Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 160812

Area Forecast Discussion
National Weather Service Northern Indiana
412 AM EDT Wed Aug 16 2017

Issued at 406 AM EDT Wed Aug 16 2017

Today will be another warm and increasingly humid day with
afternoon highs into the middle 80s. There is a chance of
afternoon showers or storms, especially south of Route 30. Chances
for showers and thunderstorms will increase through tonight and
persist through Thursday as a strong frontal system approaches.
Drier and cooler air then follows in the wake of this system on
Friday, followed by another low chance for rain on Saturday.


.SHORT TERM...(Today through Thursday)
Issued at 404 AM EDT Wed Aug 16 2017

Subtle boundary along/north of I-70 could become focus for
convection over southern/southwest CWA by late afternoon as
feature lifts gradually northward along eastern flank warm sector.
Lackluster mid level lapse rates and weak mid level flow to limit
chances/coverage. Better chances late tonight through Thursday as
plains trough moves into western Upper Great Lakes with deep
layer flow extruding moist airmass presently established from Gulf
into MO. While ongoing convection may limit surface heating on
Thu, still conditional severe risk with 35 to 40 kts deep layer
shear and surface dewpoints into lwr/psbly mid 70s to prove
beneficial in garnering pockets of at least moderate instability
/MLCAPE 2000-2500 j/kg/ between any breaks in cloud coverage.


.LONG TERM...(Thursday night through Tuesday)
Issued at 404 AM EDT Wed Aug 16 2017

Little substantive changes from prior forecast. Secondary wave races
across northern CONUS and digs underneath prior trof undergoing
filling over northern Great Lakes/eastern Ontario for low chances
convection on Saturday. And another period of low chance pops early
next week with potential frontal boundary approaching CWA Monday
associated with initially high belted energy through Canada.
Feature then sags southeastward into Upper Great Lakes by Day
7/Tue with surface reflection taking on more east to west
orientation through the southern Great Lakes.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 115 AM EDT Wed Aug 16 2017

Some light fog has been developing across the area overnight. The
airmass has become more humid; but at the same time, some high
clouds have spread over the area making it questionable how low
visibilities will drop. Favor persistence where Ft Wayne has had
at least some light fog most of the past several nights. There is
a very high diurnal fog correlation in August with lowest
visibilities very typically between 09Z to 13Z. Given the recent
observations and trends, the ongoing TAFs appear on track; have
made only minor changes. Chances for showers and storms will be
increasing late in the TAF period. Modification and additions of
showers and storms are likely with the next TAF issuance.




LONG TERM...Murphy

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