433 
fxus63 koax 300859 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
359 am CDT Sat Aug 30 2008 


Discussion... 
overall forecast is little changed. Today will be dry and warm 
with an increasing south wind. Southern Plains moisture will begin 
to return to the area tonight and Sunday. There is still a slight 
concern that widely scattered high based thunderstorms could result. 
However...instability still appears marginal at best...and 
forecast was left dry. Winds will stay up tomorrow night and boost 
min temperatures...especially in west and central sections. However...there 
may be enough cloud cover during the day Sunday to keep maximum temperatures 
a couple of degree below today. Fairly strong srly flow continues Sun 
night and mo9nday...but with modest drying at 850 mb. Still expect 
no precipitation...and temperatures will stay warm in pre frontal situation. 


Cold front should begin to move into northwest counties early Tuesday...with 
perhaps some precursor thunderstorms Monday night. After that...models 
diverge on the speed of the front. GFS continues to be the most 
progressive model...but the NAM is catching up...and so is the 00z 
European model (ecmwf). This prompted a change in my thinking from yesterday that with 
the mean long wave still in the western states...the first short 
wave driving this front would quickly lift out without much push 
behind the surface front and plenty of leftover moisture. This was 
also the scenario used by HPC yesterday in longer range frontal positions. 
However...models are definitely tending to put a lot of emphasis 
on the lead system...and use it to actively advance the long wave. 
Some caution is still needed as there is a lot of large scale 
blocking...and Canadian is still slower. 


New forecast scenario is that the cold front will mainly push 
through the area Tuesday into early Wednesday...and possibly hang up in the 
southeast corner Wednesday. Generally used a more progressive pattern on 
probability of precipitation...and allowed the northwest to become cooler and drier by Wednesday morning. 


A major forecast question falling toward the end of my forecast 
update period ending Wednesday night is the fate of the moisture and 
circulation from remnants of Gustav. Two runs of European model (ecmwf)...but not 
the latest...and the latest Canadian all tend to retain the 
circulation of Gustav and bring it north toward southeast Nebraska before 
shunting it east. This would bring copious rains to the area. 
Early morning chat from HPC casts doubt on this scenario. 
Climatology also suggests strong doubt. In the past 30 
yrs...circulation and rainfall from tropical remnants has reached 
the area only twice...Alicia in 1983 and Dolly earlier this year. 
In both cases...circulation was fairly isolated...as expected in 
the strong blocking required to bring a tropical system so far north. 
Having a circulation interact with a front would be a different 
and far wetter Kettle of fish. It also calls for rare timing where 
tropical system finds a hole in subtropical ridge...but manages to 
avoid the westerlies long enough to reach our area without 
shearing out east. Yet...it must still engulf a front. While the 
situation will need monitoring for the next few days...believe 
that remnants of Gustav will most likely end up to our southeast 
without contributing much if any rain to the area. 


&& 


Aviation... 
ffor taf sites koma/klnk/kofk. 


Valid through 31/12z. 


VFR conditions expected through taf period. Winds will increase out of the 
south as high pressure moves east of the region. 
Or taf sites koma/klnk/kofk. 


Valid through 31/12z. 


VFR conditions expected through taf period. Winds will increase out of the 
south as high pressure moves east of the region. 




&& 


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


$$ 


Pollack/griffis