Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 201042

Area Forecast Discussion
National Weather Service Northern Indiana
400 AM EDT SAT AUG 20 2016

Issued at 337 AM EDT Sat Aug 20 2016

A cold front will move through the region during the afternoon and
evening hours with showers and thunderstorms along and ahead of
it by afternoon and progressing east into this evening. Cooler
and much less humid air will arrive starting tonight and linger
into the start of the new work week. Highs will reach the upper
70s to lower 80s with lows in the lower 60s.


.SHORT TERM...(Today and Tonight)
Issued at 337 AM EDT Sat Aug 20 2016

Challenging forecast in store with regards to convective chances
into this evening ahead of a strong cold front and seasonably
strong upper level trough. Hi-Res models paint several
scenarios with the potential for up to 3 rounds of precipitation.
First is with increasing low and mid level theta e advancing
across eastern Illinois where washed out frontal/outflow
boundaries reside. Models have bounced back and forth on this and
seems the least likely with anything that could form on the nose
of the theta e moving in near 12z. Will maintain slgt chc pops
around 12z but suspect nothing will be occurring. Second round
will be pre- frontal trough currently firing convection from far
eastern Iowa to western Illinois. Extrapolation of this arrives
near/after 15z. However...several Hi- Res models tend to weaken
this area and indicate additional development taking place.
Lastly, if enough recovery can take place...sufficient forcing
will exist on the cold front with little in the way of scouring of
moisture. However by this time, atmosphere could be rather worked
over if this is indeed round 3. To complicate matters even more,
cloud cover may be rather extensive with only pockets in increased

With plenty of moisture to work with, increasing low level jet in
response to deepening sfc low moving across the northern lakes and
approaching trough, most if not all places should see at least 1
shower or thunderstorm. However, given the plethora of
possibilities and timing issues, cannot justify categorical pops
at this point. Main concern with convection will be heavy rainfall
with pwats over 1.5 inches and pushing 2 inches along the front.
Severe parameters not stellar, but enough low level shear to at
least sustain convection and bring a risk of wet microbursts.
Marginal risk remains in the SWODY1 outlook. HWO will mention
strong storms, but downplay severe threat given above concerns.

Have sped up departure of any precip this evening as forecast area
could be clear before midnight. Cooler and less humid air will
begin to move in.

One other note. With winds and waves increasing over SE Lake
Michigan this afternoon into Sunday have hoisted a Beach Hazard
Statement with moderate to high risk of rip currents.


.LONG TERM...(Sunday through Friday)
Issued at 337 AM EDT Sat Aug 20 2016

High pressure will begin to take control and hold strong into at
least Tuesday night. Highs will generally be in the 70s with lows
in the 50s. Rain chances will increase ahead of the next trough
and series of disturbances but timing/location issues warrants not
going with likely pops introduced by the Superblend.


.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 642 AM EDT Sat Aug 20 2016

Narrowing of shrt term highres solution scope affords some minor
timing changes to prior 06Z fcst which remains on track. Low level
waa wing/theta-e burst within modest low level jet continues to
spark convection fm srn WI southward into srn IL albeit more broken
owing to as yet poorly organized forcing downstream of sw through
ejecting out of SD. Xpcd this will change rather quickly through
morning as sfc based heating ensues and low level flow upticks
further ahead of intensifying sfc reflection over ern WI.

Additional development xpcd along trailing cdfnt by mid aftn w/a
period of mvfr restriction likely in tsra. Otrws post fntl caa
sweeps in tonight w/extensive low vfr based stratocu likely.


.IWX Watches/Warnings/Advisories...
IN...Beach Hazards Statement from noon CDT today through Sunday
     evening for INZ003.

MI...Beach Hazards Statement from 1 PM EDT this afternoon through
     late Sunday night for MIZ077.

LM...Small Craft Advisory from 1 PM this afternoon to 1 AM EDT Monday
     for LMZ043-046.



LONG TERM...Fisher

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