000 
fxus63 kind 202016 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
416 PM EDT Wed Jun 20 2018 


Update... 
the synopsis...near term and short term sections have been 
updated below. 


&& 


Synopsis... 
issued at 407 PM EDT Wed Jun 20 2018 


A frontal boundary will continue linger across the forecast area 
as a low pressure system approaches and pushes through the area on 
Friday and Friday night. This will keep continued shower and 
thunderstorm chances in the forecast to end the work week. 
Temperatures will cool to near or slightly below normal through 
the weekend. 




&& 


Near term /tonight/... 
issued at 407 PM EDT Wed Jun 20 2018 


The tonight timeframe begins with ongoing convection in or near 
the forecast area again. Frontal boundary will be draped west to 
east across the area. Even with the loss of heating...short-range 
forecast models depict convection continuing along and south of 
the front overnight as the front lingers over central Indiana and 
an upper level disturbance pushes closer to the area. Heavy 
rainfall remains a possibility with precipitable water in the 
1.75-2.10 inch range and slow storm motions. Even with CAPES up to 
1000 j/kg...the limiting factor for more organized convection 
continues to be the lack of wind shear. However, an isolated 
damaging wind gust cannot be ruled out completely though. For min 
temps, went closer to the warmer mav guidance staying a couple to 
a few degrees above guidance for lows tonight. 


&& 


Short term /Thursday through Saturday/... 
issued at 407 PM EDT Wed Jun 20 2018 


The aforementioned frontal boundary is forecast to linger across 
the area through Thursday night before pushing north as a warm 
front as the surface and upper level low pressure centers lift 
northeast across the forecast area Friday and Friday night. This 
will act to keep chances for showers and thunderstorms in the 
forecast during most every period...with rain showers winding down 
on Saturday. As the upper low approaches Thursday and Thursday 
night...wind shear increases slightly possibly allowing for more 
organized convection. With pwats in the 1.80-2.10 inch range for 
much of Thursday morning into the early afternoon coupled with a 
slightly increased low-level jet signature of 15-20 kts...decided 
to go with the highest pops of the period during this timeframe. 
The forecast for the track of the surface low has seemed to pick 
up some steam as many of the model solutions have the low pushing 
northeast across the northwest half of central Indiana on Friday 
and Friday night...keeping showers and thunderstorms in the 
forecast over much of the area. Flooding will continue to be an 
issue through Friday as heavy rainfall looks to remain the primary 
threat into Friday night. Cannot rule out an isolated damaging 
thunderstorm gust on Thursday or Friday. Showers look to come to 
an end from west to east Saturday morning into midday. 


Below normal Max temps are expected through the timeframe as upper 
level ridge gets shunted southward as the upper low approaches and 
impacts the area. Stuck fairly close to the regional 
initialization blend. With a frontal boundary meandering across 
the forecast area...temps will be heavily impacted by increasing 
cloud cover/convective debris, precipitation, and outflow 
boundaries. Just something to keep in mind over the next few days 
as it pertains to temperatures. 


&& 


Long term (saturday night through wednesday)... 
issued at 145 PM EDT Wed Jun 20 2018 


There are strong indications Monday will be dry with seasonable 
temperatures. Otherwise forecast confidence is low. 


The models agree about high pressure controlling Indiana weather 
Monday. Consensus temperatures should be accurate to within 2 
degrees. 


The GFS and European models don't agree well about how fronts will 
affect our weather either before or after Monday. Thus they don't 
agree well about rain chances or temperatures. 


Based on similar situations recently, it is too soon prefer a model. 
Consensus should be the best prediction. Temperatures from today's 
forecast may need to be adjusted by as much as 5 degrees. Pops for 
any given period could change by more than 20 percent. 


&& 


Aviation (discussion for 201800z tafs)... 
issued at 1251 PM EDT Wed Jun 20 2018 


There will be scattered thunderstorms early in the period. Storms 
should become more widespread late tonight or early Thursday as a 
warm front affects Indiana. Storms may cause brief vlifr in very 
heavy rain, along with gusty winds. 


Otherwise, expect mostly VFR with areas of MVFR ceilings early in 
the period. Beginning late tonight MVFR should predominate. 


The wind is going to be variable but mostly 6 knots or less. 




&& 


Ind watches/warnings/advisories... 
none. 


&& 


$$ 


Synopsis...mrd 



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