Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 192317

Area Forecast Discussion
National Weather Service Northern Indiana
720 PM EDT FRI AUG 19 2016

Issued at 357 PM EDT Fri Aug 19 2016

A few showers and thunderstorms will be possible this evening but
better chances for widespread showers and thunderstorms will be
Saturday afternoon and evening. A cold front will push through the
region Saturday night with cooler and less humid air following for
early next week.


.SHORT TERM...(This Evening through Saturday)
Issued at 355 PM EDT Fri Aug 19 2016

Main Outflow from earlier weak convective system was moving through
forecast area this afternoon with a few scattered showers and
isolated thunderstorms remaining. Hires guidance has not handled
todays convection well which leads to low confidence in this evening
and overnight forecast.

Dirty flow aloft continues with very subtle convectively enhanced
short waves moving through a region with modest to weak instability
and weak shear. Hires guidance seems to be picking up on upstream
convection over IA this afternoon but indicate a weakening trend as
it approaches NE IL. Given poor model performance last few days and
especially with this mornings decaying system have opted to carry
low chance pops through late evening. Afternoon KIWX radar showing
numerous weak boundaries in place which could potentially lead to a
few showers or storms as well.

Focus then shifts to Saturday forecast with approach of more
significant synoptic short wave trough and surface cold front. Water
vapor shows main short wave moving through northern CONUS this
afternoon. This trough expected to become more neutrally oriented
tonight and negatively tilted on Saturday. Result will be
development of a surface low over IA which will lift into WI
Saturday with trailing cold front through our area late in afternoon
and through the evening. Deep moisture surge expected with
increasing thetaE through the day and pwats nearing 2 inches. An
initial moisture surge looks possible in the morning for a low PoP
with best advection later in day closer to front and likely PoPs.

Severe potential remains uncertain and dependent on degree of
destabilization that takes place. Models rather bullish with morning
moisture and RH which would limit instability. However...any breaks
will lead to rapid destabilization and increase the severe potential
slightly. Deep layer shear will be increasing as westerlies drop
south. 0-6km shear climbs to between 20 and 30 knots near cold
front. SPC marginal risk looks good for now given the conditional
and marginal conditions. Heavy rain also a concern given high water
content available. Storms should remain progressive but any training
could pose some local flooding issues if this happens where recent
heavy rainfall occurred.


.LONG TERM...(Saturday Night through Friday)
Issued at 355 PM EDT Fri Aug 19 2016

With focus on the most impactful weather in the short term period
will generally rely on superblend init for this period. High
pressure will build in behind cold front and usher in a refreshing
airmass with highs in the 70s and lows in the 50s with very low
humidity for late August. A couple short waves look to drop
southeast within northwest flow Sunday into Monday. Models trying
to develop a little pcpn but with dry low levels prefer just to go
with some increased clouds at this point and monitor future model
trends. General slow warming trend mid to late week. Another
trough approaches mid week with increasing moisture so chance pops
again but removed likely pops within bullish Superblend init.


.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 720 PM EDT Fri Aug 19 2016

Thunderstorms have dissipated across the area this evening and will
lead to a VFR start for both sites this cycle. Light winds and ample
low level moisture will again create fog potential overnight with
prevailing MVFR at both sites after midnight and possible IFR at
KFWA during the pre-dawn hours. Approaching cold front will bring
prevailing TSRA to both sites Saturday afternoon.


.IWX Watches/Warnings/Advisories...
LM...Small Craft Advisory from 1 PM Saturday to 10 PM EDT Sunday for



SHORT TERM...Lashley
LONG TERM...Lashley

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