IWX issues Area Forecast Discussion (AFD) at Jan 5, 9:43 AM EST322
FXUS63 KIWX 051443
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
943 AM EST Sun Jan 5 2025
.KEY MESSAGES...
- A winter weather advisory remains in effect for snow along and
south of the SR 18 corridor tonight.
- Remaining cold for the week ahead with highs in the 20s and
lows approaching single-digits at times.
- Lake effect snow showers spread well inland Wednesday.
&&
.UPDATE...
Issued at 942 AM EST Sun Jan 5 2025
12Z raobs across the midwest this morning tell the tale with
extremely dry airmass positioned across the Great Lakes and wrn
OH valley. Potent cyclone over KS will open up late tonight/Mon
morning as it elongates ewd swd of stiff confluence zone across
the srn lakes.
Emerging 12Z guidance follows southward tightening qpf trends
seen in prior 00/06Z model cycles and indicative of increasing
low theta-e feed north of cyclone track impeding top down
saturation and sfc snowfall. As such and in light of further
contracting 12Z based cams guidance will forgo much of prior
advisory issuance. Small area south of SR18 from Grant ewd
through Jay may still lap into some limited advisory threshold
snowfall but even here the nrn reach of accumulating snow is not
a slam dunk. Updates forthcoming.
&&
.DISCUSSION...
Issued at 307 AM EST Sun Jan 5 2025
A winter storm is ongoing across the Nation's heartland this morning.
Water vapor shows a well-defined trough digging into the Texas
panhandle while low pressure is deepening over adjacent Oklahoma.
Warm air advection associated with this system spreads east of the
Mississippi according to 850mb charts. As a result, virga is seen on
radar over much of Indiana; dry air a byproduct of retreating high
pressures now over the central Appalachians.
Generally cold and cloudy today ahead of snow gradually overcoming
dry air tonight and creeping north. There is no significant change
in thinking with the winter storm as it grazes the US 24 corridor.
Forecast guidance this morning generally stayed close to the 12z
runs. The once overzealous HRRR (00z run this morning) has even
settled down a little bit. Thus messaging remains the same within
the winter weather advisory. Grant, Blackford, and Jay counties
could be bisected north-south with a strip of heavy snow approaching
5 inches with a sharp cut off in snow totals to the north. Two areas
of frontogenesis are forecast with this system as it moves across
Indiana; the northern most which could graze the aformentioned
counties providing a brief period of heavy snow. Elsewhere, snow
will struggle to reach southern Michigan. Therefore, POPs were
reduced here. Within the advisory area, blowing snow will be of
concern due to northeast wind gusts of 20 to 25 mph.
Snow ends soon after daybreak Monday and a lake effect snow band
impacting downtown Chicago will gradually shifts east through the
day. It arrives to far Northwest Indiana late, perhaps slipping in
LaPorte and Starke counties by sunset before diminishing Tuesday
morning. Due to the transient nature, accumulation of around 1 inch
is expected at this time.
A reinforcing shot of cold air arrive Wednesday thanks to a
shortwave dropping out of Canada. Lake effect snow will be
invigorated once more and ought to spread well inland (similar to
Friday) and it persists into at least Thursday morning. This lake
effect setup will be scrutinized at the conclusion of the current
winter storm.
To end the week, a broad trough drops into the Great Lakes region
offering a chance for widespread "system" snow. How this interacts
with a subtropical jet ejecting from the far Southern Plains will
need to be monitored. Initial pattern recognition favors the
heaviest precipitation south of the forecast area.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 548 AM EST Sun Jan 5 2025
Dry/VFR with some virga possible out of a lowering mid level
cloud deck today into most of this evening. An arcing corridor
of elevated fgen/deformation should finally squeeze out some
light snow at KFWA later tonight with flight conditions likely
lowering into MVFR for a time. Winds increase and take on a
more northerly component otherwise tonight as the center of low
pressure tracks east through KY.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory from 7 PM this evening to 10 AM EST
Monday for INZ032>034.
OH...None.
MI...None.
MARINE...None.
&&
$$
UPDATE...T
DISCUSSION...Brown
AVIATION...Steinwedel
Source:
IWX issues Area Forecast Discussion (AFD) at Jan 5, 9:43 AM EST---------------
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