Area Forecast Discussion
Issued by NWS Paducah, KY

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726
FXUS63 KPAH 230149
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
849 PM CDT MON AUG 22 2016

.UPDATE...
Issued at 849 PM CDT Mon Aug 22 2016

Mid-evening update to reflect a subtle changes in wind, moisture,
and sky cover overnight and into Tuesday morning.

Overall, the 12km NAM-WRF and 3km HRRR appear to be handling the
diurnal changes the best, although some of the NWS blended
guidance, MOS, and other high resolution sensible weather fields
are not far behind.

The deterministic GFS and HRRR guidance are consistent in holding
off any measurable rain chances within the WFO PAH public (not
fire weather) zones until after 12z. The ECMWF is a little more
aggressive, but within reason. Blended the GFS/ECMWF/HRRR guidance
during the morning hours to depict the higher probability chances
in the western four counties of Southeast Missouri, mainly along
and west of Poplar Bluff - Piedmont Missouri line.

Winds will be a little more iffy tonight, but if a slight gradient
develops from the southwest, any fog development will be markedly
reduced overnight. Re-worked temperatures and dewpoints to reflect
sharper drops, especially across Southern IL and West Kentucky.
This increased the probability of patchy fog development after 1
am CDT. Reduced or eliminated fog mention overnight over
Southeast Missouri where opaque cloud cover is expected to exceed
40 percent with time.

UPDATE Issued at 632 PM CDT Mon Aug 22 2016

Updated Aviation Discussion for 00Z TAF`s.

&&

.SHORT TERM...(Tonight through Wednesday night)
Issued at 314 PM CDT Mon Aug 22 2016

Quiet night, as high pressure moves slowly east. We should
decouple enough to have another cool night. Clouds will increase
into SEMO late.

Will continue with a chance of convection mainly SEMO Tuesday. The
GEM/EC solutions are a bit more aggressive with QPF, while the NAM
and GFS are less impressive. Still enough to have low chance or
slight chance PoPs. Eastward progression is somewhat uncertain.
Would not rule out a few light showers or sprinkles making it east
of the MS River. But not enough for PoPs just yet. Dry elsewhere
with some increase in clouds.

Model preference beyond Tuesday is a NAM/EC/GEM blend. Best
chance of any convection Tuesday night through Wednesday night
will be across our northern most counties (up along I-64), as weak
mid level systems drive the chance mainly north of our area.
Wednesday afternoon, there could be some diurnal convection
mainly west KY into into SE IL / SW IN, before drier air and NVA
spread across the area Wednesday night from the SW.

It will become warmer and more humid through the short term upon
return southerly flow. Generally used a blend of MOS and
persistence.

.LONG TERM...(Thursday through Monday)
Issued at 314 PM CDT Mon Aug 22 2016

We will start out the long term with an upper level high centered
over the Gulf Coast states, with the northwestern edge of this high
nudging into our CWA. Models continue to have night and day
differences with regards to any possible rainfall on Thursday with
the ECMWF continuing to show dry conditions (not a lot of moisture
to work with) and the GFS indicating a more "dirty" ridge with some
activity possibly forming during the day. However, the main
precipitation band should be coinciding with a frontal boundary that
will be way off to our northwest at that time.

That frontal boundary will make its way into the region Thursday
night into Friday. Again, the ECMWF continues to be indicating
fairly dry conditions as the front weakens substantially as it
approaches. The GFS is also steadfast with its wetter solution. Both
models are fairly decent with regards to timing though. Given that
the GFS precip ensemble mean and the Canadian do not indicate a dry
frontal passage, gives more credence to not changing POPs too much
but definitely not go completely dry.

During that time, the upper level high which was centered over the
western Gulf Coast states at the beginning of the long term period,
will steadily shift eastward. With high pressure at the surface, any
precipitation chances for the weekend will likely be tied to any
small pieces of energy rotating around the upper high. The best
chances seem to be situated in the western sections of the CWA where
moisture appears a bit better. However, this far out in time, it is
would be wise to not get too fancy with POPs, although the going POP
strategy shows the aforementioned trend.

&&

.AVIATION...
Issued at 632 PM CDT Mon Aug 22 2016

May concern is shallow fog possibility developing overnight.
Mentioned in all TAF locations, but expecting lowest conditions at
KCGI, which is notorious for fog formation. May touch IFR in some
spots but mainly MVFR conditions within the patchy shallow fog.
Light to calm winds will be present through the period, with a
general east direction this evening shifting to south/southeast
tomorrow. Low potential at a few -SHRA or sprinkles at KCGI and
southeast MO tmrw morning/afternoon as disturbance spreads
moisture northeast, but probability too low to include in TAF at
this time. Otherwise mid level cigs will move into KCGI and KPAH
by morning.


&&

.PAH Watches/Warnings/Advisories...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$

UPDATE...Smith
SHORT TERM...CN
LONG TERM....CW
AVIATION...SP



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