141 
fxus63 koax 031934 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
234 PM CDT Thursday Jul 3 2008 


Discussion... 
high pressure is moving into the area...bringing somewhat fewer 
clouds and pushing weather southeastward. Subjective 12z upper air analysis 
indicates upper ridge centered in southwestern Utah...with trough coming 
ashore in western US generating 500mb heat falls up to 60m. Weak 
shortwave was analyzed in ctrl Montana...as well as in S ctrl 
Nebraska/ctrl-wrn Kansas...with stacked upper low centered in eastern Hudson 
Bay/northern queb. 850mb cold front extended from low in northern queb 
through southern Michigan/northern Illinois/IA-MO border/east ctrl Kansas toward southwestern Kansas. Bulk 
of 850mb moisture was confined southeast of that front...with some higher 
dewpoints also noted in the northern rockies from ctrl ab through Montana 
toward western South Dakota. Thermal ridge was well defined in southwestern US/Great 
Basin...with 16c temperatures at 700mb along an axis from northern Nevada to ctrl 
Arizona. At 19z...surface high was centered in southeastern South Dakota...with ridge axis 
extending across ctrl Nebraska/northwestern Kansas. 


Main forecast concern is in small potential for thunderstorms and rain tmrw nt...with 
increasing potential as upper ridge breaks down from late weekend 
into early next week. 850mb high is forecast to pass through the MO 
valley towards the middle-MS valley tmrw...leaving srly flow in its 
wake to transport moisture northward into ctrl Kansas/S ctrl Nebraska. GFS/NAM are 
consistent in developing convection after sunset in ctrl/eastern Nebraska as 
low-level jet gets going in KS/neb. Have held onto schc 
probability of precipitation...though did consider increasing to chance...particularly 06-12z 
Sat. Did remove probability of precipitation from Friday afternoon as cap looks to hold through the 
day...and also did scale back probability of precipitation in eastern County Warning Area as low-level 
jet/Theta-E axis remain further west. Kept a small schc pop in the 
swrnmost County Warning Area 12-18z Sat to take care of any lingering 
shra/tsra...though do expect diminishing coverage of any remaining 
precipitation quickly in the morning. Remainder of Sat/Sat nt look dry as 
upper-level shortwave ridge moves across the MO valley. 


Upper wave moving into Pacific northwest is forecast to move across the northern 
plains/southern Canada sun...helping dampen the upper ridge into more 
zonal flow across the Continental U.S.. though main jet core/storm track 
should remain north of the County Warning Area...expect some activity to drop out of the 
Dakotas/Minnesota sun and particularly sun nt/Mon...affecting mainly the 
northern County Warning Area. Weak/slow-moving cold front is forecast to move through the 
County Warning Area on late Monday nt/early Tuesday...pushing precipitation chances southward through the 
County Warning Area Monday nt/Tue. S of this front...expect temperatures to warm quite a 
bit...possibly peaking on sun as most of County Warning Area remains dry. Temperature forecast 
will be complicated by precipitation chances sun nt through Tuesday...and have 
stuck pretty close to guidance/HPC as a middle-of-the-Road 
solution. Front should moderate temperatures back to climatology or just below 
in its wake. 


Kept forecast dry after Tuesday nt in wake of front as surface high again moves 
through...with strengthening upper ridging in the western US. Return 
flow will again become established by thurs/Fri...though warming 
middle-level temperatures appear to keep the regin well capped...with upper 
jet/storm track pushed well northward into Canada/northern plains/northern Great 
Lakes. Expect temperatures to push above climatology /well into the 90s/ in that 
regime by the end of the week. 


&& 


Aviation... 
for taf sites koma/klnk/kofk through 04/18z. 


VFR conditions expected through 04/18z. Surface high pressure over eastern South Dakota will 
move to the Great Lakes region by Friday morning. This will allow north-northeast surface 
winds to gradually become east tonight then southeast on Friday. Developing cumulus 
field over Iowa could provide koma occasional ceilings around 4000 feet from 19-23z 
today. 


&& 


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


$$ 


Mayes/chermok