560
FXUS63 KIND 061658
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1258 PM EDT Thu Aug 6 2026

.KEY MESSAGES...

- Occasion showers/t-storms today into next week, with greatest
  chances today through Friday night

- Localized ponding/flooding of low-lying areas will be possible
  where repeated rounds of downpours occur

- A few strong/severe storms are possible this weekend into early
  next week...with low confidence on exact details

&&

.FORECAST UPDATE...
Issued at 904 AM EDT Thu Aug 6 2026

Surface analysis this morning shows a broad Bermuda high pressure
system in place, providing warm, southerly gulf flow to Indiana and
the Ohio Valley. A meso low was found near St. Louis, and this
associated with a MCS cluster over MO and IL. This MCS was waning,
with warming tops. Radar shows thunderstorms with this feature over
Central IL, and a few showers had reached western Central Indiana.
Aloft, a broad, shallow trough was in place across the northern half
of the CONUS, with an axis near the Mississippi River. Dew points
across Central Indiana were in the 60s.

Given our steering flow aloft, the decaying MCS should track ENE into
central Indiana. However due to the warming tops and the unfavorable
time of day, this system should continue to weaken upon approach.
Pops will still be needed, particularly in the western parts of the
forecast area as this system should continue to weaken upon arrival.
HRRR shows limited precip reaching the area through the day, however
at a minimum, some high clouds/convective debris clouds will pass
through the day. These clouds may help to keep highs a bit cooler
than persistence. Overall, ongoing forecast remains in good shape.

&&

.DISCUSSION (Today through Wednesday)...
Issued at 400 AM EDT Thu Aug 6 2026

Today through Friday night...

Synoptic pattern through the next four 12-hour periods will
feature a rather stagnant set-up between two broad and well-
maintained upper level features...a trough over central/south-
central Canada and a subtropical ridge across mainly the southern
two-thirds of the CONUS, except through the OH/TN Valleys where
heights will be more neutral courtesy of the southern end of the
Canadian trough`s axis. This will place central Indiana in a sort
of saddle point...south of any sub-seasonal air, but north of any
consistent above normal readings. Quasi-steady flow of small
weaknesses curling around this axis, casually extending to the
southeast of the Canadian trough will keep an overall disturbed
pattern over the local region, amid precipitable water values of
1.70 inches or so per southerly flow around a Bermuda high ridging
west into the Carolinas.

However, overall weak forcing will keep any scattered to briefly
numerous showers occasional in nature.  Generally isolated thunder
will be sub-severe with greatest potential impact ponding of low-
lying areas due to weak storm motion.  Timing of higher chances/
coverage of convection will focus around early this morning from
upper forcing...and then perhaps also mid/late afternoon if clouds
can partially clear enough to facilitate better daytime heating...
with both of these periods favored more west of Interstate 69.
The diurnal uptick in clouds/showers Friday will most likely be for
eastern/southeastern counties ahead of a more southern-tracking mini-
vort coming up the Ohio Valley.  A spatially larger-scale shift east
of the quasi-stacked trough, across Indiana, could potentially bring
several hours of scattered rain coverage around Friday night`s early
overnight...ahead of quieter weather to start the weekend.

Higher humidity will be the rule through the end of the workweek,
with dewpoints nearing 75F Friday on southwest breezes gusting up to
15 mph.  Cloudier skies to promote smaller diurnal temperature
ranges from 66-72F in early mornings to a damp 81-86F during
afternoons.

Saturday Through Sunday...

Synoptically, Saturday morning shows a quasi-stationary surface
front across northern Indiana, situated along the southern edge of
an elongated 500mb trough stretching across the Upper Great Lakes.
Boundary layer moisture transport remains elevated ahead of the
boundary, with ensemble means from the GEFS and EPS maintaining PWAT
values near 1.8 to 2.0 inches, representing the 90th percentile for
early August climatology. HREF probability-matched mean guidance
indicates convective initiation by mid-to-late Saturday morning as
low-level thermal advection and weak PVA associated with an embedded
vorticity maximum traverse the region. Model soundings across
central Indiana depict MLCAPE values rising to 1500-2500 J/kg during
peak afternoon heating. Weak kinematic forcing, characterized by 0-
6km bulk shear of 15-20 kts, will preclude well-organized mesoscale
convective systems, but slow cell motion along the quasi-stationary
front presents a localized threat for training convection and flash
flooding. Forecast soundings show a deep CAPE profile with freezing
levels above 14,000 feet.

By Sunday, the surface boundary will continue to lift to the north
further into the Great Lakes and have less overall impact on central
Indiana weather. Aloft an upper-level ridge centered over the
Central Plains will slowly strengthen with minor height rises across
the area. 700-500mb temperatures will also warm a degree or two
helping to build a mid-level cap with will help to suppress
thunderstorm development. Mesoscale models including the HREF
members suggest isolated High temperatures both days will range from
the mid to upper 80s, with heat indices approaching the low to mid
90s.

Monday Through Wednesday...

The broad synoptic regime during the extended period will feature an
amplified mid-level ridge across the South-Central Plains and an
anchored longwave trough over the northeastern CONUS, establishing
active west-northwesterly flow aloft over the Ohio Valley.
Deterministic GFS and ECMWF runs, alongside GEFS and EPS cluster
analyses, remain in general agreement regarding this large-scale
pattern, though variance exists regarding the exact timing and
magnitude of embedded shortwave troughs propagating around the
northern periphery of the ridge.

There has been a slight trend for the jet stream to be further north
into the Great Lakes which has led to lower rain chances across the
Ohio Valley. That being said, the thermodynamic setup will maintain
strong thermal instability, with diurnal CAPE values frequently
exceeding 2000 J/kg. Lifting associated with shortwave disturbances
traversing the broader trough, coupled with nocturnal LLJ
strengthening (25-35 kts at 850mb), will foster potential for
upstream MCS development over the Upper Midwest that could track
southeastward into the CWA. Given the synoptic uncertainty inherent
in timing northwest flow impulses at days 5 through 7, POPs will
remain capped in the chance category (20-40%) throughout the week.
Outside of convective active periods, subsidence beneath the ridge
interface will promote warm and humid surface conditions, with high
temperatures consistently reaching the upper 80s to low 90s and
maximum afternoon heat indices nearing 100 degrees.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1257 PM EDT Thu Aug 6 2026

Impacts:

- Mainly VFR this afternoon
- MVFR Possible overnight, toward 071200Z

Discussion:

GOES19 continues to show a decaying convective MCS over IL and
Indiana with a mid level cloud deck across the TAF sites. Radar
shows decaying showers trying to progress east near the Wabash.

The decaying system is expected to continue to weaken and push
across the TAF sites this afternoon, providing VFR Cigs. HRRR
suggests enough clearing could be had for a pop up TSRA late this
afternoon and early evening. Confidence is low for this, thus a VCTS
mention will be used for now. Overnight, low dewpoint depressions
and light winds will likely lead to fog and/or MVFR Stratus
development around diurnal minimums.

&&

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

$$

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