IWX issues Area Forecast Discussion (AFD) at Jan 11, 6:20 PM EST416
FXUS63 KIWX 112320
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
620 PM EST Sat Jan 11 2025
.KEY MESSAGES...
- A period of light snow possible Sunday, mainly in the
afternoon and evening along and north of US 24. Minor
accumulations possible (dusting-1").
- Very cold Monday night through Thursday morning with below-zero
wind chills at times.
- Periods of lake effect snow in the coming week.
&&
.DISCUSSION...
Issued at 227 PM EST Sat Jan 11 2025
Mid level ridging building overhead, and backed/diminished boundary
layer flow, will bring an end to any lake effect snow flurry
activity by early this evening. This ridging will be brief as a
shortwave trough and a weak sfc low track east-northeast through
the Upper Midwest and western/northern Great Lakes. Warm
advection driven light snow showers likely develops within a
leading 30-40 kt low level jet on Sunday (mainly aftn-eve).
However, lacking moisture return and northward bypass of better
forcing suggest minor accums at best (up to an inch, best
chances northwest of US 24). Still cannot completely rule out
some patchy drizzle with a potential mid level dry slot
suggesting low chances (10-20%) for shallower saturation and
thus insufficient ice nuclei. Additional snow showers and light
accums then continue into Sunday night as the primary shortwave
and arctic cold front track through.
Blustery/cold west-northwest flow will settle in behind the arctic
front Monday through Wednesday, with Tuesday likely the coldest day
behind a secondary vort lob/front dropping south from central
Canada. Wind chills will likely be stuck below zero at times away
from a Lake plume that will mainly be relegated to near and north of
the MI state line. ECWMF/GEFS ensemble blends show a 30-50% for wind
chills <=15 degrees below zero (Advisory levels) for a time Monday
night, and again Tuesday night. This air mass will no doubt ignite
the LES machine for our west to west-northwest LES belts,
particularly on Tuesday behind the secondary cold front. Dry nature
to the incoming arctic air will likely limit flake size and
accumulations, though roads may be slick in spots with reduced
visibilities.
Pattern will briefly reload and flatten out a bit allowing for a
welcomed brief thaw late in the week (highs well into the 30s by
Friday). Ensemble guidance is then in good agreement in upper
ridging developing across the northeast Pacific into Alaska next
weekend into the following week. This will force deep longwave
troughing to develop over central North America with chances
for a more severe arctic intrusion and/or the potential for an
active storm track along a baroclinic zone.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 620 PM EST Sat Jan 11 2025
Primarily VFR conditions anticipated overnight but there are a
few patches of MVFR stratus in the area that could briefly
impact the terminals at times. Much better chances for (low-
end) MVFR ceilings arrive Sunday morning as next trough
approaches and low levels slowly re-saturate. This system will
bring more light snow mainly during the afternoon hours with IFR
conditions expected. Some freezing drizzle could mix in at
times but the window for drizzle is very brief and will hold off
on mentioning in the TAF for now.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 7 AM Sunday to 7 PM EST Monday for
LMZ043-046.
&&
$$
DISCUSSION...Steinwedel
AVIATION...AGD
Source:
IWX issues Area Forecast Discussion (AFD) at Jan 11, 6:20 PM EST---------------
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