084
FXUS63 KIND 220546
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1246 AM EST Mon Dec 22 2025

.KEY MESSAGES...

- Moderating pattern into the middle of the week with unseasonably
  mild conditions expected Wednesday-Friday

- Breezy conditions develop Monday with winds gusts to 25 mph

- Near record high temperatures in the 60s possible on Christmas Day

&&

.FORECAST UPDATE...
Issued at 1042 PM EST Sun Dec 21 2025

Minimal adjustments to the forecast this evening. Satellite imagery
shows mainly clear skies over Indiana however a long fetch of
pacific moisture stretching from near Hawaii to the Plains within
the mid and upper jet will bring high clouds later tonight and into
tomorrow to the region. Surface high pressure shifts eastward with
low level flow becoming southeasterly tonight then due south by
tomorrow afternoon. A increasing low level jet brings Gulf moisture
northward through the day, arriving into SW Indiana before sunset.
Forecast soundings indicate a strong low level inversion setting up
as warm air advection streams in aloft, trapping incoming low level
moisture near the surface. In this set up, CAMs shows widespread low
stratus developing under the inversion across the Mid Mississippi
and Ohio Valleys as moisture advects in. Despite mid and high level
clouds most of the day, warm air advection should be strong enough
to push highs well into the 40s and low 50s by the afternoon hours
before much lower clouds push in.

&&

.SHORT TERM (This evening through Monday)...
Issued at 200 PM EST Sun Dec 21 2025

Atmospheric setup this afternoon features a broad surface ridge,
with the axis drifting over Central Indiana. This will allow winds
to briefly go calm, unfortunately the upper level flow remains
transient and progressive. Surface ridge will quickly depart to the
east late tonight, and in its wake will be a robust return flow from
the south/southwest that will usher in much warmer air and moisture
back into the Ohio Valley as strong isentropic ascent to parcels
will rapidly lift north from the gulf coast.

Tonight the surface ridge pushes east, allowing the pressure
gradient to return on the backside. This will allow winds to turn
southerly and increase, along with an end to the clear skies as
moisture quickly arrives overnight in the form of increased clouds.
At sunset expect a brief, somewhat steep, radiation of surface temps
to occur under optimal conditions. Temps will likely settle into the
mid/upr 20s before they steady or possibly start to rise around
daybreak Monday.

Monday/Monday Night... The main feature of this period will be the
warm air advection. There will be a weak surface pressure low that
will skirt the Great Lakes but this will help to lift a warm frontal
boundary further north. 850mb thermal ridge coupled with a solid
moisture push from the south as a modest low-level jet of 30-40kts
will help to expand north moisture. Highs Mon have been nudged up a
couple of degrees into the upper 40s and very possibly around 50 for
portions of Central Indiana. Given the abundance of moisture
throughout the profile Mon ngt, and continued south/southwesterly
flow and a beefy thermal ridge in the low-levels, temps will likely
not fall much at all Mon ngt.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 200 PM EST Sun Dec 21 2025

Broad warm air sector will encompass all of Central Indiana with
a broad low-amplitude system impacts the region. Temps as a result
will easily rise into the 50s, despite the mostly cloudy sky
cover. There is a very weak moisture starved front that will make
an attempt to sag south into the northern counties Tue, although
expect the southerly flow to prevail and keep this feature to the
north. As we push into Christmas Eve the thermal ridge
intensifies. Strong southerly breezes will push dew points into
the upper 40s to mid 50s, which is exceptionally high for late Dec
across Indiana. This should allow some scattered showers to
develop across the area, with the couple strong ascending
isentropic lift to parcels. But again the main feature worth
noting will be the surface temps that will likely be around 60.

Christmas Day through the day after... Ensembles continue to prog 2
to 3 standard deviations above normal for the 850mb thermal ridge
that will reside overhead. The center of this ribbon of warm air is
progged to be over the Ohio Valley, which should further support
temps easily pushing into the mid 60s on Christmas Day. It is
conceivable that some locations in southern Indiana could touch 70
degrees. Then heading into Friday not much will change, but there is
some relaxing to the thermal ridge overhead so likely going to see
temps just hold in the upper 50s to lower 60s. Deep moisture remains
locked, but with a lack in upper-level forcing any precipitation
that develops should be manageable. Guidance still indicating the
upper level pattern will begin to flatten to more of a transient or
zonal setup, as a frontal boundary approaches late Fri. Timing for
this boundary could be a bit sooner, as the zonal flow indications
amongst ensemble members has been indicating more spread and this is
an indicator in reduced confidence in timing.

Saturday through Sunday...Seasonable airmass returns to the region
for the weekend, which should bring temps back into the upper 30s to
40s, with a periodic chance of precipitation. Nothing significant at
the moment, but some ensemble members are hinting that a stronger
arctic ridge of high pressure may attempt to build in again from the
northwest from the Canadian Rockies.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1245 AM EST Mon Dec 22 2025

Impacts:

- Light southerly winds increasing tomorrow afternoon with gusts to
  20 kts

- MVFR stratus arriving from the south late Monday afternoon and
  evening

- Drizzle and potential IFR condition possible Monday night

Discussion:

Light and variable winds persist for a few more hours before winds
become southeasterly before sunrise. By this afternoon a 25-35 kt
southwesterly low level jet moves overhead. Gusts up to 20 kts are
possible into the evening hours as stronger gusts mix down to the
surface. Winds should gradually become more southerly with time.

Mid/high-level cloud cover should gradually increase ahead of an
approaching system over the Plains. Strong moisture advection
associated with this system will bring MVFR stratus northward near
between 20z-00z, but confidence is low in how quickly cigs may drop
before 00z tomorrow evening.

After 00z, guidance shows stratus rapidly fill in allowing all
terminals to become MVFR or lower. There is a good signal for
drizzle at times Monday night into Tuesday, so we will introduce it
into the TAFs along with minor reductions in visibility. Some
guidance depicts further reductions, potentially into IFR
territory...but model agreement is not as high regarding this. We`ll
include a SCT006 group for now to show this potential.

&&

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

$$

UPDATE...CM
SHORT TERM...Beach
LONG TERM...Beach
AVIATION...Eckhoff