Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 191657

Area Forecast Discussion
National Weather Service Paducah KY
1157 AM CDT TUE JUL 19 2016

Issued at 1157 AM CDT Tue Jul 19 2016

Nice cu field has developed roughly over the southern half of the
region, and some isolated showers are beginning to develop out of
it. Look for continued development through southeast Missouri, the
southern tip of Illinois and the Purchase and Lakes area of
Kentucky through mid-afternoon. There is little shear, so look for
individual showers and storms to be short-lived. However, given
the considerable surface-based CAPE, a few very localized
damaging wind events cannot be ruled out.

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


.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.


Issued at 1157 AM CDT Tue Jul 19 2016

Although some isolated convective development is underway along
the southern border of the area, not sure how much coverage there
will be, so will need to update KCGI and KPAH if SHRA/TSRA develop
nearby this afternoon. There is some evidence of convection trying
to move south into/through our region tonight, but odds are too
low to mention anywhere at this time. Will insert MVFR fog at all
sites for a few hours straddling sunrise. Certainly cannot rule
out lower conditions, especially given what happened this morning.
Winds will be light and variable throughout the period.


.PAH Watches/Warnings/Advisories...
IL...Heat Advisory until 7 PM CDT Wednesday for ILZ075-080-081-084-

MO...Heat Advisory until 7 PM CDT Wednesday for MOZ076-086-087-100-

KY...Heat Advisory until 7 PM CDT Wednesday for KYZ001>006.



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