543
FXUS63 KIND 080431
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1231 AM EDT Tue Sep 8 2026

.KEY MESSAGES...

- Sunny and Warmer on Tuesday.

- Brief return of heat midweek with a chance of storms late Wednesday
  Afternoon into Thursday.

&&

.FORECAST UPDATE...
Issued at 937 PM EDT Mon Sep 7 2026

The overall airmass will begin to shift overnight as wings veer from
NE to SE. In return, moderate moisture advection is expected to
occur. This setup along with some subsidence aloft typically leads
to valley fog in areas more sheltered from any gradient wind. For
this reason, patchy fog has been added for most of the mid-Wabash
River Valley.

No other major changes have been made to the ongoing forecast.

&&

.DISCUSSION (This evening through Monday)...
Issued at 227 PM EDT Mon Sep 7 2026

Surface analysis this afternoon shows strong high pressure in place
over Lake Huron, providing easterly surface flow to Central Indiana.
Aloft, strong ridging was in place over the upper midwest, resulting
in NW flow across Indiana. Water Vapor imagery shows subsidence in
place across Indiana and OH. Dew points were in the 50s as mixing
has produced lower values. GOES19 shows mostly sunny skies
across the area.

Tonight and Tuesday...

The upper ridging over the northern plains states will push east to
the eastern Great Lakes tonight and Tuesday, keeping any forcing
dynamics well north of Central Indiana. The strong surface high
pressure will drift SE to the middle Atlantic states by Tuesday, but
continue to maintain control of our weather. Forecast soundings and
time heights show a dry column with subsidence in place through
Tuesday. Dew point depressions tonight may be small, resulting in
patchy fog, especially in rural areas.

On Tuesday a mid level inversion appears to remain in place, and
this should again prevent much in the way of CU development,
resulting in another mostly sunny day. Temperatures will be warmer,
as southerly flow will develop allowing warm air advection. Look for
Highs to reach the middle and upper 80s

Wednesday...

The upper ridging across the area will have broken down to a
progressive, nearly zonal, flow across the northern CONUS by
Wednesday. A short wave within this flow will be pushing across
southern Canada through the day, keeping the best forcing dynamics
there. Within the lower levels the tail of an associated cold front
will be pushing across the Upper midwest and central Plains. Upper
forcing along the tail of the front is limited. However, southerly
flow ahead of the front streaming into Indiana will allow for an
even warmer and more humid air mass to arrive. Dew points will surge
into the 60s. Forecast soundings by late afternoon show diurnal
convection possible with marginal CAPE available. Thus will keep
things dry through 18Z, but afterward due to diurnal heating and
instability, chance pops for showers and storms will be included,
into the evening hours. Look for highs in the lower 90s.

Thursday...

With upper flow nearly parallel to a surface front early on
Thursday, chances for rain will continue, especially south. An upper
impulse should finally push the front south by early Thursday night.

Locally heavy rain will be a threat with precipitable water values
over 2 inches and the potential for training storms (with the slow
movement of the front).

Clouds/rain will keep temperatures cooler with highs around 80 for
most areas.

Friday and beyond...

Uncertainty rises in this period. The upper ridge to the southwest
will try and increase its influence over central Indiana. Meanwhile,
upper waves moving through the flow to the northeast of the ridge
will try to keep the ridge away and bring rain chances to the area.

For now, believe the best chances for rain will be on Saturday, but
that may change. Temperatures will begin to increase again as the
ridge attempts to build northeast, but readings should remain below
90 for the most part.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1231 AM EDT Tue Sep 8 2026

Impacts:

- Fog likely at KLAF early this morning

Discussion:

High pressure will drift south along the East Coast throughout the
day today maintaining dry weather. Despite scattered cirrus moving
across the region...radiational cooling will be supportive of patchy
fog development at the outlying sites in the predawn hours with KLAF
likely to be the main terminal impacted. Diurnal cu will develop by
midday as winds veer to S/SW for the afternoon. Cu will diminish
near or just after sunset with light S/SE winds tonight.

&&

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

&&

$$

UPDATE...Updike
AVIATION...Ryan
DISCUSSION...Puma/50