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Area forecast discussion for southeast South Dakota/southwest Minnesota/northwest Iowa 
National Weather Service Sioux Falls South Dakota 
340 am CDT Sat Jul 5 2008 


Discussion... 
decent Theta-E gradnt with warm air advection and weak shortwave feedng curnt convectn 
far southern James River to MO seems to run up agnst a brick wall of more 
stable air and shlwr moisture to the east. Expect curnt activity to linger 
altl past 12z and may appchg sux as it moves southeastward but should be out of 
the way quickly. Otherwise latr development will depend on a combo of heating 
and convergnce with surface trough and all this xco heating will become more 
favorable tonight as next shortwave flattens ridge moving across area. This signals 
a decent amount of saunshine and a warm day today...not to mention windy 
conds esply east. Curnt projections have winds falling a little short of 
advisory criteria and will leave out accordngly. Hi temperature guidance today 
looks reanbl. 


Big qstn is extent of convectn tonight. Extent of init development tough to 
Guage but one thing in favor of upping probability of precipitation a little is decent 
convergence pattern which would favor convectn that develops being 
halfways persistnt. Storm Prediction Center adjustmnt of slight risk area further eastward into 
our forecast area from earlier day 2 outlook looks good. With instblty 
spreading over area...severe threat area and hiest probability of precipitation should gnly match. 
Will go only up to 40 percent part of forecast area for now but July is a 
good month climatologically for late night convectn so it could be a 
busy late night comng up. 


With ridge flattening and not much penetration of drier morte stable 
air...expect a respite fromn thunderstorm chance only over northern forecast area sun 
into sun evening before late Sun night and Monday resurgence arrives. This 
will persist through Monday night. Will keep Tuesday mention of slight chance thunderstorms north 
for now...dry is favored by NAM but it may be too strong and fast on 
southern Canadian shortwave and developing coolr nwrly flow. Will keep Wednesday through 
Friday dry as upper ridge bulds into area. Temperatures will warm back up some 
this period after the little cooldown by Tuesday. 


&& 


Aviation... 
VFR through 06/00z and continuing gnly outside of any convectn through 06/12z 
with local and short lasting lower conds in any convectn. 


&& 


&& 


Fsd watches/warnings/advisories... 


South Dakota...none. 
Minnesota...none. 
Iowa...none. 
NE...none. 


&& 


$$ 
Williams