Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 091145
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
645 AM CDT Wed Jul 9 2014

.UPDATE...
Issued at 645 AM CDT WED JUL 9 2014

The AVIATION section has been updated for the 12Z TAF issuance.

&&

.SHORT TERM...(Today through Friday)
Issued at 307 AM CDT WED JUL 9 2014

The skinny band of showers and thunderstorms over the southern
Pennyrile should finally push southeast of the region in the next
hour or so. The cold front is hard to find at this time, as winds
have become calm in many locations, and light west southwest winds
have developed elsewhere. The 07Z METAR plot shows a weak surface
trough up in northern Illinois, and winds ahead of it have become
west southwest/southwest.

The 00Z models push that trough southward near the area this
afternoon, and the GFS and NAM, as well as the Hi-Res WRF runs are
generating some minor QPF in the north/northeast in the afternoon
and evening. Looking at model soundings, the NAM generates a
shallow layer of instability beneath the mid-level inversion. It
appears to be deep enough for at least some light showers. The GFS
does not develop this layer of instability, so will not mention
the showers in the forecast, but will increase PoPs closer to 15%
in the north this afternoon and east this evening.

The GFS is faster than the NAM to lessen the influence of the
surface high for Thursday, putting us in a weak warm advection
regime. The NAM continues to generate some shallow instability
similar to today, and we discount this just as for today. Decided
to keep winds light and variable Thursday and Thursday night. The
models do increase the warm advection aloft Thursday night, but it
is hard to find any support for convection/precipitation in the
model soundings so will keep the forecast dry Thursday night as
well.

By Friday, an impulse in the weak northwest flow aloft, coupled
with the low-level warm advection may be sufficient to sustain some
showers and storms into southeast Missouri and southern Illinois.
Figure anything that reaches the area will die a quick death with
a relative lack of low-level moisture over the region. Decided to
spread a slight chance PoP along the northwest periphery of the
forecast area to fit in with neighbors.

As for temperatures, stayed near consensus of available guidance
for highs today. Leaned toward the warm side for highs Thursday
and then back to consensus for Friday with clouds increasing over
the region. For lows, leaned toward the warm side tonight, with
the low-level moisture hanging on better over the southern half of
the area. Also went on the warm side Thursday night with warm
advection ongoing just off the surface.

.LONG TERM...(Friday Night through Tuesday)
Issued at 307 AM CDT WED JUL 9 2014

Models are at least consistent on the overall pattern if not some of
the details through the extended period. In the upper levels, a
strong ridge will extend from the Southern Plains to the Northwest
while a trough will hang on in the East. Our location along the
periphery of the trough along with disturbances in the mid and upper
levels will dictate much of our weather through the period.

A warm front will lift north of the region by late Friday. Southerly
winds will bring a return to warm and muggy weather for the weekend.
A ridge of 850 temps in the lower 20s noses into our area on Sunday.
However, tis the season of the mesoscale convective system and the
models certainly hint at the development of several through the
weekend. Where they track will play a role in our cloud cover, temps
and precip chances. Have the greatest chances of showers and storms
over the northeast part of the forecast area tapering to slight
chances over southeast Missouri.

By the start of the new workweek, a strong area of low pressure will
drop down into southern Ontario and Quebec. This will push a cold
front south through the region. Models hint at another round of
cooler and drier weather by the middle part of next week.

&&

.AVIATION...
Issued at 645 AM CDT WED JUL 9 2014

Area VAD wind profiles indicate northwest winds just off the
surface, so would expect to see northwest winds establish
themselves at all sites with mixing this morning. Speeds should be
comfortably under 10kts. There is some disagreement in guidance as
to the potential for 4-7kft ceilings late this afternoon and
evening mainly at KEVV and KOWB. If they develop, a few light
showers could also develop. There should be a very light north
wind through the night, and coupled with some lower cloud potential,
will not forecast fog anywhere for tonight.

&&

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

$$

UPDATE...DRS
SHORT TERM...DRS
LONG TERM...ML
AVIATION...DRS





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