Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 161726

Area Forecast Discussion
National Weather Service Northern Indiana
1226 PM EST Mon Jan 16 2017

Issued at 1220 PM EST Mon Jan 16 2017

Rain will remain likely this afternoon, especially across far
northern Indiana and southern lower Michigan where a period of
freezing rain is still possible through early afternoon.
Additional light ice accumulations are possible early this
afternoon mainly across southern lower Michigan. Rain will become
more widespread tonight into Tuesday morning as temperatures warm
well above freezing and low pressure lifts into the Great lakes.
Drier and slightly cooler conditions are then expected behind this
system into Wednesday before a warmer and at times wet pattern
develops for the second half of the week into next weekend.


Issued at 1100 AM EST Mon Jan 16 2017

Previous forecast remains in good shape this morning. Temperatures
have warmed into the lower 30s across most of the area which has
resulted in mainly just wet roadways this morning, although have
received some reports of scattered slick spots on roadways across
far north including southwest lower Michigan where isentropic lift
has been most pronounced this morning. Sfc wet bulb temps across
these locations are not warming into the lower 30s, so have no
plans for an advisory and will continue to cover this threat with
an SPS through early afternoon. Fog will become the other forecast
issue to deal with this afternoon and tonight. The potential does
exist for some dense fog tonight, although more widespread rain
moving in this evening could mitigate extent of this threat.
Updated forecast will be sent shortly with just minor tweaks to
cover current PoP trends.


.SHORT TERM...(Today through Tuesday Night)
Issued at 423 AM EST Mon Jan 16 2017

Leading elevated warm advection wing in advance of a Central Plains
low pressure system will bring chances for light freezing rain to
mainly far northern IN and MI this morning into the early afternoon.
Latest colder look to model/ob trends a little concerning for
some light icing, especially in nw IN (including South Bend) and
lower MI 13-19z. However, confidence on impacts/ice accretions in
these areas remain too low for a headline given a rather dry/deep
sub-cloud layer under only modest cross isobaric flow on 290-295k

A notable increase in dynamic forcing and moist isentropic ascent
with the approaching system will bring periods of rain to the entire
area tonight, likely becoming more showery/convective/heavier by
later tonight-Tuesday morning under mid level wave and associated
pivoting frontal occlusion. High moisture content within low level
jet core (PWATS nearing 1 inch) and height fall centroid track (~120
meter fall at 500 mb) through the area support going high PoPs,
slight thunder chances, and rainfall amounts in excess of a half
inch in many areas. There is some concern that sfc temps may hover
near freezing in far ne IN/sc Lower MI later this aftn/early eve
given prevailing easterly wind component. This could result in
some light icing here into the early evening. Turning milder
otherwise with areas of fog possible tonight into Tuesday,
especially north near the sfc reflection track.

Rain chances then diminish into Tuesday afternoon and Tuesday night
as primary system pushes off to the east, though lingering low level
moist/cyclonic flow in tandem with a separate northern stream
impulse may be enough to generate some additional drizzle/light
rain in areas.


.LONG TERM...(Wednesday through Sunday)
Issued at 423 AM EST Mon Jan 16 2017

Wednesday will likely feature dry/slight cooler conditions as weak
ridging/subsidence briefly builds in. Above normal temperatures and
several opportunities for rain then for the rest of the week into
next week as more amplified southwest flow sets up.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1212 PM EST Mon Jan 16 2017

Cigs/vsbys continue to deteriorate early this afternoon, with
prospects of appreciable improvement minimal through the
afternoon. Corridor of warm advection forced rain and pockets of
freezing rain have lifted north of the terminals as of midday with
no additional freezing rain threat anticipated. Widespread fog
will continue this afternoon into this evening with LIFR/IFR
conditions. Vsbys may drop to one quarter of a mile late this
afternoon into tonight, with greatest threat of vsbys to this
extent at KSBN. Rain will become more widespread this evening as
an upper level short wave continues to eject northeast out of the
Southern Plains, which may at least provide some minimal vsby
improvement this evening. Periods of rain will persist overnight
before diminishing in coverage early Tuesday morning as deeper
moisture axis and short wave forcing begin to depart. Will also
have to watch LLWS potential tonight, with a period from 06Z-12Z
looking to be the greatest threat as a low level jet in advance
of this short wave impinges on northern Indiana.




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

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