587
FXUS63 KIWX 170517
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1217 AM EST Mon Nov 17 2025

.KEY MESSAGES...

- Rain is likely late Monday night into Tuesday. Snow may mix in
  briefly early Tuesday for areas north of US 30. Brief, minor
  snow accumulations are possible.

- Warmer temperatures return starting Wednesday. Rain chances
  increase as well Thursday and Thursday night.

&&

.UPDATE...
Issued at 902 PM EST Sun Nov 16 2025

Decoupling and clear skies have allowed for sharp downward
hourly temp trends over past few hours. The exception is closer
to Lake Michigan where trajectories off a much warmer Lake
Michigan are preventing this decoupling from occurring. Near
term forecast soundings indicating a vast number of depictions
on low level mixing over next several hours. A better decoupled
NAM type sounding appears to be verifying better in the near
term which should allow lows away from Lake MI to drop into the
mid-upper 20s tonight. Lakeshore areas remain more in question
due to potential that better decoupling may never occur
tonight. Previous forecast has this trend captured well and only
adjustment was to make slight downward trend in hourly temp and
min temp grid away from Lake Michigan.

&&

.DISCUSSION...
Issued at 233 PM EST Sun Nov 16 2025

A short period of quiet weather will exist for the next 24 hours or
so as the weekend trough continues to shift east and we await the
first in a series of increasingly stronger waves set to bring a
fairly active 5 to 7 day period.

Before getting to the upcoming forecast challenges, impressive
push of dry air apparent in sfc obs across the SW third or so
of the area with dewpoints in the lower teens and even some
single digits, resulting in RH values of 20 to 25%. Winds
luckily have behaved to some extent, but overall elevated fire
danger still lingers mainly for areas southwest of US 30.

Now the shift to the first, well defined wave of interest
currently moving into southern Nevada. Although it will dampen
somewhat, a rather potent circulation is still expected as to
shifts across the central Plains by 00Z Tue. Models have been
fairly consistent on a narrow fgen band setting somewhere across
NE IN/NW Ohio into southern Lower MI. HI-res models show a band
of what should be rainshowers attempting to take shape in the
00Z to 3Z Tue period that will help pre- condition the
environment in this same area, even if the moisture doesn`t
reach the ground. Strong wet bulbing/dynamic cooling is also
evident on the models with low level thermal profiles cooling
quickly in the 6 to 12Z Tue period before the entire area shifts
NE. Luckily overall QPF will be on the order of a tenth or so
and snow ratios should`t be real bad given temps in the upper
20s to around 30. Some brief Tue AM commute issues could occur
somewhere NE of US-30 and especially further NE where the colder
air will reside longer. Will continue depicting at least some
light snow accumulation, but the potential for a quick 1 to 2
inches of snow in a narrow swath does exist, but will be
difficult to capture the most favorable location. Forecast at
this point won`t depict that given numerous variables noted, but
something to be monitored in coming forecasts. SW of this
swath, some light rain is possible in the same period, but
amounts overall will be light.

Another lull in precip is expected Tuesday night into Wednesday
evening as some modest upper level ridging takes place. This will
allow temperatures to warm back closer to, if not somewhat above
normal in the 50s. Trends over the past several days have been for a
rather wet setup Thursday into Friday. 12Z GFS/Canadian are more
suppressed with rainfall as northern and southern stream energy
don`t quite meet up and stronger ridging takes hold at the sfc to
limit the northern extent of the rainfall. In addition, the
southern stream wave shows signs of weakening as it moves
towards the area by Friday. As is typically the case, main
feature isn`t featured the best in the models so changes will
continue in the overall forecast. Suffice to say, any precip
should be in the form of rain.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1214 AM EST Mon Nov 17 2025

The existing TAF remains on track at this time resulting in only
a minor wind direction adjustment to KSBN. High pressure in
place through the TAF period gives way to incoming low pressure
prior to daybreak Tuesday. -RASN at KSBN appears most favorable
beyond this 06z valid period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until noon EST today for LMZ043-046.

&&

$$

UPDATE...Marsili
DISCUSSION...Fisher
AVIATION...Brown