IND issues Area Forecast Discussion (AFD) at Jan 1, 2:48 PM EST409
FXUS63 KIND 011948
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
248 PM EST Wed Jan 1 2025
.KEY MESSAGES...
- Cloudy and Cold Today; Flurries possible
- Partly Cloudy and cold Tonight
- Light snow accumulation are expected Thursday night into early
Friday morning with impacts possible to the morning commute.
- A significant Winter system will likely effect the Midwest and
Ohio Valley late this weekend and early next week.
&&
.FORECAST UPDATE...
Issued at 913 AM EST Wed Jan 1 2025
Flurries are expected to continue within broad cyclonic flow this
morning and afternoon. There was a bit of drizzle that accompanied
this mornings flurries due to lack of saturation depth. However,
this should change over the next few hours as the PBL cools within
CAA.
A more pronounced wave embedded within the cyclonic flow is expected
to arrive the afternoon providing some increased chances of isolated
to scattered snow showers over NE central Indiana. With the greater
vertical ascent, snow rates may be breifing great enough to lead to
light accumulations (0.1-0.3"). Primary areas of concern would be
Kokomo to Muncie late this morning into the early afternoon.
&&
.SHORT TERM (Today and tonight)...
Issued at 330 AM EST Wed Jan 1 2025
Synopsis:
Surface analysis early this morning showed strong low pressure in
place over WNY and PA, providing cyclonic flow across much of the
region. High pressure was found over Kansas and the western plains
states. GOES16 showed extensive cloud cover across Indiana and
points far upstream and west, to Minnesota, Iowa and eastern Kansas.
Aloft, water vapor imagery showed a large, broad trough in place
over the center of the United States, and a deeper part of this
trough was found over the eastern Great Lakes, associated with the
surface low. Temperatures across the area were in the mid to lower
30s.
Today -
Models suggest a quick moving, weak short wave within the troughy
flow aloft, passing across Indiana. Meanwhile, lower level moisture
is shown within the time height sections to linger through much of
the day as cold air advection will be in play. 850MB temps are
expected to drop to near -10C tonight. The mid level ridge axis does
not look to arrive in Indiana today, adding further support for
lingering lower levels clouds through the day. Forecast soundings
fail to show any kind of deep moisture available. Thus with the
lingering lower level moisture and weak forcing aloft, a stray
flurry or some very light drizzle cannot be ruled out. Given our
cloud cover and cold air advection highs will only reach the lower
30s.
Tonight -
Models suggest a quiet overnight. The mid level ridge axis is
expected to push toward Indiana, while cyclonic flow across the area
ends. This will be due to high pressure over the southern plains
building east into the Tennessee and Ohio river valleys. Forecast
soundings trend toward a dry column overnight and time heights show
the lower level cloud deck gradually exiting. Thus will trend toward
a becoming partly cloudy type forecast tonight. Cold air will remain
in place, as 850mb temps remain around -8C, along with lighter
winds. This will allow for overnight lows in the lower 20s.
&&
.LONG TERM (Thursday through Tuesday)...
Issued at 330 AM EST Wed Jan 1 2025
Overview...
The change of calendars will coincidentally also bring a change of
weather regimes to most of the CONUS as elongated and amplified
polar/arctic surface high pressure slowly builds southeastward into
the central and eastern CONUS under what should be a split H500 flow
through the middle/majority of the long term period.
On the front end of the arriving polar air will be a weak clipper-
type system progged to bring light accumulating snow to mainly the
northern Midwest. A stronger and slower southern-stream storm
system will bring the potential for heavy snow and other
precipitation types around the late Sunday to Monday timeframe.
Reinforcing arctic air is expected to arrive by the end of the
long term to maintain sub-seasonal and very cold conditions across
Indiana into mid-January.
Thursday through Saturday night...
