109 
fxus63 kilx 141540 
afdilx 


Area forecast discussion 
National Weather Service Lincoln Illinois 
1040 am CDT sun Mar 14 2010 


Discussion... 
issued 1034 am CDT sun Mar 14 2010 
central Illinois still under the influence of cyclonic flow from 
exiting low. Cloudy drizzly skies and rather moderate temperatures to 
continue through the day. Updated the weather grids to continue 
the mention of drizzle northwest of the Illinois River valley. Probability of precipitation for 
the afternoon closer to some stronger dynamics and lift in the southeast 
will stay in the forecast as some pop up showers already 
developing along the southern Illinois/in border. Only moderate changes to 
the zones...update out shortly. 


Hjs 
&& 


Aviation... 
issued 647 am CDT sun Mar 14 2010 


A large/complex area of low pressure...covering a large chunk of 
the eastern United States...will continue to impact the central 
Illinois terminals through the 12z taf period. However...these 
impacts will begin to lessen with time as the low drifts further 
east. IFR/low end MVFR ceilings should climb solidly into the MVFR 
category by later today as drier low level air filters into the 
region. Winds will stay northerly in the wake of the low and will 
become gusty at times during the daytime hours today. 


Bak 
&& 


Previous discussion... 
issued 115 am CST sun Mar 14 2010 


Latest water vapor imagery showing pesky upper low spinning over 
the Carolinas...with a secondary energy lobe across Ohio. Surface 
analysis showing a trough associated with the Ohio low about to 
the clear the extreme southeast County Warning Area. Much of the shower activity 
has diminished...with just some drizzle lingering in a few areas. 


Main forecast challenges involve lingering shower chances in the 
cyclonic flow today...as well as additional chances Tuesday night 
and Wednesday with a shortwave dropping southeast into the region. 


Short term...today through Wednesday... 


General agreement exists among the models on this upper low spinning 
along the middle-Atlantic coast through tonight...before finally 
moving offshore. Cyclonic flow will continue over the County Warning Area through 
this evening...then will finally begin to ease up. Low-level jet 
from New York will continue to send some moisture westward into 
the Midwest. Still a bit of isentropic lift available to help 
trigger a few showers...primarily east of I-55. Not a lot of 
movement in temperatures expected today due to extensive cloud 
cover. 


Lingering effects of the upper low should keep the eastern County Warning Area 
fairly cloudy through much of Monday...with some breakup in clouds 
further west. This will result in coolest conditions across the 
far eastern County Warning Area...with the warmest in the far west. More uniform 
temperatures expected on Tuesday. 


Upper ridging across the western U.S. Expected to tilt northeast 
into the Canadian prairies...with a shortwave dropping southeast 
along the periphery of the ridge Tuesday. Models having a bit of 
difficulty resolving how deep this shortwave will become...I.E. 
Whether or not it will evolve into a closed low. In any event... 
there will not be a lot of moisture available...and the latest 
models keep the bulk of the quantitative precipitation forecast further west into Missouri. Will 
need to watch this for some consistency...but will not remove the 
probability of precipitation from the current forecast at this time. 


Long term...Thursday through Saturday... 


Upper ridge expected to break down after midweek...with more of a 
zonal flow on Thursday. However...a strong shortwave will push 
across the plains on Friday...swinging toward the Midwest on 
Saturday. Significant differences exist among the long-range 
models on the ultimate configuration of the associated synoptic 
features...with the GFS much stronger than the European model (ecmwf). However... 
both agree that Friday night and Saturday represent the next 
significant rain chances. 


Geelhart 


&& 


Ilx watches/warnings/advisories... 
none. 
&& 


$$