Pre-Christmas Storm Plains/MW/GL 12/21-12/22

[Hawkeye]

48 minutes ago, bud2380 said:

DVN Winter Storm Watch calling for 5-10".  Interesting, higher than I expected.

Given recent model runs, I can't see 10" falling around here.  5" maybe, if it does not fade any further.

[Tony]

18z ICON looking really solid for many. 

[Hoosier]

15 minutes ago, Bellona said:

LOT mentioning rivaling GHD blizzard! Wow!

It will definitely be colder than that storm. 

Winds maybe similar, with a potential exception being near the IL shore which won't really have the full benefit of onshore flow/less friction this time.

Snow amounts, well, tbd.

[bud2380]

The GFS brings that lead wave just far enough into Eastern Iowa to give us a solid hit before the main event.  That will be crucial to snow totals here.  If we can get 2-4" from the lead wave, we'll hit 6"+ for the storm.  If not, then 6" will likely be the ceiling.  

 

[winterfreak]

18z GFS is getting close to totally missing KC. Frustrating.

[Bellona]

I'll take that run of GFS!

[GDR]

Trends not good for kc at least you have the chiefs

[jcwxguy]

cutting it awfully close for us in eastern nebraska 

[BMT]

18z GFS

[bud2380]

 

Can't complain, just wish I could trust it. 

 

[winterfreak]

1.8” with kuchera. Yikes.

[Hoosier]

I'm gonna make this prediction now...

On Thursday night, there will be people around northeast IL/northwest IN worried about the "dry slot rapidly approaching."  But given the expected system evolution and slowdown, eventually that will stop progressing northeast as more snow rotates around the w/sw side of our system.

[mlgamer]

18z GFS, NAM, RDPS has me stuck at about 0.30" QPF. 18z ICON about half that. That's just not going to cut it.

I'm hoping better sampling on the 00z runs and after leads to better results.

[CentralNebWeather]

NWS Hastings disco says snow ratios will be about 20:1. 

[tStacsh]

7 minutes ago, Hoosier said:

I'm gonna make this prediction now...

On Thursday night, there will be people around northeast IL/northwest IN worried about the "dry slot rapidly approaching."  But given the expected system evolution and slowdown, eventually that will stop progressing northeast as more snow rotates around the w/sw side of our system.

I'm worried about the dry slot.   I probably won't get into any action until Friday afternoon or  night if the low passes over head.  

[Hoosier]

I wonder if RC from Amwx is lurking here.  Literally made basically the exact same post that I did in regards to snow ratios in Chicago's historic snowstorms.  

[winterfreak]

2 minutes ago, sumweatherdude said:

Regardless of how this ends up, the GFS is so inconsistent that it is essentially a POS.  It's worthless.  It may be correct for some for this specific storm.  But in general, it's inability to have any consistency means it cannot be trusted by anyone for any future storms. 

I tend to agree. 18z EURO on deck in a couple of hours.

[KCflakes]

18 minutes ago, winterfreak said:

1.8” with kuchera. Yikes.

Speechless 

[Bellona]

Gfs seems pretty similar to a lot of others. Though that in and of itself doesn't mean squat. I think 8 or so is a good call right now in wloo

[winterfreak]

EAX. Too bullish imo. I think 1-3 or 2-4 is far more likely at this point.

[OmahaSnowFan]

[OmahaSnowFan]

Quite the AFD from Omaha- everything from lasers to power outages to increasing the snowfall amounts but could go higher!

National Weather Service Omaha/Valley NE
336 PM CST Mon Dec 19 2022

...Updated Forecast Discussion...

Corrected to revert autocorrected SLRs to "lasers"... LOL.

.DISCUSSION...
Issued at 335 PM CST Mon Dec 19 2022

Key Messages:

 - Light snow is falling across much of the area this afternoon.
   Travel impacts today are expected to remain low, but some
   slippery conditions are possible on untreated surfaces. Total
   snowfall up to 1 inch is possible, especially along and south
   of I-80.

