742
FXUS63 KIND 230110
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
910 PM EDT Fri Aug 22 2025

.KEY MESSAGES...

- Partly Cloudy tonight and Saturday.

- Turning much cooler and less humid on Sunday.

- Temperatures near to below normal throughout the next week with
  little to no chance for rain until the end of the month

&&

.FORECAST UPDATE...
Issued at 909 PM EDT Fri Aug 22 2025

Undulations within the more elongated gravity waves have created
a mesoscale sector of broken strato-cu around 4-5kft. This has
kept near surface temperatures steady, despite surpassing the
typical beginning of diurnal cooling. Clouds are still expected to
dissipate this evening, of which can be visualized well in IR
imagery, but this delayed onset of diurnal cooling will likely
keep dew point depressions slightly higher. For this reason, the
forecast has shifted towards less coverage of broken ground fog,
with the primary impacts expected to be over well irrigated crop
fields and low lying river valleys.

Otherwise, no significant updates were needed to the ongoing
forecast.

&&

.SHORT TERM (This evening through Saturday)...
Issued at 239 PM EDT Fri Aug 22 2025

Surface analysis early this afternoon shows a strong area of high
pressure in place stretching from the eastern Great Lakes, to
Indiana and IL. Aloft, strong high pressure was found over the
American southwest, with a strong ridge axis stretching northeast
across the plains to Illinois and Indiana. GOES16 water vapor
imagery shows very strong subsidence in place across Indiana and
Illinois due to these two systems. GOES16 shows some lingering lower
level stratocu across Central Indiana.

Tonight...

Models indicate the strong upper high to the west will allow its
ridge axis to sag farther south. This will push the surface high
pressure system over Indiana farther south, but it will continue to
dominate Indiana weather overnight, providing clear skies and light
winds. Clouds across the area are expected to clear as heating is
lost this evening. Models do suggest that dew point depressions
overnight will fall to 1-3F, resulting in some patchy fog toward
daybreak. Given the dewpoints in the lower 60s, lows in the lower
60s will be expected.

Saturday...

The strong upper high to the west is expected to sharpen a new ridge
axis across the Rockies. This will help an upper low over Central
Canada slide eastward through the day. This system will have a an
associated surface cold front with this that will sag southward and
reach NE IL by late afternoon. Behind that front will be our much
cooler weather for Sunday and the week ahead.

However, before all of this arrives, Central Indiana will remain
within the warm sector of the passing low to the north, with little
in the way of forcing dynamics aloft. Forecast soundings on Saturday
show a dry column with afternoon CU expected. Mid levels remain very
dry as the soundings also show a CAP in place. Furthermore, lower
level flow never becomes southerly and any gulf moisture fails to
arrive. Thus we will look for a partly cloudy and slightly warmer
day within the warm sector. Again, look for highs in the lower 80s.

&&

.LONG TERM (Saturday night through Friday)...
Issued at 239 PM EDT Fri Aug 22 2025

A significant pattern change is in the forecast for much of the
Great Lakes and Ohio Valley featuring well below normal temperatures
and dry conditions for the foreseeable future.

While relatively cooler temperatures have been observed over the
past several days, an even stronger front ushers in a Fall-like
airmass on Sunday bringing some of the coldest temperatures of the
season thus far!

Synoptically, deep upper troughing remains in place over the Great
Lakes and Southern Canada through the entire week, keeping Indiana
within a northwest flow pattern aloft. Smaller waves dropping
southward from Canada are forecast to bring reinforcing shots of
cooler air into the region by the end of the week, further
prolonging the extended period of below normal temperatures. At the
surface, high pressure will be the dominant weather influence
locally, keeping the atmospheric profile dry enough to inhibit any
precipitation develop as moisture starved waves pass by overhead.
High pressure briefly slides south of the state on Wednesday,
switching flow around to the southwest, before another front brings
another round of below normal temperature anomalies for the weekend.

Sunday through Wednesday, expect highs in the low to mid 70s with
lows each night falling into the upper 40s to low 50s! Tuesday and
Wednesday morning will feature the coldest temperatures since early
June with widespread upper 40s for Central and North Central
Indiana. Would not be surprised to see lows at or below 45 degrees
in low lying, wind sheltered areas.

Brief and weak warm air advection on Thursday ahead of the next
approaching front should result in highs a few degrees warmer than
earlier in the week with temperatures in the mid to upper 70s. Very
dry antecedent conditions should and subsidence from high pressure
nearby should inhibit precipitation development along the front.

The forecast becomes a little more uncertain next weekend and into
early September as longer range guidance struggles with how
blocking patterns evolve. High confidence exists in a pattern
supportive of below normal temperatures into early September, but a
lot of uncertainty remains in the timing and location of incoming
synoptic features. It is looking possible that rain chances increase
once again by around Labor Day as longer range guidance continues to
hint at an area of low pressure in the vicinity, but it is too soon
to dive into any further details as run to run changes are likely.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 725 PM EDT Fri Aug 22 2025

Impacts:

- Patchy fog near daybreak with periodic MVFR vsbys.

Discussion:

GOES16 continues to show BKN VFR stratocu across Central Indiana.
A subtle are of subsidence within gravity wavy propagation,
should slowly erode this stratocu deck through the evening, with
FEW clouds around 10kft following

Strong high pressure across the region will continue to dominate our
weather through the TAF period providing mostly clear skies and
light winds overnight. Dew point depressions are expected to fall to
1-3F, thus some diurnal MVFR fog will possible. Any fog that does
develop will quickly mixout by 13Z, leading to a return to VFR.


&&

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

$$

UPDATE...Updike
SHORT TERM...Puma
LONG TERM...CM
AVIATION...Updike