227 
fxus63 kind 220510 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
1230 am EDT Monday Mar 22 2010 


Aviation...discussion for 6z tafs. 
Sites should see deteriorating conditions over the next few hours as 
rain bands and MVFR ceilings and visibilities move north. Forecast 
soundings show ceilings dropping to IFR from south to north and 
staying there with rain continuing through the day. Currently looks 
like low ceilings may hang around for a few hours after the rain 
ends and thus will keep them at least lower MVFR through the end of 
the period. Wind gusts out of the northeast around 18-25 kts should 
continue through the night and into the day tomorrow before 
subsiding as the low pressure center pulls further away and the 
gradient lessens. 


&& 


Update... 
raised probability of precipitation to 100 percent across the southern counties tonight and 
raised them a bit elsewhere across the forecast area based on radar 
trends. Also...intialized temperatures and dew points based on latest 
observations but left overnight lows alone. 


&& 


Short term... 
main focus of short term will be duration of rainfall as a low 
pressure system moves across the Tennessee Valley. Current visible 
satellite is showing the surface low spinning over northeast 
Missouri...while the radar mosaic is indicating widespread 
rainfall moving into southwest Indiana. 


Models are in decent agreement with this system...showing rainfall 
gradually increasing from southwest to northeast across central 
Indiana today. It looks like the best lift will still be late this 
afternoon/evening...and sufficient isentropic lift should support 
steady rainfall through the overnight hours. Isentropic lift cuts 
off quickly around Monday 12z...but cross sections are still showing 
ample moisture along with a band of frontogenetic forcing across 
southern Indiana. So...kept likely probability of precipitation across most of warning 
area through tomorrow morning. The middle levels will dry out by 
tomorrow afternoon...but another shot of reinforcing isentropic 
lift on the back side of aforementioned low could trigger some 
additional showers around Tuesday 06z. Gem/GFS/NAM are in agreement 
with the ending time of rain. So went with a blend...with rainfall 
moving out of central Indiana by Tuesday 12z. Zonal flow and drier 
conditions will follow in the system/S wake. 


Temperatures...models in decent agreement through short term...so went 
with a blend. Did lean toward the warmer end of guidance for 
tonight/S lows due to cloud cover. Monday...went with a blend. 
Monday night...went a bit cooler over northwest portions of area 
as clouds slowly start clearing out. Tuesday...liked warmer highs 
across the west and cooler highs over eastern portions of area as 
clouds clear from west to east. 


&& 


Long term /Wed night through Sunday/... 
extended models and ensembles show reasonable agreement for the 
beginning of the forecast period then begin to diverge toward the 
end of the week/next weekend. Warming trend begins to wane on 
Thursday as another cut-off upper low sets up across the Southern 
Plains and moves east...possibly bringing another chance for rain to 
the forecast area Thursday into early Friday. Then an upper ridge 
quickly builds back over the region for Saturday before an upper 
trough from the northwest swings through late next weekend. 


&& 


Ind watches/warnings/advisories...none. 


&& 


$$ 


Update...mk 
short term...tdud 
long term...smf 
aviation...cp/jh