December 2024 General Discussion

[sbnwx85]

Tomorrow, believe it or not, is December. The start of meteorological winter. The best three months of the year. Cold and dry outside the lake belts to start. Speaking of lake belts…

 

[RogueWaves]

5 minutes ago, sbnwx85 said:

Tomorrow, believe it or not, is December. The start of meteorological winter. The best three months of the year. Cold and dry outside the lake belts to start. Speaking of lake belts…

 

I think S. Bend's moment looms..

[sbnwx85]

Just now, RogueWaves said:

I think S. Bend's moment looms..

I hope so. Monday’s event has potential to be intense but relatively short. The best lake effect dynamics have north and east of here so far. Still lots of potential with the NW flow next week. 

[RogueWaves]

22 minutes ago, sbnwx85 said:

I hope so. Monday’s event has potential to be intense but relatively short. The best lake effect dynamics have north and east of here so far. Still lots of potential with the NW flow next week. 

Lived in S. Bend for winters of 98/99/00/01/02. Five yrs when NW LES events were non-memorable if we even had one? Ofc, super Nino '98 was the first yr with like 72F in Feb. Got Jan of '99 and it's awesome bliz and a roughly 3 wk winter. I think Nov/Dec 2000 was the best period but again, not due to any historic LES events. 

[Spartman]

[sbnwx85]

31 minutes ago, RogueWaves said:

Lived in S. Bend for winters of 98/99/00/01/02. Five yrs when NW LES events were non-memorable if we even had one? Ofc, super Nino '98 was the first yr with like 72F in Feb. Got Jan of '99 and it's awesome bliz and a roughly 3 wk winter. I think Nov/Dec 2000 was the best period but again, not due to any historic LES events. 

That ‘99 storm cemented my love of winter forever. I grew up in nearby Elkhart - just 15 miles away from South Bend. But it was far enough away from the lake that the biggest lake effect event I can remember from my childhood was around 6”. Elkhart did get a 18” lake effect event back in 2019.

[OrdIowPitMsp]

Morning low of 6F to kick off December. The urban lakes are beginning to freeze over. 

[bowtie`]

1 hour ago, OrdIowPitMsp said:

Morning low of 6F to kick off December. The urban lakes are beginning to freeze over. 

Looks like 18 this morning down here this far south. I have no idea the state of the local urban retention ponds though. I am not going out to water when it is this cold.

[Brian D]

Lows in the sd's n teens. Min's hit just after midnight then started to rise as clouds moved in overnight. Looking forward to the clipper moving through Tues. Looks like 1-3". Would get more if the center of LP swung down a little more to get E winds, but more of a WAA with W-SW winds. Time to build snowpack in town. Already 2-4" otg in the higher terrain. 

[sbnwx85]

Cloudy and cold today. A couple flurries. It was nice to see the sun yesterday. Lake effect still looking good for tomorrow. I’m thinking 5-8”+ for the Michigan counties just north of South Bend. 3-6” throughout the city seems like a good bet.

[sbnwx85]

Latest HRRR run makes me think I’m going to be under.

[Torchageddon]

Got another 20cm/7.9" since last night which is above what wun (wunderground) had for me, close to TWN. We got the heaviest snow rates of the season at 11 with the big band that was well forecast to dip south giving everyone at least 10cm within hours. Looked great with the roof drifts and heavy snow - not to mention the dark skies to the north just before we were hit as the sun came out the opposite side. We got a little sun in the aft again. I'm happy with the sun coming out more than expected. I need a sunny winter.

I suppose I'm now at 80cm/31.5" since Fri morning. I see people around my neighborhood cleaning some off their roofs. There is so much its been many years since anything that heavy as been plopped on us. I'm getting concerned.

[Chinook]

snowfall analysis, apparently updated at 00z, (and 12z) which I totally forgot about

[OrdIowPitMsp]

0.4” overnight. Nickels and Dimes this winter so far. 
 

We’ve now been below freezing for 7 days. Lakes are completely frozen over.

[Pascy619]

The past couple GFS runs have been gross. 

