Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 171012

Area Forecast Discussion
National Weather Service Northern Indiana
612 AM EDT Sun Sep 17 2017

Issued at 348 AM EDT Sun Sep 17 2017

A weak frontal boundary will enter the region, bringing chances
for showers and thunderstorms into Tuesday night. High today will
reach the low to mid 80s before cooling slightly into the upper
70s to lower 80s for Monday and Tuesday.


.SHORT TERM...(Today and Tonight)
Issued at 348 AM EDT Sun Sep 17 2017

Low level moisture advecting into western areas was allowing for the
day starting in the mid to upper 60s (mid 50s to lower 60s east).
Little more than some cirrus from upstream, likely dying convection,
will invade the sky through the morning. Temperatures will climb
into the 80s across the area with dewpoints in the lower to middle
60s by afternoon resulting in 1000 to 2000 J/KG of surface based
CAPE. Limited convergence along a weak frontal boundary as well as
increased flux of sfc/850 mb theta-e will increase lift along the
boundary and allow widely scattered to scattered
shower/thunderstorm development. Shear is almost non existent
resulting in poorly organized storms and minimal if not zero
severe risk.

NAM12 showing some lingering forcing and sporadic showers behind the
front tonight. Can`t fully rule out with frontal boundary not that
far east of the area so will leave chc pops in and let day shift
look at model runs.


.LONG TERM...(Monday through Saturday)
Issued at 348 AM EDT Sun Sep 17 2017

After a brief lull Monday morning, the frontal boundary just to
the south will likely light up again with showers and
thunderstorms as a slightly stronger wave approaches. Models past
couple of days have attempted to bring low likely pops in western
areas as convection develops to the west and moves in mainly Mon
night into Tues. Consensus has been to nudge back to high chance
with more of a scattered coverage once again.

After Wednesday, the region looks to be sandwiched between
building upper level ridge to the east and deepening trough to the
west. This should result in a generally dry forecast and return
to above normal temperatures in the 80s. Had to remove spurious
pops added in by blend of models. Can`t rule out a wave riding the
ridge and getting close enough to western areas for a stray
shower, but no worth mention at this point.


.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 556 AM EDT Sun Sep 17 2017

WAA ahead of cdfnt over nw IL resulting in sct-bkn 6-7kft based
clouds across nrn IN early this morning which is expected to
persist into this aftn with some diurnal cu also developing. Cdfnt
should move into nw IN this aftn and then slowly se tonight. Band
of post-frontal showers expected to intensify some this aftn as
airmass destabilizes. Still some uncertainty in how widespread
showers/tstms will be and on timing, especially of any pre-
frontal development, so for now plan to just continue with a
period of VCTS in the tafs for this aftn/eve. Some post frontal
stratus/fog lowering flight conditions to mvfr likely behind this
slow moving front tonight with ifr also possible.




LONG TERM...Fisher

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