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Area forecast discussion...updated 
National Weather Service Topeka Kansas 
611 am CST Wednesday Mar 10 2010 


Update... 


Updated for the 12z taf issuance. 


&& 


Discussion... 


See previous discussion. 


&& 


Aviation... 


Most recent push of cooler air and associated stratus deck is 
beginning to stall as low level flow weakens and will eventually veers 
around to the northeast with the approach of the next strong storm 
system over the southern High Plains. Will continue the trend of 
slowly improving ceilings to 1500-2500 by late morning with VFR visibilities 
that should persist through 00z. Area of convection should 
approach the taf sites after 00z as wave lifts out and main 
forcing begins. Will continue with MVFR visibilities in -shra and IFR 
ceilings on through the end of the forecast period as upper low lifts 
out across the area overnight. If system lifts out further north 
of projected track may need to include thunder in the prevailing 
period. 


&& 


Previous discussion... /issued 348 am CST Wednesday Mar 10 2010/ 


Discussion... 
water vapor show the second of two closed lows beginning to move out 
from the southern rockies with a surface low developing over the 
southern High Plains. Main concerns with the forecast are chances 
for strong convection and potential for measurable snow on the back 
side of the system. 


Biggest question regarding severe thunderstorms is whether the warm 
front will be able to lift far enough north to where there could be 
some surface based instability. The NAM keeps the front south of the 
forecast area with a strong cap over the boundary layer...while the 
GFS and European model (ecmwf) just lifts it into far southern portions of the 
forecast area. There is more than enough deep layer sheer and middle 
level lapse rates look to be steep as the upper low lifts northeast 
across eastern Kansas. There is the potential for some low top 
supercells lifting northeast ahead of the surface low across east 
central Kansas. With this in mind it looks as if there is a small window 
for strong T severe thunderstorms towards late afternoon and early 
evening when the steep middle level lapse rates move overhead before 
the low lifts east and the instability is lost. See swody1 for 
further details. 


As for snowfall on the back side...HPC forecasts to possibility for 
a couple inches of snow to accumulate in the 06 to 15z time frame 
Thursday. Looking at the GFS forecast soundings...surface temperatures never really 
fall below freezing for cnk and fby with 925 mb temperatures holding around 
+1c. With this in mind think the any snow is likely to be heavy wet 
snow that may easily melt on contact with the ground...and 
potentially mixed with rain for most of the event. Therefor have 
gone with lower snow amounts with maybe a half to one inch possible 
over north central Kansas. If it looks like surface temperatures will be 
colder...snow amounts could increase with a decent deformation band 
setting up on the west and northwest side of the upper low. 


Do not see much in the way of warm temperatures for the rest of the week 
and with the upper low spinning over the MO river...precipitation chances 
have been retained through Friday night. Have continued with lows in 
the middle 30s with highs in the lower to middle 40s...except for today 
were highs across the eastern and southeast parts of the forecast 
area should warm into the upper 50s and lower 60s with some limited 
insolation. With models keeping a northerly component to the winds 
and clouds likely wrapping around the back side of the slow to 
depart upper low...have lowered highs for Saturday and Sunday. 
Otherwise no other changes were made to the forecast beyond Friday. 


Wolters 


&& 


Top watches/warnings/advisories...none. 


&& 


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