IWX issues Area Forecast Discussion (AFD) at Dec 2, 8:34 PM EST737
FXUS63 KIWX 030134
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
834 PM EST Mon Dec 2 2024
.KEY MESSAGES...
- Lake effect snow showers, heavy at times, over southwest
Michigan this afternoon will spread south into a portion of
northwest Indiana by evening and continue overnight. 6 to 12"
with locally higher amounts is expected over Berrien into
northwest Cass Michigan counties with lesser amounts in
surrounding areas.
- Dry weather returns Tuesday afternoon into Wednesday morning
before some additional rain and light snow develop later
Wednesday through Thursday.
&&
.UPDATE...
Issued at 827 PM EST Mon Dec 2 2024
A few changes have been made over the past couple of hours to
the forecast, mainly to reflect a slight increase in snow
amounts further east and south (still overall rather minimal and
not requiring additional headlines). Much of Berrien county
enjoyed a brief breather, but additional snow showers, more
cellular in nature, have moved back in and should continue to
impact at least the NE half or so of the county, possibly
reaching to South Bend. Growing concerns continue on final snow
amounts for much of LaPorte county possibly into western St
Joseph county IN, but upstream trough still looks to bring at
least a period of snowfall later tonight into early Tuesday so I
will keep headlines and overall amounts generally the same.
Portions of Berrien into Cass county appear to still be facing
the greatest accumulation threat with locally up to a foot of
snow or more possible in a few locations.
&&
.DISCUSSION...
Issued at 120 PM EST Mon Dec 2 2024
Strong ern lake Michigan centered thermal troughing driving robust
low level convergence zone and intense lake snow bands this aftn
through sw MI. Background steering flow weak attm but will pickup a
bit heading into tonight and expect this will spread further inland
into the South Bend metro especially north of US20. Overlap of
potential mesolow tracks puts ground zero for the heaviest storm
total snowfall accumulations around 18" across nrn Berrien and
perhaps into nwrn Cass with much less south and east given limited
inland penetration before these bands breakup quickly Tue morning.
Headlines are generally good although will drop St Joe MI given the
above reasoning.
Thereafter attn shifts to next incoming nrn stream disturbance
progged to dig sharply through the nrn lakes late Wed. Robust warm
advection noted ahead of this wave yet handcuffed by poor moisture
return which will limit a more vigorous precip response. Prior pop
alignment/extent had this relatively handled well with just a tweak
to two warranted that favors northeastern half for some minimal snow
accumulation. Good secondary cold advection burst in wake of this
sys along with wrn bound of attendant mid lvl moisture plume will
also drive some spirited lake enhancement snow early Thu
particularly through srn MI/nrn IN.
Thereafter upper pattern flips as ern Canada negative height anomaly
shifts north in response to deep meridional troughing developing over
the wrn US. This will lead to a reversal in temps with strong
moderation expected by late weekend and an increasing chance of
rain.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 609 PM EST Mon Dec 2 2024
Low confidence forecast for KSBN over the next 12 to 18 hours as
finer details of the lake effect event remain poorly defined and
highly variable. KSBN had a glancing shot from the initial band,
dropping to 4 miles briefly, with the main area now NE of the
airport. Scattered snow showers may impact the airport for the
next several hours with vsby excursions to IFR at times, but
predominately MVFR (mainly cigs) may take hold as the trough
passes through. Expect amendments as the event evolves.
Overnight into early Tuesday, a renewed band, currently across
NE Lake MI will drop south and could set up another band that
impacts KSBN. Given how the current evolution has been less than
stellar, concerned how this one will shape up so I will make
minor changes, but further updates will likely be needed with
the 6Z TAF.
At KFWA, only potential impacts for the next couple of hours
will be if the SW to NE oriented band dropping south from N of
KGSH to NW of KANQ holds together. If it does, a small window
from maybe 2 to 4Z could see flight impacts, but for now will
leave VFR conditions in place and amend if needed.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 10 AM EST /9 AM CST/ Tuesday for
INZ005-103.
Winter Storm Warning until 10 AM EST Tuesday for INZ104-204.
OH...None.
MI...Winter Storm Warning until 10 AM EST Tuesday for MIZ078-177-
277.
MARINE...Small Craft Advisory until 3 PM EST Tuesday for LMZ043-046.
&&
$$
UPDATE...Fisher
DISCUSSION...T
AVIATION...Fisher
Source:
IWX issues Area Forecast Discussion (AFD) at Dec 2, 8:34 PM EST---------------
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