[sbnwx85]

Very scientifically interesting AFD from IWX this morning on the lake effect potential.

DISCUSSION... Issued at 440 AM EST Mon Dec 2 2024
Overall no major changes to the forecast thinking from yesterday. Highest confidence in 8+" remains over the eastern half of Berrien County into NW Cass. Lower confidence in warning-criteria totals for St. Joseph IN but latest hi-res suggests far northern portions of the county will get clipped with heavier rates later today. Did delay the start time for areas outside of Berrien/Cass though. Went with advisory for northern La Porte, Elkhart, and St. Joseph (MI) with the lowest confidence on the eastern side of St. Joseph (MI) and the western side of La Porte. No headlines to the south but may have to watch northern Marshall and northern Kosciusko. We will continue to fine-tune the location of the lake effect snow bands through today and some changes to headlines may still be possible.
Details below...
Morning water vapor shows robust shortwave currently diving into the Upper Midwest. Low level wind profiles will continue to slowly veer through tonight as this midlevel trough axis passes and low level lake aggregate troughing becomes better established. LES which is currently hampered by WNW fetch, dry air entrainment, low inversion heights, and overall meager instability will gradually intensify and organize through tonight. Equilibrium levels still expected to climb above 10 kft by this afternoon per latest hi-res forecast soundings. 0-2km delta theta-e values also drop below zero by this afternoon and strong ascent/supersaturation in the DGZ will promote large flakes and high (potentially over 20:1) SLR`s. Of greatest concern though is the increasing potential for meso-low formation over SE Lake MI and into Berrien County this afternoon as suggested by the latest runs of the HRRR and RAP. Already starting to see some hints of this in latest GRR radar imagery given overall weak synoptic flow becoming increasingly convergent over the eastern lake thanks to very warm lake waters/induced troughing. If this verifies...much higher snowfall totals are likely in the 18-00Z time window. Models have been mixed on whether this feature drifts far enough south to impact South Bend before dissipating but latest runs seem to be trending further south and this was the primary reason for going with a warning in St. Joseph (IN).
There may be a brief lull in activity during the evening hours before the low level flow veers further and briefly connects with Lake Superior during the late overnight hours. Even here some models are hinting at a "type-VI" (dominant single band with a meso-low on the southern end) moving down the lake in the 06-12Z period. Instability parameters remain highly favorable but final lake effect band intensity and snowfall amounts will be heavily driven by the degree to which this band can become organized. The biggest negative factor for this event continues to be the highly variable low level wind directions. Stronger synoptic flow is anticipated tonight with only a brief window of favorable down-axis fetch/Superior connection before flow quickly backs once again Tue AM. Significant questions remain if this will be enough time to allow a single band to fully develop, or if (as hi-res models suggest) it is more of a broken/transient hybrid with pockets of heavier snow and possible small-scale circulations that never fully organize into a single continuous band. Either way the chances for heavy snowfall rates to remain stationary in one particular area for a long time remain low and warrant a cautious approach to overnight snowfall totals for now. Additional changes are quite possible as we progress into tonight though.
Continued to make very few changes to the NBM-initialized long term grids. LES will end quickly late Tue AM as flow backs SW and dry conditions will persist trough most of Wed. Highs even climb above freezing on Wed with some brief but modest WAA. This will be short- lived though as another deep upper low dives into the Great Lakes Wed night and sends a strong cold front through the area. Moisture availability is not ideal but expect some SCT rain showers along the front followed but blossoming lake effect snow behind the front. Still plenty of time for adjustments but currently expect strong NW flow will bring a cold (but dry) airmass with limited fetch for significant snow accumulations. LES ends by Fri with a longer period of light WAA expected over the weekend into early next week that will return temps to seasonal norms.

[Frog Town]

12 minutes ago, Pascy619 said:

The past couple GFS runs have been gross. 

Models trying to handle the quick pattern changes form Cold-to warm-to Cold again.  Kind of have to let them go for a bit.  

[mannynyc]

First accumulating snow in Grinnell, Iowa. I didn't measure but it's probably no more than 1.5 inches. I'll take whatever we get at this point. 

