826
FXUS63 KIND 300446
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1146 PM EST Mon Dec 29 2025

.KEY MESSAGES...

- Wind gusts around 25 to 35 mph will persist through late afternoon
  then diminish tonight

- Wind chill values around zero to a few degrees below through
  tonight

- Return to seasonable winter temperatures the rest of the week with
  chances for flurries and light snow Tuesday and Wednesday evenings

&&

.FORECAST UPDATE...
Issued at 907 PM EST Mon Dec 29 2025

Cyclonic flow and a persistent shallow saturated layer within the
snow growth layer beneath an inversion aloft have allowed both low
stratus and scattered flurries/snow showers to persist into the
evening, longer than originally expected - not terribly unusual for
such patterns.

A gradual thinning of the saturated layer and erosion of cloud from
the west will help the snow taper off later tonight from southwest
to northeast, but in the meantime have upped PoPs much of the night
to keep a mention of these snow showers/flurries going. A light
dusting in some spots is certainly possible given the persistence of
the light snow and the high snow-to-liquid ratios observed in the
Arctic airmass.

Made some minor downward adjustments to low temps per latest hourly
numerical guidance, massaging the diurnal curve a bit as the drop
should be slow until clearing begins to work its way in from the
west later tonight.

&&

.SHORT TERM (This evening through Tuesday)...
Issued at 248 PM EST Mon Dec 29 2025

Expansive stratus deck persist across Ohio Valley this afternoon,
with the return to winter conditions at the surface. Strong cold air
advection still in place across Indiana, with a tight isallobaric
gradient beginning to relax marginally and allow the better mixed
layer to decrease with only gusts on occasion still gusting to 45
mph. Expect as the late afternoon hours progress this will further
decrease, which will allow the headline to expire at the current
planned time of 21Z. Enough lift is still present coupled with
moisture that is allowing the vertical parcel momentum to still
generate some light snow showers and flurries, although it has been
trending to be more flurry dominant than anything else. Temperatures
have settled into the mid/upr teens, and the thick cloud cover
should inhibit temps from plummeting much lower overnight.

Tonight...Upper level 500mb trough axis pivots east across the
region tonight, with a surface ridge sliding south/southeast through
the TN valley. This will reinforce the northwest flow within the
boundary layer for Indiana. No additional moisture is present, so
expect flurries to generally become more sporadic or end by late
this evening if not sooner.

Tuesday through Tuesday Night...With the deep trough still After
record warmth on Sunday and a line of convection that produced wind
damage across parts of the region...winter has returned with a
vengeance early this morning. Westerly winds have been consistently
gusting at 45 to 50mph over much of the forecast area since last
evening. Temperatures which just a scant 6-8 hours ago were in the
mid and upper 60s now range from the mid 20s to lower 30s at 07Z.

Low pressure is in the process of reaching its peak intensity near
980mb over Lake Huron early this morning. The Ohio Valley is now
firmly in the backwash of the intense low but a surface trough
extending west from the low is set to pivot across the region later
this morning into the afternoon before high pressure finally begins
to exert its influence tonight.

The strong cold advection in the postfrontal environment was aiding
in flurries and narrow bands of light snow showers over central
Illinois in the vicinity of the elongated wave aloft to the
southwest of the upper low. The ongoing flurries and light snow
showers to the west will shift across the northeast half of the
forecast area over the next several hours then continue through the
morning as the upper wave swings through in tandem with the surface
trough. Steepening lapse rates within the boundary layer will aid in
coverage as well with snowflakes persisting into the early afternoon
before diminishing from the southwest as drier air aloft advects
into the region. Expecting little if any impact from the snow with
no accumulation as snow remains light and winds continue to
efficiently blow flakes around. Flurries may linger over northeast
counties until near sunset with dry conditions going forward into
tonight.

Sustained winds currently are at 20-30mph across the northern half
of the forecast area with gusts routinely hitting 50mph. Further
south...gusts have generally been no higher than 40mph. Plan to
continue the Wind Advisory over the entire forecast area but may be
able to remove southern counties by midday should gusts remain at
current levels. As the surface low pulls away to the northeast this
afternoon...gusts will begin to decrease with the pressure gradient
relaxing.

Finally...have kept cloud coverage high through tonight as model
soundings show moisture remaining trapped beneath an inversion.
Drier air aloft will work down into the boundary layer by tonight
but it may be the predawn hours Tuesday before lower stratus
significantly diminishes from the west.

