Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 152328
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
728 PM EDT Tue Aug 15 2017

.SYNOPSIS...
Issued at 718 PM EDT Tue Aug 15 2017

Dry conditions are expected overnight into Wednesday morning with
patchy fog possible. Lows tonight will drop into the 60s, with
highs on Wednesday in the low to mid 80s. A couple rounds of
showers and thunderstorms will be possible from Wednesday
afternoon into Thursday as a low pressure system tracks into the
Great Lakes region. Drier and cooler air then follows in the wake
of this system on Friday, with another low chance for rain on
Saturday.

&&

.SHORT TERM...(This Evening through Wednesday)
Issued at 253 PM EDT Tue Aug 15 2017

Isolated showers/storms will remain possible across nrn IN/nw OH
into the late afternoon and early evening near a remnant cold
front/aggregate lake breeze. Coverage/chances/intensity will be
limited by dry mid levels and warm profile.

Dry conditions are expected tonight into most of Wednesday as
shortwave ridging amplifies in advance of an upper trough ejecting
east into the Central US. MOS and SREF probabilities are relatively
aggressive with fog/stratus development overnight given light winds,
mainly clear skies and lingering near surface moisture near diffuse
boundary (best chances across portions of ne IN/nw OH).
Coverage/impact of any fog is uncertain at this range, especially in
the north as some drier air settles in post-frontal.

A few showers/storms may pop up during the mid-late afternoon hours
tomorrow along/southwest of US 30 near an instability gradient.
Lacking flow/forcing should keep any convection below severe limits.
Temperatures tonight/Wednesday are expected to be similar to
today otherwise.

&&

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 253 PM EDT Tue Aug 15 2017

Good surge of moisture and elevated instability (PWATS nearing 2"
and sfc dewpoints up near 70F) Wednesday night into Thursday morning
will set the stage for increasing rain/thunder chances. This will
occur as ramping southwest flow (in advance of the above mentioned
upper trough) forces a warm front northeast into the region, with
the best chances for precipitation likely later Wednesday night
into early Thursday. System cold front and/or pre- frontal trough
then becomes the potential trigger for additional convection
during the afternoon and evening on Thursday. 30-35 knots of deep
layer shear and the potential for a moderately unstable boundary
layer in warm sector may present a conditional severe risk by
Thursday aftn/eve, though expected cloud contamination and poor
lapse rates thanks to warm/moist profile appear to be limiting
factors for severe wx at this time. As a result have no problem
with SPC`s marginal risk.

Dry/less humid air will lead to fair weather and cooler temps post-
frontal into Friday. The next shortwave in persistent wnw flow aloft
amplifies through the region on Saturday with the next chance for
showers/storms. Dynamics with this system appear decent for August
standards, however, moisture return is somewhat limited resulting in
low chance PoPs for now. Subsidence/height rises then allow high
pressure to build in for Sunday and Monday with fair wx.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 718 PM EDT Tue Aug 15 2017

VFR this evening into the overnight hours with mostly clear skies
and light and variable winds. Crossover temps to be reached
overnight and with light wind field and residual moisture could
see some fog formation outside of typical mid summer corn canopy
ground fog. Best chances look to be southeast but HRRR and SREF
probs not as pessimistic as earlier. CONS blends still showing
areas of 2sm or less in the southeast and have kept IFR mention at
KFWA but just MVFR at KSBN. Conditions improve Wednesday after
sunrise to VFR but mid level deck and some CU possible as next
system approaches. Small chances for shra late Wednesday toward
00z but not worthy of another line in terminals given late arrival
and uncertainty.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...Steinwedel
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...Lashley


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