384 
fxus63 kpah 181954 
afdpah 


Area forecast discussion 
National Weather Service Paducah Kentucky 
254 PM CDT Friday Jul 18 2008 


Discussion... 
main concern is the potential for isolated/scattered thunderstorms 
over the next several days. 


Isolated air mass thunderstorms have developed in the daytime 
heating over southern Kentucky and Tennessee this afternoon. Without 
much organization...expect this activity to dissipate by evening... 
with mainly clear skies overnight. 


Over the weekend...we can no longer ignore the potential for 
convection. Even though the hint has been there in isolated form for 
the past few days...both the NAM and GFS appear to have locked onto 
a solution which includes a mention of thunderstorms in the Saturday 
afternoon/evening forecast...albeit only a slight chance. The weak 
energy responsible for tomorrow/S thunder chances will shift to our 
eastern counties Sunday...resulting in a slight chance over the 
eastern half of the forecast area. 


Models continue to have a difficult time agreeing on a solution for 
next week...with a myriad of potential outcomes possible. Generally 
speaking...an upper-level trough is forecast to develop somewhere 
over southeastern Canada and the Great Lakes region...as an upper- 
level ridge builds over the western United States through the course 
of the week. Our area will rest on the southwestern extent of the 
influence of the northeastern trough...with the added influence of a 
southward-sagging weak frontal boundary as well. As a result...we 
decided upon little change to the going forecast...with no higher 
than 30/35 probability of precipitation Monday through Wednesday. The best chances will 
exist over the Evansville area in closer proximity to the better 
upper-level support...with much lower chances over the Ozark 
foothills of southern Missouri. At this point...we plan to keep 
Thursday and Friday dry with the caveat that as models demonstrate 
more consistency...precipitation chances can be added as needed. 
However...we tend to think that the influence of the building ridge 
to our west will constitute a drying trend late in the week. 


As far as temperatures are concerned...we favored a blend of 
available MOS guidance through Sunday...especially during the day. 
At night...we generally relied on a blend of the NGM FWC and Eta model met 
guidance with the GFS mav MOS a cool outlier tonight and too warm 
Saturday night. Extended forecast temperatures reflect a blend of 
GFS mex and HPC guidance values. 


&& 


Aviation... 
look for mainly VFR conditions through 18z Sat as surface high 
generally remains in control off to the east. Will likely see patchy 
MVFR fog once again across the region for a few hours late tonight 
to just after sunrise Sat. 


&& 


Pah watches/warnings/advisories... 
Kentucky...none. 
MO...none. 
Illinois...none. 
In...none. 
&& 


$$ 


Public...rjp 
aviation...GM