Special Weather Statement, NWS Indianapolis, IN

Area Forecast Discussion
National Weather Service Indianapolis IN
629 PM EDT Fri Apr 3 2026

.KEY MESSAGES...

- Wet pattern through Saturday, with multiple rounds of showers and
  storms expected, which may produce occasionally heavy rainfall
  and renewed flooding along area waterways

- Strong to severe storms possible this afternoon and evening into
  Saturday; damaging winds and hail will be the primary concerns

- Drier and cooler weather Sunday through early next week. Potential
  for lows in the low to mid 30s Monday through Wednesday mornings.
  Frost or freeze conditions possible.

&&

.MESOSCALE UPDATE...
Issued at 629 PM EDT Fri Apr 3 2026

Early evening convection has developed across Central and
Northcentral Indiana, mainly associated with a couple notable
boundaries. All boundaries are found easily from the satellite
imagery, with a weaker less potent boundary displaced to the
southeast of the Indy Metro. The other is along the northern suburbs
of the Indy Metro, then the more active boundary along the northern
periphery of the forecast area from Warren/Fountain counties
stretching east through Tippecanoe into Carroll county. This
boundary is slowly drifting north, but along and just north there is
considerable upscale growth to the convective elements.
Unfortunately the boundary is equally adding some enhance helicity
and allowing a few updrafts to demonstrate some rotation based off
of latest radar imagery.

The environmental features are demonstrating around MUCAPE of
1000J/Kg within that northern boundary, further south MUCAPE is
marginally less but still worth a mention. Along the northern half
of the forecast area a layer of stronger wind shear is also found
within the 0-6km layer roughly in the 35-45kt range. This would
suggest that the continued development or sustaining the
current/ongoing convection will occur. But as convection lifts north
towards White County the environment is more favorable which is
along the stronger gradient of dynamics in the lowest 3km of the
atmosphere. Lapse rates are the one element keeping the atmosphere
under some control around 6-6.5 deg C/km which should help to limit
some stronger development and coverage for convection this evening
across Central Indiana.

&&

.SHORT TERM (This evening through Saturday)...
Issued at 302 PM EDT Fri Apr 3 2026

A warm front is lifting north across Indiana this afternoon, and
stretches roughly from Champaign IL through Lafayette eastward
through Kokomo then into Ohio. Satellite imagery reveals the front
well, with a rough unstable cumulus field south of it and a stable
wave-like stratus layer to the north. As the front lifts northward
this afternoon, enough instability should develop for showers and
thunderstorms.

THIS AFTERNOON

ACARS soundings out of IND confirm this with increasing instability,
around 1200 J/Kg MUCAPE as of 2pm. Concurrently, radar imagery has
started to show a few weak echoes around this time. We are likely
beginning to reach convective temperatures which are in the mid 70s.
As temperatures gradually increase, convection should become more
widespread and gain intensity.

Convective coverage will be limited by relatively weak synoptic
lift. Our primary lifting mechanisms are confined to buoyant forces
and isentropic lifting from the front itself. This should help keep
activity fairly discrete this afternoon. Effective shear is fairly
modest, between 20-30 knots. However, this may be enough to allow
for some storm-scale organization. A few multicell clusters or even
an isolated supercell is possible.

Model soundings show modest lapse rates between 6-7 C/Km today, with
a very moist profile up through the EL at 10-12 Km. Hodographs have
some curvature within the lowest 3km, but not a whole lot. Still,
enough is present to allow for an isolated mesocyclone as mentioned
above. This could allow for a large hail, wind, and isolated tornado
threat. The overall chances are low, but greatest near the front
itself which will quickly lift northward out of our CWA this
afternoon and evening.

SATURDAY

Further west, surface low pressure is expected to develop over Iowa
this afternoon and move northeastward overnight. Thunderstorms are
expected to develop along the system's cold front which extends
north to south from Kansas down into Oklahoma. Convection is modeled
to congeal into a line, progress eastward, and enter Indiana around
10-12z Saturday morning. Most if not all guidance show it in a
weakening state as it arrives. Overall, severe potential seems low
due to limited instability. However, a potent low-level jet may
allow for sporadic wind gusts with any of the stronger convective
cores. This potential increases through the day as the line heads
eastward, and may pose a more organized severe weather threat by the
time it reaches Ohio.

Temperatures remain warm through the night tonight within southerly
flow. Readings overnight may not drop out of the 60s. However, as
the cold front arrives an abrupt wind shift is expected with rapidly
falling temperatures. Readings may drop from the 60s/near 70 quickly
into the 50s during the afternoon hours. By Saturday night, lows in
the 30s are expected. Frost is possible by Sunday morning, but
breezy conditions may limit this somewhat.

