Weather

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Area forecast discussion 
National Weather Service Green Bay WI 
509 am CDT Monday Oct 13 2008 


Short term...today through Tuesday. Concerns on temperatures 
today...precipitation with front this afternoon/night period. 


At 09z...cold front lies over central Minnesota. High pressure extends to 
the west over the Ohio Valley. Temperatures over the state at this 
time very mild for this time of year...still in the upper 
50s/lower 60s. Sat trends show high clouds beginning to thin over 
area...while some clouds/moisture at 5k to 6k shifting north...more 
extensive area now lifting north through central Illinois. 


Highly amplified upper pattern to shift to a more zonal pattern 
during this period as western long wave lifts out and eastern high 
is suppressed over the southeastern states. Models fairly 
similar...some minor timing difference...bringing cold front 
through the state late aftn/evening. Precipitation with front expected to 
be along/behind front. Main forcing splits around region with 
front weakening as it moves east into County Warning Area. All models showing 
lessening trend with quantitative precipitation forecast...with NAM staying dry over eastern 
zones. 


Have backed off on precipitation during morning period today...shifting it 
east across the area this afternoon/tonight. Not a lot of thunder 
seen with system yesterday. Instability waning even more today...thus 
backed off/removed thunder from much of forecast. 


Real question is temperatures for today. Flow shifts more to the 
SW bringing more warming to Lakeside locations. 850 temperatures still 
rather mild 12 to 14 c. Given some sun this morning and current 
mild temperatures...bumped temperatures up. Fly in ointment may be 
advancing broken/overcast clouds over Illinois...will need to monitor through 
morning hours. 


Dry weather returns on Tuesday with return to more seasonable temperatures. 


Long term...Tuesday night through Sunday 
weak high pressure will build into Wisconsin Tuesday night. The 
secondary wave that has been forecast over the last several days 
has shifted further south by the WRF/GFS. The Canadian and European model (ecmwf) 
models are the only models that bring precipitation into northern 
Wisconsin. Did remove precipitation Tuesday night as precipitation 
will be a little slower to make it here if it does come true. Will 
leave the current forecast of small chances for rain based on 
coordination with surrounding offices and some good continuity 
on the Canadian and European model (ecmwf) models. 


High pressure will build into Wisconsin Wednesday night...then 
slide east of the state Thursday. Next upper level disturbance 
will approach the upper Great Lakes region Thursday night...and 
across the region on Friday. Some timing differences noted between 
the GFS/European model (ecmwf) during this period. Only major change was to add a 
mention of precipitation on Friday. 


Canadian high pressure will move across Wisconsin Friday night and 
Saturday. Models have been consistent over the last two runs with 
return flow late Saturday night and Sunday. Steep middle level lapse 
rates and 850mb warm advection should trigger showers and isolated 
thunderstorms over the north Saturday night into Sunday. Later 
shifts will need to add precipitation if the current trends 
continue. 


No significant changes were made to temperatures during the 
period. 
&& 


Aviation...VFR conditions expected through today...with ceilings 
lowering into MVFR range this evening as cold front shifts east 
through state. Strong low level flow to mix out this am...with gusty SW 
surface winds through today. 
&& 


Grb watches/warnings/advisories... 
none. 
&& 


$$ 
Te/eckberg