184 
fxus61 Kiln 212341 
afdiln 


Area forecast discussion 
National Weather Service Wilmington Ohio 
641 PM EST Friday Nov 21 2008 


Synopsis... 
high pressure will build into the region tonight and will remain 
in control through the weekend...offering dry conditions and below 
normal temperatures. A cold front will push across the region on 
Monday bringing the next round of precipitation. 


&& 


Near term /through Saturday/... 
high level clouds ahead of 500 mb short wave will begin to work into the west and 
SW late. 


Kept previous low temperature forecast...which is cooler than mav numbers...but 
not as cold as FWC. 


&& 


Short term /Saturday night through Sunday night/... 
at surface high pressure will be across the eastern Ohio Valley...but 500 mb short wave will 
drop southeast across the region bringing middle and high clouds. Short wave moves across 
the region Sat night. Forecast area will then be on back side of high in broad 
southerly flow. Not much lift of moisture across the region for Saturday. 


Cold front moves out of the Great Plains and into the MS valley late 
Sunday night. Ahead of the fnt good isentropic lift develops after 
06z. GFS as is typical is quicker than the NAM with the return 
precipitation. Went 2/3 GFS 1/3 NAM blend for probability of precipitation Sun night. Looks like 
lows will occur early Sun night...then rise towards morning. 
Thickness are indicating that the precipitation across the S will fall as 
rain. Most locations in the S will have warmed above 
freezing...but there will be chance of freezing rain from just S of mgy-iln-pmh. 
Across the northern 2/3 thicknesses should be cold enough for S. 


Previous forecast temperatures for highs on Sat where very similar to new 
MOS...so no change there. Went a blend of guidance for lows Sat 
night. Tried to stay of cooler side of guidance highs for Sunday. 
As mentioned earlier went with rising temperatures late Sunday night. 
For lows...went with sref values. 


&& 


Long term /Monday through Friday/... 
HPC modelers are suggesting a blend of the 0z European model (ecmwf) and the 0z GFS 
for the extended period over the Ohio Valley. Looked at the 
numerical GFS guidance and with very few exceptions the high and low 
temperatures were within 2 degree for cmh cvg and day. Probability of precipitation on Monday are 
consistently likely but have come down at day and cmh from near 
categorical. Behind the system on Monday increasing the probability of precipitation...chances 
drop to a minimum on Wednesday and then climb back to their climatological 
norms around 30% as a system ejects NE from the lower Midwest. 


500 mb low tracks southeast into gtlks in a clipper type fashion on Monday...with 
it pivoting over PA and spinning deeper over New York state by Tuesday. 500 mb 
pattern from European model (ecmwf) pulls the low north-northwest where the GFS spins the energy 
over New York and translates some of it in this direction. At this moment 
in time...a compromise between the two but leaning towards a closed 
upper low appears more likely than not to ME. Surface features during 
this time will have a strong cold frontal passage on Monday with 
showers primarily ahead of it...possibly changing to snow before 
ending Monday afternoon/evening. Wrap around moisture may indicate le 
shsn into Tuesday...but the flow pattern is suggesting more westerly llvls 
which is not favorable for lake effect. 


As the low pressure system exits high pressure builds in from the 
west. This high pressure system should control the weather through 
the end of this extended period...being centered over ohvly Thursday 
night. The next system will probably hold off until after Friday before 
coming up from the lower Midwest...but a slight increase in chances 
appears prudent...more to the SW late on Friday. 


Temperature guidance is not showing any major changes from numerical 
guidance and/or previous forecast. Minor edits should be relatively 
unnoticed. 


&& 


Aviation /00z Saturday through Wednesday/... 
VFR conditions will continue through the taf period. Light west-northwest 
winds will shift SW after 14z. A weak short wave will bring broken/overcast high 
clouds after 14z. 


Outlook...MVFR ceilings/visibilities possible due to rain and snow showers 
on Monday and Tuesday. 


&& 


Iln watches/warnings/advisories... 
Ohio...none. 
Kentucky...none. 
In...none. 


&& 


$$ 
Synopsis...sites 
near term...sites 
short term...sites 
long term...franks 
aviation...