IND issues Area Forecast Discussion (AFD) at Oct 21, 2:46 AM EDT215
FXUS63 KIND 210646
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
246 AM EDT Tue Oct 21 2025
.KEY MESSAGES...
- A few light showers and brief stronger wind gusts with the passage
of a cold front early this morning
- Windy conditions this afternoon and evening with gusts up to 35
mph, isolated light showers possible across northern portions of
central Indiana
- Seasonably cool temperatures into this weekend with frost/freeze
potential Wednesday and Thursday nights
&&
.SHORT TERM (Today and Tonight)...
Issued at 246 AM EDT Tue Oct 21 2025
Band of mid level clouds rapidly moving across central Indiana early
this morning as a cold front tracks into the northern Wabash Valley
just after 06Z. Scattered light showers and sprinkles were
accompanying the front into east central Illinois with a dry frontal
passage south from that point. Temperatures were in the mid and
upper 50s with gusty southwest winds.
The aforementioned cold front will move quickly through the forecast
area over the next few hours and will be clear of the region prior
to daybreak. Weak surface ridging will reestablish for the morning
in wake of the front but a strong upper low over the upper Midwest
currently will move into the Great Lakes by tonight. Broad cyclonic
flow will develop with abundant moisture associated with the cold
pool aloft. Central Indiana will remain on the fringe of the deeper
moisture with clouds and potentially isolated light showers and
sprinkles this afternoon and evening across northern portions of the
forecast area with dry and mainly clear skies elsewhere.
While a few light showers are possible with the frontal passage
early this morning...a brief uptick in gusty winds is likely to be
the primary impact over the next few hours. KIND ACARS sounding
showing very nicely a dry and subsident layer beneath 800mb with a
low level jet accompanying the front. This would support some
potential for a brief uptick in wind gusts to possibly as high as
35mph in and near any showers despite the presence of an inversion
near 900mb. Gusts will drop off quickly about an hour or so after
the front passes.
Skies will largely clear as well by sunrise with a cloudfree start
to much of the morning as the surface ridging shifts across the
area. This will be temporary as a combination of cold advection and
the approach of the upper low into the Great Lakes supports cu
development for the afternoon focused especially across the
northeast half of the forecast area followed by more extensive cloud
cover over this same area into this evening as a wave aloft pivots
around the base of the upper trough. This will create quite the
variance across the area with minimal cloud cover over the lower
Wabash Valley to mostly cloudy skies for much of the region
northeast of I-74. Cannot rule out a few light showers or sprinkles
over far northeast portions of the forecast area this afternoon and
evening as well. Winds will increase again for this afternoon and
tonight with the potential for gusts to peak at 30-35mph at times.
Temps...low level thermals support highs near normal in the low and
mid 60s this afternoon. Lows tonight will fall into the lower 40s.
&&
.LONG TERM (Wednesday through Monday)...
Issued at 246 AM EDT Tue Oct 21 2025
The upper level flow pattern across the country will be much more
amplified for much of the rest of the work week. The aforementioned
upper low and associated trough will slowly pinwheel into eastern
Canada with a ridge over the western U S moving into the Plains.
Eventually the upper flow will transition to a quasi-zonal split
flow regime bringing warmer air and an increasing risk for showers
by the weekend.
Wednesday through Friday
The region will remain under the influence of broad upper level
troughing through Thursday with cool and dry conditions. Central
Indiana will remain on the periphery of the deeper moisture plume
associated with the upper level cold pool on Wednesday keeping more
extensive cloud cover across the northeast half of the forecast area
with mainly sunny skies further to the southwest. Much of the region
to the northeast of Indianapolis is likely to be mostly cloudy with
model soundings showing near saturation in the 850-800mb layer. A
weak frontal boundary will swing through the Ohio Valley late
Wednesday night and may lead to a brief and subtle increase in cloud
cover as it passes while also reinforcing the cooler airmass across
the region.
Despite the potential for lingering clouds and some question as to
whether the boundary layer can fully decouple Wednesday
night...there will be at least an opportunity for modest frost
accrual as temperatures bottom out in the mid 30s. With the arrival
of a high pressure ridge and deep subsidence for the tail end of the
work week...a greater concern for frost accrual and potentially the
first freeze of the Fall will come Thursday night as lows could drop
to around 30 degrees in some locations. Seasonably cool daytime
temperatures are expected Wednesday through Friday with highs
ranging from the mid 50s to lower 60s from northeast to southwest.
Continued breezy conditions both Wednesday and Thursday will lend to
a more distinctive Fall feel to the air as well.
Friday Night through Monday
The upper level flow will modify for the weekend and bring warmer
air into the Ohio Valley but it will be counteracted by increasing
clouds and scattered showers as weak waves aloft drift over top of a
ridge focused over the lower Mississippi Valley. Overall rain
amounts do not look particularly impressive with the moisture fetch
eventually becoming disrupted as the ridge flexes into the region by
Sunday. Highs will rise into the low and mid 60s Sunday and Monday
as warm advection strengthens on the lee side of a deepening surface
low over the Plains.
That low pressure will be influenced by a strong upper level jet
diving out of the northern Pacific Ocean and set to carve out a deep
trough across the western half of the country by Monday. Low
pressure will intensify as it moves into the upper Midwest with an
increasingly wet...windy and unsettled pattern developing for the
region through the first half of next week.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1231 AM EDT Tue Oct 21 2025
Impacts:
- Low level wind shear for a few hours through 08-09Z
- Brief wind gusts peaking near 30kts in the 06-08Z timeframe with
cold frontal passage
- Wind gusts of 20-30kt this afternoon
Discussion:
A band of mid level clouds is rapidly expanding east across central
Indiana in advance of a cold front crossing Illinois. These clouds
will swing across the terminals into the predawn hours with a few
light showers or sprinkles at KIND and KLAF. Winds may briefly gust
to near 30kts along and immediately behind the frontal passage
before winds drop back to around 10kts after 09Z.
Skies will clear prior to daybreak as surface ridging reestablishes.
Diurnal cu will develop within the cold advection by midday with
steadily increasing cu and a mid level deck as a well established
cold pool aloft expands across the Great Lakes into this evening.
Winds will pick up again for the afternoon and evening with gusts at
20 to 30kts from the west.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
SHORT TERM...Ryan
LONG TERM...Ryan
AVIATION...Ryan
Source:
IND issues Area Forecast Discussion (AFD) at Oct 21, 2:46 AM EDT---------------
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