Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 050937

Area Forecast Discussion
National Weather Service Northern Indiana
437 AM EST Mon Dec 5 2016

Issued at 422 AM EST Mon Dec 5 2016

Clouds will linger through tonight with patchy fog possible at
times. A weather system will spread some light precipitation
across the area Tuesday. Some light snow accumulations are
possible on grassy areas. Travel issues appear to be limited.
Much colder air will spread over the area Thursday with lake
effect snow developing. Highs will be in the 30s through
Wednesday, then in the 20s Thursday and Friday. Lows will be
around 30 tonight then falling into the teens later this week.


.SHORT TERM...(Today and Tonight)
Issued at 422 AM EST Mon Dec 5 2016

Have maintained a mention of some fog today over west areas,
mainly west of highway 31 given some of the high resolution/WPC
models and upstream fog development over western Illinois. Given
abundant cloud cover and some fog, have cut high temps a few
degrees over these areas. Otherwise, the cloud cover will linger
through tonight. Some light precipitation is possible late tonight
over southern areas ahead of the next system. It looks like any
travel issues through tonight should be at a minimum given
temperatures holding near freezing tonight.


.LONG TERM...(Tuesday through Sunday)
Issued at 422 AM EST Mon Dec 5 2016

A number of weather systems this period are expected to produce a
variety of weather across the forecast area through this week.
An upper low will eject northeast Tuesday. This system will become
more of an open wave then earlier expected and track farther
southeast than earlier expected. This will limit precipitation
Tuesday. Given this track, and thermal profiles, continued to
trend back snow accumulations. The limited upper motion and a warm
layer will also limit snowfall. At this point, some light wet snow
accumulations are possible over mainly grassy areas Tuesday.

Much colder weather will follow Thursday. The ECMWF continues a
weakening of the wave and subsequent snow Wednesday night. Kept a
small chance of snow with this system before much colder air arrives
Thursday. 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 northwest flow will favor snow
accumulations over far southwest Lower Michigan into northwest
Indiana. Lake effect snow will diminish from late Friday into early
Saturday as winds back to the southwest.


.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 106 AM EST Mon Dec 5 2016

Primarily ifr/lifr threshold ceilings until this aftn as low level
thermal trough weakens and inversion aloft compresses.  In addition
suspect continued nocturnal cooling within moist boundary layer and
further augmented by melting snowfall will yield some mvfr fog
restriction overnight into Mon am. Otherwise backing low level flow
within increased subsidence this aftn may provide for a period of
vfr improvement and will cautiously mention with this fcst.




SHORT TERM...Skipper
LONG TERM...Skipper

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