IND issues Area Forecast Discussion (AFD) at Sep 21, 12:33 PM EDT156
FXUS63 KIND 211633
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1233 PM EDT Mon Sep 21 2026
.KEY MESSAGES...
- Showers diminishing during the day today
- Damp and dreary today
- Much cooler temperatures for the first half of the week, gradually
warming back to near normal levels by next weekend
&&
.FORECAST UPDATE...
Issued at 920 AM EDT Mon Sep 21 2026
Widespread rain now across eastern Indiana and western Ohio with
scattered lighter showers in its wake. Noticeable change in the
airmass with cool and breezy northeast winds and temperatures
largely in the upper 50s and lower 60s over all but far southern
portions of the forecast area at 13Z.
Remnant MCV showing up nicely on the radar over the western forecast
area this morning. This feature will continue to press east over the
next several hours and should be out of the forecast area by 18Z.
There remains potential for additional scattered convection to
develop in association with the MCV for the rest of the morning...
but an overall trend towards decreasing rainfall coverage has
already started and will continue into the early afternoon.
The rest of the day will certainly have an early Fall feel as lower
stratus remains in place trapped by a boundary layer inversion and
northeast winds continue leading to a damp and dreary day. Highs
will largely hold in the mid and upper 60s north of Interstate 70
with 70s further south.
Zone and grid updates out.
&&
.DISCUSSION (Today through Sunday)...
Issued at 258 AM EDT Mon Sep 21 2026
Early This Morning...
The surface front has moved south of central Indiana, but a couple
of upper impulses along with a surface wave riding along the front
are bringing enough forcing for numerous showers and some
thunderstorms to move into the area.
This forcing will continue through the predawn hours, so have gone
with higher PoPs over much of the area. For much of the area, CAPE
is elevated with an inversion closer to the surface. Will have to
watch the far south where better instability remains closer to the
surface, but odds for any severe weather remain low. Heavy rain and
localized flooding will be the threats as some training of cells may
occur.
Today and Tonight...
At 12Z, rain from one of the upper impulses will likely still be
ongoing for parts of the area. Will go likely PoPs for portions of
the east and southeast early in the period. Some of the latest
hourly guidance is showing another upper impulse generating more
numerous showers moving west to east during the morning. Not
confident enough yet to up PoPs elsewhere at this time, but will
keep an eye on how things develop.
Otherwise, chances for rain will diminish during the day as overall
forcing exits. Will have most areas dry by 21Z.
Moisture will be trapped below an inversion so will keep skies
mostly cloudy. With the clouds and cooler air behind the front,
highs will only reach the middle 60s far northeast to near 80 far
southwest.
Clouds will continue to hang around tonight. Lows will be in the 50s.
Tuesday and Wednesday...
A weakening upper low will approach the area on Tuesday. Forcing
will be weak, so for now have not gone with any mentionable PoPs.
However, wouldn't be surprised to see some isolated showers develop
during the afternoon.
The upper low will be east of the area on Wednesday. Most forcing
will be east of the area, but an isolated shower is possible in the
extreme east during the afternoon.
Lingering moisture will keep skies mostly cloudy on Tuesday, with
western areas seeing some partial clearing on Wednesday. Highs will
generally be in the upper 60s to middle 70s.
Thursday and beyond...
Surface high pressure will keep the weather quiet during this
period. Temperatures will remain below normal into the first part of
the weekend, then readings may return to above normal (highs around
80) by next Monday.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 1233 PM EDT Mon Sep 21 2026
Impacts:
- Predominant MVFR ceilings expected through much of the period. IFR
at times early this afternoon and again late tonight primarily at
KBMG
- Gusts near 20kt possible through the afternoon, mainly at KLAF
Discussion:
Showers have largely shifted east of central Indiana early this
afternoon but plentiful low level moisture lingers and is trapped
beneath an inversion. This will ensure low stratus goes nowhere over
most of the next 24 hours. Ceilings will reside in the MVFR category
this afternoon before potentially briefly breaking out to low VFR
levels for a few hours this evening. Strengthening of the inversion
late tonight will aid in ceilings slipping back to between 1000-
2000ft with the possibility of IFR ceilings at KBMG. Low ceilings
will continue on Tuesday.
Northeast winds will continue through the forecast period. Periodic
gusts to around 20kts are expected at KLAF this afternoon...
otherwise will see a steady 10-15kt wind at all terminals.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Ryan
AVIATION...Ryan
DISCUSSION...50
Source:
IND issues Area Forecast Discussion (AFD) at Sep 21, 12:33 PM EDT---------------
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