Area Forecast Discussion
Issued by NWS Paducah, KY

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193
FXUS63 KPAH 191152
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
652 AM CDT TUE JUL 19 2016

.UPDATE...
Issued at 645 AM CDT Tue Jul 19 2016

For aviation section only.

&&

.SHORT TERM...(Today through Thursday night)
Issued at 250 AM CDT Tue Jul 19 2016

Big story will continue to lie with the heat...which will
gradually spread east across the eastern half of the forecast
region with time. Will hold off on heat advisory east for today,
as most of those areas should stay in the 100 to 105 range. Will
handle with SPS for now. However, will continue heat advisory west
of a Mayfield, KY to Mt Vernon, IL line. May even need to upgrade
much of this area to Excessive Heat Warning a future packages as
it is beginning to look as though we could have 4 or more
consecutive days with heat indices of 105 or greater.

Will leave mention of isolated storms in most locations for the
next day or so, until the upper ridge really builds in on Thu.
However, most locations will stay rainfree. If isolated storms do
manage to develop with temps in the mid 90s, would need to monitor
for some damaging wind gust potential.

.LONG TERM...(Friday through Monday)
Issued at 250 AM CDT Tue Jul 19 2016

The medium range models were in decent agreement until about Day 6
and 7. Ensemble means suggest perhaps the deterministic 12Z/00Z
ECMWF was the odd model out with a significant mid level shortwave
diving through the upper Midwest by Sunday, vanquishing the dominant
mid/upper ridge over us. However, the deterministic 00Z GEM seemed
to support the ECMWF scenario, at least part way. The 00Z GFS
solution had the shortwave damped out more, farther north, and
faster, and thus the southern CONUS ridge holds up better.
Interestingly, the ECMWF/GFS MOS temp guidance was quite similar for
Sunday and Monday, though the ECMWF was warmer for Friday/Saturday.
For this forecast, we will continue to forecast heat advisory
criteria Friday and Saturday, with slowly decreasing heat and
humidity starting Sunday.

Despite the differences in the mid level features, an induced
surface low pressure trof depicted by the models should create a
wind shift in the PAH forecast area sometime Sunday night/early
Monday. It does appear that PoPs will ramp up from almost nil to
chance/slight chance by Sunday (Day 6) as the frontal boundary
approaches the PAH forecast area, providing focus for convection in
the unstable atmosphere in place. Plentiful warm air aloft will
limit mid level lapse rates, though low level rates will be steep.
This means we should see mainly isold pulse showers/tstms in the
weak shear atmosphere, outside of a possible well-developed MCS.

The limited PoPs should translate through the southernmost reaches
of the PAH forecast area Sunday night/Monday. After highs in the
upper half of the 90s Friday and Saturday, a slightly cooler/drier
air mass behind the front should provide comparatively tolerable
highs near 90, mainly east of the MS River.

&&

.AVIATION...
Issued at 645 AM CDT Tue Jul 19 2016

Patchy dense fog will burn off 13-14z. Otherwise, VFR conditions
expected to prevail through most of the 12z TAF period. Isolated
thunderstorms cannot be ruled out, but will not be included
explicitly at this time.

&&

.PAH Watches/Warnings/Advisories...
IL...Heat Advisory until 7 PM CDT Wednesday for ILZ075-080-081-084-
     085-088-089-092>094.

MO...Heat Advisory until 7 PM CDT Wednesday for MOZ076-086-087-100-
     107>112-114.

IN...None.
KY...Heat Advisory until 7 PM CDT Wednesday for KYZ001>006.

&&

$$

UPDATE...GM
SHORT TERM...GM
LONG TERM...DB
AVIATION...GM



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