Area Forecast Discussion
Issued by NWS Northern Indiana

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036
FXUS63 KIWX 160402
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1102 PM EST Sun Dec 15 2019

.SYNOPSIS...
Issued at 233 PM EST Sun Dec 15 2019

1 to 3 inches of snow possible south of Route 24, 1-2 between
Route 24 and HWY 30, and dusting to 1 inch north of HWY 30. A
swath of locally higher amounts is possible, best chances
along/south Route 24.

Brief window of freezing rain/drizzle as snow wanes towards
sunrise across far southeast along Route 24.

Monday daytime mostly void of additional precip.

Second round of light snow possible Monday night into Tuesday
morning.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 151 PM EST Sun Dec 15 2019

Bottom line up front for first round:

- Winter Weather Advisory issued for Grant, Jay, and Blackford
Counties in IN late tonight into Monday morning.

-1 to 3 inches of snow possible south of Route 24, 1-2 between
 Route 24 and HWY 30, and dusting to 1 inch north of HWY 30.

-A swath of locally higher amounts is possible, best chances
 along/south Route 24.

-Brief window of freezing rain/drizzle as snow wanes towards
 sunrise, but only isolated glazing expected.

-Daytime mostly void of additional precip.

This portion of the discussion will focus on the first round of snow
tonight into Monday morning. 12z model runs have come in fairly
similar to each other (except for the 12z CMC which has underdone
the QPF across the far SE) with just minor differences of location
on "highest" snowfall amounts.

Leading shortwave with a deepening trough over the Four Corners
will quickly send PVA and low/mid-level Fgen bands into from ssw
to nne this evening. The precipitation which will accompany these
features will be in the form of snow due to temperatures below
freezing throughout the column. There are still some slight
differences in timing of the outer edge of wintry precip entering
the far SSW; between 23z and 01z. As seen in yesterday`s and
today`s forecast soundings, a near surface dry layer will help to
slow the onset of snow by an hour or two; which should account for
the slight differences in model timing. Despite these timing
differences, there is moderate to high confidence that a locations
south of HWY 30 will be experiencing precipitation by 3z.
Locations north of HWY 30 will likely be delayed by a few more
hours, and locations north of I-80 are somewhat questions if they
will occur.

Best low/mid-level Fgen banding continues to be focused generally
south of Route 24 during the overnight hours before weakening
towards daybreak. The concern for a swath of locally higher snow
amounts continues, and has several days of continuity across the
SE CWA counties in IN. As we move from 09z to 12z, forecast
soundings show the DGZ losing saturation as heights aloft
gradually increase. While there remains a brief window for a
transition from snow to freezing rain/drizzle as precip starts to
wane, but any light glazing should be fairly isolated.

As mentioned above storm total amounts with this round of wintry
weather will generally be 1 to 3 inches with a dusting for lower MI.
The combination of 2 to 3 inches of widespread snow, expected
locally higher amounts, timing of the snow, and the potential for
isolated ice glazing is sufficient to issue a Winter Weather
Advisory for tonight through Monday morning.

Models are in fair agreement that Monday daytime will be fairly void
of additional precipitation given increasing heights aloft in
response to the deepening upper trough over the southern High
Plains/eastern Colorado Plains. Persistent cloud cover during the
day should help to keep high temperatures in the lower 30s.

&&

.LONG TERM...(Monday Night through Sunday)
Issued at 151 PM EST Sun Dec 15 2019

Bottom line up front for second round:

-Expected Monday evening into Tuesday morning.

-Snow amounts of a dusting to 1 inch for most locations; 1 to 2
 inches possible mainly for Blackford, IN; Jay, IN; Lima, OH.

-Adjustments to amounts possible.

Similar to the first round of wintry weather, models have come
into a general consistency. The exception for this round is the
12z EC which has come in further suppressed to the south. This
would limit snow amounts event more than what is mentioned above.

The forecast is based on a general blend of the 12z GFS/NAM/CMC
and 00z EC. As such, upper trough axis begins to move east over E
KS/W MO by Monday afternoon. A secondary push of PVA as well as
low/mid-level Fgen banding lifts across central IN and into the
area by the early evening. This will allow for the second round of
snow to lift north into the southern and southeast counties around
7PM EST. While there is general agreement in track, there remains
differences on just how far north this round will expand given
differences in sharpness of the upper trough.  It is entirely
possible the north and northwest counties see little to no snow
with this round. Maintained previous forecast line of thought by
keeping amounts limited to one to two inches mainly across the
southeast. Some adjustments remain possible.

Models have come into better agreement for a glancing blow of a cold
front diving out the upper Midwest on Wednesday. With that being
said, wind chills on Wednesday morning could drop into the single
digits. Mainly quiet weather is expected into next weekend.
&&

.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1102 PM EST Sun Dec 15 2019

Snow in the process of overspreading the terminals attm with IFR as
expected. Intense/leading warm advection driven snow band south of
KFWA may spread north into the terminal by midnight per trending
highres rap/hrrr solutions and made some downward adjustments there
w/06Z fcst issuance. Nevertheless blossoming mid Mississippi valley
convection currently breaking out through ern AR/wrn TN will with
time shutdown moisture flux ongoing north and snow will diminish
quickly toward daybreak.

Thereafter IFR threshold IFR/LIFR cigs will persist through Monday
morning within moist erly low level flow.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory from 9 PM this evening to 7 AM EST
     Monday for INZ032>034.

MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...CM
SHORT TERM...CM
LONG TERM...CM
AVIATION...T


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