 - A winter storm is expected Wednesday night through Thursday.
   It`s impacts will continue through at least Friday. Hazardous
   pre- holiday travel expected with accumulating snow and gusty
   winds up to 50 mph to create potential blizzard or ground
   blizzard conditions. In addition, dangerously cold wind chills
   up to 35 to 50 below zero.

 - Winter Storm Watch issued for the system mid-week. A Wind Chill
   Warning issued for Wednesday night through Friday night. More
   details below.


A shortwave slowly pushing northeast through the area has produced
light snow across much of the CWA through the day today with
widespread light accumulations there. Some drizzle has been
reported further west. Current temps are within a few degrees of
freezing in the southeastern half of the CWA with numbers much
colder behind the cold front draped across the area. Norfolk is
currently at 11F and has been languishing near that number all
day. The front doesn`t make much progress south today, but is on
the move. Valley was at 25F at 2pm and 30 miles east of here the
Omaha metro was in the mid-30s. Winds are diametrically opposed
at these two locations - north here, south there.

Expect the snow to end later this evening with some lingering
drizzle. Lows range from single digits below zero north of the
Platte River and single digits above zero south of it. Wind chills
could dip as low as 20 degrees below zero in far northeastern
Nebraska with much colder conditions yet to come.

Expect dry and cold conditions on Tuesday with highs ranging from
single digits above zero along the SD state line to near 20 along
the Kansas state line.

A clipper system barrels southeast on Wednesday, bringing
significant impacts to the area and some of the worst winter
weather of the season so far in this area. Snow begins in the
northwestern portion of the CWA as early as 8am Wednesday. Expect
snow only as temps will be well below freezing until perhaps
Sunday. The first wave of snow will primarily affect the northern
tier of counties in the area with the snow eventually pouring
south as a shortwave rides the front northeast. Have increased
QPF... but maybe not as much as I could have. Decided to prevent a
wild increase in snow at this point as any changes in QPF are
exaggerated by SLR (snow to liquid ratios) of 15-20 due to the
very cold temps. SLRs could be higher and most of the guidance
suggests that it will be, but with the strong winds, expect some
fracturing of the dendrites which will lower totals.

Expect efficient snow accumulations with a few hours of 1/2" per
hour, especially south of I-80. POPs are well above 90% for most
of the area at some point on Wednesday night / Thursday with a
deep dendritic growth zone co-located with some frontogeneis. IT
IS GOING TO SNOW.

Winds will wait until after midnight to pick up with the strongest
cold air advection. The CAA will be sharp with some areas losing
10-15 degrees Celsius an hour at 850hpa. At the surface, temps
will plummet through the night and continue to slip or hold steady
through the day on Thursday. Will end up with temperatures near
records... with afternoon highs among the coolest on record.
December 1989 set the marks. Visibility is expected to be very
low. Expect them to dip under 1/4 a mile and probably produce
whiteouts at times.

Snow ends on Thursday afternoon and evening as the deepens and
sweeps northeast. With the high SLRs and increased QPF, have
increased snowfall totals to 3-6" over the western half of the area
and 5-11" over the eastern half. (These are the 25-75th
percentiles). 12" would be common in western Iowa if we met the 90th
percentile of snowfall. Areas east of a line from Sioux City to
Beatrice can expect a 60% or better chance of 6" of snow.
Points in western Iowa have a 70-80% chance of seeing 6" or more.

Have elected to keep the WINTER STORM WATCH going through Friday
evening with the expectation of winds gusting 40-50mph. Blizzard
like conditions are expected whether the snow is falling or just
laying around. The probabilistic WSSI has only a 10-20% chance of
blowing snow Thursday and Friday, but it`s hard for me to fathom
that it doesn`t create widespread travel impacts. Anyone caught in
the elements, including those who underestimated the travel
impacts, will be subjected to dangerous cold.

