755
FXUS63 KIND 081720
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1220 PM EST Wed Jan 8 2025

.KEY MESSAGES...

- Mostly cloudy but clearing this afternoon from west to east

- Lows near zero Tonight

- Light snow accumulations of 1-2 inches possible Friday

- Below normal temperatures continue through the next week and beyond

&&

.FORECAST UPDATE...
Issued at 839 AM EST Wed Jan 8 2025

Satellite RGBs show low stratus across roughly the southeast two-
thirds of the area, beneath a band of midlevel stratus. We will make
minor adjustments to sky cover to be more aggressive in the
southeast where stratus will continue for much of the day. Also
increased further northwest due to aforementioned midlevel stratus.

The stratus has been thick enough for some light flurries earlier at
KIND, and this may be possible across the southeast half through the
morning. Definitely non-measurable and non-impactful though.

Model spread on today`s temperatures is minimal, and middle-
tier/50th percentile guidance did fairly well yesterday, so no need
for adjustments today.

There is a significant spread on temperatures tonight owing to
radiative processes over snow cover. The pattern should support
decreasing clouds but we will look at that more closely through
the day and adjust as needed. Regardless, it will be the coldest
night in central Indiana since January 21st of last year, and we
have started pushing messaging of cold impacts and warming
shelters.

&&

.SHORT TERM (Today and tonight)...
Issued at 302 AM EST Wed Jan 8 2025

Today...

Tricky forecast due to the stratocu deck, that is hanging around
much longer than the model soundings and models in general have been
hinting at. This has kept temperatures up mostly in the 20s through
the early overnight. GOES-16 RGB nighttime microphysics imagery and
obs were showing some clearing over the upper Wabash Valley but also
more stratocu was moving in from east central Illinois into the
upper Wabash Valley. If that area or any other area can clear across
central Indiana, strong inversion and dew points in the middle teens
along with very light WNW winds would support some pre-dawn fog as
BUFKIT hints at. However, with broad cyclonic flow and still some
trapped low level moisture, we are betting the stratus will continue
to hang around through the morning.

Better chance for some breaks in the low clouds this afternoon as
drier air filters in from Missouri. That said, an upstream mid deck
may also move in then. So, there are a lot of moving parts to the
forecast. For now, will keep it mostly cloudy the rest of the night,
monitor for breaks and potential fog and keep overnight lows up in
the teens as opposed to single digits. Temperatures this afternoon
will also be problematic and depend a lot on cloud cover. Lower and
middle 20s look like a good place to start with that in mind and
after comparing with adjacent offices.

Tonight...

Better confidence in eventual clearing this evening and tonight from
west to east as Arctic high pressure approaches and upper troughing
moves into the Appalachians. This will result in light to calm winds
and a strong inversion. The extensive snow field combined with these
factors should allow for the coldest temperatures of the week and
likely several degrees below the Hi-Res models with daybreak lows
near zero degrees. The exception will be over our far northern
sections, where little snow fell from the last system. NBM50 looks
good for that area and NBM25 elsewhere. This is matching up nicely
with our neighbors as well.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 302 AM EST Wed Jan 8 2025

The main focus in the extended period will be the continuing cold
pattern and the potential for snow late this week. There is high
confidence temperatures are going to remain cold through the period
though some moderation is likely over the weekend with southerly
surface flow returning.

At the surface, high pressure overhead keeps central Indiana dry on
Thursday. Thursday morning will start off very cold with portions of
the area seeing temperatures near zero or in the single digits below
zero. Plentiful sunshine and return flow should help temperatures
warm back up into the 20s though. Expect clouds to then begin
increasing Thursday night ahead of an approaching system. This will
likely limit diurnal cooling overnight keeping lows in the teens for
much of central IN. Eastern portions of the area could still
potentially fall to near the upper single digits depending on how
long it takes for clouds to move in. Winds chills in the single
digits are likely due to winds remaining slightly elevated.

Long range guidance continues to show a low pressure system
developing along the gulf coast states and moving across the
Southeast on Friday. Models are in good agreement that this system
remains south, but another weak system moving through the Great
Lakes Region at the same time will help pull gulf moisture
northward. This combined with increasing large scale ascent from the
polar and subtropical jet phasing is expected to promote widespread
light snow.

It appears precipitation will begin sometime around daybreak Friday
and continue into Friday night before tapering off. P-type issues
are unlikely with forecast soundings showing thermal profiles
below zero through the column. Snowfall accumulations of 1-2
inches are possible across much of central Indiana. However, the
higher end amounts should be more focused towards southeast
portions of the area where guidance shows slightly stronger
forcing and deeper moisture. Locally higher amounts cannot be
ruled out across the far southeast.

Another reinforcing shot of cold air is expected behind the late
week system which should keep temperatures below normal into next
week. Quiet weather conditions are likely Saturday with high
pressure, but a subtle wave moving in Sunday could support flurries
or light snow showers. The one limiting factor is moisture will
remain displaced well south keeping QPF very light.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1220 PM EST Wed Jan 8 2025

Impacts:

- Gradual backing of winds to southerly

 Discussion:

Low and midlevel stratus is exiting the area and ceiling
restrictions are unlikely through the rest of the TAF period. Only
potential impact could be patchy shallow freezing fog early in the
morning, but in this pattern with snow cover and no moisture
advection, usually this manifests as frost. Will monitor trends for
potential visibility reductions late tonight. Right now, that is low
probability.

&&

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

$$

UPDATE...BRB
SHORT TERM...MK
LONG TERM...Melo
AVIATION...BRB