Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 151553

Area Forecast Discussion
National Weather Service Northern Indiana
1153 AM EDT Sun Apr 15 2018

Issued at 1150 AM EDT Sun Apr 15 2018

Rain will diminish in coverage and intensity from southwest to
northeast this afternoon as a disturbance lifts northward across
the Great Lakes region. Periods of light freezing rain and icy
conditions will gradually come to end this afternoon across Branch
and Hillsdale counties in southern Lower Michigan as temperatures
warm into the mid 30s. Minor river flooding is possible late
weekend into early next week due to the recent rainfall. Scattered
rain showers this evening will transition to snow showers late
tonight into Monday, but little to no snow accumulation is
expected. Much below normal temperatures will persist through
much of this week with the exception of Wednesday when a brief and
minor warmup will occur.


Issued at 1150 AM EDT Sun Apr 15 2018

Upper vort max rotating trough parent circulation centered across
southeast Iowa will continue to shear and weaken across the
western Great Lakes this afternoon. Combination of this upper
forcing and enhanced frontal forcing will allow last organized
rain band to lift northeast across the area through mid afternoon.
Storm total rain amounts have come in slightly less than
forecasted a few days ago, and thus some adjustments have been
made to river forecasts.

Other concern this morning has been freezing rain/ice
accumulation. Sfc temperatures have been very slow to warm under stout
easterly flow regime. Reports of ice accumulation have been
primarily for bridges and overpasses, sidewalks, and elevated
surfaces. Will likely allow Indiana counties in this advisory to
expire at 16Z, although may need a brief extension for a few hours
for Branch and Hillsdale where sfc temperatures continue to hover
around freezing.


.SHORT TERM...(Today)
Issued at 332 AM EDT Sun Apr 15 2018

Second round of widespread rain blossoming across the area as
expected this morning given ramping LLJ, approach of midlevel
vorticity spoke, and surface low/occluded front. Moderate rain will
continue through at least the midmorning. Dry slot pushes into our
W/SW counties by late morning but latest hi-res guidance suggests a
second wave of precip will clip our far eastern counties during the
late afternoon before front fully clears our area around 00Z. Have
therefore raised afternoon PoPs/QPF a bit for those far eastern
counties. Despite this slight delay in full eastward exit...still
agree with previous shifts that any flooding impacts will be minor.
Best moisture plume (PW values near 1.5 inches) is focused east of
our area today and our eastern zones picked up the least rainfall
with the initial batch yesterday morning. Instability is also very
limited and doubt precip will be very efficient without a convective
component. Expect around 0.5-0.75 inches of additional rain during
the daytime period...mainly confined to NW OH and Hillsdale.

Surface temps holding at 32F for Hillsdale and Coldwater this
morning and no changes planned to inherited advisory. Freezing
rain/UP reported in the area by automated stations but no reports
regarding impacts/accumulation. Impacts likely confined to elevated
surfaces given warm ground and road temps. Ice accumulation is
difficult with such marginal temps/dewpoints (and such a strong warm
layer aloft) but certainly worth maintaining advisory given
potential for light ice accum on elevated surfaces early this
morning. Temps holding just above freezing outside of far NE so no
expansion planned. Any ice will melt quickly after sunrise given
very high sun angle, marginal temps, and approaching WAA.


.LONG TERM...(Tonight through Saturday)
Issued at 332 AM EDT Sun Apr 15 2018

Lull in precip anticipated this evening with well-established
midlevel dry slot but chance for SCT/light showers will increase
overnight and especially by Monday as primary height fall centroid
passes overhead. NW flow/CAA will also support a changeover to
primarily snow by late tonight, continuing into Monday. This will
likely be another situation of snow as predominate precip type given
upper 20s dewpoints/modest precip rates in convective showers but
little/no accumulation is anticipated given warm ground and upper
30s temps. Winds will also be gusting to around 25-30 mph in what
will be another very raw day in the winter that will not end.

Flurries/light snow showers likely to continue through Tue morning
given persistent moist, cyclonic flow and passage of a few embedded
vorticity maxima but dry conditions will develop by Tue afternoon as
low level ridge axis passes and winds back. Unfortunately it will be
short-lived as another vigorous midlevel low is slated to enter the
Great Lakes on Wed. This will bring another chance of rain...though
much lighter with highest QPF in deformation zone well north of our
CWA. Some CAA/cyclonic flow on the backside that will maintain
showers into Thu. However...thermal profiles are more marginal and
expect primarily for perhaps far north early Thu
morning. Another wave may then impact our area next weekend but
confidence is very low regarding track/details. Roller coaster temps
expected...oscillating between normal (Wed) and well below normal
(Tue and Thu-Fri).


.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 606 AM EDT Sun Apr 15 2018

Mainly IFR conditions and rain will persist at the terminals this
morning in advance of an occluded front. This feature moves
through northern IN this afternoon with easterly winds becoming
variable for a time...and eventually westerly by later
today/tonight. Precipitation should become more showery in nature
mid afternoon and beyond. Flight conditions may improve into MVFR
for a time this aftn-eve (best chances at KFWA).


IN...Winter Weather Advisory until noon EDT today for INZ006-007.

MI...Winter Weather Advisory until noon EDT today for MIZ079>081.

OH...Winter Weather Advisory until noon EDT today for OHZ001.




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