608
FXUS63 KIND 100445
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1145 PM EST Sun Nov 9 2025

.KEY MESSAGES...

- Winter Weather Advisory for Central and North Central Indiana 3AM
  to 10AM EST Monday where 1-2 inches of snow is expected

- Wind gusts of 20-30 mph today and again Monday.

- Lows in the 20s Sunday night and Monday night, with wind chills
  in the teens at times Sunday night into Monday night.

&&

.FORECAST UPDATE...
Issued at 843 PM EST Sun Nov 9 2025

Another round of snow is expected late tonight into Monday morning
across Central Indiana.

An complicated atmospheric set up for is responsible for the early
season snowfall in this part of the CONUS. Aloft, an anomalously
deep trough over the Great Lakes dives southward into Indiana over
the next 24 hours with an upper level vort max rounding the western
edge of the trough and pushing south along the IL/IN border tonight.
Additionally, a weak perturbation over eastern Lake Michigan is
evident within the midlevel isobars, indicating a deeper wave of
energy through the column pivoting around the overall low. The
strong thermal gradient between the anomalously warm waters of Lake
Michigan and surface temperatures has resulted in a surface meso low
to form off the shore of Benton Harbor Michigan, under the mid level
wave. Surface wind directions south of the developing meso low have
backed to the west with a broad cyclonic wind field now evident on
surface observations across the lower Great Lakes.

Strong northwest flow through the region has advected in a deep cold
airmass into Indiana with 850mb temperatures as low as -13C and
below freezing surface temperatures now reported across the state.
The incoming system off Lake Michigan is tapping into the
anomalously warm lake waters resulting in widespread snow developing
north of Central Indiana. Very steep lapse rates in order of
8.5C/Km, MUCAPE up to 250 J/kg and the strong thermal gradient are
leading to very heavy snowfall rates across Northern Indiana and in
the vicinity of the lake. As this meso-low and associated upper
level wave push south/southwestward, it will bring this moisture
with it, resulting in widespread snow close to the system. While the
best dynamics remain near the Lake, the environment over Central
Indiana is still conducive for accumulating snow tonight with low
level moisture and lift within the dendritic growth zone and
steepening low level lapse rates. Heavy snow accumulations will
remain within the Lake effect Snowbelt in northern Indiana; however
enough moisture will be pulled southward for minor snow
accumulations of up to 1-2 inches for much of Central Indiana along
and north of the I-70 corridor. The higher snowfall amounts locally
look to be around western portions of Central Indiana, near the
center of the incoming meso-low as this will be the area with the
best forcing for ascent for heavier snow.

With temperatures plummeting into the low to mid 20s by the morning
in addition to accumulating snow during the morning commute, will go
ahead and issue a Winter Weather Advisory for the Indianapolis Metro
area and points north and westward including Kokomo, Lafayette, and
Terre Haute. Morning travel may be impacted as snowfall rates and
falling air temperatures may be enough to overcome warmer road
temperatures leading to slick spots. Timing of snowfall will be in
the 3AM to 10AM timeframe with a sharp cut off from north to south
as snow ends this morning.

&&

.SHORT TERM (This evening through Monday)...
Issued at 247 PM EST Sun Nov 9 2025

Upper-level analysis shows deep troughing over the northern Plains
and into the Great Lakes. A more concentrated area of vorticity
within the trough is located over Lake Superior. Guidance shows the
trough digging southward with the vort max reaching Indiana around
sunrise Monday.

At the surface, a low pressure system which passed through Indiana
last night is deepening over the Mid-Atlantic states. Strong
northwest flow behind the departing low has allowed cold air to
quickly move southward. Temperatures, which peaked before sunrise,
have been steadily dropping through the 30s today. Continued cold
air advection is expected as the upper-level troughing moves
southward.

Temperatures...

Guidance is in very good agreement showing a continued drop into the
mid 20s tonight. Combined with brisk northwesterly winds between 10-
20 gusting to 30mph, wind chills as low as 10 degrees F are likely
tomorrow morning and again Tuesday morning. Highs on Monday are
expected to remain in the 30s, especially if there`s a layer of snow
on the ground (higher surface albedo will help offset increasing
sunshine Monday afternoon). Above-freezing temperatures are still
anticipated, which will help any accumulated snow melt through the
day Monday.

