IWX issues Area Forecast Discussion (AFD) at Jan 6, 7:10 PM EST022
FXUS63 KIWX 070010
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
710 PM EST Mon Jan 6 2025
.KEY MESSAGES...
- Light lake effect snow showers and a slight chance for
freezing drizzle near the Lake Michigan lakeshore (mainly
LaPorte and sw Berrien counties) tonight into early Monday.
Minor snow accumulations of a dusting to 1 inch could create a
few slick spots.
- Lake enhanced snow showers expected Wednesday into Wednesday
night, mainly north of US 30 where a dusting to 2" will be
possible.
- Remaining seasonably cold with additional chances for snow
Friday afternoon into Friday night.
&&
.DISCUSSION...
Issued at 150 PM EST Mon Jan 6 2025
Backing flow will allow the ne IL and far nw IN lake plume to edge
east into La Porte/Starke/sw Berrien tonight into Tuesday morning.
This lake thermal trough definitely begins to lose its integrity as
it shifts east with drying/subsidence eventually taking its toll on
inversion heights. Have already observed these shallow inversion
heights limiting ice nucleation with reports of freezing drizzle
mixed with snow upstream so far today. Very minor snow or ice issues
cannot be ruled out into our Lake MI shoreline zones tonight as a
result, though confidence in impacts/precip remain very low given
the weakening trend. Seasonably cold and mainly dry elsewhere as
lake clouds likely settle in for most Tuesday into Tuesday night in
cyclonic nw flow.
A potent mid level wave drops south though the western/southern
Great Lakes from western Ontario Wednesday into Wednesday night,
with an associated lake enhanced low level trough pivoting into at
least northern portions of the forecast area before dissolving on
Thursday as high pressure builds in. System is moisture starved but
should elicit a decent lake response with snow showers making it
well inland (mainly along/north of US 30) Wed aftn-eve with minor
accums and travel impacts possible...especially in our favored nnw
flow lake belts within the trailing lake aggregate trough, though
quick height rises and dry airmass likely limiting factors for
higher end LES impacts.
Medium range guidance has remained consistent in a deep positively
tilted mid level wave shifting east across the region Friday
afternoon into Friday night. A piece of a secondary trough over
northern Mexico likely gets ingested quickly northeast with some
degree of phasing with the northern stream component. It's the exact
degree of this phasing and timing of the individual waves that will
dictate the evolution of this system, determining if enough moisture
gets this far north for accumulating snow or not. Lots of moving
parts and low confidence at this range with broadbrush chance PoPs
retained. Temps remain slightly below average otherwise through the
period.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 710 PM EST Mon Jan 6 2025
An upper level vort max dropping across southeast Lower
MI/southeast Ontario has resulted in some increase in lake
enhanced light snow showers/flurries, but these should remain
primarily northeast of KFWA before ending this evening. Synoptic
scale mid subsidence is becoming prevalent behind this wave
with scattering of low clouds across southern Lower Michigan.
Expecting this scattering trend to continue into KFWA vicinity
by 02Z or 03Z. Meanwhile, lake effect showers and patchy
freezing drizzle are ongoing this evening across extreme NW
Indiana, slowly shifting east through time. Observations near
the lake beginning to show some signs of land breeze development
which could slow eastward progression of this band a bit this
evening. Development of this land breeze, northerly fetch, and
dry air entrainment lead to lower confidence in precipitation
extent, duration at KSBN and will go dry this cycle at KSBN
until better confidence can be attained. MVFR low clouds should
work back into KSBN area by 02Z or 03Z as this lake plume nudges
east. If precip does occur at KSBN, cannot completely rule out
some patchy light freezing drizzle overnight into early Tuesday
given marginal RH near the -10 deg C layer. MVFR cigs should
affect terminals again for Wednesday as lake modified low level
airmass shifts eastward.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 4 PM EST Tuesday for LMZ043-046.
&&
$$
DISCUSSION...Steinwedel
AVIATION...Marsili
Source:
IWX issues Area Forecast Discussion (AFD) at Jan 6, 7:10 PM EST---------------
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