Weather

475 
fxus63 koax 291945 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
245 PM CDT Friday Aug 29 2008 


Discussion... 


Temperatures and winds will be the main concern through Labor Day. 
After that...attention turns toward potential for precipitation. 


Upper air charts from 12 showed the following. At 850 mb...a cool 
and dry airmass was in place with moisture only as far north as 
southern Kansas and southern MO. Decent moisture was in place southwestward into nm and 
southern Arizona. Moisture-wise...the pattern was similar at 700 mb. Wedge 
of hot air extended from southern and central California into western Colorado. Strongest 
middle and upper tropospheric winds were occurring from the Pacific 
across southern parts of British Columbia...Alberta and man then across northern Minnesota. At the 
surface...high pressure was in place over NE and Iowa. 


Tonight through Saturday...high pressure at the surface will slowly 
slide eastward and S/southeast winds will increase. Went toward the cooler end 
of available guidance with dry air in place. The pressure gradient 
also remains fairly weak through 12z...then increases on Saturday. 
Have lows tonight in the 50s and highs Saturday 85 to 90. Fairly 
good pressure gradient continues at the surface Saturday night 
into Tuesday. At 500 mb...a moderate trough digs over the western U.S. 
And a ridge builds over the eastern part of the nation. Did not follow 
the NAM model output for Sunday. It developed some precipitation over the 
area as a vorticity maximum moves up from the SW. Will have to watch that... 
and may need to make adjustments later. 


From available guidance...it appear that Gustav will move through 
the Gulf of mex and move toward la. GFS and European model (ecmwf) were in pretty 
good agreement in regards to large scale features through 12z 
Monday. Then the GFS tended to lift a shortwave out of the western U.S. 
Longwave across the northern plains with more intensity than the European model (ecmwf). 
Believe that the 12z GFS was a little too fast with that...and so 
its frontal timing is probably too fast for Tuesday. Used a blend 
of European model (ecmwf)/GFS/HPC guidance. 


Current forecast introduces a slight chance for thunderstorms over 
northestern NE Monday night. Then we continue with chance or slight chance 
probability of precipitation through Friday. There is a lot of uncertainty by Thursday and 
Friday...so forecast confidence in the forecast details drops to or 
below normal by then. Precipitation could be heavy along and ahead of the 
front Tuesday into Thursday...since middle level moisture band will 
probably be in place and precipitable water could reach around two 
inches. 


Highs Sunday should reach the upper 80s to around 90...upper 80s and 
lower 90s Monday...then middle to upper 80s Tuesday. Clouds and precipitation 
will likely hold highs down and lows up later in the week. 


&& 


Aviation... 


For taf sites koma/klnk/kofk. 


Valid through 30/18z. 


No significant aviation concerns through the period with high pressure 
prevailing over the region. 


&& 


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


$$ 


Discussion...Miller 
aviation...Dee