Dry yet chilly conditions under thickening clouds Thursday will
precede the first, weaker wave. The light snow's onset should be
earliest over the Upper Wabash Valley, yet suspect little/no impacts
to the late day rush hour. A solid period of light to perhaps
moderate snow is expected through evening hours, especially
along/north of the I-70 corridor where forcing will be focused. The
trough's quick progression should lead to snow tapering off from
west to east from late evening to pre-dawn hours. Around an inch
of accumulation should be the rule for the region's northern
half...with probably a rather thin coating south of I-70.
Marginally warm ground to start may melt off a small early portions
of the snowfall...yet may also contribute to travel impacts on
untreated surfaces after 00Z. Expect highs in the mid- to upper 30s
Thursday and lows by late Thursday night ranging from mid-20s along
the far south to upper teens north of the I-70 corridor, thanks in
part to the thin blanket of fresh snow. Wind chills early Friday
will drop into the single digits for central/northern zones.
The remainder of the week will feature unseasonably cold conditions
with modest temperature spreads ranging from lows in the teens to
highs in the 20s. Sky cover should trend from scattered clouds to
mostly clear conditions by Saturday...although this may promote a
few colder spots dropping into the single digits early Saturday
morning. Wind chills Friday night should drop to around zero for
much of the region.
Sunday through Tuesday...
Main focus of the long term then turns to the potential for a
significant winter storm within the early week. A strong short wave
is expected to plunge from the Oregon coast to the Texas Panhandle
by the Sunday timeframe. This should induce a broad and
collaborated fetch of both Gulf and Atlantic moisture into the
Midwest ahead of low pressure that will should track somewhere
between the TN and OH Valleys. The arctic high aligned from Ontario
down to the Carolinas will hold cold air at the surface for most/all
of the episode, with widespread snow expected at the system's onset
into central Indiana by late Sunday.
After this, considerable uncertainty still exists with latest
ensemble members noting the surface low's track and corresponding
warm advection aloft should produce a swath of mixed precipitation,
potentially heavy, somewhere between I-70 and southern Kentucky.
Low confidence exists in where a parallel band of moderate to
heavy snow may occur along/north of the area of greater mix/ice.
Yet, appears a stronger system is more likely to bring heavier
precip (of any type) farther north...and that what should be a
more WSW- ENE track would not encourage a major progression of
heavy mix/ice northward as the system crosses Indiana. Another
wild card in the synoptic set-up is reinforcing arctic air
beginning to simultaneously plunge down the Canadian High
Plains...should this feature be quicker to plunge down into the
CONUS, it could serve to twist the storm system and mixed
precipitation types farther north...although this does not appear
to be likely at this time. We encourage partners and the public
to stay tuned for updates later this week as this likely impactful
and potentially dangerous scenario unfolds for the Midwest.
Please recognize a light/moderate outcome of precipitation is
equally likely to a heavier possibility. Nevertheless the
supporting upper wave's detachment from the faster jet to the
north will allow the system to track slowly east, increasing its
time and possible duration of moderate to heavy precipitation
rates.
The end of the long term may see lingering snow showers through at
least 1-2 periods around the Monday Night-Tuesday timeframe with the
trough perhaps slow to depart eastward. Equally cold or colder
conditions expected into the mid-week. Any areas with moderate or
greater snow cover may fall to near zero at night and only rebound
into the teens during the day. Subzero wind chills are possible
through the late night/early morning hours.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 148 PM EST Wed Jan 1 2025
Impacts:
- Snow Showers with MVFR CIGs possible at KIND and KLAF
- Gusts to 25kts through 07Z
Discussion:
A weak mid level disturbance passing aloft may result in a few light
snow showers at KLAF and KIND. Within snow showers slight VIS
reductions and MVFR ceilings are possible.
Winds will remain out of the W/WNW through most of the TAF period.
These will be sustained between 10-15kt with gusts to 25kt through
at least 06Z, possible a little longer.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Updike
SHORT TERM...Puma
LONG TERM...AGM
AVIATION...Updike
Source:
IND issues Area Forecast Discussion (AFD) at Jan 1, 2:48 PM EST---------------
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