IND issues Area Forecast Discussion (AFD) at Oct 16, 1:44 PM EDT068
FXUS63 KIND 161744
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
144 PM EDT Fri Oct 16 2026
.KEY MESSAGES...
- Strong post-frontal northwest winds will gust between 30 and 40
mph Friday morning and afternoon
- Widespread frost likely late Saturday night and Sunday morning.
&&
.DISCUSSION (Today through Thursday)...
Issued at 124 AM EDT Fri Oct 16 2026
Current Weather through Friday:
The Ohio Valley will be going through a significant pattern change
over the next 24 hours as a mature low pressure system continues to
push eastward within an amplified positively tilted upper level
trough. The orientation of this trough created a less aligned
phasing of the mid to lower level low of which has created a
multitude of weaker boundaries out ahead of the primary cold front
and a slower arrival of polar air. One of these confluence
boundaries was the initiation point for a broken line of strong to
severe thunderstorms this afternoon and evening. As of 04Z, this
line has weekend significantly with only scattered showers remaining
over far E/SE Indiana.
Another area of low level confluence can be observed over NW Indiana
and E Illinois, of which will be the source for additional showers
and isolated weak thunderstorms tonight into tomorrow morning.
Lapse rates within this sector of the low are weak in the mid levels
of which should keep convective tops capped below 15kft and the
thunder threat very isolated.
The surface low will continue to mature overnight within strong
upper level jet dynamics. In return, CAA will continue to increase
pushing the cold front quickly E/SE passing through central Indiana
between 09-13Z. A few showers will be possible along the frontal
passage, but any additional QPF should be less than 0.1".
For the remainder of the day, central Indiana will be within a much
cooler airmass with dew points in the 40s and high temperatures in
the mid to upper 50s. Modest lapse rates up to 850mb will likely
lead to efficient PBL mixing in the afternoon with gusts upwards of
40 MPH. A few isolated showers cannot be ruled out as saturation at
the top of the PBL remains coincided with the previously
mentioned steep low level lapse rates; that said, any QPF will be
minimal. As the late afternoon and evening approaches, mean low
level winds back towards 330-360 degrees, of which provides an
efficient fetch across Lake Michigan. While a majority of any lake
effect rain showers will likely remain north of central Indiana,
isolated to scattered showers over NW portions of the area will
remain possible from 21- 01Z.
Friday Night through Sunday Morning:
The remainder of the forecast period will become rather stagnant as
the upper low associated with today's trough passage will detach
from the flow and become cutoff over the Eastern Coast. This in
combination with a weak split flow upper jet will keep low level
conditions fairly similar through the weekend and into next week.
While the bulk of the forecast will remain similar, slight
fluctuations in surface pressure over the next 5-7 days will still
lead to slightly different temperatures and wind speed/direction
over the forecast period.
Continued CAA Friday night will lead to cold morning lows Saturday
morning, but there is some uncertainty on the extent of any frost
given consistent 6+ MPH surface winds and marginal temperatures
around 36-38 degrees. Greatest chances will be within sheltered
areas in NE portions of central Indiana, but likelihood of occurrence
is currently below 50%. The aforementioned strong CAA will lead to
height rises beneath 850mb and therefor building high pressure
Friday night through most of Saturday. The centroid of this surface
high is expected to overlap with the core of the mid level polar
airmass late Saturday though Saturday night leading to our coldest
temperatures of the season. Frost looks definite for most of central
Indiana on Sunday morning, but there is still some significant
uncertainty in below freezing temperatures. Much of this will depend
on the timing of the surface high passage along with how it faces
with the 850mb temperatures. Ensemble probabilities indicate greater
around a 50% chance for NE/E portions of the area, which will be the
focus for any freeze headlines in later updates.
Remainder of Sunday through Wednesday:
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 (18Z TAF Issuance)...
Issued at 143 PM EDT Fri Oct 16 2026
Impacts:
- MVFR ceilings through tonight.
- Wind shift to northerly around 00z.
- Wind gusts 20 to 30 knots through 04Z
- Periodic rain showers with minimal VIS impacts.
Discussion:
Cold air advection has kept low cloud cover in place today. Ceilings
have been oscillating between MVFR and VFR. A trend towards
predominant MVFR is anticipated this afternoon into tonight.
Clearing is likely on Saturday as high pressure builds in.
A secondary upper-level trough arrives this afternoon bringing
renewed rain shower activity. Tempo and Prob30 groups have been
introduced to cover the most likely timing of these showers.
Winds have been gusty out of the west-northwest, with average gusts
between 20 to 25 knots so far today. A switch to northerly is
expected once the upper trough and showers arrive. Northerly winds
could be more gusty than today, with gusts pushing 30 knots in
places. Winds begin diminishing after about 04z tonight, dropping to
less than 10 knots by 12z Saturday morning. A few gusts to 15-20
knots could persist into the day Saturday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
AVIATION...Eckhoff
DISCUSSION...Updike
Source:
IND issues Area Forecast Discussion (AFD) at Oct 16, 1:44 PM EDT---------------
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