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fxus63 ktop 200830 
afdtop 


Area forecast discussion 
National Weather Service Topeka Kansas 
330 am CDT Wednesday Aug 20 2008 


Discussion... 


Synopsis...00z upper air analysis indicated an active pattern across the US. 
Upper level low over the Southern Plains seemed to have started to lift to 
the NE given the upper level jet structure. Upstream...kicker system 
was seen moving through the Great Basin with an upper level ridge 
continuing to build over the northern plains. 07z surface analysis continued to indicate surface 
hi pressure from eastern Iowa into southeast Colorado. Regional radar mosaic indicated showers 
increasing across northern Arkansas/southern MO associated with the upper low. 


Forecast...upper level low over the Southern Plains shld continue to lift slowly 
NE today into eastern OK and then southeast Kansas tonight. Weak isentropic lift 
on the 320 k surface does increase through the morning over the southeast County Warning Area and 
may see an increase in showers by late morning. 00z model suite is 
drier than previous runs for our County Warning Area. This seems in part due to 
continued low level dry air advection from the east through the day today 
limiting the top down saturation. Also...the operational models 
take the best upper level pv advection and associated forcing to the 
east of the forecast area. Although this forecast package will trend in this 
drier direction...it should be noted that ensembles /both the sref 
and GFS/ still indicate decent coverage of very light quantitative precipitation forecast. Thus will 
back probability of precipitation for today and tonight back into the chance Cat. Point 
forecast soundings show weak stability but little in the way of 
instability. Thus will continue with the mention of just showers. Upper 
level low continues to shift northeastward during the day on Thursday taking the best 
forcing and moisture to the east. Cold pool aloft does track over 
the eastern County Warning Area though during the day...and with some surface heating will 
likely see some scattered showers continue in parts of the area. Did 
increase temperatures a touch on Thursday with some sun expected and warming 
850 mb temperatures. Removed probability of precipitation for Thursday night with dry air advection as 
the low level flow turns SW for the forecast area. Next weather maker for the County Warning Area 
will be pushing through the northern plains during the day on Friday and this 
continues to look to send a cold front into Nebraska/Iowa during the day. Shld 
actually see a nice day ahead of the fnt with mostly sunny skies 
and a return to near normal temperatures. Thunderstorms and rain which develop alng the fnt to 
our north look to track into the northern County Warning Area on Friday night. Going probability of precipitation seem 
appropriate with the best coverage over the NE County Warning Area. Still some 
uncertainty as to what happens to the fnt over the weekend...but 
see no reason to change going forecast which preferred the more 
progressive GFS of moving the fnt through the area. 


&& 


Aviation... 


Evening model runs back off on amounts of precipitation but hold close to 
cloud decks in previous taf. Will continue to bring conditions 
down to MVFR...however will delay another hour or so as column takes 
a bit longer to saturate and precipitate as forcing is not strong 
over taf sites. 


&& 


Top watches/warnings/advisories...none. 


&& 


$$ 


Boustead/67