Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Indianapolis in 
711 PM EDT Tuesday Jun 18 2013 


Update... 
the aviation section has been updated below 


&& 


Synopsis... 
issued at 330 PM EDT Tuesday Jun 18 2013 


A cold front will move through the area early tonight bringing 
scattered thunderstorms. Overnight high pressure will build in and 
then persist across the area through the end of the work week. 
Another system could bring some more rain early next week. After a 
brief cool down Wednesday...above normal temperatures will return 
for the weekend into early next week. 


&& 


Near term /late this afternoon and tonight/... 


Issued at 330 PM EDT Tuesday Jun 18 2013 


Scattered thunderstorms have formed across central Illinois along 
the cold front...and these will spread east-southeast across the 
southern half of central Indiana this evening. Meanwhile isolated 
storms have formed across northern Illinois. 


An upper trough and an upper jet will move across the area late this 
afternoon and early this evening. These should aid in scattered 
thunderstorm development...especially near the cold front. Plenty of 
instability around as well. Will go high chance probability of precipitation south before 
00z with chance or slight chance north. 


After 00z...will keep slight chance probability of precipitation north /as storms are across 
northern Illinois at the moment/ and chance probability of precipitation south. Will quickly 
diminish probability of precipitation though as instability wanes after sunset. Will be dry 
all areas before 06z. 


There could be some strong to severe storms across southern sections 
of the area ahead of the front...and Storm Prediction Center has this area in a Severe 
Thunderstorm Watch until 02z. 


For temperatures went closer to the warmer met MOS numbers since 
drier air is taking is time coming south behind the front. 


&& 


Short term /Wednesday through Friday/... 


Issued at 330 PM EDT Tuesday Jun 18 2013 


Focus is on any chances for rain...then on sky and temperatures. 
Models are close enough with most features that a blend can be used. 


High pressure will move in during the short term...with an upper 
ridge just to the south and west. 


The NAM keeps a dewpoint gradient across the forecast area...and 
then generates isolated convection along it at times during the 
short term. However the NAM looks too high with its 
dewpoints...especially compared to the other models. Thus believe 
NAM/S convection is also overdone...so will keep forecast dry 
through the short term. 


Skies will be clear to partly cloudy during the period with the high 
in control. For temperatures generally stuck with a blend which 
looks good given expected sky cover and dewpoints. 


&& 


Long term /Friday night through Tuesday/... 


Issued at 147 PM EDT Tuesday Jun 18 2013 


An upper ridge will maintain control over the region through most 
of the extended period...however there will be periods where it 
will weaken or break down slightly as a few short waves cross 
through the region and bring small chances for showers and 
thunderstorms to the region starting Sunday and continuing through 
early next week. Allblend handled the pattern well so did not 
deviate except for quality control. 


&& 


Aviation /discussion for the 19/0000z taf issuance/... 


Issued at 702 PM EDT Tuesday Jun 18 2013 


The severe threat has diminished across taf sites...but there is 
still potential for isolated pop-up storms through sunset. This 
activity would be too isolated to mention in tafs though at this 
time. High pressure/subsidence will build into central Indiana 
tonight...resulting in clear skies and VFR conditions for duration 
of taf period. Winds have already shifted to the northeast at kind 
and klaf...and they will do so at khuf and kbmg as well within 
the next few hours. Sustained speeds will range from 5 to 10 kts. 




&& 


Ind watches/warnings/advisories...none. 


&& 


$$ 


Synopsis...50 
near term...50 
short term...50 
long term....smf 
aviation...tdud 


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