Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 110353
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1052 PM EST Sun Dec 10 2017

.SYNOPSIS...
Issued at 1255 PM EST Sun Dec 10 2017

There will be just a chance of light snow showers north of the
toll road through tonight. Dry and mostly cloudy otherwise tonight
with lows into the lower to middle 20s. A fast moving clipper
system will bring renewed snow and lake effect snow chances Monday
through Tuesday night. Several inches of accumulation are
possible this week, especially in and near the lake effect snow
belt region.

&&

.SHORT TERM...(This Evening through Monday Evening)
Issued at 246 PM EST Sun Dec 10 2017

A minor low amplitude disturbance, embedded in northwest flow,
will force a weak sfc trough the area early this evening. Nothing
more than clouds and few flurries expected with this wave given
weak forcing and shallow moisture profile.

A more robust shortwave will drop southeast into the Northern
Plains tonight and into the Lower Great Lakes by later Monday/Monday
evening. Leading WAA/isentropic ascent wing will focus an area of
light snow on the nose of this warm advection into WI/MI Monday
morning through mid afternoon. The southern edge of this precip
shield will likely clip our far northern zones, with areas
along/south of US 30 likely remaining mainly dry. Deeper ascent
with the main vort max...and tightening low level baroclinic
response... should promote full top-down saturation and chances
for a healthier fgen band to set up across lower MI (and possibly
far nrn IN/nw OH) in the afternoon and evening, though where
exactly this sets up is still uncertain. Pacific origin with
850-700 mb layer specific humidities nearing 3 g/kg enough to
support a quick 1-3" of snow and difficult travel where banding
materializes.

&&

.LONG TERM...(Tuesday through Sunday)
Issued at 246 PM EST Sun Dec 10 2017

Active/cold pattern this week gives way to a milder weekend...

A larger scale vort lobe and 160 kt upper jet dropping south-
southeast from northern Canada will phase with the above
mentioned clipper system into the Eastern Great Lakes and
Northeast US Tuesday into early Wednesday. Deep/cold northwest
flow on the backside on this negative height anomaly will likely
lead to another significant LES event locally...this time focused
a little farther east. Excellent lake-induced thermal troughing,
longer duration/persistence of nw flow trajectories, and favorable
LES parameters suggest significant impacts/accums are likely in
favored nw flow lake belts. There could even be headline worthy
impacts well inland into ne IN given upstream preconditioning and
strong boundary layer flow. This period will continue to monitored
for Winter Wx headlines...with cold/breezy conditions the story
otherwise.

The parade of minor/low amplitude shortwaves and reinforcing shots
of cold air will continue through the remainder of the week as upper
troughing remains in place across the Eastern US. The result will be
a continuation of below normal temps and several chances for light
snow followed by LES, though details at this forecast range remain
uncertain. Upper troughing does look to briefly relax next weekend
which should allow milder air (near normal for mid Dec) to
overspread.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1052 PM EST Sun Dec 10 2017

Transient MVFR cigs will persist through daybreak before abating
timed with well mixed warm sector advancing ewd ahead of stout upper
disturbance dropping rapidly sewd out of Alberta.

Went ahead and introduced snow mention late in regard to
rapid/intense lake band development overnight Monday and to also
highlight gusty northwest winds.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Gale Watch from Monday evening through Tuesday morning for
     LMZ043-046.

&&

$$

SYNOPSIS...Murphy
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...T


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