559
FXUS63 KIND 301853
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
253 PM EDT Tue Sep 30 2025

.KEY MESSAGES...

- Dry with unseasonably warm afternoons this week

- Drought persists and worsens across Central Indiana into October

&&

.SHORT TERM (This evening through Wednesday)...
Issued at 253 PM EDT Tue Sep 30 2025

The early Autumn heat wave continues across the region as high
pressure and ridging dominate the weather pattern. There is a low
fire weather threat each afternoon as minimum relative humidity
values plummet into the 15-25% range.


This afternoon and tonight...

Latest satellite imagery shows clear skies over Indiana and much of
the Great Lakes region as high pressure stretches from Central
Canada down into the Southern Plains. Local soundings show deep low
level mixing taking place this afternoon, resulting in plummeting
humidity values reaching critical fire weather thresholds.
Northeasterly flow also northeasterly flow plays a part in much
drier conditions than what guidance suggests as winds from this
direction are technically downsloping from Ohio (elevation 1200 ft
agl) into Central Indiana (elevation around 600 ft agl). Today`s
anomalous set up has resulted in afternoon RH values in the 15-20%
range for a few locations in addition to sporadic gusts to 20 kts.
With all this in mind, there is a low fire weather risk through the
rest of the afternoon.

Expect rapidly rising humidity and plummeting temperatures after
sunset as radiational cooling takes place. Overnight lows once again
fall into the mid 50s to lower 60s...warmer in urban areas.

Tomorrow...

Very similar set up for tomorrow as surface high pressure is still
north/northeast of the region keeping northeasterly flow and
subsidence over the state. Guidance shows a very weak upper level
trough approaching from the west. This trough is largely moisture
starved and should only bring higher clouds aloft. Expect cirrus
clouds to thicken through the day and into tomorrow night with the
only impacts to the surface being slightly "cooler" high
temperatures in the 80-85 degree range. Brought afternoon dew points
and RH down to the NBM 5th percentile to account for afternoon
mixing and guidance not handling this pattern very well. Expect
afternoon RH values to reach critical fire weather thresholds once
again; however winds at or below 10 kts with only sporadic gusts to
15 kts should keep the fire threat relatively low... but still non
zero.

&&

.LONG TERM (Wednesday night through Tuesday)...
Issued at 253 PM EDT Tue Sep 30 2025

High confidence in the long term forecast as a hot and dry weather
pattern continues for the region into early October. Surface high
pressure and ridging aloft will be the dominant weather influences
for Indiana`s weather in the next 7-14 days, keeping the summertime
heat locked in place with little to no chances for rain.

Little change in the day to day weather in the coming week as high
pressure slowly shifts from the Great Lakes to the Northeast to the
Mid Atlantic. A weakening moisture starved upper trough passes
overhead Wednesday and Thursday resulting in an increase in high
level clouds, but the only surface impacts will be slightly "cooler"
high temperatures in the lower 80s. Ample sunshine returns late week
into next weekend with highs reaching at least into the mid 80s..and
possibly upper 80s. Expect large diurnal temperature ranges in this
type of pattern with relief from the heat each night as lows drop
into the mid 50s to low 60s.

The main concern each day through next weekend are low afternoon RH
values dropping into the 15-30 percent range and the worsening
drought conditions. Model guidance struggles with drier air mixing
down to the surface and typically keeps dew points and RH too high
in patterns like this. Afternoon RH and Dew Points will likely be
closer to the NBM 5th percentile or lower each day. Watching the
possibility for an increased fire weather risk this week due to such
dry and hot conditions. Winds remain under any critical thresholds,
but the prolonged stretch of heat and dry weather may still lead to
an elevated fire weather risk.

High confidence exists in a weather pattern supportive of well above
normal temperatures and below normal rainfall continuing into Mid
October. Guidance struggles to break down these strong blocking
patterns in the long term, typically bringing in chances for rain
and storm systems too fast. While there are 20 PoPs around October
7th, this is a low confidence forecast that will likely change in
the coming days. While some longer range models and ensembles show a
few chances for rain by Mid October, low confidence exists in any
one solution. For now, keeping the extended forecast hot and dry.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 253 PM EDT Tue Sep 30 2025

Impacts:

- none

Discussion:

Little changes made to the TAFs for the 18z issuance. High pressure
centered near the Hudson Bay remains the dominant weather influence
across Indiana keeping skies clear and low level flow out of the
northeast. VFR cigs and vis expected for the next 24-36+ hours at
all sites. Winds will follow a diurnal curve, increasing during the
day and diminishing at night. Deep mixing this afternoon has
resulted in sporadic gusts to 20 kts to mix down to the surface.
Added a tempo group for KIND through 22z to account for the gust
potential.

&&

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

$$

SHORT TERM...CM
LONG TERM...CM
AVIATION...CM