IWX issues Area Forecast Discussion (AFD) at Jan 7, 5:21 AM EST945
FXUS63 KIWX 071021 CCA
AFDIWX
Area Forecast Discussion...CORRECTED
National Weather Service Northern Indiana
521 AM EST Tue Jan 7 2025
.KEY MESSAGES...
- On Wednesday, lake effect snow showers spread well inland.
- Very cold Wednesday night and Thursday night with single-digit
lows outside of lake effect clouds.
- There are more chances for snow this weekend into early next
week.
&&
.DISCUSSION...
Issued at 234 AM EST Tue Jan 7 2025
The passage of an upper-level trough through the Great Lakes this
morning has put an end to the day's earlier lake effect snow band.
As is typical this time of year, I've increased sky cover for today
with plenty of stratus noted upstream on satellite. High resolution
guidance and cross sections favor this as well with trapped low-
level moisture. Temperatures have been pretty uniform these past
couple of days and today will be no different with highs generally
in the mid to upper 20s.
Just as this round of lake effect ends, attention then turns to
Wednesday's lake effect snow. Forecast soundings and high resolution
guidance show very favorable LES parameters; EQL just shy of 10k FT,
ample DGZ depth (near 4k FT), plenty of lift and favorable northwest
wind flow (that isn't too strong as to shred dendrites). Guidance is
depicting a strong single-band to race south along the eastern shore
early Wednesday morning, eventually moving onshore as wind becomes
from the northwest. It is this transition from north to northwest
flow that decreases confidence in the band's residence time over any
given location. However, I am concerned that small area Berrien
county could see at least a few inches in a short amount of time.
Inland, lake effect snow showers/flurries ought to move well inland
on Wednesday. This is due to favorable upper-level support in
response to a thermal trough aloft dropping in from Ontario. This
trough is maximized Wednesday afternoon/evening and would suggest
lake effect snow showers surviving well into northwest Ohio.
Incoming high pressure over the Mid-Mississippi Valley will disrupt
lake effect parameters Thursday morning. Very cold in the wake of
this trough with Wednesday night (and Thursday night) lows in the
single-digits outside of lake effect clouds.
This weekend into early next week, active northwest flow favors
episodes of snow and a reinforcing shot of cold air. Cluster
analysis for 500mb Friday night when a trough is lifting into the
Midwest reveals guidance is generally binned by parent model, thus,
uncertainty continues with how said trough interacts with Northern
Plains energy. A parade of clipper systems is then possible starting
Sunday night.
&&
.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 435 AM EST Tue Jan 7 2025
Overnight subsidence in the cloud layer continued to have a
major impact on snow showers moving inland from south Lake
Michigan. Snow showers just upstream have ended, but widespread
cloudiness continues under a very strong subsidence inversion
below 050. Moisture/clouds will remain trapped below the base of
the inversion with MVFR to possibly low VFR ceilings remaining
through the TAF period as low level winds back to the northwest
and continue to tap into the very mild Lake Mich water
temperatures for this time of year. The south interior Lake Mich
temps were >6C. Another round of lake effect snow showers will
set up late tonight. Added a PROB30 group late for now at SBN.
Otherwise, kept ceiling basically 025-030 through the period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 4 PM EST this afternoon for LMZ043-
046.
&&
$$
DISCUSSION...Brown
AVIATION...Skipper
Source:
IWX issues Area Forecast Discussion (AFD) at Jan 7, 5:21 AM EST---------------
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