090
FXUS63 KIND 230244
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
944 PM EST Mon Dec 22 2025

.KEY MESSAGES...

- Light rain and drizzle expected tonight into early Tuesday,
  patchy fog possible as well

- Warming trend into Wednesday, rain returns Wednesday night

- Breezy conditions Saturday into Sunday, turning colder towards
  Monday

&&

.FORECAST UPDATE...
Issued at 944 PM EST Mon Dec 22 2025

A warm front is across the far southwest forecast area this evening,
with a sharp dewpoint gradient associated with it. Radar shows
isolated showers and sprinkles developing in the vicinity of the
front.

Moisture has increased aloft as noted by gradually lowering
ceilings. However, the dry air ahead of the warm front is stubborn.
Dewpoints are in the 20s to around 30 on the north side of the
front. IND ACARS sounding shows this dry layer nicely.

The sprinkles/light showers ahead of the warm front will have to
overcome this dry layer before reaching the ground. In addition,
models have been overdoing the coverage of rain and drizzle so far
per trends seen on radar.

Given the above, have significantly cut PoPs in the very near term,
and lowered them a bit later in the night. Some expected lift in the
low level moisture layer should still produce drizzle, but
confidence has lowered a bit in coverage of it. Left mention of
drizzle and fog in for now and will monitor to any needed changes
overnight.

Temperatures should remain steady or rise as the warm front moves
north. Adjusted hourly temperature forecasts as needed to reflect
current trends.

&&

.SHORT TERM (This evening through Tuesday)...
Issued at 1250 PM EST Mon Dec 22 2025

Tonight.

Main focus for the short term period will be tracking a combination
of light rain and drizzle tonight along with a lower-end threat for
fog.  Synoptically a low pressure across the Northern Great Lakes
will be moving through during the overnight hours while gradually
strengthening with weak isentropic lift across the Ohio Valley. This
isentropic lift will help to saturate the lower levels with a
combination of drizzle and light rain expected late this evening
into tonight. Surface winds will generally remain in the 5-10 mph
range which will help to limit the threat for fog, especially dense
fog, but at least some lowered visibilities due to drizzle look
likely as the cloud bases drop to just a few hundred feet.

Ahead of the rain arrival, any ongoing wind gusts should dissipate
after sunset with the loss of diurnal heating allowing for the
boundary layer to decouple. Dry and quiet weather will continue
through the early evening hours with highs generally in the upper
40s to low 50s. With the widespread cloud cover and continued
southerly flow tonight, expect temperatures to remain mild with
lows in the low to mid 40s.

Tuesday.

The stronger southerly flow will come to an end during the daytime
hours on Tuesday with a weak frontal passage but with a window of
clearing during the afternoon and evening hours, temperatures will
be able to climb into the mid to upper 50s. There is likely to be a
lag on the daytime heating with good model agreement in the low
clouds and drizzle sticking around through the morning, but drier
air aloft advecting in should help to clear skies by the mid
afternoon hours. There may be a few wind gusts of 15-20 mph during
the morning, but in the aftermath of the front, winds should relax
as the low pressure continues to move eastward.

&&

.LONG TERM (Tuesday night through Monday)...
Issued at 1250 PM EST Mon Dec 22 2025

Tuesday Night Through Through Friday.

Generally quiet weather is expected Tuesday night into Wednesday
with broad ridging across much of the central US. Surface winds will
shift from the northwest to northeast and finally southeast through
the night as the aforementioned low pressure system exits the East
Coast and the main influence becomes the weak surface high across
the area. Models continue to trend wetter for the Wednesday night
into Thursday timeframe with a weak trough within the broader
northwesterly flow aloft. The morning model runs have strengthened
this weak system with broader model agreement in rain amounts up to
around a tenth of an inch. Any precipitation will come to an end by
Thursday morning with weak northerly flow in the aftermath.

This change in the forecast decreases confidence in the potential
near record temperatures that have been discussed over the last few
days with a fair amount of uncertainty now as to how far north the
60+ temperatures will be. Current thoughts are now that the
Indianapolis area will be at or below 60 with the low to mid 60s
mainly limited to areas south of I-74. Another weak system may bring
additional precipitation Thursday night into Friday but chances are
low outside of the northern portions of the state with higher
confidence in low to mid 60 degree temperatures during the day with
stronger southerly flow across the state.

Saturday Through Monday.

A much stronger upper level low pressure system will move through
during the weekend across the Great Lakes region but the only
impacts to central Indiana will be the cooler and breezy conditions
Saturday into Sunday. Surface winds will be more westerly than
northwesterly through Sunday which will help to limit the strength
of the CAA but expect to see daytime highs struggle to rise out of
the 30s Sunday with the potential for single digit to low teens
Monday morning. There may be a few wind gusts of 25-35 mph Sunday
afternoon when the pressure gradients are maximized and the boundary
layer deepens to around 3kft. Looking further into the week this
cooler stretch looks brief with broad ridging and much warmer
temperatures returning towards early January.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 618 PM EST Mon Dec 22 2025

Impacts:

- Ceilings lowering through the evening, dropping to IFR/LIFR after
  06Z
- Combination of DZ and BR bring IFR vsbys at times overnight

Discussion:

Patchy MVFR ceilings are already in the area, and ceilings will
continue to lower through the evening. IFR and worse ceilings will
become predominant at most sites by 06Z. Drizzle and fog development
will lead to MVFR visibility with IFR visibility at times overnight.

Conditions will slowly improve Tuesday morning, with the potential
for VFR returning to most sites Tuesday afternoon.

Note that non-convective LLWS is possible overnight, roughly 05-09Z.
Not quite confident enough to include at this time.


&&

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

$$

UPDATE...50
SHORT TERM...White
LONG TERM...White
AVIATION...50