512
FXUS63 KIND 011407
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1007 AM EDT Wed Apr 1 2026

.KEY MESSAGES...

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

- Potential for strong to severe storms at times, primarily late
  Thursday and again Saturday

- Strong non-thunderstorm winds expected Thursday and potentially
  Saturday, with frequent gusts of 35-40 MPH possible

- Drier and cooler weather for early next week

&&

.FORECAST UPDATE...
Issued at 1006 AM EDT Wed Apr 1 2026

Wide ranging conditions expected across Indiana today as a cold
front separates a warm and humid airmass to the south from a colder
airmass to the north. Current observations indicate the quasi-
stationary front stretches west to east just south of I-70. A 20+
degree temperature gradient exists on either side of the front with
low 70s to the south and upper 40s in North Central Indiana. The
main area of remains in North Central Indiana on the north side of
the front where the best low to mid level frontogenetical forcing is
located. IND ACARs soundings show a sharp boundary layer inversion
with steep mid and upper level lapse rates above it, supporting
embedded thunderstorms within the larger area of rain.

For the rest of the morning and early afternoon, expect the most
widespread rain to persist in North Central Indiana. Satellite and
radar depicts a weakening meso-low in Illinois, which may enhance
coverage and intensity of rainfall north of I-70 through the early
afternoon. This low will also work to spark off additional scattered
convection just to the south of the main rain shield along the I-70
corridor. Convection in Central Indiana should be more intermittent
until the next wave of showers and embedded storms in Missouri
tracks along I-70 and into the state by early afternoon. Confidence
is increasing that this next round of showers and storms will track
further south than the convection early this morning. Best chance
for more widespread showers and an embedded storm looks to be south
of I-70. Best thunderstorm chances remain in the warm sector in
South Central Indiana where the environment supports additional
surface based storms. Along I-70 and in the Indy Metro area, mainly
plain rain expected with a few lightning strikes possible early to
mid afternoon; however CAMs shows decreasing instability in the mid
levels later today lowering lightning probs overall north of the
front.

&&

.SHORT TERM (Today through Friday night)...
Issued at 328 AM EDT Wed Apr 1 2026

An active pattern remains the expectation for the remainder of the
week, with multiple opportunities for showers and thunderstorms,
with one or more at least low chances for a strong storm or two.

A frontal zone continues to sag into the region this morning,
currently draped from near St. Louis to Indianapolis/Muncie and
Columbus, Ohio. This boundary, in part reinforced by a rain cooled
airmass to its north, will continue to sag southward during the
day and should stall near the southern border of the forecast area
later today before lifting back northward as a warm front tonight
into Thursday.

Relatively weak elevated instability north of the boundary will put
a cap on embedded thunder chances today, though modest surface based
instability should develop south of the front, wherever it happens
to stall, and this, combined with the frontal forcing, will likely
produce at least some scattered thunderstorm activity. Deep layer
shear is strong enough to support some storm organization, so an
isolated strong storm is not out of the question, though this
limited threat will likely be slightly more likely to our east.

The primary concern will be at least a minor hydrologic threat as
flow is aligned to a significant degree, though not perfectly,
boundary parallel, which could produce areas of training in a
background setting featuring precipitable water values near or above
climatological max.

A bit of a lull in rain chances can be expected late tonight into
early Thursday as the area reemerges into the open warm sector with
the warm front pushing rapidly northward in response to a strong
surface low and upper level wave moving northeastward out of the
central Plains into the upper Great Lakes.

The shower and thunderstorm threat will ramp back up again on
Thursday afternoon into Thursday night as one or more rounds of
prefrontal convection associated with the aforementioned system move
through the region. Deep layer shear will remain plentiful, and low
level shear will be substantial as well owing to strong low level
flow and some veering in the warm advection regime. The degree of
destabilization is in question giving the threat a somewhat
conditional nature, but even modest instability in such a flow
environment would pose at least a decent wind threat with minimal
trouble mixing down 50+KT flow within a few thousand feet of the
surface, as well as concern for a tornado or two.

Outside of thunderstorms, Thursday will again be quite windy, with
PBL mixing and steep low level lapse rates likely able to mix down
frequent gusts of 35-40 MPH with isolated higher gusts possible.
Similar gusts may be possible on Saturday as well depending upon the
depth of mixing.

