Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 190803

Area Forecast Discussion
National Weather Service Northern Indiana
403 AM EDT FRI AUG 19 2016

Issued at 357 AM EDT Fri Aug 19 2016

Warm and humid conditions will persist through Saturday with a
slight chance of a shower or thunderstorm this afternoon. Highs
will reach the lower to middle 80s. A generally quiet night is
expected with increasing chances for showers and thunderstorms
late Saturday afternoon into Saturday night as a cold front sweeps
across the area.


.SHORT TERM...(Today and Tonight)
Issued at 357 AM EDT Fri Aug 19 2016

Outflow boundary, from convection that developed upstream this past
evening, was making its way across the forecast area with at best
widely scattered showers and an isolated storm. Stratiform precip
was quickly falling apart across Northern Illinois with loss of
forcing and refocusing of convection now back into Iowa and
Minnesota where storms were moving to the east and northeast.
Challenge today will be effects of the outflow moving through and
remnant mcv that will track se out of wisconsin into the area this
afternoon. Limited instability will be in place with little shear.
Chance exists that measurable rain may not occur as large stable
bubble could settle into the area. Have opted to go dry in the 12 to
18z window but hold with at least a 20 pop this afternoon for threat
of a pop up shower or storm. Assuming cloud cover can clear out,
highs in the lower to middle 80s should be in store with a warm and
muggy night as we await the approach of the advertised trough which
will be moving through the eastern plains tonight.


.LONG TERM...(Saturday through Thursday)
Issued at 357 AM EDT Fri Aug 19 2016

Main story will be approach of strong trough digging into the
western great lakes at the start of the period. Previous forecast
generally kept intact with trough and associated cold front set to
move into western areas late Saturday afternoon and progress east
Saturday night. Some hints that arrival in the west could be a few
hours slower...but given strong and progressive nature of the
trough have kept with previous trends. superblend of models brings
in marginal categorical pops into far nw sections. With the best
convergence and forcing on or just ahead of the front best
scenario will be for a broken to possible solid line of showers
and storms to move through. marginal risk for severe storms in
place for the day as 1000-1500 j/kg of sfc based CAPE arrive with
the front along with pwats around 2 inches. timing and amount of
destabilization will play a factor in severe potential with
greater threat remaining heavy rainfall.

Trough will clear the area by Sunday morning...with much cooler and
less humid air arriving with highs only in the 70s. Return flow will
be slow to establish but should materialize by mid week. A series of
waves will bring slgt chc to chc pops through the end of the period.


.AVIATION...(For the 06Z TAFS through 06Z Friday Evening)
Issued at 141 AM EDT Fri Aug 19 2016

Complex fcst this period. Upstream arc of convection ovr nrn IL has
turned south following outflow surge and axis of low level theta-e
ridge. Hwvr ern flank of outflow likely to bubble further east for a
time yet this morning of which may come close to KSBN terminal.
Point chances of this occurring appear minimal though and will defer
mention at this time.

Primary question going forward is influence of well developed MCV
over se WI as it tracks into wrn lwr MI this aftn. Short term
highres guidance suggests favorable destabilization will ensue
through this morning yet complicated by eventual layout of
stabilizing post outflow bubble. Regardless swwd trailing arc of MCV
maybe enough regardless to spurn new convective initiation across
nrn IN/srn MI toward 18Z. Will forego a mention just yet in favor of
trends in near term guidance and reaccess with 12Z fcst.

Otrws general vfr xpcd underneath considerable high cloud debris
overnight yet concede a transient period of mvfr restriction
possible assuming sufficient clearing.


.IWX Watches/Warnings/Advisories...


LONG TERM...Fisher

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