Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 092340

Area Forecast Discussion
National Weather Service Northern Indiana
740 PM EDT Wed Aug 9 2017

Issued at 740 PM EDT Wed Aug 9 2017

High pressure will continue to provide mainly clear skies, light
winds, and seasonable temperatures through Thursday. A cold front
will swing through Thursday night into Friday with chances for
scattered rain showers and perhaps a few thunderstorms. Cooler and
drier air then filters in this weekend into early next week.


.SHORT TERM...(This Evening through Thursday)
Issued at 307 PM EDT Wed Aug 9 2017

An expansive low level ridge centered from the Lower Great Lakes
east toward the Mid Atlantic will gradually shift east tonight into
Thursday with winds becoming more south-southwest tomorrow. This
will remain the dominant feature resulting in more dry/fair wx
and continued slow warming trend.


.LONG TERM...(Thursday Night through Wednesday)
Issued at 307 PM EDT Wed Aug 9 2017

A seasonably strong shortwave over the Dakotas this afternoon will
minor east-southeast through the Great Lakes by Thursday night-
Friday. A leading pre-frontal trough type feature on the leading
edge of height falls may allow showers and perhaps a rumble of
thunder to survive into areas mainly west of I-69 Thursday night.
The associated primary cold front then swings through on Friday with
additional showers/isolated thunder chances. Surface dewpoints
increasing into the low-mid 60s under cool cyclonic flow aloft
should support at least weak boundary layer destabilization near
this convergent boundary, though local area split in between better
large scale support to the north, and more pronounced theta-e return
through the Mid MS Valley, precludes anything more than a 30-40% PoP
at this fcst range. Models suggest 30-35 knots of deep layer shear
possible on Friday. However, meager lapse rates and lacking moisture
should limit the severe potential if any convection develops in the

Below normal temps/humidity levels and mainly dry conditions are
expected this weekend into next week as longwave troughing takes
hold across Eastern NOAM. Cannot completely rule out shower chances
Sunday into early next week, especially Sunday-Sunday evening south
of US-30, as a series of smaller scale perturbations rotate through
in wnw flow aloft. With that said opted to hold with a mainly dry
forecast given overall dearth of moisture with main baroclinic
zone settling off to the south.


.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 739 PM EDT Wed Aug 9 2017

Steadfast surface ridge over the southern portion of the Great
Lakes to provide long duration of VFR conditions. Some
patchy/shallow ground fog may form again over northeast
IN...though mid 50s crossover temp suggests to omit mention for
now. Expect uptick in southerly flow and cu development by midday
Thu in advance of system moving from the Dakotas into the western
portion of the Upper Great Lakes.




SHORT TERM...Steinwedel
LONG TERM...Steinwedel

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