234 
fxus63 ktop 212000 
afdtop 


Area forecast discussion 
National Weather Service Topeka Kansas 
300 PM CDT Thursday Aug 21 2008 


Discussion... 


500hpa low continues to lift to the northeast today. Next weather 
making shortwave sliding along southern British Columbia. Tropical 
Storm Fay continues to pummel northeast Florida. Locally...very 
moist low level environment...evident on 12z top sounding has 
allowed thick stratocu to linger across the County Warning Area. With a bit of 
instability and lift from the departing elongated wave...pesky 
scattered showers remain mainly across the eastern half of the 
forecast area. 


Short term forecast focus will be on fog potential overnight. 
Middle/upper level atmosphere clear out tonight as subsidence and dry air on 
the backside of the departing trough slips across NE Kansas. Models 
fairly consistent with the residual boundary layer moisture 
lingering across mainly northeast and east central Kansas...as far 
westward as Geary and Riley counties. Southerly winds will begin to 
pick up ahead of the northern trough...and boundary layer should be 
mixy enough to prevent dense fog. Instead...think that stratus is 
more likely to develop with just patchy fog to deal with. 
Therefore...increased cloud cover...especially east overnight...and 
tweaked going weather grids to reflect more patchy nature...and to 
refine the midnight to a few hours after sunrise time frame. 
Friday...attention turns northward. Aforementioned southerly winds 
and clearing skies after the morning stratus will allow to temperatures to 
climb to the upper 80s and lower 90s before front comes through 
Friday night. 


Lunde 


As the upper trough moves across the northern plains and southern 
Canada Friday night and Saturday...a cold front is forecast to move 
south into northern Kansas. The position of the front come Saturday 
morning is a question mark depending on the amount of convection 
associated with the front and resultant cold pool outflows. Frontal 
boundary could even be pushed as far south as northern Oklahoma or 
far southern Kansas. The front is forecast to stall across central 
Kansas mainly along or south of Interstate 70. A zonal to a west 
northwest flow aloft will set up across the Central Plains with a 
upper high centered over the southern rockies on Saturday. The upper 
high retrogrades southwest as flow becomes northwest across central 
and eastern Kansas. Easterly flow behind the front will again 
continue to yield temperatures below normal. Shortwaves move 
southeast in the flow across southern Nebraska into northern Kansas 
on Sunday and Sunday night. Have kept chances of precipitation going 
and front if it does not wash out may also act as a focus for 
convection. 


Monday through Wednesday still looking dry with a model ensemble 
blend accepted for the period showing more of a zonal flow with the 
southern edge of the westerlies to the north of Kansas. Near the end 
of next week models are suggesting the presence of a front moving 
into the Central Plains. The timing for 7 days away and confidence 
not very high to include precipitation chances at this time. 


53 


&& 


Aviation... 


Several concerns during the next 24 hours...the first of which is 
continued MVFR ceilings at each of the three terminals early this 
afternoon. Still expect to see periodic improvement with MVFR cloud 
deck scattering out through the rest of today. Focus then turns to 
the overnight period. Ample low level moisture lingers over 
northeast Kansas. Model forecast soundings continue to show visible 
reduction and potential stratus deck developing after 06z. Surface 
winds will begin to pick up from the south tonight ahead of an 
approaching trough...so am more inclined to emphasize IFR stratus 
deck than a significant visible reduction through 15z. Lunde 


&& 


Top watches/warnings/advisories...none. 


&& 


$$ 


Lunde/53