Weather

977 
fxus63 keax 071103 
afdeax 


Area forecast discussion 
National Weather Service Kansas City/Pleasant Hill MO 
603 am CDT sun Sep 7 2008 


..update aviation discussion... 


Discussion... 
/402 am CDT sun Sep 7 2008/ 
a challenging forecast in terms of precipitation chances through the 
early part of the week. Temperatures will also be tricky due to the 
anticipated cloud cover and possible precipitation for the next 
couple days. 


An upper shortwave trough is now making an exit toward northeast 
Missouri...taking the associated shower activity eastward with 
it. This has left the forecast area without precipitation early this 
morning...between the exiting showers to the east and an area of 
showers and thunderstorms that has developed over south central into 
southeast Kansas and northeast Oklahoma. This area of precipitation 
is very similar to what occurred yesterday morning...resulting from 
isentropic lift near the 310k surface. This area of isentropic lift 
is forecast to weaken as it spreads northeast toward central 
portions of Missouri. Therefore...have gone with low end 
precipitation chances for the southern forecast sections during the 
daytime today. 


Temperatures today will again pose a challenge. Rather extensive 
area of stratus has developed over most of the forecast area early 
this morning. Though ceilings are expected to improve into the 
afternoon...skies are expected to remain mostly cloudy throughout. 
Have trimmed temperatures back to the lower to middle 70s for 
today...only slightly warmer than yesterday. 


The evening model runs of the GFS and sref showed to be quite 
similar through Tuesday...with the NAM only slightly different 
through Monday. That said...not too much to argue with the rather 
consistent model solutions...remaining generally on track with the 
going forecast. Main items to resolve will be the movement of the 
middle level baroclinic zone and surface front tonight through 
Monday. The models have been consistent in shifting the baroclinic 
zone north today and tonight...with it forecast to reach northern 
Missouri during the early morning hours Monday. The GFS takes the 
baroclinic zone a bit further north than the NAM. Despite the minor 
placement difference...the models agree on bringing a shortwave 
across southeastern Nebraska toward northwest Missouri 06-12z 
Monday. This should aid in the development of showers and possibly 
some thunderstorms...especially over the northern half or so of the 
forecast area overnight tonight. 


The models then agree on additional shortwave energy to drive the 
front south on Monday. Increased chances for showers and some 
thunderstorms will come in the Post frontal airmass Monday into 
Monday night. A period of gusty north winds should follow the 
front Monday afternoon and evening. There should be a modest range 
in temperatures across the forecast area for Monday...dependent on 
the speed of the front. 


Any lingering precipitation across the eastern and southeastern 
forecast sections should move out Tuesday morning. Cooler and drier 
air will spread across the region as a surface high moves across. 


Did cut back precipitation chances mainly across the southern 
forecast sections for Wednesday. Kept low end precipitation chances 
across northern Missouri with a warm advection regime and closer to 
a possible shortwave passing by. Otherwise few changes made past 
Wednesday. 


Stoflet 


&& 


Aviation... 


For the 12z tafs...ceilings and visibilities should improve by middle 
morning...likely going into the VFR category by noontime as bulk of 
low level moisture moves east with exiting short wave. Area then 
undergoes a brief period of zonal flow during the afternoon and 
evening hours...before next short wave starts to dig into the 
northern plains late tonight. In response to this short wave...a 
front will be taking shape over northern Missouri...which may 
provide the focus for more low clouds and fog overnight. Not out of 
the question rain may make it into the sites by 12z...but low level jet should 
support higher threat of rain west of the region...so will keep tafs 
dry for now. 


Pc 


&& 


Eax watches/warnings/advisories... 
MO...none. 
Kansas...none. 
$$