938
FXUS63 KIND 290527
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
127 AM EDT Fri Aug 29 2025

.KEY MESSAGES...

- Dry and quiet weather for the weekend into early next week

- Next chance for rain arrives September 3rd-4th with another shot
of cooler air behind the front

&&

.FORECAST UPDATE...
Issued at 918 PM EDT Thu Aug 28 2025

The last of the isolated showers have diminished across northern
counties as a cold front presses south through the forecast area.
Pockets of mid level clouds lingered otherwise skies were clearing
from the north. 01Z temperatures were in the 60s.

The front will continue its southward progression tonight and while
a stray light shower cannot be entirely ruled out in its vicinity...
coverage does not warrant a precip mention going forward. Skies will
become clear after midnight as progressively drier air expands south
into central Indiana behind the front. Despite the drier air enough
moisture will linger within the shallow near surface layer that
patchy fog is likely to develop in the predawn hours across the
northern half of the forecast area and focused especially in areas
that received rainfall earlier today. Will need to monitor an area
of stratus anticipated to expand southwest from northern Ohio and
may reach northeast portions of central Indiana towards daybreak.

Lows will fall into the lower 50s across northern portions of the
forecast area and would not be shocked to see a few locations dip
below 50. Expect mid and upper 50s south of Interstate 70. Zone and
grid updates out.

&&

.SHORT TERM (This evening through Friday)...
Issued at 239 PM EDT Thu Aug 28 2025

Today brings a welcome break from the recent dry streak across
Central Indiana as a weak frontal boundary and trough axis spark off
scattered showers. Latest satellite and radar imagery clearly depict
the clouds along the positively tilted trough axis extending from
Southern Ontario into Central Indiana. Moisture advection along the
front has been sufficient to overcome such dry antecedent conditions
to support more widespread shower activity than what guidance has
been suggesting over the past week. Weak low and mid level lapse
rates have kept these showers mainly low topped and fairly light
through the early afternoon hours. Subtle clearing behind this
morning`s showers has resulted in just enough surface heating and
destabilization for convective showers and isolated storms to
develop along the I-65 corridor in North Central Indiana. ACARs and
RAP soundings limit CAPE to 250 J/kg, but it has been enough to
support a few lightning strikes south of Lafayette thus far.

Expect continued shower and thunderstorm activity for the next hour
or so along the I-65 corridor from around Indianapolis to points
southeastward as stable air to the NW advects in, putting an end to
the shower activity. These storms are likely forming off a low to
mid level NW-SE oriented boundary with just enough lift from the
passing shortwave/trough axis to support this activity. Enough 0-1km
and 0-3km shear in the range of 15-25kts exists to support some
organization and maintenance of this convection. Have updated the
forecast and thunderstorm probs accordingly based on latest data.
While most locations should pick up less than a tenth of an inch of
rain, heavier showers may result in isolated spots with up to a
quarter inch of precipitation. This looks to be the last chance for
rain for the month of August, so expect most of Central Indiana to
end the month 1-2 inches below normal for precipitation, despite
today`s showers.

Tonight...

Subsidence behind the trough axis and with the incoming area of high
pressure should result in clearing from northwest to southeast this
evening. Tonight`s low level inversion will likely trap leftover
moisture near the surface, increasing tonight`s fog chances as
efficient radiational cooling takes place. Currently have patchy fog
wording for most of the region in the 2am-8am timeframe. Expect the
most widespread and denser fog to be in the Wabash River Valley and
in low lying areas that picked up rainfall earlier today. All fog
should lift and dissipate shortly after sunrise. Tonight`s lows
range from the upper 40s to low 50s in North Central Indiana to the
upper 50s in Souther Indiana as the cooler air lags behind the
frontal boundary.

Friday...

High pressure settles in over the Great Lakes region Friday, with
the coolest air associated with this incoming Canadian airmass
remaining north and east of Indiana. Despite northerly low level
winds, 850mb temperatures in the 10-12C range and ample solar
insolation will support much warmer highs in the low 70s for the
north and near 80 across Southern Indiana.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 258 PM EDT Thu Aug 28 2025

Large-scale troughing will persist over the Midwest and northeastern
US through the long term with little in the way of change through
the duration of the forecast period. Thus, cooler than normal
weather with highs generally in the 70s and lows in the 50s are
expected to continue.

Precipitation chances will be low since synoptic-scale forcing looks
to be limited while surface high pressure will exist over the Great
Lakes, at least through early to mid week. Cloud cover from upstream
convection may be present at times along with some patchy morning
fog. Otherwise, pleasant weather is anticipated.

Around mid next week, guidance is hinting at an upper-level low
developing within the large-scale troughing. The resulting system
could linger for a few days, providing an extended period of
scattered showers and/or thunderstorms. There remains uncertainty
within deterministic guidance so will keep PoPs at slight to chance
for now.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 127 AM EDT Fri Aug 29 2025

Impacts:

- Patchy fog possible prior to daybreak Friday.

Discussion:

Mainly VFR conditions expected through the TAF period.

A cold front has passed through central Indiana causing surface
winds to turn northeasterly. A light northeast flow will continue
through daybreak before becoming almost due north. A return to a
northeasterly direction is again likely after 00z.

Some patchy fog is possible by sunrise at the typically fog-prone
terminals. Fog will likely be shallow in nature allowing visibility
to vary over short period of time. Brief periods of MVFR or lower
visibility is possible.

Scattered low clouds around 4000-5000ft may be present at times
tonight. High cirrus is expected to arrive around or a little after
sunrise and could become BKN at times.

&&

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

$$

UPDATE...Ryan
SHORT TERM...CM
LONG TERM...KF
AVIATION...Eckhoff