DECEMBER 2023 Observations and Discussion

[Grizzcoat]

LET's GO!!!   Will almost certainly be above avg temps for the first 10 days for most reading but it does look rather active. After the 12-13th-- things get more interesting as we head into the Holidays' with much more potential for below normal temps compared to the opening 10days.

Let's discuss.

System for Fri night into Saturday is getting more interesting for much of IA.

[Madtown]

Rink building has started....please keep that warm air away!

[bud2380]

Surprise storm to start out the month?  GFS really trending towards a snowy start here in Iowa.  Let's see if the other models latch on.  

[bud2380]

UK looking like it has a similar idea.

 

[bud2380]

Canadian as well.

 

[Minny_Weather]

I arrive to my new home in Alexandria on the 12th. I'd actually love some above average temps to help me ease into it lol

[Hoosier]

Euro has been creeping north with the first system late Thursday and Friday.  

Could get cold enough for a band of wet snow on northern fringe.  Worth keeping an eye on.

[Tony]

40 minutes ago, Hoosier said:

Euro has been creeping north with the first system late Thursday and Friday.  

Could get cold enough for a band of wet snow on northern fringe.  Worth keeping an eye on.

18z NAM looking more juiced and slightly north as well.

[Iceresistance]

How is "December" all caps?

[Hoosier]

34 minutes ago, Tony said:

18z NAM looking more juiced and slightly north as well.

Just saw it.  lol I think that's probably overdone given the marginal setup, but I think there should be enough cooling to flip to snow.

[Hoosier]

41 minutes ago, Tony said:

18z NAM looking more juiced and slightly north as well.

Would add that the area near the IL shore may have trouble with the onshore flow and lake temps running well into the 40s, especially farther out from shore.  Would probably be non-accumulating snow near shore if it does snow.

[bud2380]

18z GFS for the Friday evening/Saturday AM system.

 

[Clinton]

All global models have a wet storm ejecting from the 4 corners and 3 more waves of energy in the next 7 days.  Should we start a thread for this active stretch?

[Timmy Supercell]

2 hours ago, Iceresistance said:

How is "December" all caps?

Cuz it's about time December earns its keep around here.

[Niko]

Not bad at all......keep hope alive......6"+ for Metro Dtw!! Near 5"or so for my area.

 

 

[mlgamer]

00z NAM moving the snow off of me to the north. Such is life on the rain/snow line...

[Minny_Weather]

1 hour ago, Niko said:

Not bad at all......keep hope alive......6"+ for Metro Dtw!! Near 5"or so for my area.

 

 

So many people outside of a 10 mile wide band are going to be pissed

[OttumwaSnomow]

Like JB used to say "heck of a way to ruin a warm up"!!

[Clinton]

No snow coming for mby but some much needed rainfall looks imminent and I will gladly except that. 0z GFS

[gimmesnow]

16 hours ago, Iceresistance said:

How is "December" all caps?

Hopefully it's a sign the second half of the month will be LEGENDARY

[Tom]

12z NAM...

[Tom]

Don't forget about the 4 corners...what a fantastic start to the ski season out here...one of my bucket lists for this season will be Taos, NM...this year's LRC pattern is GOLDEN for this region.  Arizona is sorta in the transient location where we will likely see warm ups while just to my N and E the storm track will ride up and over the SW ridge.

[FV-Mike]

57 minutes ago, Tom said:

12z NAM...

Like the wording from LOT

expectations are for a widespread precip
event across a vast majority of the forecast area Thursday night
and Friday morning. Precip type will be rain south of a Chicago to
Mendota line, with increasing chances for a transition to all
snow from north of Dixon to McHenry County. Where the cutoff in
the precip shield settles is a looming big question that will have
implications with how much (if any) accumulating snow occurs into
the northwest third of the CWA. Given the increasing signal in
guidance (especially EPS and CMCens) for accumulating snow and the
factors noted above, have increased snow probs with some minor
accumulations (<1") in the forecast late Thursday night into
Friday morning. While still a lower (~20%) chance exists for
several inches of accumulating snow in the aforementioned area,
this solution is no longer an outlier within the broader ensemble
of guidance. This is especially the case if the low-level
baroclinic zones further contracts and supports a band of f-gen in
a dynamically cooled thermal profile.

 

[Tom]

11 minutes ago, FV-Mike said:

Like the wording from LOT

expectations are for a widespread precip
event across a vast majority of the forecast area Thursday night
and Friday morning. Precip type will be rain south of a Chicago to
Mendota line, with increasing chances for a transition to all
snow from north of Dixon to McHenry County. Where the cutoff in
the precip shield settles is a looming big question that will have
implications with how much (if any) accumulating snow occurs into
the northwest third of the CWA. Given the increasing signal in
guidance (especially EPS and CMCens) for accumulating snow and the
factors noted above, have increased snow probs with some minor
accumulations (<1") in the forecast late Thursday night into
Friday morning. While still a lower (~20%) chance exists for
several inches of accumulating snow in the aforementioned area,
this solution is no longer an outlier within the broader ensemble
of guidance. This is especially the case if the low-level
baroclinic zones further contracts and supports a band of f-gen in
a dynamically cooled thermal profile.

 

This system snuck up I'm sure for a lot of met's who prob were discounting the snowy solution.  Good luck!  If a couple inches of snow fall, this would really be a fast start to Chicago's snow season.