&&

.LONG TERM (Saturday night through Friday)...
Issued at 302 PM EDT Fri Apr 3 2026

A few day period of dry, yet colder conditions expected Sunday
through the first half of next week before temperatures warm back
toward and above seasonal norms.

Broad troughing moves in over the Great Lakes region on Sunday with
Indiana being under the influence of northwesterly flow aloft.
Surface high pressure becomes centered over the Plain while an area
of low pressure races northeast into Quebec resulting in a much
colder airmass advecting in from the northwest. This pattern sets
the stage for a few day period of below normal temperatures with the
threat for frost/freeze conditions by next week.

On Sunday, much drier and colder air is advected in by strong
northwesterly flow. Aloft, the upper level trough axis pushes in
overhead, potentially sparking off an afternoon shower. The threat
for this is low; however forecast soundings and BUFKIT profiles show
an environment conducive for widespread afternoon cumulus. There may
be enough moisture for an isolated shower to develop during the
early afternoon as the trough axis pushes through, but overall
expect a dry day. Steep low level lapse rates from cold air
advection aloft will allow for stronger wind gusts of 20-25 mph to
mix down to the surface through the day, making it feel even colder.
Temperatures Sunday morning bottom out around 40 and struggle to
rise into the lower 50s.

A weak wave and surface boundary within the northwest flow move into
the Great Lakes region late Sunday night. With limited moisture
associated with this, the only sensible impacts for Central Indiana
will be elevated winds around 5-10 mph overnight Sunday into Monday
morning then gusts to 20-25 mph again Monday afternoon. These winds
may help prevent frost/freezing conditions during the morning hours
despite the cold airmass in place. Keeping forecast lows in the
upper 30s for Central Indiana; thinking patchy frost could be
possible in South Central Indiana where winds may be weaker allowing
for better radiational cooling. Highs rebound into the mid 50s to
near 60s by Monday afternoon.

Another Canadian high pressure system becomes centered over the
Great Lakes by Tuesday afternoon bringing a reinforcing shot of
colder air to the region. With the high center nearby Tuesday
morning, winds may drop off enough to allow for better radiational
cooling, especially for North Central and northwestern portions of
Indiana. Best chance for lows near or below freezing will be along
and north of I-70. Lower confidence if winds will diminish enough to
allow for frost formation as the center of the high will be over
Wisconsin early Tuesday. Despite slightly elevated winds, Tuesday
morning looks like the best set up for potential frost or freezing
conditions.

Later into the work week, strong low pressure traverses the
US/Canadian border while high pressure shifts east, placing Indiana
once again in a much warmer southerly flow pattern. An extensive,
elongated frontal boundary extends west/southwestward from this low
back to the central Plains and stalls out somewhere in or just north
of the region. This will reintroduce chances for showers, and
perhaps a few storms Thursday or Friday. Great forecast uncertainty
exists toward the end of next week regarding the exact evolution of
the set up and placement of synoptic features. Confidence is
increasing through in a much warmer and potentially wetter pattern
setting back up the latter half of next week and into the following
weekend.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 141 PM EDT Fri Apr 3 2026

Impacts:

- Wind gusts between 20-30kt possible throughout the TAF period
- Scattered showers with possible thunderstorms this afternoon and
  evening
- Widespread showers and embedded thunderstorms Saturday morning
  into afternoon.

Discussion:

MVFR ceilings this afternoon. MVFR or lower on Saturday with
rain/storms.

A warm front is lifting north across Indiana and breezy
southwesterly winds have taken hold. Winds should range from 10-15kt
with gusts between 20-25kt at times. Speeds decrease a bit overnight
to around 10kt while becoming more southerly. A return to
southwesterly is anticipated Saturday morning. Winds continue from
the southwest until a cold front arrives late Saturday afternoon
with a wind shift to westerly.

Most guidance shows showers and thunderstorms this afternoon along
the warm front. However, this activity will be scattered in nature.
Timing these showers/storms for any particular terminal will be
tricky, so a Tempo group was added to cover the most probable time
frame.

A stronger line of storms associated with the cold front arrives
Saturday morning. Rain is likely, with embedded thunderstorms. A
prob30 was included for thunderstorms with reductions in visibility.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

MESOSCALE...Beach
SHORT TERM...Eckhoff
LONG TERM...CM
AVIATION...Eckhoff