657
FXUS63 KIND 111226
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
826 AM EDT Wed Mar 11 2026

.KEY MESSAGES...

- Widespread minor/moderate river flooding continues south of I-70

- Locally heavy rainfall is expected tonight into Wednesday, which
  will exacerbate or prolong ongoing flooding

- Scattered severe storms with all hazards are possible tonight and
  Wednesday

- Record warmth today but cooler temperatures expected Thursday

&&

.FORECAST UPDATE...
Issued at 826 AM EDT Wed Mar 11 2026

Surface analysis late this morning shows low pressure over SW MI. A
cold front extended southwest from the low into NW Indiana and
eastern IL. This placed much of Central Indiana still within the
warm sector as temperatures at many locations continued to remain
around 70. Radar shows a QLCS ahead of the front, pushing across
western Central Indiana. Water vapor across the CONUS shows a
moderate trough in place across the plains states, with moist
southwest flow ahead of the trough streaming into the Ohio Valley.

This morning...the ongoing QLCS will make progress across Central
Indiana along with a strong LLJ. HRRR suggests 850mb winds of 70
knts pushing quickly across the forecast area this morning, quickly
driving the QLCS across Central Indiana. Given these strong winds
aloft, severe threat remains valid for any winds that could mix down
to the surface. HRRR suggests the stronger thunderstorms should exit
the area near 11a-12p, but cold pool rain still may linger into the
early afternoon. Thus continued high pops will be used for much of
the day.

Additional development across southern and southeastern parts of
Central Indiana will possible this afternoon as the front sags
southward and begins to interact with the warmer and favorable
airmass still in place to the south.

Given the cold air advection expected in the wake of the front, look
for temperatures to fall into the 40s by late afternoon.

&&

.MESOSCALE UPDATE...
Issued at 731 AM EDT Wed Mar 11 2026

An anomalously warm/moist air mass is in place across central
Indiana this morning within strong warm advection regime. An
upstream QLCS is oriented oblique to the deep shear vector, and
given its magnitude it will be favorable for mesovortices and
tornado potential. These will be most likely where cold pool-driven
surges are most pronounced causing line reorientations to more north-
south. From the apex of any bowing segments northward is where the
highest threat of tornadoes will be this morning across central
Indiana. Otherwise, damaging wind will be the primary threat
particularly with any rear-inflow jet/surge structures, given weakly
stable lower troposphere and strong momentum aloft (i.e., ~65-knot
at 1-km) easily displaced downward to the surface.

&&

.SHORT TERM (Today and tonight)...
Issued at 230 AM EDT Wed Mar 11 2026

Quiet conditions remain across central Indiana early this morning
with gusty S/SW aiding in temperatures hovering near 70 degrees at
06Z. Convection up to this point has remained confined to the
northwest of the forecast area in close proximity to the frontal
boundary. The approach of a stronger surface wave...now located
across northeast Missouri...has enabled storms to track further
south over the last few hours into west central Illinois. This will
be the area of convection to monitor for impacts across the forecast
area after 09Z and continuing into the morning with the potential
for additional storms during the afternoon.

Through Late Morning

The ongoing convection across central and western Illinois is
highlighted by an impressive bookend vortex that is moving towards
KBMI as of 06Z. Mesoanalysis shows the storms in this area are
feeding off an environment with ample 0-3km CAPE overlaid by an area
with stronger BL shear. A recent VAD profile from KILX also
continued to show an impressive elongated right turn to the
hodograph in the lowest 1-2km with SRH values in excess of 400 m2/s2
in the lowest 500m. Extrapolation of the bookend could end up
clipping the northern Wabash Valley around 0730Z and will be the
portion of the forecast area that will need to be most closely
monitored over the next couple hours although it has showed a recent
weakening trend.

The presence of the strong low level SRH values will support an
isolated tornado risk with the bookend but the overall wind profile
is not as supportive of a greater tornado threat being further away
from the frontal boundary to the north. Remain more confident in
damaging wind gusts becoming the primary risk as these storms move
into our northwest counties with stronger 850mb flow arriving from
the southwest with the jet. 50kt+ winds as low as 2-3kft will not
take much to get pulled to the surface by the convective line. Large
hail also remains a concern with the steep lapse rates in the mid
levels and modest instability within the hail growth zone.

