 60.

.LONG TERM...(Tuesday night through Sunday)
Issued at 333 AM EDT MON AUG 22 2016

The weather will be mostly dry throughout the extended period as mid
and upper level ridging takes hold of the southeastern US. At the
surface, high pressure will slide off to the east Tuesday afternoon,
with return flow bringing slightly warmer and more humid air back
into the region. This will allow for some isolated showers to return
to the forecast during the second part of the work week. A shortwave
is expected to push through the Ohio Valley late Wednesday into
Thursday with the best forcing grazing our northwest counties. As
this feature departs Thursday afternoon, a cold front will spill
south and wash out as it tries to move across the forecast area.
What is left of the boundary would be over the area on Friday,
leading to a few isolated showers or storms. High pressure will be
reinforced over Kentucky into the upcoming weekend, with a return to
dry and mild conditions. Temperatures will average a couple degrees
warmer than climatology in the afternoons, with mild overnight lows
around 70 degrees.&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)

Skies are generally mostly clear to clear at this time with high
pressure building in. Fog so far has mainly affected the deeper
valleys and non TAF site locations. Just enough mixiness appears
to be present at this time and this should linger for the next
couple of hours to generally hold off fog there for now. However,
by the 9Z to 12Z window the gradient should ease enough for
some fog either developing at the TAF sites or lifting in from
nearby valleys. This fog should be in the MVFR or IFR range, with
vis likely remaining above airport mins at the TAF sites including
SME given more optimistic trends in recent guidance. The fog
should lift and dissipate by 14z, giving way to VFR. A few
diurnally driven CU near 5KT may be experienced. Winds will be
light and variable with the high in place.


.JKL Watches/Warnings/Advisories...


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