Indiana’s Weather For Today

Thursday headlines:

– Light snow focusing mainly near and north of I-70 this afternoon and evening with light accumulations

– Single digit chills most of today

– Rain chances and near normal temperatures return for this weekend

Technical discussion via the Weather Service:

After the snow showers from Wednesday afternoon and evening…mainly
clear skies with bitterly cold air has settled over the Ohio Valley
early this morning. A mid level cloud deck is however rapidly
expanding east toward the Wabash Valley and serves as the precursor
for more wintry mischief on the docket for later today as a wave
aloft traverses through the region. 08Z temps were in the teens and
low to mid 20s with subzero wind chills over northern counties as
westerly winds remain gusty.

As stated above…the tranquil weather ongoing is temporary as a
fast moving wave aloft within a split flow regime will move quickly
across the lower Great Lakes this afternoon and evening. Model
guidance is still struggling with the specifics which is not
surprising considering the transient and subtle nature to the mid
level wave. With that being said…there are several signals that
support a more widespread light snow focused across the northern
half of the forecast area with at least some potential for an
overachieving band that may bring light accums.

An elongated axis of mainly mid level clouds extends from the
northern Plains southeast into the Mid Mississippi Valley. These
clouds will pivot into the forecast area from the west over the next
several hours…initially focusing over the southwest half of
central Indiana before encompassing the entire area by late morning.
The actual wave aloft is currently well back to the northwest over
the western Dakotas in a disjointed state. As the wave though dives
into the deep upper trough aided by the split jet structure and
stronger flow aloft…expect it to strengthen as it approaches the
region by early to mid afternoon. Modest flow through the boundary
layer will contribute to an axis of low level convergence organizing
west to east across the region in proximity to an area of mid
level frontogenesis during the second half of the afternoon.

The mid and upper level dynamics discussed above support the
development of an area of light snow focused especially along and
north of I-70 by mid afternoon and extending into the early evening
hours. There are other factors that hint at the potential for light
accums to overachieve in some locations. Despite expected qpf values
of just a few hundredths…snow ratios will be elevated and likely
somewhere in the vicinity of 15-18:1 for the duration of the event.
Additionally…the influx of low level moisture will lead to a
saturated column extending perhaps as far up as 600mb with the
dendritic growth zone likely well within the saturated layer for at
least a few hours later this afternoon focused again over the
northern half of the forecast area. Have bumped up pops as a result
of the above thoughts with growing confidence in a 3 to 5 hour
period of light snow along and north of I-70. Snow will become more
scattered in coverage before diminishing by late evening as the wave
aloft weakens and associated forcing is lost while strong high
pressure over the western Great Lakes begins to exert its influence.
Skies will gradually clear late tonight.

Overall accums at this point will likely be from a few tenths in the
I-70 corridor to nearing one inch in far northern counties from
Lafayette to Kokomo. There is potential for a few spots to exceed
the highest totals around an inch should any enhancement in banding
take place and developing trends via mesoanalysis will be able to
provide a clearer picture as the snow moves in. Any subtle shift in
the track of the wave could shift the higher snow totals north or
south. Once again despite light accums…timing is not ideal for
late day with the evening rush likely being impacted. With road and
air temps well below freezing…snow will stick on contact and slick
conditions will develop. Will highlight via an SPS.

Temps…undercut guidance for highs today as the combination of the
clouds already expanding into the area and lingering cold advection
will cause temperatures to struggle to rise. Expect upper teens and
lower 20s along and north of I-70 with mid and upper 20s further
south. Lows tonight will range form the teens to lower 20s north to
south.

The long term period will warm up, seeing temperatures largely near
to slightly above normal throughout. Friday however will start out
with one more day of colder conditions with highs in the 30s to near
40. In addition to the warmer days, there will also be multiple
chances for rain as warmer, wetter, and more progressive weather
pattern sets up across the Great Lakes region with a persistent
trough overhead.

The first system is set to move in Saturday, with models continuing
to push back the arrival of the frontal system and line of rain
closer to the afternoon hours. Still seeing a decent surge of
moisture out of the Gulf with the center of the surface low passing
just north of the forecast area. Some areas could see as much as an
inch of precipitation with this wave, and highest amounts expected
across the south. This delayed timing also pushes back when rain
should exit to during sometime late Sunday.

The next wave to move through will be in quick succession to the
weekend wave, leaving only a brief break before more rain is set to
move into central Indiana by Monday morning. The amount of moisture
with this system is less clear as there are discrepancies as to
where the longitudinal axis will set up. Should the moisture tongue
stretch into the upper Great Lakes, more QPF will be expected, but
if not, a bulk of the rain may stay further south over the Ohio
Valley. With rain likely coming to an end by midday Tuesday expect
dry weather and slightly cooler temps for midweek. An additional
system is again possible for later next week.

INDY SEVEN DAY FORECAST
Today: Morning sun and afternoon clouds. Afternoon snow showers possible. High 25.

Thursday Night: Mostly cloudy, with early evening snow showers. Partly cloudy overnight. Low 18.

Friday: Partly to mostly cloudy. High 35.

Friday Night: Clouding up. Low 29.

Saturday: Mostly cloudy. Scattered showers in the afternoon. High 48.

Saturday Night: Scattered showers. Low 40.

Sunday: More showers, especially in the morning. High 49.

Sunday Night: Mostly cloudy. Spotty showers after midnight. Low 39.

Monday: Showers are likely. High 54.

Monday Night: Scattered showers early. Clearing later. Low 37.

Tuesday: Mostly sunny. High 43.

Tuesday Night: Partly cloudy. Low 28.

Wednesday: Partly sunny. High 40

NWS CHARTS FOR TODAY/TONIGHT