Weather

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fxus61 Kiln 212246 
afdiln 


Area forecast discussion 
National Weather Service Wilmington Ohio 
646 PM EDT Thursday Aug 21 2008 


Synopsis... 
surface high pressure centered near New England will move slowly 
eastward over the next few days. A cold front will move into the 
region from the northwest on Saturday night into Sunday. 


&& 


Near term /until 6 am Friday morning/... 
upped probability of precipitation across Indiana and moved the 20 pop back into Ohio a 
little more as 500 mb vorticity lifting north through Illinois/in around 500 mb low is 
kicking off shra/tsra. Atmo across eastern in/extreme western Ohio has 
destabilized this afternoon with convective available potential energy 1000-1500 j/kg. 


Still expect convection to die quickly this evening as vorticity lifts 
north. Clouds will decrease after midnight. 


Dewpoints will be a little higher tonight compared to previous 
nights...so went a little warmer for lows. Went close to mav temperatures. 


&& 


Short term /6 am Friday morning through Saturday night/... 
models in pretty good agreement for Friday...as high pressure at surface 
and 500 mb reasserts itself over the region. Temperatures at numerous 
locations have reached 90 degrees. With southeasterly flow at surface and ground 
drying out went with the warmer mav guidance for highs on Friday. 


With the high building back west on Friday...the models are slowing the 
return of the deeper moisture. Therefore as cold front pushes through the 
Great Lakes...dont expect as good of a chance of pop-up convection. 
Instead will have to wait for frontal passage for the better lift. Therefore 
removed probability of precipitation on Sat and lowered probability of precipitation to the northwest for Sat night. 


Didnt stray too far from mav for temperatures through the period. 


&& 


Long term /Sunday through Thursday/... 
guidance is slowly coming together but only through about Tuesday 
afterwards its anybodys guess as to how strong and where Fay's 
remnants will be. HPC solution of a cold front stalling over Tennessee Tuesday 
night and Wednesday and then weakening to a stationary front with some 
slight newrd push on Thursday seems reasonable considering there is 
little upper level flow to steer tropical remnants into ohvly. The 
high over the upper Midwest on Monday is well established through the 
atmosphere and has good upper level support. Showers and 
thunderstorms are expected ahead of it on sun as a cold front 
works into ohvly NW-se. As the high is pretty well established by 
Monday I felt confident enough to cut out any precipitation in the 
forecast and do not believe that the dynamics on sun will be that 
strong to support long lived storms nor widespread activity along 
the front...but there should be thunderstorm activity noted along 
it...ending overnight in the south and southeast. 


Temperatures will start out in the middle to upper 80s on Sunday and 
then drop to the low 80s Monday and Tuesday as cooler high pressure builds 
north of the region. Overnight low temperatures will see a much nicer drop 
from the upper 60s to around 70 Sunday morning...to around 60 by 
Tuesday morning. Nighttime lows will remain in the lower 60s both Monday 
and Wednesday...rising slightly by day 7 on Thursday. High temperatures 
will remain around or just above the climatology of lower 80s Wednesday but then 
should modify back to the upper 80s for Thursday. 


Details are hard to work out beyond Tuesday/Wednesday but this should be the 
cooler part of the forecast with the passage of a strong high 
pressure system. Moisture from remnants of Fay may slide back into 
the region on Wednesday/Thursday but I am trying to temper this downwards as 
any easterly gradient coming over the Appalachians is downward and 
drying motion. I put in lower chances and only stratiform precipitation for 
the extended as confidence on days 6 and 7 is quite low. 


&& 


Aviation /00z Friday through Tuesday/... 
sluggish upper trough continues to lift slowly north across 
Missouri/Arkansas this evening. Srly flow ahead of this feature 
pulling abundant Gulf moisture north through the Mississippi Valley and 
into the lower Ohio Valley. Weak middle level vorticity lifting through Indiana this 
evening combining with some instability to allow for scattered convection 
to develop across western forecast area. This activity will remain west of 
the terminals over the next hour or two (kcvg/kluk/kday) and is 
already showing signs of weakening as heating diminishes. Middle and 
hi level clouds will continue to drift across the terminals overnight. 
Middle level ridge and surface hi pressure centered over middle Atlantic region will 
extend back west into the Ohio Valley Friday...with east/southeast flow bringing 
drier and more subsident air into the forecast area as day progresses. 
Result will be more sunshine and decrease in extent of cirrus into the 
afternoon. 


Outlook...thunderstorms will be possible on Sunday. 


&& 


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


&& 


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