Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 210640

Area Forecast Discussion
National Weather Service Indianapolis IN
240 AM EDT Thu Jun 21 2018

The LONG TERM Section has been updated below.


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 705 PM EDT Wed Jun 20 2018

Reduced pops significantly early in the evening as activity has
struggled to build and maintain itself and coverage of convection
has been steadily waning. Expect things to be relatively quiet,
with only an isolated pop up or two, until somewhat more organized
convection to the west arrives and/or additional development
along the stationary front occurs later tonight. This is well
supported by recent runs of the HRRR. Previous discussion follows.

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 /Sunday through Wednesday/...
Issued at 238 AM EDT Thu Jun 21 2018

Ensembles have come into better agreement tonight on the upcoming
weather pattern in the extended. Trailing end of the upper trough
that is expected to affect the area during the short term will be
in the process of moving over the local area on Sunday. Will keep
some PoPs in the forecast for Sunday to cover this feature.

Upper ridging is expected to temporarily move over the area early
next week, before the next trough approaches from the Plains towards
the middle of next week. Will go with a dry forecast for Monday and
Tuesday under the upper ridge, and add chance PoPs for Wednesday as
the next trough approaches.


.AVIATION (Discussion for the 21/06Z TAFs)...
Issued at 1155 PM EDT Wed Jun 20 2018

VFR expected for the first several hours of the period. MVFR
conditions, and perhaps some brief IFR, will develop later tonight
into Thursday as showers and storms overspread the area with
passage of a frontal system.

Will limit convective mention to VCTS owing mainly to timing and
coverage concerns. Expect activity to be mainly showers with
embedded thunder.

Ceilings will lower as the frontal system passes. Appears most
areas will remain MVFR but IFR may occur briefly.

Visibilities will be unrestricted outside of precipitation.

Winds through the period will be 10KT or less, occasionally




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