Temps...should fall into the teens and lower 20s after daybreak
before subtle recovery occurs later today. Low level thermals
support highs largely in the mid 20s. Lows tonight will be in the
teens.locked in across the region, it appears a series of weak
clippers will skirt the region starting Tue ngt. Guidance has
continued to indicate the next clipper will quickly dive into the
Great Lakes region midday Tue, laying out a frontal boundary in it`s
wake. This boundary and some added moisture will trail this feature
late Tue into Wed. But for Tue prior to this feature we expect some
steady erosion to the cloud deck that it should produce some clear
skies for Indiana or at least more breaks. Upstream this afternoon
we are already noticing this, so we have a higher degree of
confidence that we will indeed be able to erode the stubborn stratus
deck Tue midday. With winds relaxing Tue, and less of a potent cold
air advection airmass, we should be able to rebound temps into the
upr 20s.

Tue ngt... clouds will steadily thicken again from the northwest to
southeast, in advance of the next clipper system. Temps ngt
should stabilize in the teens to lower 20s.

&&

.LONG TERM (Tuesday night through Monday)...
Issued at 248 PM EST Mon Dec 29 2025

A pattern more typical of winter will continue for much of the week
as we stay in a colder northwesterly flow pattern. A few weak
clipper systems moving through this northwesterly flow will impact
the Great Lakes region bringing light snow chances to central and
southern Indiana.

Wednesday through Thursday...

The best chances for snow will arrive on Wednesday evening as a mid
level wave/clipper system moves across the area. This will be
associated with a stronger upper level jet and coincide with the
arrival of a cold front sending overnight lows Wednesday into
Thursday back into the teens with windchills potentially down into
the single digits. While the orientation of the upper level jet is
more favorable for snow, we lack any appreciable surface low that
would accompany the mid-level shortwave. Because winds stay out of
the north we won`t see any noticeable increase in moisture ahead of
this clipper system. So, the QPF forecast remains on the lighter
side. Did nudge QPF up a tad from what the NBM was suggesting of
zero QPF over central Indiana. Most models and ensemble members have
at least 0.01 QPF along and north of the I-74 corridor. Snow Ratios
would be around 12-14 to 1, so any QPF that is present should be
able to squeeze out to a Trace to upwards of a half an inch in some
locations in north-central Indiana. Thursday remains on the cooler
side with temps in the low to mid 20s but should see some clearing
skies.

Friday into the weekend...

The pattern of a ridge in the west and trough in the east that kept
us on the cooler side this week begins to break down as we head into
the weekend. Higher pressure gradually builds into the S/SE US
allowing for winds to shift to the south to southwest. Temperatures
begin to warm back to near to slightly above normal over the weekend
with highs approach 40 degrees by Sunday and Monday. Confidence in
the forecast beyond the weekend is low as overall flow pattern
across the CONUS becomes messy and could potentially see the
redevelopment of a ridge in the west and trough in the east. Either
way we are probably back to the near to slightly below normal temps
next week.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1146 PM EST Mon Dec 29 2025

Impacts:

- Widespread MVFR ceilings persisting to near or just past daybreak
  Tuesday

- Occasional flurries or light snow showers ending overnight

- W/SW wind gusts peaking at 20 to 25kts at times Tuesday afternoon
  and evening

- Scattered flurries possible at KIND and KLAF Tuesday evening

Discussion:

Scattered flurries and light snow showers continue late this evening
but will diminish overnight as an upper level wave moves off to the
east. The low stratus will linger however for the next several hours
with clearing slowly expanding east by daybreak or shortly after.
Winds remain gusty but continue to tail off and should fall back to
10-15kts during the predawn hours.

Any clearing on Tuesday will be temporary as mid level clouds will
overspread the region from the north during the afternoon as low
pressure tracks into the Great Lakes. Scattered flurries or light
snow showers will likely expand across the northeast half of central
Indiana Tuesday evening before departing off to the east late
Tuesday night. Winds will again become brisk Tuesday afternoon and
evening as an attendant frontal boundary approaches from the
northwest. Expect peak gusts around 20 to 25kts at times.

&&

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

&&

$$

UPDATE...Nield
SHORT TERM...Beach
LONG TERM...Stumpf
AVIATION...Ryan