Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 111743 AAA

1243 PM CDT Fri Jul 11 2014

Issued at 1243 PM CDT FRI JUL 11 2014

The AVIATION section has been updated for the 18Z TAF issuance.


.SHORT TERM...(Today through Sunday night)
Issued at 314 AM CDT FRI JUL 11 2014

Not much to argue with between the 00Z models for this short term
period, and there is little change from the existing forecast.

The upper ridge continues to build strongly eastward over our
entire region through Saturday, with little flow aloft. At the
surface, ridging will continue to dominate the region today and
tonight, before shifting east and allowing some light southerly
flow to develop across the area on Saturday. This should lead to
dry weather and a nice warming/moistening trend.

Saturday night, the flow aloft will begin to increase a bit across
the north, bringing the prospect of the tail end of a MCS reaching
the I-64 corridor. Will limit PoPs to just slight chances in that
area. As the large and intense upper storm system shifts southward
toward the Great Lakes/Upper Midwest Sunday, the westerly flow
aloft will continue to slowly increase from the north, and a cold
front will push closer to the region.

The low-level flow will be southwesterly Sunday. This should help
push the low-level thermal ridge right over our region, and pull
at least lower 70 dewpoints through the entire region through the
day. It will be quite oppressive with highs in the mid 90s over
much of the region and afternoon heat indices near 100 degrees. It
should stay below Heat Advisory criteria, but will mention in the
triple digits in the HWO.

Despite the heat and humidity, model soundings have a hard time
generating much instability prior to 00Z Monday. However, figure
that isolated to scattered thunderstorms will be possible through
the afternoon, and there is still the possibility of some decaying
convective system moving into the northern half of the region in
the morning.

Figure that a few storms may pulse up to produce isolated
damaging winds in the afternoon, but the storms will be pulsy at
best during the day. Despite increasing wind fields through the
day, they will still not be strong enough to support rotating
updrafts until 00Z or later in the evening. With precipitable
water values climbing to 1.75" on Sunday, locally heavy rainfall
will also be a concern.

.LONG TERM...(Monday through Thursday)
Issued at 314 AM CDT FRI JUL 11 2014

Medium to high confidence in the extended.

Models have come into much better agreement with unfolding scenario
of a fropa early in the week and cool dry high pressure in its wake.

One thing that stands out is lack of deep moisture with the approach
and passage of cold front. Models agree on reducing the instability
to about half what previous runs indicated...i.e. CAPE have fell
from around 4k j/kg to around 2 possibly 3 considering which model
you believe. LI`s however still remain high with around -4 to -5
which is still a significant decrease. Without a fropa and possible
MCS or remnants thereof would not be to concerned. However we do
have the aforementioned and with adequate instability to continue to
demand a close weather watch for Sunday into Monday time frame.
Thats where the medium confidence comes into play. The high
confidence is uncharacteristically in the later part of the extended
with a strong high and northerly flow for most of the week. This
will bring us some very cool temperatures for this time of
year...possibly 10 degrees below normal for the mid week at least.
Relative humidity will also be unseasonably low.


Issued at 1243 PM CDT FRI JUL 11 2014

Retreating high pressure will allow a warm front to the south and
west of the TAF sites to lift northward through the period. With
the exception of MVFR fog at KCGI/KPAH between 08-12Z, VFR
conditions shoulod prevail through the period. VCSH are possible
after 15Z at KEVV near the aforementioned frontal boundary. Light
and variable to calm winds will continue at all istes through
14-15Z, then pick up out of the south southwest AOB 5 knots.




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