Area forecast discussion 
National Weather Service Indianapolis in 
1251 PM EDT Thursday Sep 18 2014 


Update... 
the aviation section has been updated below. 


&& 


Synopsis... 
issued at 350 am EDT Thursday Sep 18 2014 


A very weak and dry cold front will push south across our region 
today. High pressure will build into the Great Lakes late today and 
tonight. The high pressure system will move on to the east Friday 
and Saturday...but a ridge will extend west across our region. 
Temperatures will become warmer towards Saturday as an upper ridge 
over the central and western U.S. Temporarily builds towards the 
Ohio Valley. 


A cold front will move south across our region Sunday. High 
pressure behind this cold front will dominate our weather Monday 
through Wednesday of next week. 


&& 


Near term /this afternoon/... 


Issued at 942 am EDT Thursday Sep 18 2014 


Surface analysis late this morning shows high pressure in place 
over the Great Lakes and Ontario...providing a cool and dry 
northeast surface flow to central Indiana. Dew points remained in 
the comfortable upper 40s to around 50. 


Forecast soundings reveal convective temperatures that are 
unattainable. Time height sections also show a dry column with 
subsidence. Furthermore upper ridging across The Rockies is 
expected to begin a slow push eastward toward the Mississippi and 
Ohio River valleys today. Thus only sunny skies are expected today 
with a few cumulus possible. 


As for temperatures...ongoing forecast highs seem quite reasonable given 
weak cold air advection in place from the northeast and latest lav 
guidance. 


Overall...sunny skies and a pleasant afternoon is expected. Only 
minor changes made in the grids. 


&& 


Short term /Friday through Saturday night/... 
issued at 350 am EDT Thursday Sep 18 2014 


Dry conditions along with a warming trend will be the rule through 
Saturday as the high pressure system moves on to the east...but a 
surface ridge remains across our region at least into early 
Saturday. 


Models move a cold front south into our region by early Sunday which 
will generate scattered thunderstorms across our region by Saturday 
night. The Euro brings precipitation into our far northwest by late 
Saturday. But most most models keep US dry until Saturday night. In 
regards to probability of precipitation went with a model blend with thunderstorms becoming 
likely over northern sections and chance probability of precipitation elsewhere Saturday 
night. 


In regards to temperatures went closer to the cooler met 
temperatures on Friday and towards the warmer mav numbers Saturday. 
850 mb temperatures will be from +9 to +12 celsius early Friday 
warming to +16 to +18 celsius by late Saturday. Went with a model 
consensus on temperatures most other periods. 


&& 


Long term /Sunday through Wednesday/... 
issued at 350 am EDT Thursday Sep 18 2014 


A cold front moving through central Indiana will keep chances for 
thunderstorms in the forecast on Sunday. Models have been trending 
faster with this feature so took out any lingering probability of precipitation on Sunday 
night. The remainder of the long term looks dry with upper ridging 
overhead and high pressure at the surface. Temperatures will remain 
below normal throughout. 


&& 


Aviation /discussion for the 181800z tafs/... 
issued at 1251 PM EDT Thursday Sep 18 2014 


Scattered diurnal cloud cover based around 040 expected to dissipate 
around sunset. 


Based on expected crossover temperatures...patchy MVFR visibility 
restrictions may develop in the rural areas towards 190600z. 


Surface winds 050-070 at 6-8 kts this afternoon will diminish to 6 
kts or less after sunset. 


&& 


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


$$ 


Synopsis...jh 
near term...puma 
short term...jh 
long term....cp 
aviation...jas 


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