[Hawkeye]

An early RRFS prediction.

[WinterSquall23]

14 hours ago, Niko said:

Not bad at all......keep hope alive......6"+ for Metro Dtw!! Near 5"or so for my area.

 

 

 

13 hours ago, Minny_Weather said:

So many people outside of a 10 mile wide band are going to be pissed

 Close enough to drive wherever this sets up.  Mby , looks to be the battleground area again at least for now.  Not much room for error . 

[bud2380]

The GFS has been extremely persistent about a secondary band of snow following the main precip maker.

6pm Friday would be a winter wonderland in my back yard.  2-3" if the GFS pans out.  Extremely narrow band that I'm right in the crosshairs of somehow. 

 

 

 

 

[bud2380]

Canadian is eerily similar to the GFS

 

[bud2380]

Ukie basically the same as well.

 

[Madtown]

I dunno. All I see on all three major models is warm air all the way up into Saskatchewan and Manitoba through the 15th and beyond. Upper 40's to near 50 in a ton of places. No real storms outside of a narrow band of snow here or there. What was a its gonna cool down early maybe mid December hopefully will happen by Jan maybe. Out around town today and everyone is starting to get a little worries on if winter ($$$) will show. Here's hoping, I just don't see it atm.

[bud2380]

Euro has the same idea Friday evening, just further south than the other models and weaker.

 

[bud2380]

Any snow we do get won't stick around too long.  Euro still advertising the major warmup in the extended.

 

[bud2380]

Could have a Nor'easter early next week as well.  Not overly impressive by nor'easter standards, but not bad. 

 

 

[bud2380]

SREF Mean

[Iceresistance]

2 hours ago, bud2380 said:

Any snow we do get won't stick around too long.  Euro still advertising the major warmup in the extended.

 

And before you know it, it's nasty cold by either Mid-December or Christmas!

Trust me

[Niko]

This from NOAA:

Note: As of right now, it looks like my area could be in for a couple of inches of snowfall per NOAA.

Attention then turns to a southern stream mid/upper level wave that
will be ejecting out of the Desert southwest Thursday morning.
Partial phasing between the northern and southern streams over the
eastern CONUS results in this shortwave tracking northeasterly
across the southern Midwest and eventually into the Ohio
Valley/southern Great Lakes by early Friday morning. In advance of
this system, a weak northern stream cold front tied to a shearing
shortwave over northern Ontario is progged to drop into the central
Great Lakes overnight Thursday. Little to no precip, at least
initially, is expected along this frontal boundary given the
geographic detachment from parent vorticity. This changes Friday
morning with the arrival of the southern wave and subsequent better
moisture quality (PW increasing to 0.5-0.75in) as well as
strengthening synoptic ascent. This boundary, which looks to being
residing south of I-69 if not south if M-59 by this time, provides
an early focal point for enhanced forced lift offering a period of
light showers in advance of the main system isentropic ascent. Said
ascent then overspreads the region through the remainder of Friday
morning/afternoon. General trends amongst both deterministic and
ensembles has been for a more northerly track providing precip
across the vast majority if not all of SE MI. Only the far northern
Thumb/Saginaw Valley currently look to have any shot at missing
precipitation however though chances are trending lower.

Primary area of uncertainty wrt to this system remains on the
thermodynamic side of things given the numerous moving parts in
play. First is how far north warm air advection reaches into SE MI
which is highly dependent on the track of the mid-level wave. The
second factor is unfavorable diurnal timing (for snow) as the bulk
of QPF is expected during the daylight hours Friday. That said with
dewpoints in the lower 30s for areas north of M-59, there is the
potential for evaporative cooling during the peak precip rates
Friday afternoon to offset diurnal heating and support a shallow
enough warm layer or a complete aob freezing column to transition to
all snow. Lower ratio (solidly sub 10:1) snow would be favored in
this scenario cutting down of max potential snowfall amounts.
Additionally with the milder day Thursday and marginal freezing
temps Friday, accumulation potentials on pavement would be further
reduced likely having to rely on enhanced snowfall rates to overcome
melting. Based on 12Z trends/consistency amongst the ECMWF emsemble
family and deterministic as well as the NAM, areas north of M-59
looking to have the best shot at seeing accumulating snowfall Friday
with areas to the south having a better chance to stay all rain or a
rain-snow/melting snow mix.

[Hoosier]

3 hours ago, bud2380 said:

Any snow we do get won't stick around too long.  Euro still advertising the major warmup in the extended.

 

Just gotta get through that warm stretch and resist any cliff jumping temptation.  It looks like a month that has a good chance to finish warmer than average for a sizable part of the US, but I don't see the whole month being a torchy disaster.

[Clinton]

The MJO is going to do a quick tour of the warm phases, but I like where its going by mid month.  

The BOMM was the first to pick up on the low amplitude warm phase its also more progressive than the GEFS, it has us in phase 7 by the 7th.

[Timmy Supercell]

4 hours ago, bud2380 said:

Any snow we do get won't stick around too long.  Euro still advertising the major warmup in the extended.

 

If we get that, I wouldn't mind another t'storm before the next round of winter. 

[Stacsh]

Woah, surprise. My local forecast office is signaling possible heavy snow on this one on the north side now.   Major change from thinking earlier.    Surprise mini snowstorm?   Stay tuned.