Ambient temps hit teens below zero Thursday night. With continued
winds of 20-30mph and gusts up to 45mph, expect wind chills as
low as 40-50 below zero. This number hasn`t been recorded in Omaha
since February 2021. It was the first time in 15 years at Omaha.
Remember February 2021`s arctic outbreak? It produced rolling
blackouts in some areas. That was due mostly to the power demands.
This time we`ll have strong winds and snow pushing powerlines
around. Friday night`s wind chills will be just as cold or colder
by a couple of degrees. Power outages are a possibility.

The Wind Chill Warning continues through Saturday morning when we
will see minor improvements in temperatures. Sunday brings an
attempt at WAA. With snow on the ground, it`ll be hard to get too
warm, but perhaps some near freezing temps can be anticipated and
a little melting.

[Hoosier]

Here's a trend loop of the GFS at 500 mb from the past bunch of runs.

Focus on the runs since 00z Mon in particular.  Notice that heights are flatter out west and our big trough/closed low has shifted farther east.

 

[Clinton]

EAX put this out today. 

Afternoon AFD

The major focus for this forecast remains the Wednesday night and
Thursday time frame, with a potent winter storm moving into the
region. A mid level trough will carve into the quasi-zonal flow by
late Wednesday and will undergo persistent deepening as it dives
further south, into the northern plains. The influence from this
trough will lag a bit behind the low level features, and that may be
the difference between a massive impact system and one that brings
high impacts albeit limited snow. The low level cyclone associated
with this trough will undergo its deepening through the day on Wed
and overnight Thursday as it glides through the southern plains,
well displaced from the mid and upper level dynamics. The strength
of the surface trough will draw relatively warm air northward for
late Wednesday night, but by the overnight hours the cold front will
be blasting southward through the area as that surface trough
continues east. The low level cyclone will undergo rapid deepening
as it departs the area, so on the backside, not only will very cold
air be pouring into the area, but winds will increase to around 30-
40 mph, with gusts to around 50 mph Thursday and Thursday night. 850
mb winds are depicted in the models increasing to around 50-60 kts,
with 925 winds increasing to 40-50 kts. While it may be unrealistic
to mix down the 60 kt H85 winds, it will be very realistic to mix
down the 40-50 kt 925 mb winds to the surface. The rapid drop in
temperatures along with the strong winds will cause wind chills to
drop to around 30 below for Thursday, into Friday morning. The wind
will also coincide with some snow as the storm will be strong enough
for some snow production. The combination of the strong winds along
with periods of moderate snow will cause visibility to be a big
concern through the day on Thursday and even overnight Friday,
despite the snow being done by Thursday evening.

Snow amounts are still very uncertain, but there is come focus on
those amounts coming into view. As the mid level dynamics of this
system become organized the progressiveness of the low level cyclone
and the blasting cold front may prevent a great coupling of those
two mechanisms. Deterministic models continue to indicate the best
organization of the mid level system more on Friday, as it ejects
into the Great Lakes region, as opposed to when it`s impacting the
local area. The mid level trough will also only have a limited
residence time over the local area, which along with the progressive
low level cyclone/cold front will limit the time of the best snow
production. So, despite the general potency of this very dynamic
system, the coupling of the best mechanisms may not come to pass
directly over the area. Expect the QPF from this system to generally
be around a quarter inch, perhaps up to a half inch, again mainly
owing to the transient period with which it will impact the area.
The air mass associated with this storm will be incredibly cold and
that will yield snow:liquid ratios around 20 to 1, perhaps more at
times. So, despite the pessimism with respect to QPF, the SLR`s
being so high may still bring a shot of getting 4 to 6 inches area
wide.

By Friday morning, the falling snow will move off to the east,
leaving the area generally dry, however, with the strong winds still
in place expect difficult traveling conditions to continue mainly
due to snow on the ground being blown around.

Bottom line, while the snow amounts from this system may not be
overly robust, the combination of the strong winds, to around 50 mph
at times, along with periods of moderate snow will bring white-out
or blizzard conditions to the area. These conditions will continue
into and through Friday, as snow on the ground will continue to blow
and reduce visibility. As such, the Winter Storm Watch will be in
effect through Friday.

