309
FXUS63 KIND 031438
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1038 AM EDT Wed Sep 3 2025

.KEY MESSAGES...

- Seasonable and dry through this evening

- Rain expected tonight with amounts of 0.25" to 0.75"

- Low threat for additional rain late Friday into Saturday

- Another round of cooler and drier air this weekend

&&

.FORECAST UPDATE...
Issued at 1037 AM EDT Wed Sep 3 2025

There is still some lingering fog along an old outflow boundary
from the storms yesterday evening/night, but this should keep
dissipating with mostly clear skies expected across all of central
Indiana by noon. There is still some uncertainty on precipitation
onset this afternoon, with a range from mid afternoon to early
evening for central Indiana.


&&

.SHORT TERM (Today and tonight)...
Issued at 258 AM EDT Wed Sep 3 2025

The extended stretch of very dry conditions will be interrupted
briefly later tonight by a round of light showers and a few storms.

This morning and today will remain fairly dry and warm for all of
Central Indiana. Satellite imagery shows clear skies over the state
early this morning while clouds and showers associated with the
incoming system are still well to the northwest in Minnesota and
Wisconsin. Southwesterly flow and warm air advection ahead of the
front with ample sunshine will lead to highs in the low to mid 80s
once again. Hi-res guidance has high clouds increasing during the
late afternoon and evening hours with a lowering cloud deck after
sunset. Steep low level lapse rates this afternoon and deep mixing
should result in drier air and wind gusts to around 20 mph mixing
down to the surface at times this afternoon.

The main focus in the short term is the rain and storm chances as a
cold front pushes through the state from the northwest. Guidance
keeps the heaviest rain across northern Indiana associated with the
main surge of synoptic forcing and better dynamics, but there is
increasing confidence in a secondary axis across southern Indiana
where higher resolution models are trending towards a stronger low
level jet with a better connection to Gulf moisture. Precipitation
may begin across the far northwestern counties as early as the 5pm-
8pm timeframe, but is more likely to be more towards the 9-11PM time
frame with scattered to numerous showers and storms continuing
through the night with a gradual southeastern progression. Total QPF
looks to be in the 0.25" to 0.75" range, with more areas remaining
on the lower end due to such dry antecedent conditions. There may be
a few lingering showers towards daybreak tomorrow, but the majority
of the rain will have exited the area by morning.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 258 AM EDT Wed Sep 3 2025

Overall, a cooler but mostly dry weather pattern will be expected
this period. Best rain chances will linger on Thursday morning and
return again on Tuesday. Low chances and low confidence for precip
on Friday.

Thursday and Friday...

A cold front that will have passed across the state on Wednesday
Night may allow a few lingering showers across south and eastern
parts of Central Indiana in the morning. Best forcing from the this
front and upper wave will be exiting by 12Z...but HRRR suggests a
few lingering showers SE. Thus will keep some low pops during the
first few hours after 12Z at those locations.

Although a deep upper low will remain in place over Ontario, strong
cyclonic flow is expected to remain in place across the region. Time
heights show good subsidence across Indiana on Thursday afternoon
through Friday. Time Heights show lingering lower level moisture
which should be indicative of stratocu amid cold air advection. Thus
look for mainly mostly cloudy and cooler conditions on Thursday.

On Friday, another upper wave amid the cyclonic flow aloft is
expected to pass along with a secondary cold front. This frontal
system. Will have less moisture to work with but given the forcing
low chances for rain with very light amounts appear possible. Again,
look for highs in the 70s.

Saturday through Monday...

Dry and cool weather is expected this weekend and as we start the
new week. Aloft, strong ridging is expected over the Rockies while
the deep upper low continues to linger across eastern Canada. This
will result in northwest flow in place over Indiana along with
subsidence that results in a large area of high pressure that will
remain across the northern plains and push into and across Indiana
through Monday. This Canadian high will provide a cool air mass
across the area resulting in highs in the 70s. Some lows on Saturday
and Sunday morning will be in the 40s.

Tuesday...

Chances for rain will return on Tuesday as warmer and more humid air
arrives on southerly winds. The previous surface high will have
drifted well east of Indiana at this point, allowing this warmer
southerly flow to develop. Models suggest a weak trough aloft
passing across Indiana while a lower level warm frontal boundary
approaches from the south. Given these ingredients, rain chances
will need to be included.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 653 AM EDT Wed Sep 3 2025

Impacts:

- Showers and storms likely tonight

Discussion:

VFR conditions are expected through much of the TAF period. Patchy
fog has developed this morning but should quickly dissipate after
sunrise. An approaching front tonight will likely promote showers
and thunderstorms across central Indiana during the evening and
nighttime hours. Dry conditions are expected through at least 00Z
Thursday with rain and storm chances increasing from NW to SE after
00z. Brief periods of MVFR or worse vis and cigs under showers and
storms. After collaborating with the CWSU, added a Prob30 group for
thunderstorms at KIND 02z-05z tonight. Will adjust the timing of the
thunderstorm threat (if needed) in later forecast issuances based on
how convection develops upstream.

Expect winds to remain light and variable through about daybreak
with a predominately southerly direction before turning more
southwesterly during the day. Winds will also increase to about 07-
13 kts on Wednesday with sporadic gusts up to 20kts.


&&

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

$$

UPDATE...Updike
SHORT TERM...CM
LONG TERM...Puma
AVIATION...CM