339 
fxus63 koax 210915 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
315 am CST Sat Nov 21 2009 


Discussion... 


Typical for November the weather across the County Warning Area will be variable and 
changeable through midweek as it is becoming more likely a closed 
weather system will develop and then slowly track across Central 
Plains by Monday night through Tuesday night periods. Before then fog...low clouds 
and possible drizzle or light/small measurable precipitation chances will have 
to be dealt with. 


Shorter term...today through Sunday night. Moisture was never 
really scoured out of far southeastern zones yesterday which allowed dense fog 
formation rather early last evening. Although surface winds should 
increase a bit this morning...their increase will probably not be soon 
enough to improve conditions before 15z. Thus the dense fog 
advisory was kept in place. Although patchy fog mention this morning 
was expanded a bit northwest...felt widespread poorest visibilities would be 
confined to advisory region. Otherwise early morning fog curve 
satellite imagery showed low clouds working slowly northward through Kansas and 
these will likely impact much of the County Warning Area later today into Sunday 
and probably Monday as well. So even though 850 mb temperatures are 
forecast to remain fairly similar through Monday...maximum temperatures could 
be mildest today given that the most sunshine is expected. Made little 
changes to going forecast. Water vapor imagery showed trough 
moving into western Utah was spreading high clouds as far east as northern 
plains as of 08z and this through will move across the County Warning Area later 
today into Sunday. However...with much stronger energy forecast to 
dig down behind it late Sunday... lead wave could have a tendency 
to fragment or dampen it as it crosses forecast area. The first upper 
trough could push a surface trough toward or into northwestern zones Sun afternoon 
per NAM/GFS...but if it does it should wash out or become 
reestablished farther west on Monday as the main system approaches. 
With low level moisture spreading northward kept in drizzle late tonight and 
small precipitation chances sun and Monday along with generally mostly cloudy skies. Did 
note that there was drizzle this morning from OK into northern Texas in the 
stratus/stratocu and as moisture deepens tonight...lift from 
approaching trough could generate some here as well. 


Beginning late Monday attention turns to this trailing developing 
storm system. Generally kept forecast more closely tied to the European model (ecmwf) 
which has been farther SW/slower and more consistent than the GFS 
and was shown some support from 00z/06z NAM. Since the 00z European model (ecmwf) has 
provided no big surprises and has generally maintained its 
consistency...increased probability of precipitation a bit more in the Monday through Tuesday night 
period as confidence in its solution has increased some. Although 
European model (ecmwf) also continued to keep the system fairly warm through Tuesday west/850 
mb temperatures above 0 degree c till 00z Wednesday...left in rain/snow mention 
Monday night/Tuesday western zones given time of year and the fact that the 
Canadian/NAM were colder and supported snow over even a larger 
part of the County Warning Area. System definitely bears watching... especially 
since it will be affecting the beginning of the Holiday travel 
week and will be packing strong winds. 


Still looks like a late week warming trend setting up following 
this system...if we can avoid significant snow anyway. 


&& 


Aviation... 
taf sites kofk/koma/klnk 


06z tafs 


VFR conditions are expected through 18z as high pressure moves 
slowly east today with surface gradient increasing across the area. 
Some MVFR ceilings developing 18z-00z as moisture over the Southern Plains 
advects north with the increasing south flow. MVFR ceilings likely after 
00z. 


&& 


Oax watches/warnings/advisories... 
NE...dense fog advisory until 9 am CST this morning for nez068- 
090>093. 


Iowa...dense fog advisory until 9 am CST this morning for iaz080-090- 
091. 


&& 


$$ 


Chermok/fobert