Weather

878 
fxus61 Kiln 071442 
afdiln 


Area forecast discussion 
National Weather Service Wilmington Ohio 
1042 am EDT sun Sep 7 2008 


Synopsis... 
an upper level disturbance will track across the lower Great Lakes 
today. High pressure over the Central Plains will then build east 
into the Ohio Valley tonight. The high will move east of the 
region as a cold front crosses the area late on Monday and 
Tuesday. 


&& 


Near term /through tonight/... 
the latest RUC surface analysis indicates two primary features. The 
extratropical low remnants of Hanna exiting the northestern Continental U.S. And a 
broad area of high pressure over the Central Plains. The Ohio 
Valley sits between the two features...with a broad pressure 
gradient across the region. At the mid-levels...a broad trough 
extends over most of the northern Continental U.S. With a weak short WV moving 
across Northern Ohio. Some weak isentropic upglide along with the short 
wave have induced light showers and sprinkles across northern and western 
portions of the County Warning Area. 


This afternoon...remaining isolated showers across the County Warning Area will 
dissipate as short WV moves off to the northeast. High pressure 
will begin to build in from the west...with cloud coverage 
beginning to break and decrease into the evening. Adjusted weather and 
pop grids to account for isolated rain showers with 20 probability of precipitation. Temperatures appear to 
be in line with met guidance...recovering into the middle to upper 
70s late in the day. 


For tonight...high pressure over the Central Plains will settle 
across the Ohio Valley region. This will allow skies to become 
mostly clear for a good portion of the night. The one fly in the 
ointment will be increasing 700 mb moisture from the northwest due to 
upstream isentropic lift. Will allow for some middle level clouds to 
move into the western County warning forecast area late. Overnight lows will range from the 
upper 40s in the normally cooler locations of central and south 
central Ohio to the lower and middle 50s elsewhere. 


&& 


Short term /Monday through Wednesday/... 
have also used a blend of the GFS and European model (ecmwf) for the short term 
forecast. 


High pressure will move east of the region on Monday. 
Again...upstream isentropic lift and middle level flow should bring 
some middle level cloudiness to the western County warning forecast area during the morning hours. 
Will forecast partly sunny skies there while other locations 
should be mostly sunny. Return flow/warm air advection will boost temperatures 
into the lower and middle 80s across the region. 


For Monday night and Tuesday...an upper level trough will pivot east 
across the Great Lakes region. This will perturb a wave of low 
pressure that is forecast to track near or just northwest of the County warning forecast area 
Monday night...moving to a position near southern Quebec by Tuesday 
morning. As this low moves by to the northwest of our area...it will 
allow a cold front to push southeast into the region. It still 
appears that the best frontogenetic forcing will be along and northwest 
of the low track. Thus...will continue to keep probability of precipitation in the 30 and 
40 percent range. On Tuesday...models show some timing differences 
on the cold front as it drops southeast through the region. Will show a 
gradual decrease in precipitation chance/S northwest to southeast throughout the day. Will 
again keep probability of precipitation in the 30 to 40 percent range. 


For Tuesday night into Wednesday...high pressure is expected to 
build south into the lower Great Lakes and Ohio Valley. Skies will 
clear north to south Tuesday night with mostly sunny conditions 
forecast on Wednesday. Much cooler air will filter into the region 
with this high. 


Temperatures will be tricky on Tuesday depending on the speed of the 
front and subsequent cold air advection. Will continue to forecast highs from the 
upper 60s northwest to near 80 southeast. Highs on Wednesday will be 
cooler...ranging from the lower to middle 70s. 


&& 


Long term /Wednesday night through Saturday/... 
high pressure will move east of the region on Thursday. 
This will lead to dry conditions and a gradual warming trend. 
Next short wave will then push into the area Thursday night and 
Friday...bringing the next chance for precipitation. Will stick 
pretty close to guidance temperatures through the latter part of the long 
term. 


&& 


Aviation /14z Sunday through Thursday/... 
large area of precipitation over northern Indiana and Southern Lower Michigan associated 
with middle level shortwave. Middle level deck with a few sprinkles overspreading 
forecast area from the west this morning. Shortwave will move across lower Great Lakes 
through midday bringing an abundance of ac and SC to terminals this 
morning. Boundary layer remains quite dry and with isent lift diminishing... 
not expecting any more than potentially a sprinkle affecting the 
northern terminals this morning. 


Drier air will advect into the region this afternoon as shortwave moves off 
to the east with skies becmg partly sunny. Diurnal cumulus will linger 
this afternoon...but expect skies to clear this evening as surface hi pressure 
builds into the Ohio Valley. Scattered middle level clouds may again impinge on 
the terminals late tonight as isent lift develops upstream from next 
storm system moving through the Central Plains. Visibility restrictions are 
possible towards daybreak Monday at kluk. 


Outlook...showers and thunderstorms are possible Monday night 
into Tuesday. 


&& 


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


&& 


$$ 
Synopsis...woodrum 
near term...woodrum/Ryan 
short term...Hickman 
long term...jgl 
aviation...Ryan