467
FXUS63 KIND 161836
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
236 PM EDT Sat Aug 16 2025

.KEY MESSAGES...

- Rain likely tonight as a decaying storm complex moves southward

- Hot and humid conditions continue through Tuesday, cooler
  afterwards

- Additional showers and storms likely during a frontal passage
  Tuesday into Wednesday

&&

.MESOSCALE UPDATE...
Issued at 235 PM EDT Sat Aug 16 2025

As of early this afternoon, convection has generally remained
limited to the outflow boundary from the decayed convection that
moved through the northeastern portions of the forecast area.
Recently a Severe Thunderstorm Warning was issued for a storm to the
east of Indianapolis as it briefly showed the potential for both
severe hail and winds with good mid-level convergence. The eastern
areas of the forecast area continue to be the focus point for
thunderstorms over the next two hours, but expect focus then to
shift westward later into the early evening.

The best shear and ML CAPE continues to be across the western and
northwestern counties, but without a boundary to initiate, expect
fairly minimal coverage over the next few hours. Towards the early
evening, the cu field should fill in with at least a few showers and
storms popping up in the aforementioned area once the cap fully
erodes.

Greatest threats continue to be will be marginally severe winds and
torrential downpours along with hail in the strongest storms of the
day.

&&

.SHORT TERM (This evening through Sunday)...
Issued at 235 PM EDT Sat Aug 16 2025

Rest of Today and Tonight.

For the latest on the ongoing convection and thoughts through the
evening, see the mesoscale discussion above.

As the diurnally driven convection gradually comes to an end this
evening, focus shifts to tracking a likely MCS across Wisconsin with
good model agreement in a southerly progression through the
overnight hours. There are some differences in the timing and
strength of this gradually decaying MCS, but the WRF-ARW which
typically handles organized convection better brings in the storms
towards 6-9Z which lines up well with the NAM and is a bit faster
than the HRRR.

This MCS should have a well-defined cold pool which will allow it to
progress into Indiana while maintaining at least some threat for
damaging winds with 1000-1500 J/kg of CAPE. The lack of shear will
be made up by the strength of the cold pool but do expect a general
downward trend as it moves southward. Overnight lows will remain
mild again tonight with most spots generally falling into the low
70s.

Sunday.

Generally warm and dry conditions are expected for Sunday with some
delay in the better heating as cloud cover from the dissipated MCS
takes time to clear. This MCS should progress south of the forecast
area but if it stalls and completely dissipates there could be an
initiation point along the outflow boundary and associated
differential heating boundary. Otherwise, chances for convection
look low with only an isolated shower or storm possible during the
afternoon and evening during peak heating. As a result of the
morning clouds, daytime highs are trending lower for Sunday with
increasing confidence that highs remain sub-90 with some spots
potentially struggling to rise out of the mid 80s depending on the
thickness and longevity of the cloud cover.

&&

.LONG TERM (Sunday night through Saturday)...
Issued at 235 PM EDT Sat Aug 16 2025

Sunday Night Through Tuesday.

Quiet weather is expected to continue into Sunday night with broad
ridging continuing to dominate the weather pattern. There will be
slight northerly component to the surface winds which will allow for
some drier air to slowly work into the area, but still expect to see
dew points in the upper 60s to low 70s towards daybreak. Stronger
southerly flow returns Monday into Tuesday ahead of a frontal
passage Tuesday night into early Wednesday.

Models are all over the place on the timing of the front and the
associated weather with the passage, but generally expect to see
showers and thunderstorms ahead of the front with a low-end
potential for more organized and strong to severe convection. With
weak shear and only modest instability, organized convection
potential looks low but will need to be monitored in the days ahead.

Wednesday Through Saturday.

Cooler weather is expected in the aftermath of the frontal passage
with daytime highs in the low 80s and overnight lows in the low to
mid 60s through the remainder of the workweek. Dry air both near the
surface and aloft should keep any precipitation chances minimal, but
there does look to be a more organized and stronger upper level low
across southern Canada Saturday into Sunday which could bring
additional showers and storms for the second half of the weekend
into next week. Looking beyond into the following workweek,
conditions look to favor cooler than normal weather to finish the
month.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 130 PM EDT Sat Aug 16 2025

Impacts:

- TSRA possible at times through Sunday afternoon, especially near
  KIND/KLAF...yet high uncertainty in specifics

- Fog possible at KBMG tonight

Discussion:

Low confidence continues in TAFs given uncertainties in further
convective development today through Sunday.  Broad outflow boundary
over northeastern central Indiana will promote convective initiation
this afternoon near the Indianapolis Metro, while greater wind shear
aloft will be near KLAF.  Overall isolated/scattered convective SHRA
and TSRA are expected this afternoon into this evening...although
confidence remains low in specific timing or location under the
broad and weakly-forced upper ridge.

VFR conditions are expected outside of any convection.  Winds today
and tonight away from any convection should be sustained mainly
under 7KT.  Fog development is expected overnight, especially at
KBMG.  A decaying complex of storms/showers may cross central
Indiana early Sunday...with light northwesterly breezes possible in
its wake, towards the end of the TAF period.


&&

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

$$

MESOSCALE...White
SHORT TERM...White
LONG TERM...White
AVIATION...AGM