556 
fxus63 kind 201928 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
328 PM EDT Sat Mar 20 2010 


Near term /until 6 am Sunday/... 
analysis as of 3 PM this afternoon still depicts a stalled frontal 
boundary draped across central Indiana oriented southwest to 
northeast. Forecast focus for the near term will be rain chances 
associated with this feature. 


Short term guidance indicates this boundary will say slowly 
southward overnight...but a lack of forcing and moisture along the 
boundary will prevent any rain from forming along it. If the 
forecast area does see any rain overnight it will be in the far 
northwest corner of the area (warren County and vicinity) which is 
well behind the front and closest to the current band of anafrontal 
precipitation across northern Illinois and southwest Michigan. If this 
precipitation does make it's way southward into the area...it will be in 
the form of rain, as forecast profiles show the colder air should 
remain to our west-northwest across Illinois and northern Indiana. Have thus 
removed most mention of precipitation from the area overnight...save for 
the far northwest corner where we will carry minimal chances for 
rain. 


In terms of low temperatures for overnight this will be very tricky 
depending on frontal progression. Opted to lean toward the NAM since 
this model appears to have a better handle on the slower progression 
of this boundary, which yields temperatures ranging from the middle 30s 
(north) to middle 40s (south). 


&& 


Short term /6 am Sunday through Tuesday/... 
surface low tracks northeast along the stalled frontal Sunday 
through Monday...moving into the Ohio Valley by Monday afternoon. 
Focus for the this period will once again be rain chances. 


Short term models are generally in good agreement with the 
aforementioned scenario...with a few minor exceptions, most 
notably the GFS which takes the most southern track with the 
trough diving into the Gulf region. In any case...all models have 
significantly slowed down the progression of this system. Decided 
not to discount the GFS since it has been correct in showing this 
extreme southern track for the past 2 days, so took a blend of 
GFS/Euro/NAM. 


Based on latest model trends, have tapered back probability of precipitation 
significantly for the next 24 hours, as the best moisture is not set 
to arrive until (at the earliest) Sunday afternoon...but more likely 
Sunday night into Monday...when we will have categorical (south) to 
likely (north). Have extended mention of rain into Monday, at least 
for the eastern half of the area since they could see a few 
lingering showers from the back edge of this system. Used a MOS 
blend for temperatures during the period. 


&& 


Long term /Tuesday night through Saturday/... 
ensembles showing fairly good agreement on the overall pattern through 
Saturday. Operational runs also showing good agreement into Thursday 
with slight timing differences thereafter. A warmup should start 
Tuesday and continue Wednesday with generally upper ridging over the 
area. Another cutoff upper low should set up over the Southern 
Plains on Thursday and slowly move east and should bring chances for 
rain to the area Thursday and into Friday with temperatures falling 
a bit as it GOES by. Generally stuck close to HPC guidance. 


&& 


Aviation...discussion for 18z tafs. 
Front is barely progressing across the forecast area and is for the 
most part stationary from just south of khuf to just north of kmie. 
Mainly northeasterly winds evident north of the front with southerly 
winds to the south of it. MVFR ceilings are lagging the front by 
quite a bit and show little to no sign of advancing. Models have now 
pushed the arrival of rain back by several hours. Will keep 
conditions VFR across all sites but klaf where will bring in MVFR 
very late overnight and in the extended period of the taf at kind. 


&& 


Ind watches/warnings/advisories... 
none. 
&& 


$$ 


Near/short term...smf 
long term...cp 
aviation...cp