960 
fxus63 kmkx 181851 cca 
afdmkx 


Area forecast discussion...corrected 
National Weather Service Milwaukee/Sullivan WI 
150 PM CDT Friday Jul 18 2008 


Forecast focus on difficult timing of any convection that may roll 
through here during the next 3 days. In general...the long 
discussed meandering frontal boundary remains over central 
WI...with its exact location and associated baroclinic zone heavily 
influenced by any convection that develops in the future. A 
difficult scenario for the models to deal with...as evidenced by 
their poor performance over the last couple of days and their 
continued disparity in solutions through the weekend. 


In the very short term...scattered showers and possible storms 
are developing along the differential heating zone over the northern 
County Warning Area this afternoon. This local baroclinic zone is along the northern edge of 
the cirrus sheild. Convective temperature being reached in this 
area...but they will likely struggle as flow/deep shear is very 
weak. MLCAPES at or below 500j/kg early this afternoon. They should be under- 
achievers that diminish quickly with lowering sun angle. 


For tonight...mesoscale convective vortex currently evident on satellite imagery over the 
Nebraska/Iowa border will push east northeast overnight across far 
southern Wisconsin late tonight. A batch of showers and 
thunderstorms should accompany this feature...mainly across the 
southern half of the County Warning Area. Thus...trimmed probability of precipitation to chance category 
over the north. Sref agrees with this trend. Heavy rain may still 
accompany some thunderstorms given precipitable water/S approaching 1.75 
inches...but cofidence for a widespread heavy rain event is low. 
Therefore...removed the heavy rain mention and will not reissue 
the Flash Flood Watch. 


Beyond this short term...confidence falls off rapidly. We 
continue to run the risk of storms developing on Saturday as 
moisture remains quite high and lingering outflow boundaries offer 
possible forcing mechanisms. 


The middle level shortwave traversing the northern rockies tonight should 
reach our area late Saturday night and Sunday. There is 
cyclogenesis in the llvs upstream that increases the llv jet. Up 
to this point the llv jet has been anemic. Here the NAM and the 
GFS agree that some type of convective complex will develop in the 
return flow...they just disagree on where. The name takes it across 
far northern WI and the u.P. Of Michigan with a dry slot over southern WI. Meanwhile 
the GFS takes the convection squarely across the County Warning Area. At this 
point there is a lot of room for change on this solution and chance 
probability of precipitation will have to cover it for now. 


The 12z operational GFS has changed considerably from the 00z 
ensemble and the European model (ecmwf) with regard to Tuesday through Thursday. The GFS is 
generating a low that drifts through here very slowly for Monday night 
through Tuesday night...bringing quit a bit of convection. Since this is 
rather new...have opted to wait before re-introducing probability of precipitation for 
that period. 


For now...the extended is dry for Tuesday through Wednesday with return 
flow/warm air advection with the next approaching low brining a chance for storms 
on Thursday and Friday. 


&& 


Aviation...expect mainly VFR conditions through the next 24 
hours...although a period of MVFR conditions should be expected late 
tonight if light fog can materialize given calm winds and a moist 
boundary layer. Showers and thunderstorms may also drop ceilings to 
MVFR levels after 07z tonight...before conditions improve by late 
tomorrow morning. 


&& 


Marine...winds to remain generally light the next several 
periods...however with boundary settling over nearshore area through 
the weekend...the threat for dense fog will be increasing due to 
humid low levels and surface temperatures over nearshore remaining 
in the 50s thanks to recent upwelling. 


&& 


Mkx watches/warnings/advisories... 
WI...none. 
Lm...none. 
&& 


$$ 


Long term...05 
short/aviation/marine...18