[Chambana]

I’m in a tough spot here in Champaign. I’m gonna go with a 6.2” final call and the highest wind gust will be 53mph. I hope I’m not being bullish. 

[The Snowman]

Back in Chicagoland, not sure how to view this thing. A range of 4-20" seems fair for O'Hare, but of course that is of zero help for anyone trying to plan around the storm. Seems like we are in a high confidence situation of blizzard conditions thanks to winds gusting near 60 MPH, even if accumulations are comparatively light. Going to make for a hellacious pre-Christmas travel situation here.

[tbone8]

The graphic from IWX yet no watch issued...

[jcwxguy]

8 minutes ago, tbone8 said:

The graphic from IWX yet no watch issued...

too far out, maybe tomorrow afternoon shift

[jcwxguy]

[Grizzcoat]

[Grizzcoat]

[Hoosier]

27 minutes ago, Chambana said:

I’m in a tough spot here in Champaign. I’m gonna go with a 6.2” final call and the highest wind gust will be 53mph. I hope I’m not being bullish. 

That should be pretty doable imo.  Hopefully more.

Totals should ramp up pretty quickly as you go north from your area.  I'd actually almost lock in 12-18" (locally higher?) in northeast IL/northwest IN etc but not quite total confidence yet.

[Grizzcoat]

wider shot of 18Z euro-

[Chambana]

6 minutes ago, Hoosier said:

That should be pretty doable imo.  Hopefully more.

Totals should ramp up pretty quickly as you go north from your area.  I'd actually almost lock in 12-18" (locally higher?) in northeast IL/northwest IN etc but not quite total confidence yet.

you are looking golden my friend. Interesting to see what the NAM has when it gets in more reliable range. Fingers crossed we achieve blizzard criteria. 

[Niko]

On 12/18/2022 at 1:45 PM, jaster220 said:

Haha, I need a positive trend too amigo (noticeably absent is @Niko)

Overnight pre-18/12z worse runs for DTX, but their write-up is very well done. Worth reading for those in The Mitt.

Attention over the coming days will remain fixed upon the storm
system that is forecasted to impact the upper Midwest/Great Lakes
region during the holiday travel period of the 12/21 - 12 /23.
Attention will also be given to the arctic cold over the Christmas
holiday 12/24 - 12/26. With no real surprises or drastic changes
amongst the 18.00Z deterministic solutions, confidence is rapidly
increasing in a significant winter storm system impacting portion(s)
of the state during the middle to end of the week. Important to
stress here at the outset that given the envelope of potential
solutions, especially the well organized/relatively warm occlusion
in the control run of the ECMWF, details (i.e...precipitation type,
precipitation rate, precipitation amounts, high wind potential) will
absolutely matter and very much determine what sensible weather
impacts Southeast Michigan and your particular backyard will
observe. So while confidence is now reasonably high that impactful
weather will occur over Southeast Michigan (no real null case to be
found in the NWP), whether or not the cwa will take a direct hit
remains unknown at this time. So rather than provide a discussion on
precipitation type and amounts for a Day 5 and Day 6 system, would
like to offer one on the predictability of the system and the
differences between the GFS deterministic and ECMWF/Canadian GEM
solutions.

Great model agreement exists that a strong +175 upper level jet
packet will carve/dig into the Northwest United States Tuesday and
Wednesday. Very obvious and noteworthy in how well this jet exit
region is linked to and in tandem with Potential Vorticity trough
axis over northern Canada shortly after it arrives. Models then show
a significant portion of the PV reservoir being drawn into and
phasing into the basal portion of the trough as the upper level jet
digs into the central United States. The first big difference
between the ECMWF and GFS solutions is how fast/progressive the left
exit region dynamics remains. The ECMWF is the faster of the two
solution camps with the exit region pushing across all of Arkansas
and into Tennessee by 18Z Thursday. The GFS solution is slower and
less progressive still digging across the OK panhandle at the same
time 18Z Thursday. The big thing to note in the ECMWF is just how
well the wavelengths of the left exit region and the whole western
half of the Canadian PV reservoir match up. This allows for a much
more negative tilt, earlier, and very rapid phasing/deepening low
pressure system over portions of IN Thursday night. The net result
there is an almost instant occlusion over Southeast Michigan which
preserves just enough of the preceding mild and warm air at the
surface to really factor in on precipitation types. The GFS is
slower with the jet exit region, allows for greatest low deepening
rates over Ohio and brings more of a classic snow track for
Southeast Michigan through central Ohio. Interestingly enough, the
Canadian GEM shows more similarities to the ECMWF with the
orphaned occlusion, but is a compromise thermally to the colder GFS.

