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Area forecast discussion 
National Weather Service Topeka Kansas 
317 PM CDT Tuesday Mar 16 2010 


Discussion... 


Thursday shaping up to be a nice brief reprieve from the clouds 
and precipitation...as middle level upper ridging ahead of next 
system couples with warm air advection to bring highs into the middle 60s across the 
area with south to southwest winds. Trend continues for east 
central Kansas into the afternoon on Friday and have kept warm 
temperatures east. However western counties on track to see incoming cold 
front through the afternoon hours and will likely have falling 
temperatures as a result. 


Precipitation amounts and types are more of a challenge Friday 
night through Saturday as models differ on strength and location 
of next system. Overnight run of the GFS had eastern Kansas in the 
nose of the trowal...with deformation band moving through aloft 
and strong isentropic lift / frontogenesis over the middle level 
front across eastern Kansas. European model (ecmwf) and later run of the GFS are 
slightly more open and progressive...with surface low developing 
across OK and lifting into MO through Saturday. Forecast package 
is based on a blend of GFS/ec solutions. 


Expect to begin with a chance for rain Friday evening...with north 
central Kansas a rain/snow mix. Left isolated thunder possible across NE 
and east ctrl Kansas as front approaches and some elevated instability 
of near 200j/kg in place out ahead. Accumulation amounts may 
approach a widespread inch plus...and with ground saturated to a 
respectable depth will have to watch for flooding concerns. GFS 
soundings would suggest a changeover to snow by midnight Saturday 
morning spreading into Topeka area by 6z Saturday...spreading 
quickly across remainder of east ctrl Kansas. In fact Topeka model 
sounding at noon and 3pm suggest deep saturated layer from 800 to 
600mb all within the -10 to -20 dendritic growth zone...and may 
see best chance for accumulation to overtake surface melting at that 
time. Would anticipate a ratio in the neighborhood of 10 to 1. 
With another quarter to half an inch of precipitation forecast after the 
changeover...will have to couple with melting and watch evolution 
of system before jumping on specific amounts. 


Northwesterly flow aloft brings high pressure in for Sunday and 
Monday...then brings southerly winds around the back of the high 
on Monday. Upper flow transitions to west then southwesterly 
Tuesday. Highs in the 50s may make it back to 60s by middle week. 67 


&& 


Aviation... 


IFR/MVFR ceilings continue across taf sites. Although some thinning of 
the clouds is evident in Sat pictures...expect to see all terminals 
MVFR rest of day. Overnight...advection from northeast will bring 
IFR conditions to all terminals. Of concern is how low kmhk will 
drop as western edge of stratus deck could also see low 
visibilities in fog. Expect gradual improvement to MVFR at all 
terminals by 17/1800 UTC. 


Harding 


&& 


Top watches/warnings/advisories...none. 


&& 


$$