Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 121142
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
642 AM EST Thu Jan 12 2017

.SYNOPSIS...
Issued at 638 AM EST Thu Jan 12 2017

A cold front moving across the area will cause freezing rain and a
chance of thunderstorms across northwest Indiana and southwest
Michigan this morning with just rain across the rest of the area.
High pressure will move into the Great Lakes tonight and Friday
resulting in dry conditions and seasonably cold temperatures. Some
freezing rain is possible mainly across southern portions of our
area over the weekend as low pressure moves through the Ohio
Valley.

&&

.UPDATE...
Issued at 555 AM EST Thu Jan 12 2017

Freezing rain advisory issued for several counties in NW parts of
the area based on increasing upstream trends in convection
(including uptick in lightning) as well as air temps now around
freezing and ground temps likely near/below freezing. Leading
edge of the precip will likely be the heaviest and may not begin
to accumulate on surface right away as it runs off, but lighter
showers and drizzle will have a better chance of sticking to
surfaces. Ice accumulations of up to a tenth of an inch are
possible before everything moves out by late morning. Will defer
to day shift to monitor for any expansion southeast or in time.

&&

.SHORT TERM...(Today and Tonight)
Issued at 415 AM EST Thu Jan 12 2017

Main focus on brief icing potential in NW parts of the area this
morning.

Rapid uptick in convective development across western and central
Illinois over the past few hours, as advertised by several of the
hi res models. Stronger cells already producing lightning.
Temperatures overnight have fallen much faster than previously
forecasted (or handled by any model) resulting in increasing
concerns for a period of light icing in far NW parts of the area
in the 11 to 15Z window. Recent mesoscale discussion from SPC
highlights concerns in greater detail. While air temperatures were
on the warmer side yesterday, current temps have likely reduced
any effects of that warming. Given main impacts may occur near the
end of morning commute, opted to issue SPS highlighting concerns
with trends closely monitored over the next hour or 2 for possible
freezing rain advisory. Forward speed of convection could also
allow the activity to get in sooner.

For the remainder of the area this morning, narrow band of
showers has been lingering across SE parts of the area overnight
with SE movement slowed with arrival of next wave moving along the
front. Eventually this should slide east around 12Z and not pose
an issue. Additional showers will also likely move in from
upstream warranting increase in pops through 18Z before rapidly
ending. Temperatures will continue to fall through the morning
and potential does exist for a brief period of freezing rain on
the back edge of the rain as it departs.

Once this wave departs and the main cold front clears the area,
quiet weather will settle for the remainder of the short term
period.

&&

.LONG TERM...(Friday through Wednesday)
Issued at 415 AM EST Thu Jan 12 2017

With main focus on near term, only minor changes to long term with
concerns still lingering over the weekend as series of waves move
along stalled frontal boundary to our south. Impacts Friday night
into Saturday morning still look to be mainly confined south of
US-24 but could edge as far north as US-30 corridor. Mix of snow,
sleet or freezing rain all possible but appear amounts should be
on the light side.

As noted by previous shift greater concern may come Sunday
night/Monday morning and pronounced surge of warmer low level air
rides over cold dome in place initially across the area. All areas
would stand a chance for some sleet or freezing rain that could
cause some impacts to the Monday morning commute. Have continued
mention with trends needing to be monitored in coming forecasts.
By Monday afternoon temperatures should be far enough above
freezing to end any threat. Much like was seen over the past few
days, large temperature variations will occur Monday into Tuesday
NW to SE with many spots climbing into the 40s and also some 50s
the further SE you go. Additional waves will bring chances for
showers through much of the remainder of the period with temps
remaining in the 40s for highs.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 638 AM EST Thu Jan 12 2017

Shrtwv over nrn MO causing an area of showers and tstms over ne
IL/nw IN which should impact sbn this morning. Temps have fallen
below freezing there with caa contg so expect fzra to occur with
some pl during convection. Shra also expected at fwa with ts psbl
but temps should stay above freezing during the precip. Otrws ifr
conditions should cont through the day, becoming vfr this eve as
high pressure ridges into the wrn grtlks.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Freezing Rain Advisory until 11 AM EST /10 AM CST/ this morning
     for INZ003>005-012>014.

MI...Freezing Rain Advisory until 11 AM EST this morning for
     MIZ077>079.

OH...NONE.
LM...Small Craft Advisory until 4 PM EST Friday for LMZ043-046.

&&

$$

UPDATE...Fisher
SYNOPSIS...JT
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...JT


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