196 
fxus63 koax 082042 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
342 PM CDT Friday Aug 8 2008 


Discussion... 
in the near term...through the weekend...the primary concern is 
chances of precipitation. 


Large upper ridge remains entrenched from the High Plains through 
the intermountain region. Eastern Nebraska and southwest Iowa are 
under the influence of northwest flow aloft. Weak upper short wave 
trough at 12z over southwestern Wyoming and western Nebraska is 
forecast to drift eastward in monsoonal flow into Nebraska. This 
combined with isentropic lift at 305 to 310k....thunderstorms are 
expected to begin across central Nebraska late tonight and move 
eastward into eastern Nebraska by 12 to 15z Saturday. Main caveat is 
instability. Warm temperatures of -5 to -7 degrees c at 500 mb and 
forecast soundings do not show much elevated cape. Thus have 
introduced a chance of thunderstorms...especially in the southeast 
towards 12z Sat and continuing in the morning. 


On Sunday there is a slight chance of thunderstorms...mainly over 
southeast Nebraska. GFS leaves precipitation south into 
Kansas...but left a chance due to uncertainty in timing and location 
of upper short wave features. Isentropic lift may produce 
thunderstorms generally to the west of the County Warning Area on Monday. 


In the extended...a weak front begins to drop south into northeast 
Nebraska on Tuesday. Thunderstorms are possible on Tuesday and 
Tuesday night along this front. Frontal boundary then stalls out 
across east central Nebraska and southwest Iowa and begins moving 
slowly north on Wednesday. GFS then generates an mesoscale convective system on Wednesday 
night over northeast Nebraska and drops it southeast. It appears 
there is some convective feedback in the model...but still left a 
chance of thunderstorms with the frontal boundary in the vicinity of 
the County Warning Area. Similar event occurs in the northeast on Thursday night 
into Friday. However GFS begins to move a cold front into central 
and northeast Nebraska on Friday morning. Therefore...I have 
introduced thunderstorm chances on Friday. 


&& 


Aviation... 
for taf sites koma/klnk/kofk through 09/18z. 


High pressure will keep VFR conditions at sites throughout the 
period. Daytime heating and low level moisture could allow for 
afternoon cumulus development. Sites will see winds die down into the 
early evening hours. Believe any precipitation will remain to the 
north and south...so have left sites dry. 


&& 


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


$$ 


Discussion...Smith 
aviation...Wilkins