So until the timing of this jet exit region gets resolved, there
will remain uncertainty to the details of the event. From the 17.12Z
GEFS data, 41% percent of the variability at Day 5 could be
explained by the timing of the trough/ridge couplet. As a note, EOF1
of 24 hour mean 500 height was showing a dipole mean height
difference of some 100m. One usually does not see a magnitude this
great in this technique. Given this mean height anomaly difference,
its going to take a few ensemble cycles/days to improve confidence
on forecast timing. The upper level jet exit region of particular
interest is not forecasted to push onshore of the PACNW until 00Z
Wednesday. Cluster phase space actually showed a better than usual
integration at Day 5 of the CMCE/GEFS/EPS, but need to stress
separation does exist between GEFS and EPS. Cant say with any
certainty which of the solution camps or timing is going to verify,
however, will say its difficult to imagine the phasing of the large
PV reservoir and cyclonically curved jet exit region occurring as
cleanly as these ECMWF solutions have been.

The bottom line is its way too early to provide a discussion on
precipitation type and amounts. Again with no null case in the
deterministic solutions, measurable amounts amongst virtually all of
the EPS members and a majority of the GEFS, its difficult to
envision a failure point to a regional winter storm system. Of
particular interest in the upcoming data is what the high wind
potential will be. The combination of very strong kinematic fields
with a fresh arctic cold air mass is a recipe for a high impact wind
event. The combination of very strong winds with falling snow could
make travel virtually impossible for some part(s) of the region in
the lead up to the holiday. Any power outages ahead of the projected
cold next weekend would be very tough.

Sorry amigo..I was extremely busy! I have to do major catch-up on all of this on here and see where we at. Too many pages (LOL) ,so I will definitely not read the thread, but maybe the last 2 pages or so.

[Grizzcoat]

Winter Storm Warning

---

URGENT - WINTER WEATHER MESSAGE
National Weather Service Honolulu HI
331 AM HST Mon Dec 19 2022

...WINTER STORM WARNING IN EFFECT THROUGH 6 AM HST TUESDAY..

HIZ028-200245-
/O.CON.PHFO.WS.W.0002.000000T0000Z-221220T1600Z/
Big Island Summits-
331 AM HST Mon Dec 19 2022

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM HST
TUESDAY...

* WHAT...Heavy snow and blowing snow. Blizzard-like conditions
  possible. Additional snow accumulations of up to 8 inches. Winds
  gusting as high as 100 mph.

* WHERE...Big Island Summits above 10,500 feet elevation.

* WHEN...Until 6 AM HST Tuesday.

* IMPACTS...Travel could be very difficult to impossible.
  Blowing snow will significantly reduce visibility at times,
  with periods of zero visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning means significant amounts of snow, sleet,
and ice are expected or occurring. Strong winds are also
possible. This will make travel very hazardous or impossible. Any
travel plans to the summits should be postponed until the threat
diminishes.

&&

$$

[Niko]

So...is this possible, WOW!

This low is still 3 days away, a lot of changes can be expected.  If I end up seeing a blizzard here in the Midwest, it will be my first time y'all. I usually see them on the EC. Looking forward to this storm.

[gosaints]

1 minute ago, Grizzcoat said:

Winter Storm Warning

---

URGENT - WINTER WEATHER MESSAGE
National Weather Service Honolulu HI
331 AM HST Mon Dec 19 2022

...WINTER STORM WARNING IN EFFECT THROUGH 6 AM HST TUESDAY..

