Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 201738

Area Forecast Discussion
National Weather Service Northern Indiana
138 PM EDT WED JUL 20 2016

Issued at 342 AM EDT Wed Jul 20 2016

Humidity will gradually increase today as high pressure moves
away from the area and southerly winds develop. This may allow
isolated thunderstorms to develop west of I69 this afternoon and
tonight. Highs today will be in the upper 80s with lows tonight
in the upper 60s and lower 70s.

Hot and humid conditions are expected Thursday through Sunday as
an upper level ridge over the plains builds east into the midwest.
There is a low chance of thunderstorms through this period with
the best chances Thursday night and Sunday.


.SHORT TERM...(Today and Tonight)
Issued at 342 AM EDT Wed Jul 20 2016

MCS movg into swrn IN is expected to dissipate as it moves into
more stable airmass this morning...likely before impacting swrn
portion of our cwa. High pressure ridge over the grtlks expected
to shift se into the Oh valley today veering low level winds to
sswly across wrn portions of the cwa leading to gradual increase
in moisture/instability which combined with wk waa may allow
isolated showers/tstms to develop this aftn. Temps should be
similar to yday with wk waa offset by more cloudiness resulting
in highs mainly in the u80s.

Potential for isolated diurnal convection should linger into the eve
over wrn portions of the cwa, and with some cams suggesting another
mcs will dvlp over wi tonight and move sse, maintained low pops in
this area through the ngt. Warming trend will cont tonight with wk
waa/southerly flow limiting lows to the u60s/l70s.


.LONG TERM...(Thursday through Tuesday)
Issued at 342 AM EDT Wed Jul 20 2016

Contd warm/moist advection should lead to a very unstable airmass
over wrn portions of the cwa thu. Again forcing lacking but wk waa
pattern may support isolated tstms. A little better forcing
expected thu ngt as a shrtwv moves east across the upr grtlks
pushing a wk backdoor cdfnt across lwr mi. Instability over our
area may be sufficient by that time to sustain an mcs dropping
s-se overnight. Diurnal heating fri should allow airmass to
become extremely unstable. Upr forcing lacking but sfc boundary
may drop south from MI into our area friday and linger into friday
night providing focus for isolated deep convection. Sfc boundary
should lift back n-ne on Saturday as a stronger shrtwv and
accompanying sfc low/cdfnt move east into the nrn plains. Just a
slight chc of tstms through this timeframe as warm sector
associated with low to the nw overspreads the area. Better chc for
tstms moves in sunday as the cdfnt associated with this system
moves through the area. This should be followed by cooler/drier
conditions early next week.

Temps/heat indices remain a concern Thu-Sun. Appears heat
advisories will be needed over at least a portion of our cwa each
of these days with latest forecast temps/dwpts suggesting srn
parts of the cwa may be close to warning criteria. With just borderline
advisory criteria fcst over just wrn portion of cwa for Thu and
with some potential for convection thu ngt leaving cloud debris
and somewhat rain cooled air over the area fri, uncertainty
remains high enough to preclude introducing heat headlines attm.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 136 PM EDT Wed Jul 20 2016

Convection to the west of Indiana this aftn will likely provide
some high overhead cloud deck to KSBN with some diurnal cu for
both sites. SSW winds of 7 to 10 kts will subside this evening to
around 3 kts. An isolated tstm is possible this aftrn, but opted
to not mention in fcst.


.IWX Watches/Warnings/Advisories...



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