658 
fxus63 koax 181932 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
232 PM CDT Friday Jul 18 2008 


Discussion... 


Several forecast uncertainties continue this forecast period. 


Impulse is currently moving across north central Nebraska and continues 
to shift eastward through the westerlies towards northestern Nebraska and is weakening 
as it moves into a much more stable environment. Meanwhile...surface cold front has 
pushed southward into Kansas and MO leaving very weak surface flow across the 
County Warning Area. A few diurnally driven showers have popped up this afternoon 
and should be the case throughout the afternoon as convective 
temperatures are exceeded. 


As the evening rolls on...expect diurnally driven showers and 
thunderstorms to dissipate as instability decreases. Ongoing impulse 
moving into northestern Nebraska could possibly make it to the Iowa border but 
confidence is low as the complex moves into less favorable environment. 


Mesoscale convective system is forecast to roll across southern South Dakota late tonight 
leaving a chance for thunderstorms to slide across far northern counties into 
the morning hours. By afternoon...instability greatly increases 
ahead of surface boundary that will stretch from northwestern Kansas into northestern Nebraska 
and northwestern Iowa. Any left over morning boundaries will complicate 
the situation...but main focus should be along surface convergence 
that will bisect the entire County Warning Area. 


Thunderstorm chances continue on Sunday as frontal boundary hangs up over 
the South Dakota/Nebraska border and flow becomes more nwrly sending disturbances 
across the northern plains. Very unstable airmass will be in place on 
Sunday however cap is expected to be quite Stout. High temperatures will be 
in the middle to upper 90s with dewpoints in the middle to upper 60s 
which could send heat indices to the 100 to 105 range. 


In the extended...models continue to have hard time developing an 
amplified ridge over the Central Plains. In fact...newest extended 
runs push a middle level shortwave down through the area which keeps 
probability of precipitation going through the forecast. 


&& 


Aviation... 


For taf sites koma/klnk/kofk through 19/18z 


Unsettled weather conditions expected at taf sites through tonight 
and tomorrow. Thunderstorms will move across and north of kofk 
through 22z. Then some chance of thunderstorm activity again for 
kofk...koma and klnk after 22z. Saturated ground combined with 
light winds and high dew points will lead to patchy fog between 10z 
and 15z. 


&& 


Oax watches/warnings/advisories... 
NE...none. 
Iowa...none. 
&& 


$$ 


Griffis/Meyer