Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 041708

1208 PM CDT SUN OCT 4 2015

Issued at 1208 PM CDT SUN OCT 4 2015

Aviation update.


.SHORT TERM...(Today through Tuesday night)
Issued at 317 AM CDT SUN OCT 4 2015

The weather through 4 pm CDT today will be the most challenging
for this forecast period. Winds aloft weaken as the influence of
the ridge builds in from the west as the upper low works into
northern Florida. There is still plenty of north-south oriented channeled
vorticity at mid levels, but both high resolution and medium range
model soundings show rapid mixing and drying of at the low and
middle levels, especially to the east over Southwest Indiana and
parts of the Pennyrile of West Kentucky.

At this point, although most guidance show signifcant clearing
this afternoon over the most of the WFO PAH forecast area, will go
with a slightly slower transition to clearing skies through the
morning. With an already mixed planetary boundary layer, an
insolation should translate through the layer allow for at least a
moderate rise in temperatures, with some greater subsidence west
of the impressed inverted trough over Central Kentucky. This
should help clear skies and warm temperatures slightly faster this
afternoon. This mixing will slowly translate west into Southeast
Missouri and Southwest Illinois later this afternoon.

Diminished the coverage of isolated light rainshowers or drizzle
during the morning as lift in and above the mean 850-700 mb
moisture layer becomes separated with time and drier air advects
into the area.

Otherwise, tranquil weather will dominate through early in the
week as ridging builds into the area. Added some patchy fog
overnight the next couple nights, mainly in climatologically
favored areas.

.LONG TERM...(Wednesday through Saturday)
Issued at 317 AM CDT SUN OCT 4 2015

Above average confidence through most of the long term period before
models begin to diverge.

High pressure at the surface and aloft should keep the region dry
through Thursday. Precipitation chances make their way into the long
term forecast starting Thursday night as the high pressure breaks
down and allows the approach and passage of a cold front. There
might be just enough instability to produce a few thunderstorms over
the western and northwest sections Thursday night, then over the
entire CWA on Friday.

Beyond Friday is where models begin to differ. Friday night the GFS
has the region completely dry with surface high pressure
overspreading the area in the wake of the front. During the same
period the ECMWF is a little slower scouring out the moisture and
precipitation associated with the front, so opted for a compromise
between the two.

Model solutions on Saturday continue to differ. The GFS brings the
northern edge of overrunning precipitation into parts of southeast
Missouri as a system develops over the southern plains. The ECMWF
shows high pressure overspreading the area, but also hints at the
possibility of a couple areas of light precipitation with nothing
going on over the southern plains. Again opted for a compromise.

Temperatures should be above normal through the period.


Issued at 1208 PM CDT SUN OCT 4 2015

Gradually improving cigs from east to west through the afternoon
and early evening from MVFR/IFR category. NNE winds around 10 kts
through sunset will become light tonight. Some of the models are
still pessimistic with low level moisture overnight, so confidence
is low in overall clearing. Will use a trend forecast approach.
Less cloud cover and lighter winds tonight may also result in some
fog. To what degree is very uncertain at this time.



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