HIZ028-200245-
/O.CON.PHFO.WS.W.0002.000000T0000Z-221220T1600Z/
Big Island Summits-
331 AM HST Mon Dec 19 2022

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM HST
TUESDAY...

* WHAT...Heavy snow and blowing snow. Blizzard-like conditions
  possible. Additional snow accumulations of up to 8 inches. Winds
  gusting as high as 100 mph.

* WHERE...Big Island Summits above 10,500 feet elevation.

* WHEN...Until 6 AM HST Tuesday.

* IMPACTS...Travel could be very difficult to impossible.
  Blowing snow will significantly reduce visibility at times,
  with periods of zero visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning means significant amounts of snow, sleet,
and ice are expected or occurring. Strong winds are also
possible. This will make travel very hazardous or impossible. Any
travel plans to the summits should be postponed until the threat
diminishes.

&&

$$

Was checking this out earlier today. Kona low right?  The big island has the coolest microclimates

[Niko]

NOAA:

Nice write -up - They think somebody here in S MI could see 10"+. Impressive!!!

Explosive development/bombogenesis to take place Thursday-
Friday as 1002-1007 MB surface low ejects out of Southern-Central
Mississippi River Valley and deepens toward 970 MB with the low
pushing into the Central Great lakes by Thursday night. There is
conflicting data/uncertainty with the influence of the Great Lakes
on the low pressure center(s), as a large elongated area of low
pressure develops, with possible double barrel lows stretched across
the Great Lakes region, which leads to timing issues with the wind
pop surging into southeast Michigan. Just utilizing the 06z euro
ensemble mean, peak wind gusts around 50 MPH Friday
afternoon/evening, with just a slow unwinding of the low/wind
speeds as we head into Christmas eve. Certainly a lot of members
indicating 55-60 mph peak gusts, with just a select handful
above 60 MPH. With operational run indicating 850 MB of 75 knots,
the potential scorpion/sting jet will bring the risk of damaging
wind gusts, which unfortunately would lead to tree damage and power
outages. Still uncertain if this feature will directly hit us
however, could end up south of the border which is the direction
the 12z euro came in with. Regardless, prolonged wind
gusts in excess of 45 mph appear likely.  Arctic air spilling in
as we head into Christmas could make for a life threatening
situation if any power outages take greater than 24 hours to
restore. Frozen pipes could become a concern as well for the less
than energy efficient homes as temperatures likely fall into the
single numbers, but Lake Michigan should provide a good buffer from
temps getting much colder/worst. On the flip side, Lake Michigan
will not be doing us any favors with the deformation snow and Lake
enhancement on the backside of this storm system. So, even with the
Gulf and Atlantic moisture arching in (specific humidity of 3 g/kg
at 700 MB) on Friday and exiting/lifting north-northeast, 850
MB temps of -20 C and strong westerly winds will likely be conducive
to snow squalls/white-out conditions into Christmas Eve with the
prolonged cyclonic flow persisting into Christmas day likely
producing lingering scattered light snow showers/flurries as well.
Still way too early to project snowfall amounts, but even if one
assumes the warm conveyor/trowal development on Thursday/Thursday
evening will be a cold rain (max temp in profile reaches 4 C) or
perhaps a little sleet/freezing rain, suspect the post low
deformation and Lake enhancement will be supportive of snow
accumulations in excess of 5 inches, assuring a white Christmas. A
double digit snowfall total is still in play for parts of southern
Lower Michigan as well, stay tuned.

[gosaints]

2 hours ago, Hoosier said:

I'm gonna make this prediction now...

On Thursday night, there will be people around northeast IL/northwest IN worried about the "dry slot rapidly approaching."  But given the expected system evolution and slowdown, eventually that will stop progressing northeast as more snow rotates around the w/sw side of our system.

Still so many hours out from the 2nd part of the storm wrapping up.  And that piece of energy just parks off the Pacific coast the next 24 hours