[A-L-E-K]

that's a cool building^

[sbnwx85]

Someone in SW Michigan could wake up to a foot and a half of snow by tomorrow morning.

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. 

[sbnwx85]

Looking like some big bust potential on the lake-effect locally. Bands seem to be setting up more to my east. HRRR catching onto it as well. I may get shutout at home but still end up with several inches at work.

[cyclone77]

MLI/DVN both finally got their first measurable snowfall today, both with 0.4".  Picked up 0.3" here.

[RogueWaves]

1/2 inch at home. 10-15" at work. Snowy day!

[RogueWaves]

With the amt of snow OTG and not melting beforehand, this clipper brings legit shot at bliz conditions for NWMI Wed night into Thurs. I like the GEM's over all depiction

[RogueWaves]

DTX almost sounds stoked for the arctic fropa potential

Active winter pattern then sets up for the midweek period as a
deepening mid-level shortwave drops out of northern Canada into the
upper Great Lakes. Lead ascent arrives over the central Great Lakes
Wednesday morning tied to lobe(s) of vorticity preceding the main
parent trough. Forecast soundings struggle to reach saturation up
through the DGZ, instead advertising a shallow saturated layer below
800mb that resides between 0 to -8C... which could result in pockets
of light freezing drizzle during the morning-early afternoon period.
A transition to all snow becomes likely by late afternoon-evening
with the arrival of the lead cold front that brings the DGZ down
into the still shallow saturated layer. Better accumulating snow
chances arrive late evening-overnight Wednesday as the clipper
matures into a closed low somewhere near the northern Lake Huron
shoreline. The mid-level trough drives directly over SE MI during
this timeframe further supported by the level exit region of curved
jet streak at the base of the upper trough. Together these provide a
significant boost to ascent along the arctic cold front that will be
simultaneously crossing southern lower MI with forecast soundings
finally show a notable increase in saturation up to 700-650mb.
Expectation at this time is for a quick burst of accumulating snow
along the front with local probabilistic guidance showing rates
between 0.1-0.25"/hr being most favored. Fast frontal progression
limits resident time which should keep accumulations to 0.5-1.5".
That said, there is convective instability (50-100 J/kg) that
crosses the DGZ in some forecast soundings which could boost provide
a boost into higher snowfall rates.

Besides the snow potential with this clipper, wind will also be a
cause of concern. There has been a gradual shift south with the low
track within the ECWMF ENS/GEPS (trend not observed within the GEFS)
placing it over either the Georgian Bay or towards Sudbury which
leads to a tighter gradient over SE MI. Surge of arctic air results
in mixing depths increasing to >6kft tapping into these stronger
winds aloft (35-45kts) offering a chance to see wind gusts at the
surface in excess of 40mph. If trends persist with the low tracking
closer to our area, will have to monitor potential for gusts to
reach or exceed 45mph (advisory criteria).

[OrdIowPitMsp]

While this pattern is cold and dry we’ve still managed to sneak flurries/light snow out of any minuscule stratus deck. Eeked out another 0.2” of daytime mood flakes yesterday.

1.7” season to date 

[sbnwx85]

One of the bigger forecast busts we’ve had in a while. My 3”-6” call for South Bend was horrible but not as bad as NWS’ 8”. I think too much shear inland prevented the lake bands from getting into Indiana. Parts of SW Michigan did well with 10+”. On to the next one. 

[Brian D]

Clipper starting to make its presence felt here this morning with flurries. Looks like the biggest snow totals will be to my N to NE with some stout winds tomorrow. 

[sbnwx85]

That clipper should reinvigorate the lake effect machine after it passes through. Winds will be higher than previous events this week so it’ll be even more impactful in areas that have snow on the ground. I think 3-5” is a good call here with a multi-band set up covering a wider area.

[michsnowfreak]

Was perfect kicking off December on Sunday cutting down the Christmas tree with a light blanket of snow on the ground and cold winter air. Most of the snow melted yesterday with sun and mid 30s. Should see some snow tmrw night.