830
FXUS63 KIND 081251
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
851 AM EDT Mon Jun 8 2026

.KEY MESSAGES...

- Scattered/numerous showers, few t-storms/downpours arrive today
  with greater coverage in PM...isolated flooding possible

- Humid and very warm this week...nearly daily rain chances
  continue through Friday...readings near 90F Wednesday-Thursday

- Late this weekend: slightly milder, lower rain chances

&&

.FORECAST UPDATE...
Issued at 851 AM EDT Mon Jun 8 2026

Surface analysis this morning shows warm and humid southerly flow in
place across Central Indiana. This was due to low pressure over
western KS, and strong high pressure was found over Upstate NY.
Water vapor shows an upper trough over the middle Mississippi river
valley. A tropical plume of moisture was found streaming northward
ahead of the trough across TN/KY and IN. A band of showers over SW
Indiana was streaming north toward LAF and IND.

This afternoon, the wave of showers to the southwest is expected to
push north across the area. Additional showers and storm development
is also expected. Forecast soundings show deep saturation arriving
this afternoon, with some limited instability through the afternoon.
Convective temperatures appear to be around 80, with CAPE over 1200
J/KG. PWATs are suggested to be over 2 inches...very moist...which
will result in some heavy downpours with showers and storms. HRRR
suggests storms developing and increasing in coverage through
afternoon hours. However precising timing and locations are a bit
more uncertain. Thus the ongoing forecast of high pops this
afternoon appears on track, although constant rain is not expected.

&&

.DISCUSSION (Today through Sunday)...
Issued at 344 AM EDT Mon Jun 8 2026

Humid and at times rainy midsummer style pattern to continue this
week as central Indiana sits south of rather active, yet retracted
jet that will maintain generally south-southwesterly flow through at
least the mid-week.  Near to short term will additionally feature
weaker-forced but rather broad short wave upper trough lifting from
Middle Mississippi Valley this morning, across Indiana today and
tonight.  Broad ascent coupled with ribbon of Gulf moisture hosting
precipitable water values at times in excess of 2.00 inches through
dawn Tuesday will promote scattered to widespread showers and
potential for areas of heavy rainfall, especially south/west of
Indianapolis.

Held off on any headlines at this time given great confidence in
heavy rainfall over southwest and probably south-central zones whose
past 11-day rainfall totals are mainly zero to maybe 0.40 inches.
Greater flooding concern for NW counties / E-central areas that have
picked up mainly 2.00-4.00 inches of rain over past 1-2
days...namely from Lafayette south to I-74 corridor west of Metro
(Saturday) and to a lesser extent NE/E of downtown Indianapolis
(Sunday).  Lower confidence in appreciable additional rainfall
through early Tuesday for these areas, with greatest chances of
heavy rainfall south of US-36 over to the I-65 corridor.

Previous discussion follows for mid to late week timeframe:

Tuesday...

The upper trough will still be in place over Ohio on Tuesday and
models continue to suggest some lingering lower level moisture
during the morning hours. This could lead to some very light rain
showers as through the morning, particularly across the eastern
parts of the forecast area. Much better clearing is expected to
arrive by afternoon as the trough axis exits farther east. Forecast
soundings at that time suggest a dry column on Tuesday afternoon,
but warm temperatures in the upper 80s.

Tuesday Night...

There is low confidence for precipitation on Tuesday Night at the
moment. Models are showing sufficient low and mid level saturation
overnight as a poorly defined upper wave passes, amid what should be
ridging building in the wake of the departed trough. The lower
levels appear unorganized also, just depicting warm and humid
southerly flow in place. Thus will continue to keep some mention of
pops in the forecast due to model trends, but confidence is low.

Wednesday...

More warm and humid SW flow will be in place on Wednesday with
little in the way of forcing available other than diurnal heating.
Forecast sounding suggest typical afternoon and evening instability
showers will be possible given the warm and humid air mass. Will
include pops for now. Low confidence.

Thursday and Friday.

The commencement of the long-term period on Thursday and Friday
features central Indiana deeply embedded within a progressive,
moisture-rich warm sector. Recent global deterministic runs of the
GFS and ECMWF, along with support from the GEFS and EPS ensemble
means, show a consensus that a stagnant subtropical ridge off the
Carolinas will keep the local area under a regime of steady low-
level warm air advection and moisture convergence. Boundary layer
moisture will be robust for mid-June, with surface dewpoints progged
to consistently reach into the upper 60s and lower 70s. Strong
diabatic heating operating on this high theta-e airmass will lift
afternoon maximum temperatures into the upper 80s and lower 90s on
Thursday, yielding highly unstable atmospheric profiles. Soundings
show MLCAPE values exceeding 2000 to 2500 J/kg during peak afternoon
heating. While mid-level lapse rates remain somewhat modest, the
lack of significant convective inhibition means that isolated to
scattered pulse-type thunderstorms will easily trigger along any
remnant mesoscale outflow boundaries.

A more organized severe weather and heavy rainfall threat
materializes by late Thursday into early Friday as a deeper mid-
level trough pivots out of the Upper Midwest and pushes a cold front
toward central Indiana. This synoptic feature will provide the
necessary large-scale dynamic ascent and wind shear to organize the
highly unstable environment. Forecast models indicate 0-6 km bulk
shear vectors increasing to 35 to 45 knots, shifting the convective
mode from unorganized pulse cells into a forward-propagating linear
structure or robust multi-cell clusters. Damaging straight-line
winds and isolated large hail will be the primary hazards with any
severe cores ahead of the front. Furthermore, precipitable water
values are projected to climb toward 1.75 to 2.00 inches, which sits
well above the 90th percentile for early June. These high moisture
profiles indicate extreme precipitation efficiency, and any training
convective elements ahead of the slow-moving boundary will pose a
localized flash flooding threat, particularly across areas with
saturated antecedent soils.

Saturday and Sunday.

A pattern shift then takes place late Friday night into Saturday
morning as the surface cold front clears the southern counties of
Indiana. Strong anticyclonic building will commence as a sprawling
1024 mb Canadian high pressure system drops southward across the
Great Lakes. Robust cold air advection will take hold through
Saturday morning, driven by a sharp northwesterly wind shift. Deep-
layer subsidence and dry air entrainment will rapidly clear out the
tropical moisture plume, forcing precipitable water values down to
under 0.75 inches by Saturday afternoon. There are some signs of
another system towards Sunday with the Canadian model and its
ensembles showing a mesoscale driven system, but confidence is very
low at this time, especially considering how far it lies from the
other global models.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 739 AM EDT Mon Jun 8 2026

Impacts:

- MVFR CIGs in scattered -SHRA, arriving SW to NE within 12Z-16Z
- Periods of -SHRA/few TSRA through afternoon, isolated downpours
  possible.

Discussion:

VFR conditions across the terminals this morning are expected to
quickly deteriorate to MVFR. An upper trough will be working across
the state. Plentiful moisture, daytime heating and upper forcing
across the area will allow for shower and thunderstorm development
this afternoon. Confidence for rain and storms through the day is
high, but confidence for precise timing and locations is low.

Thus large windows of VCSH and VCTS will be used through the day.
Areal coverage of showers and storms will diminish this evening as
heating is lost, but as the upper trough will still be in the
vicinity, a few showers and storms will still be possible.


&&

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

$$

UPDATE...Puma
AVIATION...Puma
DISCUSSION...AGM