Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 091944

National Weather Service Northern Indiana
244 PM EST Fri Dec 9 2016

Issued at 1219 PM EST Fri Dec 9 2016

Dry air has begun to move into the region as high pressure edges
closer and has allowed for the lake effect snow to recede back
towards the lake. Snow is expected to continue for a time closer to
the lake in Northwest Indiana and Southwest Michigan. Then, low
pressure will move northeast from the Southern Plains towards the
region Saturday night and Sunday, and possibly into Monday, with
snow. The snow is expected to change over to rain south of Route
30 before ending. Even colder air comes in behind a cold front
expected to move through around midweek next week.


.SHORT TERM...(This Evening through Saturday)
Issued at 242 PM EST Fri Dec 9 2016

Dry entrainment along srn periphery of ongoing lake effect shsn
continues to mitigate significant additional snow accumulations.
Thus with aftn issuance will sandbag remain advisory counties.
That said expect light snow showers will continue for much of the
night across sw MI particularly through Berrien and Cass county
within short fetch wrly flow. Hwvr overall poor moisture
depth/shallow inversion will yield 1/2 inch or less additional.

Otherwise primary attention turns toward potent sw disturbance off
the WA coast this aftn coming onshore tonight. Rapid development of
downstream waa seen in all model guidance by late Sat aftn although
forcing/moisture advection overtop cold dome minimal initially and
does not ramp appreciably until daybreak Sun in response to ewd
translation of intensifying low level jet. Regardless accumulating
snow expected late Sat night.


.LONG TERM...(Saturday Night through Friday)
Issued at 242 PM EST Fri Dec 9 2016

Just enough spread in solution scope aloft...esp with thermal
profiles tied to general intensity differences among individual
model solutions to prevent an agreeable watch coordination this
aftn. That said... did bump pops much higher in consideration of
general agreeable consensus scope. While details still sketchy...
satellite depiction of upstream sw over the nepac ocean this aftn
gives a preferred nod toward stronger solutions aloft. This would
yield to a threat of mixed precip through srn areas by Sun
aftn/evening yet also point to a period of heavy snow potential
Sun morning through Sun aftn (north). In the least will issue a
Winter Storm Outlook this aftn to highlight the potential for
significant snowfall accumulations (6-10") late this weekend
especially US 30 north.

Thereafter perturbed nrn stream flow develops within stout north to
south baroclinic zone stretching from the central plains east
through the OH valley. Lots of signal noise/spread indicated mid
period (Tue) with potential sys streaking through the TN/OH valley
and again toward next Fri/Sat. Most consistent signal has been for
gradual swd suppression of bitterly cold arctic airmass bottled up
through nw Canada and blended temps at this range look like a good
start... some 20 to 25 degrees below normal for this time of year.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1219 PM EST Fri Dec 9 2016

Dry air begins to filter into the region and wind direction changes
to more westerly as the main energy rotates away from the region, so
expecting snow at SBN to slowly recede towards the lakes during in
the first portion of the forecast period. In any snow, CIGs have
been reduced to low MVFR and VIS to IFR so will continue that for as
long as snow continues. Still expecting cloudy skies to continue as
a result of lake instability at both sites, but especially at SBN
where MVFR CIGs are still expected into the early overnight hours.


IN...Winter Weather Advisory until 4 PM EST /3 PM CST/ this afternoon
     for INZ003-004.

MI...Winter Weather Advisory until 4 PM EST this afternoon for MIZ077-

LM...Small Craft Advisory until 7 PM EST this evening for LMZ043-046.




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