IND issues Area Forecast Discussion (AFD) at Dec 12, 5:27 AM EST
320
FXUS63 KIND 121027
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
527 AM EST Thu Dec 12 2024
.KEY MESSAGES...
- Light snow focusing mainly along and north of I-70 this afternoon
and evening with light accumulations
- Cold today with a warming trend commencing on Friday
- Rain chances and near normal temperatures return for this weekend
&&
.SHORT TERM (Today and Tonight)...
Issued at 314 AM EST Thu Dec 12 2024
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.
&&
.LONG TERM (Friday through Wednesday)...
Issued at 314 AM EST Thu Dec 12 2024
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.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 527 AM EST Thu Dec 12 2024
Impacts:
- Wind gusts diminishing early this morning
- Light snow spreading across northern portions of central Indiana
afternoon and early evening...impacting KLAF and possibly KHUF and
KIND
Discussion:
Mid level clouds are expanding into southwest Indiana early this
morning and expect that to expand across the region through the
morning hours. Westerly winds remain periodically gusty but will see
winds diminish over the next few hours.
A mid level wave will pivot through the region this afternoon with
an area of light snow impacting northern portions of central Indiana
and especially KLAF with reduced visibilities and occasionally lower
ceilings. Have introduce a tempo group for a few hours this
afternoon at KIND but there is higher uncertainty with how far south
the snow will make it and it will be close at KIND. KHUF may briefly
see light snow early this afternoon but expect most of the snow will
remain north of the terminal.
Scattered snow showers and flurries will linger into this evening
before ending. Westerly winds will persist at 5-10kts once gusts
drop later this morning then veer to northeast tonight.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
SHORT TERM...Ryan
LONG TERM...KF
AVIATION...Ryan
Source: IND issues Area Forecast Discussion (AFD) at Dec 12, 5:27 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412121027-KIND-FXUS63-AFDIND)
---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!