809
FXUS63 KIND 312339
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
739 PM EDT Sat Oct 31 2026

.KEY MESSAGES...

- Light rain chances tonight through Sunday with minimal accumulations

- Unseasonably warm conditions Monday and Tuesday, reaching the low 70s

- Active weather with thunderstorms and heavy rain Tuesday night into Wednesday

&&

.DISCUSSION (This evening through Saturday)...
Issued at 124 PM EDT Sat Oct 31 2026

Overview.

A quiet start to the week will gradually transition to active and
much warmer weather by midweek before colder, drier air returns next
weekend. A weak disturbance brings a slight chance of light rain
tonight and Sunday, though most areas will see very little
measurable precipitation. Cloud cover will persist into early next
week as winds turn southerly, driving temperatures well above normal
into the low 70s by Tuesday. A strong low pressure system and
accompanying cold front will bring widespread rain, gusty winds, and
thunderstorms late Tuesday night into Wednesday. High pressure
builds in behind the front for Thursday through Saturday, bringing
dry conditions and seasonal temperatures back to central Indiana.

Tonight Through Sunday.

A broad 500mb shortwave ridge continues to shift into the eastern
Ohio Valley as a low-amplitude trough lifts northeast out of the
lower Mississippi Valley. Ahead of this weak impulse, 850mb warm air
advection and isentropic lift will continue to transport mid-level
moisture across central Indiana.
Model soundings and the 12Z HREF mean indicate a substantial dry
layer below 700mb, characterized by surface dewpoint depressions in
excess of 15 degrees. HREF component members consistently
demonstrate that initial radar echoes will struggle against this sub-
cloud dry air, resulting predominantly in virga during the evening
hours. As top-down saturation gradually occurs overnight, dew point
depressions will drop sufficiently to support scattered sprinkles
and light rain showers, primarily across the southern and western
portions of the CWA. Measurable QPF will remain minimal, with
ensemble means generally showing less than 0.05 inches through 12Z
Sunday.

Extensive multi-layered cloud cover and light southeasterly winds
around 5 to 10 mph will limit diurnal cooling overnight, with low
temperatures holding in the mid 50s. On Sunday, the weak mid-level
vort max dampens as it traverses southern Indiana. Weak boundary-
layer convergence along an inverted surface trough will sustain
isolated to widely scattered light rain showers through early
afternoon, primarily east of the I-65 corridor. Weak subsidence
aloft behind the wave should allow precipitation to diminish from
west to east late Sunday afternoon, though abundant low-level
moisture trapped beneath a strengthening subsidence inversion will
keep skies mostly cloudy. Sunday high temperatures will remain muted
by cloud cover, peaking in the mid to upper 60s.

Monday Through Saturday.

The synoptic pattern becomes amplified and highly progressive early
in the week. A deep, positively tilted longwave trough establishes
over the western CONUS on Monday, inducing strong downstream height
rises across the eastern states and setting up deep southwesterly
flow through the central CONUS. A surface warm front will lift
northward across central Indiana on Monday, placing the forecast
area securely in the warm sector. The pressure gradient will tighten
in response to cyclogenesis over the central Plains, establishing a
robust 40 kt low-level jet that advects an anomalously moist airmass
from the Gulf. WAA will support 850mb temperatures rising to +14C to
+16C, supporting surface highs reaching the lower 70s on Tuesday,
roughly 10 to 15 degrees above seasonal normals.

Active and potentially severe weather remains focused during the
Tuesday night into Wednesday timeframe as the primary synoptic
cyclone deepens over the upper Midwest and drives a potent cold
front eastward. Deep convective dynamics will be heavily supported
by upper-level divergence within the right-entrance region of an
intense 130 kt 250mb jet streak, coupled with strong differential
PVA ahead of the trough axis. 500mb southwesterly flow is expected
to be around 60 to 75 kt and an 850mb jet intensifying to 50 to 55
kt with the system. This wind field generates 0-6 km bulk shear
values of 50 to 65 kt and 0-1 km storm-relative helicity values
between 150 and 250 m2/s2, which are more than sufficient to
organize convection.

The primary limiting factor regarding severe convective hazards will
be the thermodynamic profile, characterizing this setup as a classic
cool-season HSLC regime. Deterministic GFS and ECMWF runs along with
GEFS and EPS ensembles continue to show poor mid-level lapse rates
around 5.5 to 6.0 C/km. Surface dewpoints in the low 60s will
provide modest boundary-layer destabilization, but nocturnal timing
will temper surface heating, holding MLCAPE generally within the 300
to 750 J/kg range. Given the strong linear forcing along the
advancing pre-frontal trough and cold front, convection will favor
upscale growth into a linear system. The main convective hazard will
be damaging straight-line wind gusts generated by momentum transfer
within convective downdrafts tapping the 50 kt ambient flow at
850mb. An isolated tornado risk cannot be ruled out within bowing
segments or line breaks where low-level shear vectors orient
perpendicular to line segments. Deep moisture and flow parallel to
the frontal boundary could support localized training and minor
hydrological issues, though rapid frontal translation should cap
total rainfall between 1.00 and 1.75 inches.

The cold front is expected to clear eastern Indiana by midday
Wednesday, bringing an end to precipitation and initiating strong
cold air advection on brisk northwest winds. Broad Canadian surface
high pressure will build southeastward into the Ohio Valley for
Thursday through Saturday. Mid-level flow transitions to a dry, low-
amplitude northwest regime, promoting widespread subsidence and
clear to partly cloudy skies. Temperatures will return to seasonal
late-autumn levels, with 850mb temperatures falling below 0C.
Daytime highs will fall back into the upper 50s to lower 60s on
Thursday, and further into the low to mid 50s by Friday and
Saturday. Nighttime lows will settle into the upper 30s to lower 40s
across central Indiana through the end of the period.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 739 PM EDT Sat Oct 31 2026

Impacts:

- Isolated showers arriving tomorrow, brief MVFR possible at KBMG

Discussion:

VFR conditions expected through most of the TAF period with only
minimal chances for brief vsby restrictions towards BMG after 12Z
Sunday due to scattered showers. Mid and high clouds are expected to
continue to advect across central Indiana through tomorrow with
ceilings dropping to around 050 after 06Z. There may be a few
sprinkles during the overnight with better chances for rain after
12Z, primarily towards BMG.

Winds will generally out of the east at 5 to 10 kt through the TAF period.

&&

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

$$

AVIATION...Updike
DISCUSSION...White