Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 181731

Area Forecast Discussion
National Weather Service Northern Indiana
1231 PM EST Mon Dec 18 2017

Issued at 314 AM EST Mon Dec 18 2017

Cloudy skies and patchy drizzle can be expected today as highs
reach well into the 40s. Drier air will filter into the region
Tuesday through Thursday with temperatures remaining above normal.
A cold front then brings a good chance for rain later Friday into
Friday night, followed by colder and mainly dry conditions this


.SHORT TERM...(Today and Tonight)
Issued at 314 AM EST Mon Dec 18 2017

A combination of low level moisture advection and weak/brief dcva
tied to a low amplitude wave will bring chances for patchy
drizzle/light rain today...especially near a lingering sfc front
across northern zones. Drizzle/light chances diminish with time in
the afternoon as subtle upper wave exits, though low lvl boundary in
the vicinity and ample moisture could keep some activity going.
Overcast/mild otherwise with enough flow to preclude much of a fog


.LONG TERM...(Tuesday through Sunday)
Issued at 314 AM EST Mon Dec 18 2017

Northern stream energy through the Northern Great Lakes/Ontario will
force a cold front through the local area on Tuesday. Pacific
airmass to follow won`t result in much of a cool down behind this
into Tuesday night/Wednesday. Also not expecting any pcpn with the
frontal passage itself on Tuesday given overall dearth of moisture
and far northward bypass of any mid/upper level forcing.

Pattern then undergoes significant amplification late week into the
holiday weekend as -EPO ridge into the Northeast Pacific and
Alaska forces deep mean troughing into the Western/Central US.
Tight thermal gradient and overspreading height falls/jet energy
on the leading edge of this upper trough likely induces lee-side
cyclogenesis Thursday...with eventual downstream ejection
northeast into the Great lakes. Deep southwesterly flow in advance
of this developing low pressure system should finally tap Gulf of
Mexico moisture to generate a decent rain event by later
Friday/Friday night along the system cold front. Any warm
advection pcpn should remain mainly north of the area on Thursday
with temps once again above normal late week. Colder/more
seasonable air then overspreads in the wake of this system into
the weekend.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1227 PM EST Mon Dec 18 2017

Widespread mvfr and ifr conditions to prevail through the
forecast period. Steady and nearly continuous isentropic ascent
extends from the lower Mississippi river valley to the Great
Lakes. Satellite imagery is showing slightly drier air pushing
into the western portion of the forecast area, but this will be
short lived as the upslope flow and abundant boundary layer
moisture persist. Little if any change to the pattern until the
cold air surges east and south later in the week.


LM...Small Craft Advisory from 4 PM this afternoon to 4 PM EST
     Tuesday for LMZ043-046.



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

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