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fxus63 kiwx 100831 
afdiwx 


Area forecast discussion 
National Weather Service northern Indiana 
331 am EST Wednesday Mar 10 2010 


Short term... 
Wednesday through Thursday night... 
closed upper low currently depicted by water vapor satellite over 
NE/South Dakota will be focus this forecast period. Kiwx radar continues to 
show widely scattered rain showers over eastern half of County Warning Area associated with first 
wave rotating through the area. Likely to see a lull tonight as next 
main feature to bring more organized forcing for precipitation is upper low 
over The Four Corners which will phase in with plains upper low 
Thursday. Current grids reflect this timing with low chance probability of precipitation 
tonight and likely Thursday afternoon...have expanded likely into 
Thursday evening as well. Models continue to show decent forcing 
with this next wave and with late afternoon/early evening timing along with 
kindex great 30 and tt great 50 warrants continue mention of thunder. 
Satellite and surface observation shows clearing associated with dry slot behind 
this first wave is moving up into stl at this time...cant rule out SW corner 
of County Warning Area mixing out and seeing some sun so have trended toward warmer 
mav guidance there for highs today. Guidance close and reasonable 
remaining periods with lows in the 40s and highs Thursday 55-60.&& 


Long term... 
Friday through Tuesday...an upper low will have developed after the 
merger of a number of short wave troughs across the central Continental U.S.. the 
operational runs of the GFS and European model (ecmwf) have been reasonably 
consistent from run to run in the overall handling of this system. 
The GFS ensemble plume diagrams helpful in determining general 
timing and trends of the evolution of this system. Have made some 
minor adjustments to rain chances bases on these latest trends. 
Given the highly blocked up pattern...the upper low will be very 
slow to move east. Some concern for a mix of rain and snow Saturday 
night given low level thickness approaching 1310 meters. For this 
package...kept the precipitation all rain through Sunday. As for 
temperatures...favored the GFS mean ensemble mex MOS. The 
operational mex MOS temperatures look a little to warm considering 
clouds and precipitation. 


&& 


Aviation...06z tafs 


Kiwx radar showing another band of scattered rain showers moving up into the County Warning Area 
at this time. Radar trends indicating best chances for precipitation more toward 
kfwa so will include a tempo group to account for this. Otherwise 
plan to continue with MVFR visibilities overnight. RUC forecast soundings still 
show increasing moisture in low levels and potential for downward 
trend in ceilings and visibilities by daybreak. Will have tafs reflect this 
trend but keep just above IFR for now. Rest of taf period will be 
between waves rotating around upper low to the west so expect 
gradual improvement with time. 


&& 


Iwx watches/warnings/advisories... 
in...none. 
Michigan...none. 
Ohio...none. 
Lm...none. 
&& 


$$ 


Short term...logsdon 
long term...skipper 
aviation...logsdon