Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 161615

Area Forecast Discussion
National Weather Service Northern Indiana
1115 AM EST Mon Jan 16 2017

Issued at 1100 AM 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 12Z TAFS through 12Z Tuesday Morning)
Issued at 606 AM EST Mon Jan 16 2017

Low pressure over nw OK will lift ne into sw MI by the end of the
taf period. Sct showers in the waa regime out ahead of the low
should cause ocnl -fzrapl at the terminals this morning.
Questionable if precip will be heavy enough to cause slick
runways... best chc of that appears to be at sbn. Cigs/vsbys will
deteriorate to lifr this aftn/eve as the warm front associated
with this system approaches. Stronger forcing and deeper moisture
arriving will result in more sgfnt rainfall tonight, but temps
will be above freezing. Wk elevated instability could support sct
tsra as well, but expected limited coverage and some uncertainty
if it will occur precludes mentioning in tafs attm. Other concern
overnight is sgfnt llws as llj to se of path of low overspreads
the area.




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

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