Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 150611

Area Forecast Discussion
National Weather Service Northern Indiana
111 AM EST Fri Dec 15 2017

Issued at 109 AM EST Thu Dec 14 2017

A weak system will pass across the Great Lakes today bringing
scattered to numerous snow showers north of the Toll Road. Some
light snow accumulations of an inch or two are possible from today
through tonight, especially across southern Lower Michigan where
lake effect snow showers are expected to be more numerous. High
temperatures this afternoon will range from the mid 20s to lower
30s. Lows tonight will not be as cold, ranging from the mid to
upper 20s. The moderating trend will continue into the weekend
with highs in the 30s and 40s for Saturday and Sunday. The next
chance of rain and snow will arrive by Sunday afternoon.


.SHORT TERM...(This Evening through Friday)
Issued at 337 PM EST Thu Dec 14 2017

After a cold night in many spots, temperatures have managed to
recover into the 20s, coolest northeast. Clouds have been slowly
increase from west to east and while majority of lake effect has
remained north a small area of enhancement looks to be drifting
across NW counties with maybe a few snow flakes. Handling with
slgt chc as it works east. Upper level system will move through
the northern lakes late tonight into Friday night. Main impacts
will be in favored WNW or W fetch areas from Lake Michigan with
any light accumulations confined north of the Toll Road and little
more than some flurries or light snow showers north of US-30.
Winds will pick up somewhat into the 10 to 20 mph range, enough
for some slick spots and drifting snow but well shy of any
advisory criteria at this time.

Temperatures on Friday will make it a few degrees warmer, but
still remain below normal with readings only in the middle 20s to
lower 30s.


.LONG TERM...(Friday Night through Thursday)
Issued at 337 PM EST Thu Dec 14 2017

For those wanting to get rid of the cold and snow, your wish is
coming as flow becomes more zonal for the start of the weekend and
eventually southwesterly as deep trough digs into the western
states. Any light snow across southern Lower Michigan will quickly
wind down Friday night. Focus then shifts to closed low over the
4 corners region which is forecast to phase with the northern
trough by Monday as strong low pressure moves across Hudson Bay
through much of the period. Quick batch of rain or rain/snow mix
will arrive Sunday night with what will likely be a weak sfc low
moving NW of the area. Not expecting any impacts at this time with
this feature, but with cold ground and thermal profiles still
bouncing around will need to monitor somewhat.

Either zonal or slightly amplified flow will remain in place much
of the week allowing for above normal temperatures. Weak
disturbances will pass through every once in a while to bring at
least a chance of rain or snow, depending on the time of day.
Towards the end of the period, deepening low pressure over the
southern Plains will track towards the area and pose a potential
problem for travelers late Thursday into Fri. Exact track remains
uncertain with ECMWF keeping well NW of the area (all rain) and
GFS tracking southeast of the area (Snow or snow/rain). Something
that will be closely monitored in the coming days.


.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 109 AM EST Fri Dec 15 2017

Primarily VFR low clouds persist across northern Indiana early
this morning. Weak warm advection should get going during the
overnight hours in advance of next fast moving clipper system.
This short wave passage should mark a brief window of higher snow
showers chances at KSBN in the 15-19Z timeframe. Have not made
significant changes from previous TAFs in trend to MVFR cigs 2-3k
feet and MVFR vsbys in scattered snow showers during this period.
Brief residence of weak mid level thermal troughing and primarily
westerly fetch should allow for some isolated-scattered snow
showers this evening at KSBN, but chances should gradually lift
northward into southern Lower Michigan toward the end of the
period as flow becomes slightly more backed. Have also maintained
previous mention of MVFR cigs at KFWA 2-3k feet through much of
this period. West winds to become gusty for a time late morning
through late afternoon with better mixing associated with this
weak trough, but decoupling should occur fairly early this evening
as thermal trough begins to retreat.


LM...Small Craft Advisory from 4 AM early this morning to 5 AM EST
     Saturday for LMZ043-046.



LONG TERM...Fisher

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