Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 220800
AFDIWX

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

.SYNOPSIS...
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 06Z TAFS through 06Z Tuesday Night)
Issued at 1241 AM EDT Tue Aug 22 2017

Generally vfr conditions should cont this taf period, although
briefly mvfr/ifr likely in convection as well as near fropa. TSRA
developing over IL expected to cont tracking ne across nrn IN and
impact both terminals early this morning. Instability should grdly
diminish with diurnal cooling, leading to transition to large
area of shra with just isolated TS by dawn. Lower ceilings should
clear behind the front late aftn/eve. Fropa expected at sbn around
18z and at fwa around 21z.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
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.

OH...NONE.
LM...Small Craft Advisory until 5 PM EDT Wednesday for LMZ043-046.

&&

$$

SYNOPSIS...Marsili/T
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...JT


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