251 
fxus63 kmkx 061959 
afdmkx 


Area forecast discussion 
National Weather Service Milwaukee/Sullivan WI 
259 PM CDT Monday Oct 6 2008 


Forecast focus on rain showers Tuesday into Wednesday...milder 
temperatures toward the weekend. 


Latest water vapor imagery indicated a shortwave trough over the 
Southern Plains...with another over the western High Plains. 
Upstream upper ridging was noted over the western Great Lakes 
region. At the surface...weak low pressure was located over 
central Kansas. A large area of rain showers and isolated 
thunderstorms was associated with the shortwave over the Southern 
Plains. 


Short term...tonight through Wednesday night... 


A quiet night is expected tonight...as influence of strong high 
pressure remains over the area. Source region of airmass for 
tonight is Northern Ohio...where lows this morning were in the 
lower to middle 50s. Will go with similar values for tonight. 


Shortwave trough and associated vorticity maximum move toward the 
area Tuesday...then across Tuesday night into Wednesday. Decent 
upward vertical motion seen from the vorticity maximum...mainly 
from 18z Tuesday to 06z Wednesday across the area. This period 
also has best air column moisture profiles per area forecast 
soundings. 


Thus...will keep categorical probability of precipitation in the west during Tuesday 
afternoon...and across the entire area Tuesday evening. Rain 
showers should taper off Wednesday morning from west to east. Did 
not include any thunder mention due to lack of elevated 
instability in forecast soundings. Quiet weather expected for 
later Wednesday and Wednesday night...as a weak surface high 
moves through the region. 


Long term...Thursday through Monday... 


European model (ecmwf)/European model (ecmwf) ensembles the preferred extended models per HPC 
blended fields. The European model (ecmwf) digs a longwave upper trough over the 
southwestern USA Thursday and Friday...while a downstream upper 
ridge builds over the upper Midwest. This should keep the area 
dry. Warm air advection during this time should allow for a 
warmup in temperatures. 


The upper trough becomes a closed low on Saturday over the 
southwest...before opening and shifting northeast across The 
Rockies and into south central Canada by Monday. Warm air 
advection continues across the area...with 1000/500mb thicknesses 
possibly reaching 570 dkm by Sunday evening. This scenario would 
keep temperatures quite mild...perhaps cracking the 70s for highs. 


Progression of upper trough would push associated surface low 
northeast into Canada...with a trailing cold front into the area 
by Monday. This would bring the next decent chance of 
precipitation to the area. 


&& 


Aviation... 


Mainly middle and high level clouds through Tuesday morning with 
southeast flow ahead of approaching trough from the plains. 
Precipitation associated with trough expected to arrive Tuesday 
afternoon. 


&& 


Marine... 


Will keep Small Craft Advisory going. Tight gradient between departed high and 
plains trough resulting in pretty steady southeast wind. White 
Caps noted on the cams. 


&& 


Mkx watches/warnings/advisories... 
WI...none. 
Lm...Small Craft Advisory until 7 am CDT Wednesday for lmz643>646. 


&& 


$$ 


Short/long term...08/wood 
aviation/marine...10/collar