IWX issues Area Forecast Discussion (AFD) at Feb 12, 12:55 AM EST280
FXUS63 KIWX 120555
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1255 AM EST Wed Feb 12 2025
.KEY MESSAGES...
- A storm system will bring a wintry mix to the area Wednesday
afternoon into Wednesday night. Snow and ice accumulations
will make for difficult travel conditions in time for the
Wednesday afternoon and evening commute.
- There is the potential for another round of wintry precipitation
and hazardous travel Saturday into Sunday.
&&
.UPDATE...
Issued at 924 PM EST Tue Feb 11 2025
No changes anticipated to the Winter Weather Advisory headline
in effect for tomorrow afternoon through late tomorrow night.
A highly progressive system will exhibit some digging across the
northern Rockies overnight as vort filament races east across
the Four Corners region. Latest guidance supports previous
forecast trends of this lead wave remaining distinct from
northern stream upper level short wave trough with lack of
phasing. It still appears as though this progression and
somewhat disjointed nature of forcing mechanisms support
advisory levels accums/impacts for later Wednesday into
Wednesday night. Latest guidance does support a rather
impressive low/mid level frontal forcing signal, with
respectable 850-700 frontogenesis axis developing upstream and
overspreading local area after 00Z Wednesday evening. This
system will be accompanied by some strong mid/upper level speed
shear which could yield some potential for short lived slantwise
instability/CSI signal in the 00Z-06Z timeframe. Feel that the
potential of the higher snow accumulations in Winter Weather
Advisory forecast range across the far north/northwest may end
up being tied to any more focused stronger banding Wednesday
evening.
Previous forecast spatial extent of mixed precip evolution
across southeast two-thirds of the forecast area still seems
reasonable with an eventual changeover to all snow as precip
rates wind down late Wednesday night with northeast progression
of dry slot. Otherwise, a few advective wings of light snow may
precede the stronger forcing late morning into early afternoon
Wednesday which is captured with broadbrush chance PoPs.
&&
.DISCUSSION...
Issued at 247 PM EST Tue Feb 11 2025
Through Wednesday night...
Main focus remains on the Wednesday afternoon-night storm system.
Said storm system, in the act of dropping into the Four Corners,
will make the turn east-northeast through the region by this time,
with improved agreement on the associated sfc reflection
tracking northeast through KY and western/northern OH. Initial
WAA/fgen driven precip overspreads from west to east Wednesday
afternoon-early evening, ending as some light snow with a
drying deformation axis by early Thursday. The most notable
trends in 06/12z guidance include a decrease in QPF with the
main mix zone generally setting up near the US 24 corridor
(mainly snow to the north, all ptypes along/near, and a mixture
of mainly freezing rain and rain to the southeast). Given the
progressive nature to the wave, and somewhat limited SLR's (10-
12:1) thanks to a fairly deep isothermal layer close to -5C,
opted for a Winter Weather Advisory for the entire forecast area
to highlight the expected hazardous travel.
- Steinwedel
Thursday through Tuesday...
Cold, high pressure Thursday through Friday morning gives way to a
slowly amplifying 500-mb pattern downstream of a Four Corners
trough. A low is forecast to develop over the Midwest Saturday
bringing a period of snow Friday night and Saturday, perhaps ending
as wintry mix in far southern areas as weak warm air advection noses
in. This is followed by a second low Sunday which features improved
upper-level support as the Four Corners trough ejects east. Our area
is positioned to be on the northwest, cold, side of this system
which could promise a healthy dose of snow. But, there is plenty of
time to determine where this area of snow may lie. Notably colder
(lows near zero) with lake effect snow in the days that follow.
- Brown
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1249 AM EST Wed Feb 12 2025
A surface low will track southeast of the area Wednesday and
bring a wintry mix to northern Indiana. At SBN, the
precipitation should be mainly snow. At FWA, a snow/freezing
rain and sleet is likely. Updated the TAFs with the most recent
expectations. The event should still be ongoing at the end of
the TAF period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory from 1 PM EST /noon CST/ this
afternoon to 7 AM EST /6 AM CST/ Thursday for INZ005>009-
012>015-017-018-020-022>027-032>034-103-104-116-203-204-
216.
OH...Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
Thursday for OHZ001-002-004-005-015-016-024-025.
MI...Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
Thursday for MIZ078>081-177-277.
MARINE...None.
&&
$$
UPDATE...Marsili
DISCUSSION...Brown/Steinwedel
AVIATION...Skipper
Source:
IWX issues Area Forecast Discussion (AFD) at Feb 12, 12:55 AM EST---------------
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