Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 220744
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
244 AM CDT MON AUG 22 2016

.SHORT TERM...(Today through Wednesday)
Issued at 209 AM CDT Mon Aug 22 2016

Patchy fog is possible early today but should burn off quickly
after sunrise. Otherwise, it`s been a sea change in airmass with
surface dew points at this writing ranging from 54F at MVN to 63
act CEY. And through the course of the day today, we`ll see
surface high pressure currently situated across the mid
Mississippi river valley, move east to the mid Ohio river valley
by 00Z Tue. Surface-Boundary layer trajectories around the high
will continue to funnel in surface dew points ranging from the
mid/upper 50s to around 60.

The high will continue its eastward drift tonight into Tuesday,
situating itself just off the Eastern Seaboard by 00Z Wed. This
will help establish southerly return flow, mainly west of the
Mississippi, during the daytime Tuesday. As a result, we`ll see
surface dew points nudge themselves upward, with mid-upr 60s
making an appearance early in the day, and low 70s working into
the SEMO Ozarks by evening. Coincident with this moistening
tongue will be the H5 advection of positive vorticity, as a weak
short wave of energy is picked up by all models rotating across
the Ozarks/Crowleys Ridge. This area specific combo of surface-
boundary layer moistening, increasing elevated instability, and
vort aloft aided lifting, will be enough to warrant our
introduction of Pops basically along and west of the Mississippi
river for daytime Tuesday.

For Tue night into Wed., the models kind of flatten out and
envelope the aforementioned wave east of the Mississippi, while
they extend the grip of High pressure at the surface and aloft
from the mid Atlantic Seaboard back across much of the South.
Return flow trajectories do continue, so our surface dew points
remain hovering from high end 60s to and thru low/mid 70s. Backing
upper flow atop the 594 DM High at H5, centered across the lower
Mississippi river valley, will shoot some weak embedded waves of
energy from the Plains atop the ridge/across our area,
particularly with affect to the northern 2/3 of the FA,
necessitating at least a small chance Pop thru the remainder of
the short term forecast period.

Today`s temps will mirror Sundays, then with the shifting
synoptics explained above, we`ll see a return to more summer like
Highs/Lows (and humidity) by Tuesday and esp, Wed.

.LONG TERM...(Wednesday night through Sunday)
Issued at 209 AM CDT Mon Aug 22 2016

All models in general agreement and consistent with previous runs
with the upper air and surface pattern at the start of the period.
At the upper levels, a ridge is over the southeast U.S. and extends
northward to New England. An open wave, or weak upper level low is
along the Canadian border with Minnesota. At the surface, a weak
cold front runs from about GRB to northwest Oklahoma.

As the upper wave moves northeast it is expected to push the front
through our area Thursday Night. This front is much weaker than the
one that just went through our area, so do not see the scouring out
of deeper moisture and will keep low chances going through parts of
the area through the weekend.

Essentially the upper level ridge stays over the eastern U.S. with
weak waves of energy moving through the flow to our north. PW values
generally stay below 2 inches during the period so do not see
widespread heavy rain although localized is possible. Will have to
keep an eye on the tropics especially later in the period.

&&

.AVIATION...
Issued at 209 AM CDT Mon Aug 22 2016

Tempo patches/occasional MVFR to IFR vsbys in Fog are possible
thru Daybreak, but will burn off quickly thereafter. A Few to Scattered
VFR bases of diurnal cu are anticipated again today, which should
range from about 4K to 5K FT AGL, perhaps to 6K, before their
ultimate demise toward sunset. Surface high pressure centered over
the middle Mississippi river valley at the start of the period,
will drift slowly but surely along the Ohio river valley thru the
course of the forecast terminal effective time, resulting in
light/variable winds ultimately turning around to a light
southerly (KCGI/KPAH) to southeasterly (KEVV/KOWB) component by
Tuesday morning.

&&

.PAH Watches/Warnings/Advisories...
IL...None.
MO...None.
IN...None.
KY...None.

&&

$$



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