118
FXUS63 KIND 151910
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
310 PM EDT Sun Mar 15 2026

.KEY MESSAGES...

- Showers and thunderstorms expected late today, with severe storms
  possible mainly from 7 PM to 2 AM EDT

- High Wind Warning until 8pm, then Wind Advisory from 8pm today
  to 8am Monday. Wind gusts between 50-60 mph possible today, then
  up to 45 mph overnight.

- Snow showers likely on Monday with up to an inch possible

- Much colder air early this week, wind chills near zero Tuesday
  morning

&&

.SHORT TERM (This evening through Monday)...
Issued at 310 PM EDT Sun Mar 15 2026

Surface low pressure continues to strengthen over northern Illinois
as a vort max amplifies significantly over the Great Plains. The low
will then track northeastward into the Great Lakes tonight, dragging
a strong cold front through Indiana between 00z-06z. As of 2pm,
Indiana lies firmly within the system`s warm sector. Temperatures
have surged into the 70s as strong mass response promotes continued
warm air advection. Additionally, a tightening MSLP gradient has
lead to strong gusty winds with numerous observations of gusts
between 50 to 60 mph. A High Wind Warning is in effect until 8pm,
with a Wind Advisory from 8pm today to 8am Monday.

Turning our attention to the system`s cold front, this feature will
act as a focal point for thunderstorm initiation this afternoon over
Illinois. Moisture advection ahead of the front is modest, with dew
points currently into the mid 40s to low 50s. High-resolution
guidance suggests a last-minute surge of slightly higher moisture
content immediately ahead of the front, which may impact severe
weather potential this evening.

TONIGHT`S SEVERE WEATHER THREAT

As mentioned above, tonight`s threat depends on available moisture
and therefore low-level instability. First, we`ll discuss the
available dynamics, which certainly are not lacking. A strong low-
level jet from the south between 50-70kt (925mb-850mb layer) is
expected to develop this evening. This will result in highly
elongated and curved hodographs, signifying abundant speed and
directional shear. ACARS soundings show a deep elevated mixed layer
from 850mb to 650mb, which will act to mitigate open warm sector
convection. As such, forcing looks to be confined to the front
itself. With a largely southwesterly shear profile, a nort-south
oriented boundary, and a focused region of forcing...a linear mode
is preferred for tonight`s convection.

Regarding hazards, the linear convective mode combined with the
potency of the low-level jet will favor severe (60-70mph) to
significantly severe (70-80mph) wind gusts as the primary threat.
However, with such a strongly sheared low-level environment,
indicated by the long curved hodographs mentioned above, a QLCS
tornado threat is also present. This threat is contingent on near-
surface moisture/instability. Greater moisture and near surface
lapse rates, and thus lower LCLs would increase the QLCS tornado
threat with the inverse also true. QLCS spin up potential should be
maximized in line segments that become perpendicular to the
effective shear vector within the lowest kilometer of the
atmosphere. This would allow for greater rear inflow jet (RIJ) surge
potential and vertical shearing vorticity that could then be
stretched by updrafts.

SNOWFALL POTENTIAL

Temperatures fall quickly behind the front, which will pass through
the area between 00-09z. By 12z Monday, most of the region likely
falls to around freezing with continued strong cold advection
causing temperatures to drop through the daylight hours Monday.
Steep lapse rates within the cold air mass will promote scattered to
numerous snow showers on Monday. Some of the snow showers could be
briefly heavy, given steep low-level lapse rates, which may reduce
visibility and lead to hazardous travel. Snowfall likely melts on
contact with roadways early but as temperatures drop through the day
some slick spots may develop. Total snowfall accumulations should be
less than an inch on average.

Additionally, continued gusty winds between 30-40 mph throughout the
day Monday combined temperatures falling through the 20s may result
in wind chills in the teens. Even colder wind chills in the single
digits are possible Tuesday night as ambient air temperatures fall
into the teens.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 310 PM EDT Sun Mar 15 2026

Much of the long term will be dominated by NW flow as very strong
CAA from the earlier weak system helps induce high pressure in the
low levels and a deepening trough in the mid to upper levels. In
return, winter-like conditions are expected for Monday night and
Tuesday. The biggest forecast concern for the beginning of the long
term will be cloud coverage. The strong subsidence with an upstream
deep trough could lead to a low stratus layer, but continued surface
mixing and emergence of more broad subsidence through AVA could
produce some breaks. If overcast conditions remain Monday night,
lows will likely only fall into the mid to upper teens; however, if
there is some clearing, pockets of lows near 10 degree or even
lower in the valleys will be possible. For highs on Tuesday, typical
diurnal curves with 850mb temperatures around -15C should lead to
highs in the mid 20s.


The pattern begins to change mid week as 700-600mb wave progresses
eastward. This wave has modest CVA and WAA attached with it, but the
forcing is displaced from the low levels keeping temperatures cold
initially, This should lead to a weak snowfall event Tuesday night
into Wednesday morning with snowfall up to an inch possible over
portions of central Indiana. Following the passage of this wave, low
level high rises and temperature gains will promote a late week warm
up with high back near 60 by Thursday.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 137 PM EDT Sun Mar 15 2026

Impacts:

- South winds with gusts between 40-49kt this afternoon.
- Thunderstorms and MVFR conditions expected after 00Z ending by 04Z.
- Light snow with IFR conditions expected at KLAF, with snow
  showers in the vicinity expected elsewhere after 08Z.
- Wind gusts remain over 30 kts through tomorrow.

Discussion:

Strong winds have developed across the terminals early this
afternoon with multiple gusts over 45kts. Have raised to gusts to
between 47-49 kts for all terminals through 00Z.

A line of thunderstorms is expected to move west to east through the
terminals mainly in the 00Z-04Z time frame. Convection may be
severe. At this time left wind gusts just below 50 kts. MVFR and
worse are possible within convection, then general MVFR behind it.
Snow showers will develop later tonight, after 08Z, with prevailing
light snow and IFR visibilities at KLAF into mid morning Monday.
Elsewhere, VCSH and MVFR will last through tomorrow morning.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 8 PM EDT this evening for INZ021-028>031-
035>049-051>057-060>065-067>072.

Wind Advisory from 8 PM this evening to 8 AM EDT Monday for
INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

SHORT TERM...Eckhoff
LONG TERM...Updike
AVIATION...Crosbie