Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 111051

Area Forecast Discussion
National Weather Service Northern Indiana
651 AM EDT Fri Aug 11 2017

Issued at 331 AM EDT Fri Aug 11 2017

A cold front will move across the area today bringing a chance of
showers and thunderstorms, especially across southeast portions of
the area. High pressure will build in tonight with cooler and
drier overspreading the area which should then persist through
the weekend. Dry weather will continue early next week with a slow
warming trend as the high shifts to the east and southerly flow
returns. This may allow for scattered showers and thunderstorms to
return to the area by late next week.


.SHORT TERM...(Today and Tonight and Saturday)
Issued at 331 AM EDT Fri Aug 11 2017

Cdfnt movg through nw IL/srn WI expected to move across nw portion
of our cwa this morning and across the se this aftn/eve. Sct
showers/tstms have moved well ahead of the front in area of low
level theta-e advection from our cwa to central IL. Showers and a
few tstms may continue in this area as wk low level convergence
persist this morning. This would limit diurnal heating ahead of
the cdfnt today preventing destabilization and likely leading to
stronger storms developing just e-se of our cwa this aftn.
However some models, in particular NAM 12km suggests there will be
sufficient diurnal heating to allow for moderate instability to
develop across the se portion of our cwa this aftn, which combined
with 30-35kt deep layer shear will provide an opportunity for
isolated marginally svr wind/hail storms.

Rather strong caa will develop behind the cdfnt tonight.
This combined with cyclonic low level flow and a secondary shrtwv
movg through backside of upr trof over the central grtlks will
result in incrsg low clouds overnight lingering into Saturday
morning. A few sprinkles or patchy drizzle psbl in this timeframe
but not included in fcst attm. Low clouds should mix out to a sct cu
deck in the aftn as ridging builds in, allowing temps to climb into
the m70s over most of the cwa, a little cooler near the lake where
brisk n-nw winds expected, causing high waves/rip currents/
dangerous swimming conditions.


.LONG TERM...(Saturday Night through Thursday)
Issued at 331 AM EDT Fri Aug 11 2017

High pressure will continue to build across the area Sat ngt
providing cool/clear conditions with lows in the l-m50s. A shrtwv is
expected to dig se into the nrn plains Sat ngt causing tstms to
develop and spread east into srn MN/nrn IA. This activity will
dissipate as it moves into cooler/drier air associated with sfc
ridging over WI, but may spread some convective debris clouds across
our area Sunday. Temps will remain a bit blo normal with highs in
the m-u70s.

Medium range models in better agreement now that weekend nrn plains
shrtwv will shear out as it moves across the grtlks early next week.
Low level response and sgfnt moisture will remain south of our area
with dry wx contg. Ridging sfc and aloft will move across the
Midwest Tue-Wed providing contd dry wx with a slow warming trend to
temps at or a bit above normal for a change. This ridge will move
east of the area late week with upr flow becoming more zonal. Models
have sgfnt timing differences with shrtwv`s embedded in this flow
but sufficient support for one impacting our area wed ngt-thu to add
slight chc of showers/tstms to fcst.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 644 AM EDT Fri Aug 11 2017

Upper level jet support from the left exit region was waning over
the area. There should be several hours before convection
redevelops ahead of a cold front. For now, have kept the mention
of vicinity thunder at FWA but adjusted the time. Went with a 3
hour window from 18-21Z. Winds should become northwest later
today/this evening behind the front.





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