Weather

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afdtop 


Area forecast discussion 
National Weather Service Topeka Kansas 
248 am CDT Tuesday Oct 7 2008 


Discussion... 


The 7z water vapor satellite imagery showed the center of the upper 
low lifting northeast into extreme northwest MO. The upper level 
trough axis extends south-southwest across south central Kansas...into 
north central Texas. An upper level ridge axis was located across the 
east central Continental U.S. And the western Continental U.S.. 


The 7z surface map showed the front located from near Seneca 
southward to Council Grove. Scattered showers and isolated 
thunderstorms continue to develop ahead of the front...and east of 
the 500 mb trough axis from southeast Kansas...north-northeast across 
portions of east central Kansas. 


Today...the cold front will push east across northeast and east 
central Kansas early this morning...and should exit the southeast 
counties of the County Warning Area by 15z. There could be some isolated showers 
behind the front...but most of showers will occur ahead of the surface 
front. Behind the surface front winds will shift to the northwest and 
north. As the 500 mb trough axis moves east across the County Warning Area today we 
should see stronger subsidence and isentropic downglide developing. 
This will clear skies across north central Kansas this morning and the 
clearing will move east across the County Warning Area during the afternoon hours. 
Low-level cold air advection should keep highs in the middle to upper 60s across the 
County Warning Area even with afternoon insolation. North winds will increase to 15 
to 25 miles per hour with gusts of 25 to 35 miles per hour possible. 


Tonight...the north winds will diminish through the early evening. 
Clear skies and light winds will allow temperatures to drop into the 
lower to middle 40s by sunrise. The airmass looks too dry in the 
low-levels to see any patchy ground fog developing around sunrise. 


Wednesday through Saturday...a deep 500 mb trough will develop across 
the western Continental U.S. And gradually shift east towards Continental 
Divide. Zonal upper flow will gradually back to the southwest as the 
500 mb trough amplifies across the western Continental U.S.. while the center of 
the surface ridge will shift eastward across the middle MS River Valley. 
High temperatures will warm from the lower 70s on Wednesday to the 
upper 70s to around 80 degrees by Saturday. High cloudiness may 
increase Friday night into Saturday as the 500 mb trough begins to move 
east. A Lee surface trough will deepen across the High Plains late in 
the week allowing for southerly winds to increase across the County Warning Area. 


Saturday night through Monday...the 500 mb trough will lift northeast 
across the plains. Ascent ahead of the 500 mb trough and and surface 
convergence ahead of the cold front may provide the County Warning Area with a 
chance for showers and thunderstorms early next week. Not too sure 
this far out on the timing of the 500 mb trough and associated cold 
front. Though deeper Gulf moisture return may begin as early as 
Saturday. The extended forecast grids looked good and no changes 
were made. 


&& 


Aviation... 


Water vapor still showing upper low over north central with 
associated shortwave extending southward into central Kansas. 
Convection which has redeveloped with this second shortwave 
should lift north and east of all taf sites by 06z but still 
produce local MVFR ceilings/visibilities in thunder until 06z. Scattered showers 
with area of stratus and MVFR ceilings should wrap southeast around 
upper low and behind cold front surging across the area. Will 
keep ceilings in the 1500-2500 foot range through the night...with 
precipitation chances diminishing after 10z as cold air advection and subsidence ends 
precipitation later tonight/early Tuesday morning following passage of 
the trough axis. Expect subsidence and drying to erode stratus 
deck across the taf sites from west to east in the 16-18z 
timeframe with VFR conditions expected all sites by 18z. Lighter 
south/southeast winds will be followed by frontal passage in the 07z-09z 
timeframe west to east across the tafs with a switch in winds to 
the north with gusts to 20-25 kts on through 00z...then 
diminishing in the 00z-06z timeframe. 


63 


&& 


Top watches/warnings/advisories...none. 


&& 


$$ 


Gargan