Snowfall...

Snow showers are now being reported across the western half of
central Indiana. These snow showers are lake-enhanced to an extent,
as the aforementioned northwesterly winds have a long fetch off Lake
Michigan. This band of snow should pivot eastward today as winds
slowly become more west-northwesterly. Snow amounts will be light
through the afternoon, and confined mainly to grassy/elevated
surfaces.

That changes tonight, however, as the air and ground continue to
cool. An inverted surface trough (induced by lake-warmed boundary
layer and enhanced by the vort max aloft) will allow for a heavier
batch of snow tonight into Monday morning. Combined with large-scale
lift from the vort max itself, snowfall rates could be enough to
overcome residual ground warmth to allow for accumulations on paved
surfaces. High-resolution guidance shows snowfall rapidly ending
with the passage of the upper-level vort max late morning Monday.

Some high-res guidance hints at a second, but weaker, vort max
dropping southward Monday night. This could end up clipping our
northeastern counties, leading to increased snow totals up there.

Our northern counties are favored for accumulating snowfall through
Monday morning. Snowfall rates and duration will decrease with
southward extent, given the partial dependence on lake generated
instability. Amounts around an inch will be the most common
scenario, with areas of 1-2 inches north of I-70. An isolated 3 inch
amount cannot be ruled out either. Further south, amounts between a
trace and an inch can be expected.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 247 PM EST Sun Nov 9 2025

Monday Night Through Thursday.

There may be a few lingering flurries/light snow showers across the
northern and northeastern portions of the forecast area, but as the
surface and near surface winds gain a more westerly vs northerly
component, expect to see the lake enhanced snow shift north out of
the forecast area. The air advecting into the area aloft will be
much drier which should allow for skies to clear through the night
with another night of lows in the low to mid 20s likely. As the
pressure gradients relax, wind speeds will decrease but with
temperatures slightly cooler compared to Sunday night, minimum wind
chills are likely to be as cold if not slightly colder than compared
with Sunday night

Southerly flow will quickly return Tuesday with broad ridging across
all but the eastern portions of the US which will bring a return of
near to above normal temperatures by Wednesday. Deep mixing
Wednesday will help to drop dew points and bring RH values below 40
percent along with occasional wind gusts of 20 to 30 mph. Surface
flow will be more westerly on Thursday with lighter winds as another
upper level low moves across Southeastern Canada.

Friday Through Sunday.

The ridge is expected to become more amplified Friday into the
weekend with a trough to the west of the Rockies and along the East
coast along with the low end threat for some light rain across the
Ohio Valley where a weak shortwave will move southeast along the
ridge. The warming trend is expected to continue into Saturday with
the potential for highs in the mid to upper 60s. Looking into early
next week, another low pressure system looks likely early in the
week which could bring widespread rain.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1144 PM EST Sun Nov 9 2025

Impacts:

- Another wave of snow showers late tonight through mid morning.
- MVFR and IFR Conditions through mid-afternoon on Monday.
- Wind gusts to around 25 knts through Monday afternoon.

Discussion:

Radar shows a meso low over northern Indiana, with snow showers
swirling around this feature. Lake snow was wrapping into this
feature on its west side.  Cigs have briefly improved to VFR at many
of the TAF sites, but this will not persist too long.

The meso low is expected to push southeast within the cold northwest
flow in place aloft, bringing the snow showers associated with it
across the TAF sites. This will result in MVFR to IFR conditions as
these showers pass. HRRR suggests the main window for this will be
mainly from 08Z to 14Z, thus have used tempo groups to account for
the expected drops in visibilities and cigs.

Gusty northwest winds will persist through the overnight and into
Monday due to a moderate pressure gradient across the area. This
will diminish on Monday afternoon as high pressure, ridging and
subsidence builds across the region and conditions return to VFR.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 3 AM to 10 AM EST Monday for INZ021-
028>031-035>040-043>048-051>056.

&&

$$

UPDATE...CM
SHORT TERM...Eckhoff
LONG TERM...White
AVIATION...Puma