Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 140554

Area Forecast Discussion
National Weather Service Northern Indiana
154 AM EDT Sat Oct 14 2017

Issued at 145 AM EDT Sat Oct 14 2017

Showers and isolated thunderstorms are expected today along a
frontal boundary in the northwestern portions of the forecast
area. Elsewhere, expect increasing clouds. Highs will be in the
70`s, with areas in the southeast reaching 80F. Tonight will be
breezy with rain overspreading the region from northwest to
southeast. Lows will be in the 60`s. Rain showers will gradually
dissipate through Sunday morning, leaving partly to mostly cloudy
skies for the afternoon. It will be cooler, with highs only
ranging from 60 to 70F, warmest southeast. Lows Sunday night will
be in the 40`s.


.SHORT TERM...(This Evening through Saturday)
Issued at 310 PM EDT Fri Oct 13 2017

Strengthening southwest flow into tonight and Saturday in advance of
a potent upper trough ejecting east into the Northern Rockies and
High Plains will result in unseasonably mild temperatures into
tomorrow. This will also help to transport moisture into a
developing/leading baroclinic zone from Iowa east-northeast into the
Lower/Central Great Lakes. Weak elevated instability and ample
moisture return/advection into this front will likely allow showers
and perhaps a few thunderstorms to blossom...bringing increasing
chances for precipitation later tonight into Saturday into our nw IN
and sw Lower MI counties. The initial warm advection surge favors
higher PoPs late tonight/early Saturday morning, a possible lull
by the midday tomorrow, and then possible re-development by later
in the day as stronger forcing overspreads. Clouds and showers
will likely limit temp rises a bit tomorrow in these areas, while
ne IN/nw OH experiences highs in the upper 70s to near 80 within
dry/well mixed warm sector.


.LONG TERM...(Saturday Night through Friday)
Issued at 310 PM EDT Fri Oct 13 2017

Strong mid level height falls/DCVA associated with the above
mentioned upper trough, and an emerging coupled upper jet
structure, will allow sfc low pressure to deepen northeast
through the Western/Northern Great Lakes Saturday night and into
Quebec Sunday. This will force a strong trailing cold front
through later Saturday night/Sunday morning with gusty winds and
chances for a period of rain across the entire forecast area.
Strong wind field could support some stronger gusts > 40 mph with
any fine line and/or decent pressure rises in pronounced cold
advection wing post-frontal.

Shot of cool/seasonable air will be short-lived late Sunday into
Monday as pattern flattens out with positive temp anomalies
returning mid-late week.


.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 145 AM EDT Sat Oct 14 2017

A cold front extending southwestward from low pressure over northern
Ontario tonight, in combination with a developing low pressure
system over the central plains lifting northeastward along the front
through Sunday, will bring the next chances for precipitation and
MVFR/IFR conditions to the TAF sites. As of about 6Z, the front
was just about to shift slightly inland off Lake Michigan, where
it is forecast to temporarily stall. Showers have been observed
developing along the front already, and will impact KSBN through
the TAF period. KFWA will remain VFR, as rain showers are not
expected to move in until Sunday morning. Better moisture
transport directly into the northwestern forecast area begins in
the 11-15Z time frame. As a result, most of the guidance
reasonably suggests MVFR to IFR visibilities for KSBN during the
more extensive precipitation periods. Kept conditions MVFR in the
TAF for now given the observational trend in locations already
getting precipitation, but wouldn`t be surprised to see brief
drops to 2SM during any heavier showers. Have also added VCTS for
this afternoon at KSBN given instability increase. Finally winds
will pick up tonight as the low pressure to the southwest deepens
and lifts northeastward. This will lead to gusts to around 20kts
at KSBN, in addition to wind shear with stronger winds aloft.


LM...Gale Watch from this evening through Sunday evening for LMZ043-



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

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