Area Forecast Discussion
Issued by NWS Paducah, KY

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675
FXUS63 KPAH 220736
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
236 AM CDT Wed Mar 22 2017

.SHORT TERM...(Today through Friday night)
Issued at 146 AM CDT Wed Mar 22 2017

While the frontal boundary is well south of the FA now, there is
still some overrunning convection affecting/departing our southern
counties...but it is tracking to leave the FA pcpn free by/before
12Z. After that, upper ridge builds to our west, with H5 height
rises upwards to 40DM occurring over the heart of the FA, even as
broad surface anticyclone anchors across Great Lakes, and extends
its influence southward into the lower Ohio valley with
cooler/drier Canadian CP airmass. We think this combo effectively
eliminates Pops for us, although we acknowledge a lingering
boundary that could touch off some instability showers just to our
south and west, thru the day/night.

On Thursday, the mean upper ridge migrates eastward and anchors
across the Mississippi river valley, while strong height falls are
noted in the Desert Southwest, in response to a strong upper
jet/digging Long wave. This backing upper flow will stream ample
moisture southwest to northeast across the southern Plains,
allowing for convection/pcpn to initiate as the mean upper stream
jet energy spawns Lee side cyclogenesis. This developing/evolving
system effectively tracks due eastward across the Red River
valley by Friday, on a bee line to the lower Mississippi river
valley, which has by now seen its mean ridge slide eastward to the
southeast U.S. Old SWODY4 outlooks 15% svr threat for
Friday-Friday night time period just to our south and west, as
this system comes into play, and it`ll be something to keep an eye
upon as the end of the week draws near.

Coolish temps today-tonight (50s/30s) will moderate Thursday
(60s/50s) as we transition from the Trof to the Ridge. We`ll reach
into the 70s Friday in the warm sector, ahead of the next weather
system, as pcpn/thunder chances return.

.LONG TERM...(Saturday through Tuesday)
Issued at 235 AM CDT Wed Mar 22 2017

An active weather pattern is expected this weekend through at least
early next week. A series of 500 mb shortwaves will rotate northeast
from the southern Plains through the Mid-Mississippi Valley. The
associated surface lows will pass across Missouri and Illinois,
placing our region in the warm sector. Each system will undergo a
weakening trend as it passes across the central states, and the
trailing cold fronts will have little effect on our temps.

As far as the daily specifics, Saturday still looks like the wettest
day of the long-term period. A corridor of deep moisture will extend
from the Gulf of Mexico northward across the Lower Ohio Valley.
Despite strong southerly flow aloft, the models indicate temps will
struggle to reach 70 due to extensive cloudiness and precip. The
clouds and precip are forecast to keep instability in check, with
mucapes from 500 to 1000 j/kg. However, thunderstorm potential will
need to be watched because of decent shear profiles. Southerly flow
will average from 35 to 50 knots throughout the lower and mid levels
of the column. In the event of pockets of clearing and enhanced
solar heating, some intense convection would be possible in the
afternoon.

On Saturday night, convective potential will decrease as the 500 mb
closed low weakens to our north. The trailing shortwave trough will
cross the Lower Ohio Valley early Sunday morning, but there should
be little change in surface winds. Southwest low-level winds are
expected on Sunday, which will permit temps to reach the lower 70s
as skies partially clear out. Some lingering showers are possible,
mainly in the morning to the east of the Mississippi River.

The next system in the progressive flow pattern will arrive early
next week. This system will follow a similar track to the weekend
system. However, the Monday system is forecast to be relatively weak
both at the surface and aloft. Although there should be a little
more instability and moisture for the Monday system to work with,
shear profiles are not forecast to be as strong. Pops will be in the
likely category Monday. Temps will remain quite mild, with highs
around 70.

The forecast for Tuesday will lean more toward the cooler and drier
gfs camp than the ecmwf. The gfs solution calls for a weak cold
front to move through our region early Tuesday, followed by slightly
cooler and drier air. The overall southwest flow pattern will not
change, so no big changes are expected in the temp or precip
pattern.

&&

.AVIATION...
Issued at 146 AM CDT Wed Mar 22 2017

Nearby pcpn echoes on radar remain south of the terminals, and
should not impact the terminal forecast as the overrunning
boundary is keyed well to the south and will remain so. Mid and
high clouds will gradually thin/disperse with time, as
cooler/drier Canadian CP airmass works down/across the river
valley from the north/east.


&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$



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