IND issues Area Forecast Discussion (AFD) at Oct 16, 1:11 AM EDT858
FXUS63 KIND 160511
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
111 AM EDT Fri Oct 16 2026
.KEY MESSAGES...
- Line of showers and few thunderstorms crossing southeastern
central Indiana through the early overnight
- Strong post-frontal northwest winds will gust between 30 and 40
mph late tonight into Friday
- Widespread frost and localized freeze conditions are likely
Saturday night into Sunday morning
&&
.FORECAST UPDATE...
Issued at 1009 PM EDT Thu Oct 15 2026
Triple point of baroclinic system will continue to steadily cross
east-central Indiana through the late evening...while warm sector
occupying central Indiana's far southern/southeastern zones will
continue to promote showers and an isolated t-storm, although with a
quickly fleeting non-zero severe threat...with better wind shear
around the system occlusion to the northwest of Indianapolis, offset
from lingering instability mainly under 1000 J/kg well to the south.
Cold front pushing main line of convection east...will usher in
winds veering to west-northwest through the overnight before
increasing to at least 10-15 mph with gusts increasing to 20-30 mph
by daybreak. Patchy, transient mist will clear out by 06Z on the
increasing flow. Noticeably drier, and almost seasonable dewpoints
to arrive by dawn, with temperatures in the upper 40s west and
northwest of Marion County...and lows down to the mid-50s for
southeastern zones.
&&
.DISCUSSION (This evening through Thursday)...
Issued at 305 PM EDT Thu Oct 15 2026
This afternoon through Friday Night...
Current surface analysis depicts a low pressure system approaching
from the west while an associated warm front lifts north. Scattered
showers and a few embedded thunderstorms are now beginning to push
into central Indiana. Additional convective development can be
expected as the disturbance pushes across the area later today into
tonight.
Surface observations suggest the warm front is near far southern
portions of central Indiana where dewpoints are now in the lower
70s. The warm front will continue lifting northward towards the I-70
corridor. Low-level theta-e advection combined with diurnal heating
is expected to promote MLCAPE values of 750 to as high as 1250 J/KG
locally later this afternoon into the evening. Meanwhile aloft, a
mid-level jet streak from the parent trough continues to shift
eastward promoting stronger deep-layer shear. Increasing deep-layer
shear in addition to modest destabilization could result in isolated
severe thunderstorms. Effective shear values exceeding 40 kt are
expected which favors the potential for supercells or organized
storm clusters.
Enlarging low-level veering hodographs from the warm front lifting
north could support isolated tornadoes. Damaging wind gusts also
appear possible with organized storm clusters. One caveat limiting
confidence for the overall severe weather threat is uncertainty on
the degree of low-level buoyancy. Forecast soundings from the latest
CAMs depict poor lapse rates and relatively long-skinny CAPE
profiles. This suggest updraft strength may be limited. However,
even weak to modest low-level buoyancy in the favorable kinematic
environment could support isolated damaging wind gusts or tornadoes
so mesoscale trends will be monitored closely. Modest instability
will greatly limit the threat for severe hail though sub-severe hail
still appears possible.
Expect a cold front to move through late tonight advecting cooler-
drier air into the area. Look for precipitation chances to diminish
from west to east during the late overnight. Increasingly breezy
conditions are likely due to a tightening pressure gradient behind
the departing front and steepening low-level lapse rates. Wind gusts
between 25 to 35 mph should be common into Friday with sporadic
gusts as high as 40 mph. Steepening lapse rates and marginal low-
level moisture ahead of a backdoor cold front moving through late
Friday will promote scattered convective showers. The parent mid-
upper level trough overhead by this point should provide additional
forcing for convection.
Scattered lingering showers are possible early Friday night, mainly
across northwest portions of central Indiana, before the
aforementioned system shifts further east. Temperatures will drop
into the upper 30s and low 40s Friday night due to the additional
shot of cooler air. Patchy frost cannot be ruled out in sheltered
locations into Saturday morning, but breezy conditions should mostly
limit the threat elsewhere.
Saturday through the middle of next week...
A broad longwave trough will anchor across the eastern CONUS on
Saturday as a strong surface anticyclone shifts from the Upper
Mississippi Valley southeastward across the Ohio Valley through
Sunday. The core of the cold pool will sit overhead Saturday,
keeping 850 mb temperatures around 0C to +2C. Despite clearing skies
and subsidence, daytime highs on Saturday will struggle to reach out
of the mid 50s, 10-15 degrees below normal.
Saturday night into Sunday morning represents the primary frost and
low-end freeze window of the period. The surface high center will
settle directly over central Indiana by 09Z Sunday, decoupling the
boundary layer and yielding calm winds, clear skies, and a very dry
ambient air mass with dew points in the upper 20s to low 30s. Strong
radiational cooling will cause overnight minimum temperatures to
drop into the lower to mid-30s across the entire forecast area, with
rural drainage basins and traditional cold spots likely dropping
near freezing. Widespread frost is expected across central Indiana,
and freeze conditions are probable in sheltered rural areas. Frost
and freeze headlines will likely be required as confidence remains
high across deterministic GFS, ECMWF, and their respective ensemble
suites.
The anticyclone will drift eastward toward the Mid-Atlantic on
Sunday, allowing insolation to rebound highs into the upper 50s and
lower 60s. Lows Sunday night will remain cool, in the upper 30s to
lower 40s, with patchy frost confined to far eastern rural valleys
before low-level winds back to the south.
For Monday through Wednesday, the synoptic pattern transitions as
upper-level ridging builds over the eastern states and a deep trough
carves out over the western CONUS. Steady south-southwesterly return
flow will drive a significant warm air advection regime across the
Ohio Valley. 850 mb temperatures will moderate to +10C to +13C,
pushing daytime highs into the upper 60s and lower 70s by early next
week. Overnight lows will moderate into the upper 40s to mid-50s.
Long range guidance generally supports quiet weather conditions
persisting through the middle of next week as surface high pressure
remains in control. Return flow should continue to provide a gradual
moderation in temperatures.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 106 AM EDT Fri Oct 16 2026
Impacts:
- MVFR ceilings 07Z-19Z
- Wind shifts to NW early in the period.
- Wind gusts to 30kt after 15Z.
Discussion:
Much of the area is within a brief period of VFR between two weak
confluence boundaries. A cold front will quickly push to the E/SE
tonight shifting winds from SW to NE.
Cold air advection and trapped lower level moisture will provide
MVFR cigs across Central Indiana later tonight through 15Z, with
some lifting likely within diurnal heating in the afternoon. Winds
will be brisk after frontal passage, sustained between 12-15kt
with gusts nearing 30kt after 15Z.
Friday night, winds will shift towards northerly with gusts
waning. Scattered showers will be possible at KLAF.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...AGM
AVIATION...Updike
DISCUSSION...White/Melo
Source:
IND issues Area Forecast Discussion (AFD) at Oct 16, 1:11 AM EDT---------------
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