015
FXUS63 KIND 191653
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1153 AM EST Sun Jan 19 2025

.KEY MESSAGES...

- Occasional light snow across the eastern half of central
  Indiana today, with little or no accumulation expected.

- Cold Weather Advisory in effect tonight through Wednesday morning.
  10 below wind chills, possibly as low as 20 below for northern
  portions of central Indiana.

- Moderating temperatures Wednesday onward, though still below
  normal.

&&

.FORECAST UPDATE...
Issued at 928 AM EST Sun Jan 19 2025

Scattered to numerous light snow showers continue across central and
eastern Indiana this morning with a combination of lake enhanced
snow moving southwards and the remnants of a weak upper level wave
across the southern counties. Where the lake enhanced showers are
interacting with the more elevated snow showers to the south there
has been some seeder-feeder effects which is created localized
heavier snow showers.

The lake fetch will continue to become more westerly through the
rest of the morning into the afternoon which will shift the focus
for snow to the eastern counties while the broader light snow from
the southern system continues to have lesser influence by the
afternoon.  Total accumulations will be a dusting to a few tenths,
but areas where the stronger seeder-feeder effects occur could get a
quick half inch.

Temperatures have reached their highs for the day and
are expected to continue to fall with sub-zero wind chills by later
this afternoon as winds occasionally gust to 25 mph and temperatures
drop into the high single digits to low teens.

&&

.SHORT TERM (Today and tonight)...
Issued at 253 AM EST Sun Jan 19 2025

Today...

Early this morning, lower clouds covered much of the eastern two-
thirds of central Indiana, with mid and high clouds elsewhere.
Regional radar showed some echoes streaming from Lake Michigan, but
observations are not indicating much of anything reaching the
ground. Echoes are also across southern Missouri with nothing
reaching the ground.

During the day today, the influence from Lake Michigan will continue
across the eastern forecast area. Meanwhile, central Indiana will
get sideswiped from forcing from an impulse moving through the upper
trough. (Better forcing will be south of the area).

Moisture is limited, but the moisture that will combine from the
Lake influence and the southern system will be enough to work with
the forcing to produce some patchy light snow across the eastern
half or so of central Indiana. Will go with some slight chance to
chance PoPs there after 12Z through about 19Z. After then the
influence of high pressure building in from the west will end the
snow.

Drier air with the building high will erode the clouds as well
during the afternoon from west to east.

Cold advection will persist, bringing temperatures slowly down
during the day.

Tonight...

Cold and dry Arctic air will continue to flow in the area. Skies
will be mostly clear, but winds will remain up. However, even
without good radiational cooling, cold advection will bring
temperatures to below zero at most locations. The far south may
remain around zero. The model blend may be too warm as some members
are warm outliers, so nudged it down a bit.

These temperatures along with the winds will lead to widespread wind
chills at or below -10 but above -20, so the Wind Chill Advisory
looks good.

&&

.LONG TERM (Monday through Saturday)...
Issued at 253 AM EST Sun Jan 19 2025

Anomalously deep troughing over almost the entirety of North America
will lead to very cold weather for the next several days. Ensembles
are in excellent agreement showing 850mb temps as low as -25 to -30
C over portions of the Midwest early this week. Surface temperatures
below zero degrees are expected for multiple nights, with wind chill
readings occasionally reaching -15 to -20 degrees F.

Some clouds should overspread the southern half of our area Monday
night, which may prevent low temps from being as cold as they could
be. We bumped low temperatures up a bit across our southern counties
while keeping temperatures north of I-70 slightly below guidance.
Radiational cooling will be maximized in areas that see clearing,
effects of which can be washed out in lower-resolution guidance.
Tuesday night looks to have the best radiational cooling potential
as surface high pressure is directly overhead. Light winds and clear
skies along with a patchy snowpack should lead to temperatures as
low as -10 F in places. There remains some spread within guidance,
however, as some members show warm air advection beginning halfway
through the night as the high slides eastward. We will lean towards
the colder solutions for now, as a sharp boundary layer inversion
should help limit any southerly winds that begin to develop. Diurnal
mixing could lead to a nice southerly breeze (gusts up to 25kt)
during the day on Wednesday, however, which should help temperatures
rebound quickly into the 20s.

We will maintain a Cold Weather Advisory with this update, as a
majority of locations will experience wind chill values between -10
and -19 degrees F...with only isolated readings exceeding -20 F.
Confidence is very high for -10 degree or lower wind chills Sunday
night into Monday as the combination of wind and cold is maximized.
Thereafter, winds diminish leading to less frequent periods of -10
to -19 degree wind chills, but still frequent enough to warrant the
Cold Weather Advisory through Wednesday morning.

Ensemble guidance depicts the trough flattening somewhat by
Wednesday, with modest warm air advection taking hold. Temperatures
at the surface moderate but are expected to remain below normal
through the coming week. Above-freezing high temps are looking
increasingly likely by the weekend. Longer term ensemble guidance
retains mean troughing over the eastern US so below-average
temperature are favored through the remainder of January.

With the polar jet displaced well to our south...precipitations
chances look quite minimal through the next 7 days or so. There may
be a weak upper-level impulse / clipper system passing through late
this week with scattered snow showers or flurries but that`s about
it. Some of the global models bring about a more active weather
pattern towards the end of the month but no coherent signal exists
within the ensembles as of yet.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1152 AM EST Sun Jan 19 2025

Impacts:

- MVFR ceilings through 20Z at KIND/KBMG
- Occasional light snow/flurries KIND/KBMG through 20Z
- Northwesterly wind gusts 20-25kts into the evening

Discussion:

Coverage of snow will continue to gradually decrease near BMG and
IND into the afternoon hours with only brief MVFR vsbys in heaviest
showers.  Cigs will also rise to VFR by 20Z with the main impacts
afterwards being the northwesterly wind gusts to 25kts through 00Z.
Winds will remain in the 10-15kt range through the night with VFR
conditions as skies continue to clear.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory from 7 PM this evening to 10 AM EST
Wednesday for INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

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