Speedway, Indiana Weather Forecast Discussion

522
FXUS63 KIND 081838
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
238 PM EDT Mon Sep 8 2025
.KEY MESSAGES...
- Dry and cooler through Tuesday with lows in the mid-upper 40s
- Warming trend back to the 80s by mid to late week and beyond
- Abnormally dry conditions continue into the weekend
&&
.SHORT TERM (This evening through Tuesday)...
Issued at 238 PM EDT Mon Sep 8 2025
Through tonight...
Surface high pressure remains near the region providing quiet
weather conditions. Clear skies and plentiful sunshine has helped
temperatures warm into the 70s this afternoon. These temperatures
along with low RH values is making it feel very pleasant today.
Light winds will limit any fire weather concerns.
Expect temperatures to quickly fall after sunset due to a favorable
setup for efficient radiational cooling. Look for another chilly
night with lows generally in the upper 40s.
Tuesday...
Quiet weather conditions are expected on Tuesday as surface high
pressure continues to remain the dominant influence. The center of
the surface high pressure will shift well northeast of the Ohio
Valley by this point though. This will allow for winds to become
more southeasterly. The light southeasterly flow and plentiful
sunshine should warm temperatures well into the 70s. Some locations
could reach or exceed the 80F mark.
Forecast soundings show deep mixing into an anomalously dry airmass
aloft. This will result in low RH values during the afternoon and
high resolution guidance was blended in to more accurately forecast
dewpoints. Fire concerns remain low due to light winds. A subtle
upper wave is likely going to approach central Indiana late in the
day Tuesday into Tuesday night. While the airmass will be much too
dry for precipitation, some increase in mid-high clouds can be
expected.
&&
.LONG TERM (Tuesday night through Monday)...
Issued at 238 PM EDT Mon Sep 8 2025
Overall thoughts in the extended remain unchanged with no major
changes needed. Mostly dry conditions are expected through the
foreseeable future, but a low chance for rain remains in the
forecast late Saturday into Sunday as a weak system approaches.
Please refer to the previous discussion below for additional details
on the extended forecast.
Previous long term discussion...
An extended stretch of abnormally dry conditions and above average
temperatures persists for the next 8-14 days across Indiana,
potentially leading to rapid onset drought and an elevated fire
weather risk. The period begins with weak troughing over the Great
Lakes region and a building ridge over the center CONUS. The upper
ridge axis builds and continues eastward through the week stretching
from Lake Superior to Eastern Texas by Sunday. Long range guidance
has been consistent in showing this pattern developing for quite
some time, with well above average 500mb heights and 850mb
temperatures making for a high confidence forecast for hot and dry
conditions through at least next weekend.
The warming trend begins on Tuesday as surface high pressure moves
off to the northeast, switching low level flow to the southeast and
bringing a warmer airmass northward into the state. High pressure
will continue to be the dominant weather influence at the surface
through the rest of the week, keeping the atmospheric profile too
dry to support any precipitation locally. A front does push through
late Wednesday, but such dry antecedent conditions will lead to
virtually no impacts as high pressure and an even warmer airmass
advect into the region in the following days. This dry pattern is
supportive of large diurnal ranges, with temperatures quickly
heating up after sunrise...and then plummeting after sunset. High
temperatures get a little warmer each day this week, starting out in
the upper 70s to low 80s Tuesday, then by Friday and Saturday highs
approach the 90 degree mark in many spots. Lows on the other hand
remain at or below normal for this time of year... in the upper 40s
Tuesday morning and moderating into the upper 50s/low 60s by the end
of the week.
Forecast confidence somewhat decreases toward the end of the period
as longer range guidance and ensembles struggle to resolve how this
pattern evolves as weak storm systems ride up and other the ridge.
While higher confidence exists in a hot and dry forecast continuing
into the following week, it is worth mentioning that some longer
range guidance (ECMWF and ECMWF AI) has been consistent in showing
the potential for a wave and associated convection to ride over the
ridge into Indiana Saturday evening through Sunday. Have introduced
a slight chance (20%) of storms for this timeframe to account for
this threat. Confidence remains low on the exact mesoscale details
this far out, but there is enough confidence in a pattern supporting
a thunderstorm complex in the region to add PoPs for this weekend.
Despite the slight risk of storms, there is moderate to high
confidence in highs still reaching the 90 degree mark for several
days in a row, especially for Western and Southern Indiana this
weekend into the following week. CPC continues to place the entire
Ohio Valley and Midwest in a risk for extreme heat in the Sept 15-
18th timeframe...will be watching this timeframe closely and
updating the forecast as needed.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 1247 PM EDT Mon Sep 8 2025
Impacts:
- None.
Discussion:
VFR conditions expected through the TAF period with clear skies
outside of a few diurnally driven cu clouds this afternoon. Winds
will be light and variable through tonight with a generally easterly
direction. Winds slightly increase Tuesday and become more
southeasterly.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Melo
LONG TERM...CM/Melo
AVIATION...Melo

NWS IND Office Area Forecast Discussion