Area Forecast Discussion
Issued by NWS Northern Indiana

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449
FXUS63 KIWX 061133
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
632 AM EST Tue Dec 6 2016

.SYNOPSIS...
Issued at 340 AM EST Tue Dec 7 2016

A low pressure system will lift northeastward from the Lower
Mississippi Valley into the Middle Ohio Valley region by noon
today. This system will bring a brief wintry mix at the onset
before the precipitation becomes all rain. Highs today will be in
the upper 30s. Then Much colder air will filter into the region
behind the system and set the stage for lake effect snow showers
Thursday through Friday night. High temperatures by Thursday
afternoon are only expected to reach the mid 20s.

&&

.SHORT TERM...(Today and Tonight)
Issued at 340 AM EST Tue Dec 6 2016

An upper level system was near Memphis early this morning and was
moving northeast toward the Ohio River. The northwest edge of the
associated deformation zone will move across the forecast area today
and bring a mix of precipitation. A brief wintry mix is possible at
the onset, then the precipitation should become all rain as low
level thermal fields warm. Some brief snow or possibly sleet
accumulations are possible early this morning. Surface pavement
temperatures have dipped below freezing at several locations, so it
is possible there could be brief travel impacts. Precipitation
should end by early evening with skies staying cloudy to mostly
cloudy.

&&

.LONG TERM...(Wednesday through Monday)
Issued at 340 AM EST Tue Dec 6 2016

A cold front will move across the area Thursday, bringing much
colder weather into the weekend. Lake effect snow will develop
Thursday as much colder air spreads over the relatively warm waters
of Lake Michigan.  Delta T values over 20C at 850 mb with a west to
northwest flow will favor snow accumulations over far southwest
Lower Michigan into northwest Indiana. Current thoughts are 5 to 8
inches over these areas near the lake with lesser amounts farther
inland. Lake effect snow will diminish from late Friday into early
Saturday as winds back to the southwest. More snow is expected by
Sunday as a GFS/EC/GEM blend now appears more favorable for
accumulating snow.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 632 AM EST Tue Dec 6 2016

Overspread of extensive mid cloud deck in progress and along with
wwd advection of drier air out of OH had widened sfc t/td spreads.
Thus no stratus or fog concerns near term. Ragged mid level
deformation zone upstream through srn IL/wrn KY will fill in with
time as stout sw trough continues to wrap up through the TN valley.
Wwd extent of precip shield associated with this feature has
backtracked in several successive RAP model runs and thus expect a
bit longer window of light rain to materialize invof KFWA by mid
morning. Along with this will be a manifestation of mvfr conds for a
time before low level cold advection wraps in behind departing
system this aftn. Arrival of this colder airmass as residual
moisture will lead to lower bound mvfr cigs and gusty west winds
this evening.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...Skipper
SHORT TERM...Skipper
LONG TERM...Skipper
AVIATION...T


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