248 
FXUS63 KPAH 102007
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
307 PM CDT Sat Aug 10 2013

.SHORT TERM...(This Evening through Monday Night) 
ISSUED AT 307 PM CDT SAT AUG 10 2013

It looks like the worst of the convection and heavy rains are
behind us now. Will have to watch to see if anything can develop
on the real cold front near I-70 this afternoon. Visible satellite
imagery shows some vertical development. Would not expect much
development up there or for it to last very long or survive
sunset. Have had a steady stream of light showers pass east
northeast from the Bootheel along the Tennessee border areas
through the afternoon, but it is more like periodic sprinkles.
Decided to leave a sliver of slight chances along the southern
border. Just forecasting showers this afternoon and evening, but
am less confident in the overnight potential, so left a mention of
thunderstorms 06Z-12Z.

The models show some convective development over central Missouri
that would move southeast through southeast Missouri during the
day Sunday. Not real confident in much development given the drier
air filtering over the area, but will leave 20-30 pops, mainly in
the southwest. Could see some of this activity continue Sunday
evening. 

Heading into Monday morning, the models all indicate a south wind
developing and increasing dewpoints. The NAM actually develops
fresh convection overnight, but figure it will hold until the
daytime Monday. The models in general develop at least scattered
convection across most of the area Monday and Monday night as a
cold front and a significant disturbance rotate toward the area.
Good chance pops seem safe for most of the area Monday and Monday
night, but they may not be high enough.

Did not stray far from consensus guidance through the period.
Guidance does show some significant variability in highs Monday.
If the warm MAV numbers are right, some locations may actually
flirt with normal levels near 90. 

.LONG TERM...(Tuesday through Saturday) 
ISSUED AT 307 PM CDT SAT AUG 10 2013

The very persistent eastern trough / western ridge pattern that has 
been observed most of the summer will become more pronounced Tuesday 
through Friday. This will result in a very unusual mid August 
intrusion of cool dry Canadian air all the way to the Tennessee 
Valley. 

The cold front heralding the arrival of the cool air will move south 
across the Lower Ohio Valley and southeast Missouri on Tuesday. The 
timing of the front appears early enough in the day that it will 
miss the hours of peak diurnal heating and instability. Therefore 
pops will be held in the chance category...with the highest chances 
near the southern borders of Kentucky and se Missouri. Temps will be 
highly dependent on cloud cover. Given the tendency for lots of 
diurnal cu due to moist ground...will keep highs a few degrees below 
normal.

The change in air mass will take place Tuesday night and 
Wednesday...when dew points will fall down into the 50s. There is 
some concern that with the unseasonably high soil moisture...surface 
dew points and overnight lows may end up being higher than model 
forecasts. The high soil moisture would also result in more diurnal 
cumulus clouds and cooler daytime highs than the models indicate. 
For now, the forecast will follow model guidance closely. One thing 
that is quite certain is a lack of precipitation Wednesday through 
Friday as an unseasonably strong surface high moves slowly east 
across the Great Lakes / upper Midwest. 

There may be some increase in moisture and instability next weekend 
as the surface high retreats to the northern Appalachians. Will keep 
low chance pops in southeast counties of the cwa for Saturday.  

&&

.AVIATION...
ISSUED AT 1242 PM CDT SAT AUG 10 2013

It looks like the rains have finally settled south of the area, as
drier air has filtered south into the area. Some IFR and MVFR
ceilings remain along the Arkansas and Tennessee borders along
with a few light showers, but they are south of the terminals and
should not move back to the north. In general will see a
persistent scattered to broken 3-5kft layer with a mid-level deck
above for most of the period. Winds will be light and generally
from the north.


&&

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

$$

SHORT TERM...DRS
LONG TERM...MY
AVIATION...DRS