565
FXUS63 KIND 051738
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
138 PM EDT Wed Aug 5 2026

.KEY MESSAGES...

- Quiet pattern lingers today, more summerlike humidity and
  warmth by this afternoon

- Rain and storms chances return tonight and linger into early next
  week, with greatest chances Thursday and Friday

- Localized flooding will be possible at times from repeated rounds
  of convection

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

&&

.FORECAST UPDATE...
Issued at 1016 AM EDT Wed Aug 5 2026

No changes needed to the forecast this morning. Surface high
pressure remains in control of our weather, though its center has
slid east of the region. Winds are still generally calm, but are
expected to increase slightly out of the southwest this afternoon.
Cloud cover from upstream convection, associated with a cold front,
is already entering our far northwest. A gradual increase in mid to
high level cloud cover is likely throughout the day today along with
typical diurnal cumulus.

&&

.DISCUSSION (Today through Tuesday)...
Issued at 404 AM EDT Wed Aug 5 2026

Today through Thursday night...

Last portion of recent quieter, yet summery pattern will linger
through this afternoon as modest surface high pressure finally exits
east.  Broad and stronger early-autumn H500 trough spinning over
western Hudson Bay, and sending solid Canadian air into the Upper
Midwest...will twist a couple weaker vorts along its southeastern
periphery over the Midwest into the late workweek.  This mild
forcing along with a weaker low-level jet will slowly shift
noticeably better moisture just to our northwest...into at least the
Wabash Valley tonight, with perhaps a couple widely scattered
showers getting as far as the northwestern two-thirds of the CWA
Thursday.  However, latest trends suggest coverage/intensity of any
showers to trend downward Thursday as soon as mid-level support
slides east of the region.

Nevertheless, areas northwest of a Rockville to Kokomo line can
expect more scattered shower coverage from late this evening into at
least Thursday morning, where isolated storms could have a could
robust gusts...with low chances of a few disorganized t-storms far
southeast along the I-69 corridor.  Lack of organized ridging and a
rather damp column through the latter half of Thursday will still
facilitate at least a few showers and a stray TRW.  Another, more
subtle wave with associated small bump up of precipitable water
should enter the region Thursday night, so kept likely POPs for pre-
dawn hours Friday, albeit with still lower confidence in any
appreciable rainfall or stronger cells.

Dewpoints today should actually display a narrow minimum axis under
the lingering ridge, with mid-60 values possible into early evening
from Washington to Brown County to Muncie. Otherwise light southwest
winds will bring more humid and warmer conditions with highs 83-89.
Clouds Thursday to keep readings more moderated with higher humidity
with highs mainly low 80s, and mid-80s for far south/southeast zones.
Early morning minimums 65-70F through the short term.

Friday Through Saturday.

An upper-level shortwave trough currently traversing the Upper
Midwest will drive a surface cold front south-southeastward into the
Ohio Valley by Friday afternoon. Guidance from the latest GFS and
ECMWF along with ensemble clusters shows the main upper-level
dynamics lifting northeastward into eastern Canada, causing the
surface boundary to lose upper support and become quasi-stationary
across central Indiana. Deep tropical moisture transport will
precede the front, with ensemble mean PWAT values exceeding 1.8 to
2.0 inches, which sits well above the 90th percentile for early
August climatology.

HREF members indicate modest surface heating beneath cloud cover on
Friday, yielding MLCAPE values between 1200 and 1800 J/kg by late
afternoon. Kinematic forcing remains weak, with 0-6 km bulk shear
generally around 15-20 knots, precluding organized severe
convection. However, convective initiation along the front and
lingering mesoscale outflow boundaries will produce multi-cell
clusters capable of high precipitation efficiency. Given slow storm
motion parallel to the surface boundary, localized training of
storms and localized flash flooding remain the primary hydrologic
hazards through Saturday evening before the main moisture axis
finally pushes south into Kentucky.

Sunday Through Tuesday.

A broader synoptic pattern shift occurs Sunday as an expansive upper-
level ridge over the central Plains expands eastward while a broader
longwave trough settles across the northeastern US. This will
establish northwesterly flow aloft across central Indiana. With
broad ridging to the southwest, rain chances will mostly be limited
to the central and northern counties through the period with weak
shortwaves within the broader upper level flow. Daytime highs will
remain near or slightly above seasonal normals in the mid to upper
80s, accompanied by very humid dewpoints in the low to mid 70s
combining to bring a return to upper 90 to near 100 heat index
values.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 138 PM EDT Wed Aug 5 2026

Impacts:

- Showers and possibly a thunderstorm tonight into Thursday morning.

Discussion:

High pressure has weakened and slid east of Indiana this afternoon.
Surface winds are now out of the southwest, though still light
around 5kt. Light southwesterly flow will continue, becoming more
southerly overnight and perhaps calm in a few locations. Winds
return to a more southwesterly direction on Thursday.

Showers and thunderstorms are ongoing over northwestern Illinois as
of 18z Wednesday. These should progress slowly eastward today into
tonight, weakening with time. Remnant showers are possible near LAF
as early as 00z. Elsewhere, precipitation may take its time
advancing eastward. The most likely time for precipitation is
Thursday morning from 10z to 16z.

Ceilings are expected to remain VFR, but a brief period of MVFR
conditions are possible during heavier showers or storms.

&&

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

$$

UPDATE...Eckhoff
AVIATION...Eckhoff
DISCUSSION...AGM