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489
FXUS63 KPAH 221724
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1225 PM CDT Tue Aug 22 2017

.UPDATE...
Updated aviation section for 18z taf issuance

&&

.SHORT TERM...(Today through Thursday night)
Issued at 323 AM CDT Tue Aug 22 2017

Our attention now turns to a rather strong cold front pushing
southeast through the Midwest and Plains this morning. This front
will make its passage over our region this afternoon and evening.
During this peak heating time, it will encounter a good deal of
moisture with high PWs and dew points in the 70s. Should also be
quite unstable with SB CAPES in excess of 3000 J/kg. As the jet
drives the front thru, deepening shear profiles favor linear
storms/damaging wind potential along the Ohio river valley, with
the SPC slight risk zone extending southward and westward to
almost Paducah, and a marginal risk elsewhere.

The front has made nearly complete passage by 06Z Wed or
thereabouts, with pcpn dying with it. Cooler/drier air then works
in with the help of a large area of surface high pressure, whose
center is over NE/IA/MO/KS area. By 12Z Wed, dew points have
dropped into the 50s in our north, and these will drop on down
across the remainder of the FA thru/by 06Z Thursday. Will be down
right chilly Wed/Thu nights with lows down in the 50s. Highs will
struggle to near 80 or so.

.LONG TERM...(Friday through Monday)
Issued at 323 AM CDT Tue Aug 22 2017

 An unseasonably cool and dry weather pattern will be in place Friday
through the weekend. Northeast winds will maintain their hold
through this period as surface high pressure of Canadian origin
pushes very slowly eastward across the Great Lakes region. Unusually
dry air will be in place with dewpoints remaining in the 50s for
several days. This will result in a larger diurnal temperature swing
with pleasantly warm days in the lower 80s and cool nights that give
a hint of early Fall, dipping into the upper 50s to lower 60s. The
typical summertime heat and humidity will be pushed well south of
our region through the period. Peaking out further in time, the long
range models are hinting at continued troughiness over the Heartland
and below normal temperatures possibly lasting into the first few
days of September.

The remnants of Tropical Storm Harvey currently near the Yucatan
Peninsula are expected to push northwest and then intensify before
possibly making landfall somewhere in Texas late this week. The
latest guidance, 00z GFS and 00z ECMWF deterministic models, along
with the GFS and Canadian Ensemble means, are hinting at the
remnants of this system getting drawn up into the Heartland next
week. The consensus was to bring the bulk of the rain from this
system into the area Monday into Tuesday. However, the ECMWF is
slower and waits until the middle of next week. Since this is still
nearly a week out, there is a lot of uncertainty regarding this
latest trend. There remains a wide range of possibilities on where
Harvey`s remnants may end up tracking. Just something to keep an eye
on and monitor as we head closer to that time frame.

&&

.AVIATION...
Issued at 1225 PM CDT Tue Aug 22 2017

Thunderstorms will likely affect most of the taf sites this
afternoon. A strong cold front will move southeast across all sites
during the afternoon. Thunderstorms were starting to form along the
front at 17z in srn Illinois and se Missouri. These storms will
likely organize and increase, bringing some gusty winds and heavy
rain to most sites.

Once the front passes by late this afternoon, winds will become
northwest at 5 to 10 knots. A short period of mvfr cigs is possible
immediately behind the front. Otherwise, clouds will be of the high-
level variety. Skies will be clear on Wed morning with north winds.

&&

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

$$

Aviation...MY