Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 221043

Area Forecast Discussion
National Weather Service Northern Indiana
643 AM EDT Tue Aug 22 2017

Issued at 351 AM EDT Tue Aug 22 2017

Showers and isolated thunderstorms will impact the area until the
passage of a cold front today. Drier, cooler and less humid
conditions will arrive and lingering into the weekend with a slow
warm up into next week.


.SHORT TERM...(Today and Tonight)
Issued at 351 AM EDT Tue Aug 22 2017

Focus will be on convective chances through mid afternoon ahead
of a seasonable strong cold front.

Broken line of showers and storms that developed across NE Illinois
has been spreading east across the area over the past couple of
hours. Lightning strikes have diminished somewhat as the area
encounters slightly more stable air than further west, yet enough
still exists that combined with a 35 to 40 kt low level jet is
allowing for expansion of stratiform precip. In addition this same
low level jet and pre existing boundary to the south was providing a
focus for redevelopment from White County back to the west into
Illinois. A stratiform area of rain with embedded storms was also
expanding and moving towards the northeast. HRRR has been signaling
this setup the past couple of runs and with it appearing to be
taking shape have opted to increase pops into categorical in the 8
to 13Z window. Exact northern and eastern extent still questionable
so haven`t gotten to carried away. As for risk of severe, marginal
risk still remains across SE areas. Suspect this will be able to be
removed in later outlooks this morning as effective boundary should
be well SE of the area. HRRR does develop some scattered showers
before the front passes through and can`t rule this out, but should
be sub severe with best dynamics and instability east.

Once the front clear, quiet weather returns with only item to note
being the increasing west to northwest flow over Lake Michigan and
increasingly dangerous swim conditions tonight into the start of the
long term.


.LONG TERM...(Wednesday through Monday)
Issued at 351 AM EDT Tue Aug 22 2017

No sensible weather concerns for the long term as Great Lakes upper
level trough remains in place into the weekend before models diverge
on evolution of the upper flow as a stronger wave moves through
western Canada over the weekend. Temperatures will remain on the
cooler side by late August standards until towards the end of the
period with slight moderation to near normal.

Next chance for any precip may be in the form of remnants of
"Harvey" that is forecasted to reorganize over the southern Gulf
next week. Both GFS and ECMWF show this moving towards the NE into
the Great Lakes/Ohio Valley area but differ considerably on timing
and track (as would be expected this far out). Precip could start
arriving by the Monday if faster GFS solution occurs vs more of a
delay until mid to late week with ECMWF/Canadian. Will grudgingly
hold onto slgt chc pops Monday.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 640 AM EDT Tue Aug 22 2017

Convective remnant disturbance in concert with apchg upr level
trof causing a large area of shra movg across nrn IN this morning.
Ceilings/vsbys have been lowering in this area of shra and expect
that to cont until it moves east of the area late this morning
with mvfr/ifr conditions in the meantime. TS should remain south
of the terminals but may be close at FWA as storms movg ene along
srn edge of large rain shield. Otrws just an isolated TS embedded
in the rain, and not mentioned in tafs. Sw winds will be gusty
and shifting to nw this aftn as cdfnt moves se across the area.
Clouds should clear out fairly quickly behind the front with vfr
conditions expected tonight.


IN...Beach Hazards Statement from 10 AM CDT this morning through
     Wednesday afternoon for INZ003.

MI...Beach Hazards Statement from 11 AM EDT this morning through
     Wednesday afternoon for MIZ077.

LM...Small Craft Advisory until 5 PM EDT Wednesday for LMZ043-046.



LONG TERM...Fisher

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