The trailing line of convection from near KSPI back into northeast
Missouri is setting up along the spine of the low level jet and will
pivot into the western part of the forecast area by 09-10Z and
spread east through the first half of the morning. The orientation
of the convection introduces more concern for localized flash
flooding in addition to the inherent severe weather risk that will
impact the forecast area through about 15Z. Any training of
convection will have the potential to produce in excess of 2 inches
rain quickly this morning. Instability will remain sufficient
through the morning but will drop back somewhat from earlier levels
with the overall wind profile transitioning to more unidirectional
as storms move east across the forecast area. With low level jet
winds strengthening...damaging winds will remain the prevalent
severe weather threat with large hail and isolated tornadoes
becoming secondary concerns. SRH values through the lowest 1-2km
remain very strong however and support at least an isolated tornado
risk with more intense cells or with any bookend.

Separate from convective winds...an increasing signal with stronger
gradient flow develops in the wake of the morning storms but ahead
of the frontal boundary set to pass through later today. Growing
more confident in the potential for non-convective gusts to peak at
45 to 50mph at times later this morning into the afternoon focused
especially across the southeast half of the forecast area. Have
issued a Wind Advisory to highlight this threat from 12Z through
21Z.

This Afternoon through Tonight

Showers will linger in the wake of the morning convection with the
possibility of a brief lull in rain near midday. By early afternoon
the frontal boundary should be bisecting the forecast area with the
potential for renewed convective development along the boundary as
instability increases and strong shear and SRH through the near
surface layer lingers. Hodographs through the lowest 1-2km are more
straight as opposed to curved and less favorable for rotating
storms. Damaging wind gusts will be the main threat focused across
the southeast half of the forecast area for a few hours this
afternoon before clearing the region by 21Z. Additional rainfall
should be a half inch or less this afternoon with rain ending over
far southeastern counties around sunset.

The stronger gradient wind flow and the impact to temperatures
across the frontal boundary will become bigger factor throughout the
afternoon. While temps from the mid 60s to lower 70s will remain
prevalent through daybreak...temperatures will fall steadily from
northwest to southeast into the afternoon as the front passes. By
late today...expect a 20 to 25 degree difference from the northern
Wabash Valley to southeast Indiana. Must of the forecast area will
fall into the 40s prior to sunset eventually tumbling into the upper
20s and lower 30s by daybreak Thursday as skies clear and high
pressure expands into the region.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 259 AM EDT Wed Mar 11 2026

Noticeably cooler trend under quasi-persistent H500 troughiness will
return central Indiana to a seasonable mix...of occasionally mild
and brief cold conditions.  Downstream strong upper ridging over
northwest Atlantic will combine will steady flow of short waves amid
kicking west-northwest flow over the northern Rockies...to promote
more rounds of stronger cyclogenesis...first over the Upper Midwest
Thursday night and Friday...and then early next week from the
central Plains to the eastern Great Lakes.  Late-winter arctic air
will most likely follow the early-week system, plunging subfreezing
readings into much of the northeastern CONUS.

This will all translate to a bright yet cool Thursday struggling to
rebound to 50F amid moderate CAA breezes...a windy late Thursday
night and Friday from the passing northern storm...and a typical
March day Saturday with lighter breezes bringing mainly low to mid-
50s under considerable cloudiness.  Conditions to turn more active
Sunday as next system deepens while crossing the Midwest...bringing
stronger southerly gusts, mid-April temperatures, and numerous
showers/few TRWs.  A 40-degree temperature drop is possible going
into the next workweek, bringing the region`s first hard freeze in
two weeks and probably a short burst of mixed precip or wet snow.
Quick arctic air mass to end the long term will likely have one
daytime only peaking near the freezing mark and one overnight into
the teens.  Additional chances of low-impact snow towards the mid-
week when a weaker clipper system should start transition back to
near normal readings.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 647 AM EDT Wed Mar 11 2026

Impacts:

- MVFR conditions this morning into afternoon then gradually
improving

- Thunderstorms with low visibility most likely this morning

Discussion:

MVFR stratus is widespread this morning and could lower to IFR with
significant visibility reduction and strong wind gusts as a line of
thunderstorms passes this morning. This may be followed by a brief
break from ceiling restrictions but in general we have prevailed the
more pessimistic MVFR scenario into the afternoon. Strong wind
gusts will continue through the afternoon and gradually diminish
this evening.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 5 PM EDT this afternoon for INZ039>042-
045>049-051>057-060>065-067>072.

&&

$$

UPDATE...Puma
SHORT TERM...Ryan
LONG TERM...AGM
AVIATION...BRB