IND issues Area Forecast Discussion (AFD) at Sep 25, 1:15 AM EDT306
FXUS63 KIND 250515
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
115 AM EDT Thu Sep 25 2025
.KEY MESSAGES...
- Scattered showers and isolated thunderstorms at times through
Thursday morning, focused mainly across the southeast half of
central Indiana
- Patchy fog possible early Thursday
- Warm and dry weather returns late week extending through most if
not all of next week, with highs generally from the upper 70s to
mid 80s
&&
.FORECAST UPDATE...
Issued at 954 PM EDT Wed Sep 24 2025
The main focus with tonight's update will rain chances across the
far south and southeast and the threat for low stratus and fog
elsewhere across Central Indiana.
Satellite imagery and observations show an area of low pressure
riding along a boundary northeast through Western Kentucky.
Associated rainfall with this system will largely remain south of
the forecast area; however the northern edge of the precipitation
shield may nudge far enough north to impact far southern and
southeastern portions of Central Indiana...from Martin Co
northeastward to Decatur county. ACARs soundings indicate enough
instability to support an isolated lightning strike in Southern
Indiana, but overall not too concerned with the thunderstorm threat
this far north.
Further north across the majority of Central Indiana, mid to high
level clouds have already moved in overhead. While a few isolated
showers are possible tonight, the best forcing for ascent and
moisture remains well to the south, so expect most of Central and
North Central Indiana to remain dry tonight. Latest observations
indicate that cloud bases are still fairly high around 6000-10000ft
agl. As the low levels saturate tonight and surface dew point
depressions decrease, guidance indicates that low stratus may begin
to develop during the overnight hours. Any area with breaks in the
clouds may even see patchy fog development with how saturated the
surface is. The fog threat may be limited to just North Central
Indiana, on the northern edge of the cloud shield. Will watch how
everything evolves overnight and update the forecast as needed. Not
expecting a widespread dense fog event like a few night ago though.
&&
.SHORT TERM (This Evening through Thursday)...
Issued at 239 PM EDT Wed Sep 24 2025
Mostly cloudy skies continue across central Indiana this afternoon
as abundant low level moisture lingers to the north of a quasi-
stationary frontal boundary that has now drifted into far southern
Indiana. Isolated showers continue further north in the vicinity of
the I-70 corridor. 18Z temperatures were in the 70s.
The upper trough axis remains just to the northwest this afternoon
and is poised to finally pivot through the forecast area on
Thursday. The aforementioned frontal boundary is likely to move
little over the next 12 to 18 hours as a wave rides along it
tonight. Widespread convection will accompany the surface wave but
will focus near and south of the boundary with a particular focus
south of the Ohio River.
For the rest of afternoon and much of the evening...anticipate just
an isolated to widely scattered threat for showers focused
especially across all but far northern counties where slightly drier
air has advected in from the north. There will be breaks in the
stratocu but in general expect more clouds than sun through sunset.
Highest chances for rain within the forecast area will set up over
southern counties later tonight as the surface wave tracks into the
Ohio Valley. Due to the orientation of the upper trough...think
there is some merit to deeper moisture pivoting northeast up the
less side flank of the feature overnight. With that in mind...have
aligned chances for rain mainly across the southeast half of the
forecast area late tonight. Expect largely scattered coverage with
light amounts as the deepest moisture remains confined to far
southern Indiana south into the Tennessee Valley.
A plume of deeper moisture at 925mb will drift southwest from
northern Ohio by early Thursday with lower stratus expected to once
again encompass much of the forecast area with the potential for
patchy fog as well. A few showers will linger on Thursday across the
southeast half of the area as the upper trough pivots east...but
expect a largely dry day for most of the region. Progressively drier
air and deeper subsidence will expand south through the course of
the day with increasing sunshine through the afternoon.
Temps...lows will fall into the upper 50s and lower 60s over most of
central Indiana tonight. Low level thermals support highs in the low
to mid 70s for Thursday.
&&
.LONG TERM (Thursday Night through Wednesday)...
Issued at 239 PM EDT Wed Sep 24 2025
After the brief reprieve over the last few days from the warm and
dry pattern...an omega block aloft across the continental U S and
south of the mean jet stream will reestablish. This will bring a
return to warm and dry weather with little in the way of clouds
beginning late this week and lasting through next week and
potentially beyond.
The stubborn upper trough that has lingered over the region the last
few days will shift east by late week but an upper low is poised to
close off and settle over the Tennessee Valley into the first part
of the weekend. Deeper moisture will be confined to the vicinity of
the upper low with broad subsidence gradually expanding and
deepening over the Great Lakes and Ohio Valley through the weekend
as ridging builds east into the area.
Ridging aloft will then hold serve all of next week as an elongated
upper trough lingers east-west across the deep south and a
progressively deeper trough aligns along the Pacific coast by the
middle of next week. This will essentially lock the narrow but
strong upper ridge in place from the Great Lakes southwest into the
Southern Plains. The ridge axis will trickle east by late next week
as heights recover over the southeast States but the Ohio Valley
will remain firmly under its influence through the end of the
forecast period. Surface ridging will also be prevalent for much of
the extended across the area with low level flow becoming easterly
as the week progresses in response to the core of the ridge
strengthens and sets up over Ontario and Quebec.
An approaching upper level wave over the Northern Plains may be able
to buckle heights aloft and enable a cold front to drift into the
region by next weekend with a potential threat for rain. Until
then...dry weather is expected with highs generally ranging between
the upper 70s and mid 80s and lows predominantly in the 50s.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 115 AM EDT Thu Sep 25 2025
Impacts:
- MVFR ceilings return overnight, low chance for IFR
- VFR returns late morning into early afternoon Thursday
- Showers possible overnight, mainly at KBMG
Discussion:
Lower clouds will continue to develop overnight, falling into the
MVFR category. IFR cannot be ruled out, but confidence is not high
enough to include at this time. As low pressure exits and some
heating occurs, ceilings will mix out, allowing VFR to return by
early afternoon.
A few light showers will mainly be around the southern sites into
Thursday morning, with KBMG the most likely to see any rain.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CM
SHORT TERM...Ryan
LONG TERM...Ryan
AVIATION...50
Source:
IND issues Area Forecast Discussion (AFD) at Sep 25, 1:15 AM EDT---------------
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