This low will be followed in quick succession by another similarly
strong system Friday into Saturday, which will hold up the front
from fully pushing through the area until this second low passes
Saturday. Despite continued strong deep layer shear, instability is
an even larger question during this time frame, though at least an
isolated strong to severe storm threat would appear possible then as
well.

Throughout this period, deep moisture and the potential for repeated
rounds of moderate to at times heavy rainfall will gradually
increase the hydrologic concern across the region, and a localized
flash flood threat may grow with time, and hydrologic ensembles show
a fairly high likelihood of portions of the main stem rivers
returning to at least minor flood, particularly along the Wabash,
and portions of the lower White and East Fork White.

Temperatures will be well throughout the vast majority of the week,
though a strong cross-boundary temperature gradient will exist today
and tonight across central Indiana. Temperatures will frequently be
15-25 degrees above average until frontal passage this weekend.

&&

.LONG TERM (Saturday through Tuesday)...
Issued at 328 AM EDT Wed Apr 1 2026

Saturday and Saturday Night...

Active weather looks to finally come to an end on Saturday and
Saturday Night. As we being the day, models suggest ridging aloft
over the eastern Great lakes departing, but a cut off low will be
found over the upper midwest. This will place Central Indiana still
within the SW flow aloft. The cut off low and an associated moderate
upper trough will push toward and across Central Indiana, allowing
plenty of upper support to arrive in Indiana through the day. Within
the lower levels Central Indiana will start the day within the warm
sector, and a cold front will push across the state through the
afternoon and into the evening. Forecast soundings at this early
stage suggest a deeply saturated column passing, with little CAPE,
through the afternoon. Subsidence and drying is shown to arrive on
Saturday night after 00Z. Thus confidence will be high along with
high pops for Saturday at this time. Pops will need to be tapered
off on Sunday night as the moisture exits and drying, subsidence and
cold air advection arrives.

Sunday through Tuesday...

Quiet and cooler weather is expected on Sunday through Tuesday, as
strong ridging is expected to take shape over the western CONUS.
This will result lee side northwest flow to spill from Central
Canada into the Ohio Valley on Sunday through Tuesday. Meanwhile at
the surface strong high pressure is suggested to settle across the
plains, resulting in a continued flow of cool and dry Canadian air
across Central Indiana. On Monday, there is a caveat. Models show a
weaker short wave within the NW flow aloft streaming across the
Great Lakes. While this will provide some upper support,
precipitation chances appear minimal as moisture sources are
limited. Lower levels are suggested to remain dry as mid level
clouds pass with this feature. Thus will keep a dry forecast at this
time, but it will be something to watch over the next few runs to
see if enough forcing could be present to squeeze out some very
light precipitation. Otherwise, we will expect a few more clouds on
Monday as these features pass.

More sunshine and cooler weather should arrive on Tuesday as ridging
is expected to re-establish itself over the upper midwest, providing
subsidence and dry air flowing into Indiana. Temperatures on Sunday
through Tuesday will be at or below seasonal normals, thus highs
mainly in the 50s.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 638 AM EDT Wed Apr 1 2026

Impacts:

- Showers with some embedded thunder, particularly at LAF

- IFR ceilings persisting or developing at all sites but BMG

Discussion:

A boundary continues to slowly sag into the area, with winds
shifting to the north and then northeast behind it. The majority of
precipitation and thunderstorm activity are elevated north of the
boundary, and this will largely remain the case, though more shower
activity will overspread the sites today as the boundary pushes
south.

A stout frontal inversion north of the boundary will promote
deteriorating ceilings and perhaps visibilities, with IFR likely to
dominate most of the sites by or shortly after valid time and
through much of the rest of the period. BMG may remain MVFR once it
falls to that level but the gradient between IFR and VFR may be
tight, so uncertainty is high there.

Embedded thunder will be possible today, but is too uncertain for a
mention. The most likely time would be this afternoon when
instability would be maximized.

Winds will gradually shift to the north and northeast through the
period, becoming easterly this evening. This boundary will begin to
push back northward as a warm front late in the period, bringing
winds around more to the southeast and south and improving ceilings
late.


&&

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

$$

UPDATE...CM
SHORT TERM...Nield
LONG TERM...Puma
AVIATION...Nield