Area Forecast Discussion
Issued by NWS Paducah, KY

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592
FXUS63 KPAH 201928
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
228 PM CDT Wed Sep 20 2017

.SHORT TERM...(Tonight through Friday night)
Issued at 1205 PM CDT Wed Sep 20 2017

High confidence in the short term.

Models are in very good agreement with a dry forecast for the
short term. We do have a good deal of instability with CAPE values
ranging from 1-2k j/kg2 and LI`s negative five and higher. However
the models are in complete agreement on keeping a ridge of high
pressure centered over our region through the short term. This
will create a subsidence inversion aloft. This should inhibit
surface based convection through the short term. We do keep a
southerly moist flow at the surface. In contrast...forecast
sounding indicate a dry easterly flow aloft. This should limit any
elevated convection that would try to get going above the
inversion. The combination of high pressure and a warm moist
southerly flow will result in temperatures around 10 degrees above
normal for both highs and lows. In addition with dew points
ranging from middle 60s and around 70 expect above normal humidity
especially for this time of year.

.LONG TERM...(Saturday through Wednesday)
Issued at 1205 PM CDT Wed Sep 20 2017

By 12Z Saturday, a ridge of high pressure will be centered over the
upper Midwest down into the Arklatex region with a deep trough over
the western U.S. The GFS and ECMWF indicate that the best moisture
on Saturday should be situated across parts of southeast MO and west
KY...with areas closer to the AR/TN borders being the better spots.
While models are not explicitly indicating any developing
convection, would not be surprised to see something isolated develop
with the heat of the day and the GFS ensemble precip mean supports
this as well over west KY. However, with no triggers aloft or at the
sfc, chances will be rather low.

Saturday night and into Sunday, the center of the upper high starts
migrating eastward, as a weak upper level disturbance in the Gulf
moves west northwest. This will tend to bring more moisture into the
region and the possibility of more isolated storms. GFS may be
overdone with its QPF as the ECMWF is mainly dry. The GFS ensemble
precip mean indicates a bit better coverage but again over west KY,
maybe over southeast MO. With high pressure still dominating at the
surface, any afternoon thunderstorm development would be random and
isolated.

Models are in better agreement with bringing a frontal boundary or
what`s left of a frontal boundary into the area Tuesday night into
Wednesday. Models definitely still have timing issues and are having
trouble with QPF. Will leave POPs low for now.

Upper 80s to around 90 look like reasonable numbers for highs over
the weekend. Might see a degree or two drop as we head into the
early part of next week but still looking at above normal
temperatures in the mid to upper 80s.

&&

.AVIATION...
Issued at 1220 PM CDT Wed Sep 20 2017

VFR conditions are expected through this TAF cycle. Scattered Cu
field has developed and some broken coverage cannot be ruled out
from time to time. Southerly winds today will gust into the teens
this afternoon mainly at KCGI/KPAH but will become light this
evening/overnight. Some possibility at patchy fog toward sunrise
tomorrow, but winds may stay up just enough to preclude any major
development.


&&

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

$$

SHORT TERM...KH
LONG TERM...CW
AVIATION...CW



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