769
FXUS63 KIWX 180743
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
243 AM EST Tue Nov 18 2025

.KEY MESSAGES...

- Rain for a majority of the area today with highs in the 40s.

- A wintry mix is expected, especially through the morning
  hours, for south-central Michigan, far northeast Indiana and
  far northwest Ohio. A change over to rain occurs in the
  afternoon.

- A slushy wintry mix accumulation of one half inch or less is
  possible. Be alert for slippery travel conditions.

&&

.DISCUSSION...
Issued at 236 AM EST Tue Nov 18 2025

As stated on these pages many times so far this week, a challenging
forecast this morning with respect to precipitation type. This really
applies for only a handful of counties in and around Branch County
Michigan. An overwhelming majority of the forecast area today will
see predominantly rain. For the majority, rain is already arriving
from the west amid modest warm air advection associated with a low
crossing the Missouri River. Rain will taper off from west to east
through mid afternoon. Temperatures today will warm only slightly:
low-to-mid 40s for most while Branch County MI and neighboring areas
will be trapped in the mid-to-upper 30s.

For the mixed precipitation today for Branch county and surrounding
areas: A period of wintry mix this morning is expected to transition
to all rain this afternoon. A slushy accumulation of one half inch
or less remains possible.

Steady east wind this morning is providing a reinforcing dose of
cool, dry air. Incoming low-level frontogenesis near sunrise ought
to provide enough forcing to saturate the remaining 4,000FT dry
layer. Forecast soundings initially favor rain, but only by a narrow
thermal margin. An elevated (at 15,000 ft) and shallow DGZ offers a
non-zero chance for snow while wet-bulb temperatures near freezing
suggest evaporative cooling to all-snow is in the cards. This
frontogenesis lifts north quickly and simultaneously, a preexisting
500-mb jet exits to the east and thus forcing and eventually DGZ
saturation begin to fade. Additionally,  850mb temps warm through
the mid-morning hours introducing a shallow warm nose indicative of
sleet. This drying DGZ and warming thermal profile introduce a
transition to sleet. The absolute low-levels (e.g., below 900mb) are
not brutally cold enough to lend significant confidence to freezing
rain. Thus, have favored a period of sleet instead for mid-to-late
morning. Finally, a change over to all rain is expected by the
afternoon as warm air advection continues. However, this anticipated
warming has failed before in these setups. Noting the high pressure
currently over the Lake Superior and over the Appalachians, cool,
easterly flow could keep mixed precipitation ongoing through the
day. If that is the case, a slushy accumulation of one half inch
or less would be the outcome.

For the rest of the forecast period, temperatures will generally be
seasonable. A progressive upper-air pattern continues to tease
beneficial rain for the area. However, one of these once promising
systems is fading quickly. For Thursday, guidance continues to
suppress a departing Four Corners upper-level wave off to our south.
Farther north, a clipper now looks to miss our area too. In
between, high pressure squeezes in overhead. There is some hope the
lingering southern wave grazes a portion of the forecast area
Friday, but overall it appears POPs in the Thursday-Friday period
(via the in-house blend) will need to be cut in the coming days.
Similarly, inherited weekend POPs will also need scissors as high
pressure lingers, steering beneficial precipitation elsewhere.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1203 AM EST Tue Nov 18 2025

Upper level forcing will increase for the remainder of the overnight
into Tuesday morning as an upper jet streak noses across the
southern Great Lakes. This upper trough will work across northern
Indiana into Tuesday afternoon. Increasing isentropic lift overnight
downstream of this feature and eastward migration of a mid level
frontogenesis axis will help rain overspread terminals in the 08Z-
11Z period. Thermal profiles still support mainly liquid precip type
at the terminals with mixed precip types likely being confined to
lower Michigan into far northeast Indiana. Surface reflection of
this system will shift south of the terminals and potential of MVFR
cigs should increase after daybreak. IFR cigs are of somewhat lower
confidence but certainly a possibility at KSBN late morning/early
afternoon and at KFWA Tuesday afternoon/evening. Mid level fgen
forcing should be departing later Tuesday morning, but stronger
vorticity advection with the upper trough and cold pool aloft will
keep scattered showers in place through the afternoon hours Tuesday
warranting a VCSH mention.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Brown
AVIATION...Marsili