Orestes, Indiana Weather Forecast Discussion

415
FXUS63 KIND 211822
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
222 PM EDT Sun Sep 21 2025
.KEY MESSAGES...
- Isolated showers and thunderstorms possible this afternoon
and evening, becoming numerous overnight.
- Additional rainfall expected tomorrow, with highest chances of
moderate to heavy rainfall rates over southern Indiana.
- Milder with daily chances for showers and a few thunderstorms
through much of the work week.
&&
.SHORT TERM (This evening through Monday)...
Issued at 221 PM EDT Sun Sep 21 2025
Strong ridging over the Western Conus has led to broad but weakly
forced troughing central CONUS, of which in now reaching central
Indiana. Although the longwave pattern is weakly forced, shortwaves
are relatively strong inducing moderate lift across the region. This
will likely lead to periodic rain and storm chances of which began
yesterday and will continue through the short term. Initially, the
thought was there would be some diurnally induced convection this
afternoon; however, an increase in mid level subsidence ahead of the
next wave, partially observed on the 12Z ILX sounding and better
observed on IND ACARs soundings has led to a decrease in coverage of
precipitation across a majority of Indiana and is expected to
continue through the afternoon. Temperatures will remain elevated
today, but curtailed a bit by widespread cloud cover. The
current expectation is for highs in the mid 80s
Forcing will ramp up overnight as an upper level jet moves to the
northwest of the area, and upper heights fall as the upper trough
moves closer. Moisture will be plentiful, with southwest winds
providing and uninhibited flow of moisture into the area through the
night. Minimal, but still sufficient enough, diurnal cooling will
help stabilize the PBL tonight, but lapse rates above 3kft should
still be high enough for some embedded elevated convection within
numerous showers. Total rainfall amounts will likely vary greatly
depending on mesoscale features unresolvable at this time, but
generally rainfall amounts are expected to be between 0.25-1.00
inches tonight into tomorrow morning.
Additional rain is expected later tomorrow through tomorrow night
ahead of another aforementioned shortwave, there is still some model
ambiguity in specific placement of greatest rainfall, but slightly
amplified PWATs and more organized forcing may lead to an additional
0.5-1.5 inches over portions of central Indiana. That said, the
greatest probability of occurrence for moderate to heavy rainfall
late Monday is over southern central Indiana.
&&
.LONG TERM (Monday night through Sunday)...
Issued at 221 PM EDT Sun Sep 21 2025
Tuesday through Sunday...
Compared to the dry days of weeks past, large changes are expected
in our weather this week as daily chances for rain will persist.
Tuesday through Friday Morning...
Models suggest broad troughing in place aloft over the upper midwest
and into the Ohio Valley on Tuesday, with the development of a cut
off upper level low by Wednesday and Thursday. This upper low will
slowly pass across Illinois and Indiana through Friday morning.
Within the lower levels during this time a surface low will push out
of the Middle Mississippi Valley with a cold front and push toward
Michigan by Friday morning. This will keep Central Indiana within
the warm sector for a few days with the upper low in place aloft.
Forecast soundings suggest saturation within the column front time
to time during this period with pwats over 1 inch. Thus given all
these ingredients, chances for rain each day, with best chances on
Wednesday and Thursday seem reasonable. Given the expected clouds
and rain, highs will only reach the middle and upper 70s with lows
in the 60s.
Friday through Sunday...
On Friday in the wake of the cold front and slowly departing upper
low, models suggest weak ridging and subsidence building within the
pattern aloft along with the departure of the surface low and cold
front. Should this signal hold, this would suggest rain ending on
Friday morning and dry weather arriving for Friday afternoon and
into Saturday.
However, this is then followed on Saturday Night and Sunday to the
re-development of the upper low over TN and KY, with wrap around
easterly flow in place across Central and southern Indiana. Light
rain chances will persist at that time due to this feature, although
surface high pressure appears to remain in place over the Middle
Mississippi Valley. Confidence in this solution is very low at this
time due the overall evolution and progression of the previous upper
low. Temperatures through this time should be at or below normals as
cooler northeasterly flow would be expected.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 1215 PM EDT Sun Sep 21 2025
Impacts:
- Scattered convection possible this evening
- Numerous showers and some storms overnight and continue through
  tomorrow
- MVFR ceilings possible tomorrow
Discussion:
The main area of showers and thunderstorms has moved off to the
north. There is a chance for an isolated shower this afternoon,
but coverage was too low to include in the TAF at this time.
Additional showers and thunderstorms are possible this evening.
More widespread showers will move in overnight tonight with
occasional MVFR VIS and CIGs
Drier low levels will keep prevailing ceilings outside of rain in
VFR through 06Z Monday, then some MVFR ceilings may develop by 12Z
Monday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Updike
LONG TERM...Puma
AVIATION...Updike

NWS IND Office Area Forecast Discussion