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December 11-13th MW/GL Snowstorm


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It's interesting the Kuchera ratios on the Euro are higher than 10:1 while every other model has Kuchera ratios less than 10:1 with this storm.  We'll see what pans out.  Personally, I think it will end up around 10:1 which it seems to more times than not.  

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Season Snowfall: 0.00"

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1 minute ago, bud2380 said:

It's interesting the Kuchera ratios on the Euro are higher than 10:1 while every other model has Kuchera ratios less than 10:1 with this storm.  We'll see what pans out.  Personally, I think it will end up around 10:1 which it seems to more times than not.  

This was from hastings this morning mentioning the ratios in our CWA

 

So far this morning the highest snowfall totals of 2-3" were
reported in the Cambridge, Wilsonville, Kearney and Minden areas,
with varying liquid to snow ratios from 13:1 to 30:1.
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3 minutes ago, gabel23 said:

This was from hastings this morning mentioning the ratios in our CWA

 


So far this morning the highest snowfall totals of 2-3" were
reported in the Cambridge, Wilsonville, Kearney and Minden areas,
with varying liquid to snow ratios from 13:1 to 30:1.

Thanks for sharing.  Good sign.  

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Season Snowfall: 0.00"

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Update by OAX, pockets of 6-7" is possible! 

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL NOON CST
SATURDAY...

* WHAT...Snow. Total snow accumulations of 2 to 5 inches with
  localized areas of 6 to 7 inches expected.

* WHERE...Portions of east central, northeast and southeast
  Nebraska and southwest Iowa.

* WHEN...Until noon CST Saturday.
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Definitely concerned about temps, not as warm as GFS so far, but not as cool as NAM/Euro. I'm supposed to get off work at 8 (serving) but it'll probably be slow af tonight so I'll probably get cut earlier. Hopefully I walk out to snow already on the ground

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Snowfall in Lincoln, NE:

2017-18: 21.4"  

2018-19: 55.5"   

2019-20: 17.6"   

2020-21: 49.4" 

Average: 25.9"

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WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 6 AM CST SATURDAY... * WHAT...Snow expected. Additional snow accumulations of 1 to 3 inches with locally higher amounts possible. * WHERE...Portions of central, east central and south central Nebraska. * WHEN...Until 6 AM CST Saturday. * IMPACTS...Plan on slippery road conditions. The hazardous conditions could impact the evening commute. * WIND...North winds with sustained speeds near 15 MPH and gusts to around 25 MPH are forecast. This may result in minor blowing snow and temporary visibility restrictions. * ADDITIONAL DETAILS...The heaviest snow is expected to reside either side of the Interstate 80 corridor. Travel may be difficult at times due to bands of snow and reduced visibility.

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53 minutes ago, snowstorm83 said:

Definitely concerned about temps, not as warm as GFS so far, but not as cool as NAM/Euro. I'm supposed to get off work at 8 (serving) but it'll probably be slow af tonight so I'll probably get cut earlier. Hopefully I walk out to snow already on the ground

Pretty much every forecast I have seen didn't have any accumulations before 3pm, so the main show is still ahead of us... well hopefully. Once this rain/sleet mix changes over and the temps drop as night falls we shouldn't have too many issues seeing snow accumulate.

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6 minutes ago, bud2380 said:

The problem with the HRRR is it's showing about 2" by 10pm in CR & IC and I just don't see that happening at all.  So I'd just subtract that out entirely from the results.  

Same here in C.IA. Both HRRR and RAP are initializing badly. Several hours early with transistion to snow. At least here.

The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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Good AFD by DMX--- they too mention a later change than what CAM's are showing. But overall- a good setup for many. Also mention enhanced totals in NE IA for those peeps...

Area Forecast Discussion
National Weather Service Des Moines IA
404 PM CST Fri Dec 11 2020

.DISCUSSION.../Tonight through Friday/
Issued at 404 PM CST Fri Dec 11 2020

Synoptic and Meso Features:

Main focus will be on the deformation zone developing over central
Iowa this afternoon and evening with accumulating precipitation.
Strong short-wave trough has developed negative tilt, with the axis
extending from the Colorado Front Range to the Texas Gulf Coast. The
strong CVA associated with the jet streak with this short-wave is
phasing well with the surface cyclone, and the cyclone has continued
to deepen this afternoon. The surface cyclone center will stay south
of Iowa, but is on a northeast track as the jet stream begins to
round the base. Within the deformation zone, there is quite a bit to
look at. Analyzing frontogenesis fields, both synoptic scale models
and CAMs show a strong ribbon that starts near Atlantic and moves
ESE through the DSM Metro into east-central Iowa. This is largely
concentrated between the H85 and H7 levels, though there are hints
of more forcing around 925mb as well. This will move through between
now and 12z Saturday. After 6z another area of enhanced
frontogenesis develops near CID, but most of this becomes focused
east of the forecast area, but will result in heavier snow for
portions of eastern and northeast Iowa through Saturday Morning.
These same areas are also characterized by moderate to strong Q-
vector convergence, which makes sense with strong jet streak and
associated kinematic reactions. Delving into model soundings, cloud-
ice does not appear to be hard to come by for counties in Iowa
mainly south of U.S. Hwy 20 to around  U.S. Hwy. 34. With ice
introduction, this leaves rain, rain-snow mix, or pure snow the
viable precipitation type for this event. There may be a brief
period of other wintry mixes, but overnight will transition to all
snow. Temperatures will largely drive rain vs. snow this evening.
Temperatures late this afternoon will remain near 35-36F, but should
see some amount of cooling within the precipitation shield heading
into the evening. By 06z, with temperatures between 32-34F and
dewpoints closer to 30-31F, wetbulb temperatures should be near 32F
and thus is when snow is expected to take over. One quick note about
areas along and north of Hwy. 18, there does appear to be some
strong frontogenesis that is starting but cross-section and vertical
sounding analysis show a very dry layer above the surface, thus
northern Iowa will be missing out on most of this precipitation
event.


Snow Amounts and Model Guidance Comparison:

The bottom line up front, CAMs has been much more robust with
respect to total snow then some of the synoptic models. However,
both have the greatest snow accumulations along a line from near Red
Oak, IA (south of Council Bluffs) through Des Moines to
Marshalltown, with decreasing amounts then northwest of this line
and southeast of it. This area is highlighted by the current Winter
Weather Advisory. The differences, is the 12z HREF mean values have
4-6 inches within this band and localized pockets of 8-10 inches. In
the 12z GEFS members, greatest amounts were 2-4 inches, and do not
necessarily have the localized heavy amounts, but this is likely due
to the coarse resolution. In a brief discussion with WPC, it was
noted that several of the GEFS members were warm with respect to
temperatures, and as a result was turning it into liquid rain for an
extended period of time, while CAMs depicted a slightly quicker
change to snow. Given the strong frontogenesis, as well as strong
omega profiles through the DGZ, it is anticipated that there will be
enough forcing to overcome a lot of these challenges presented by
the warmer temperatures in the area of greatest accumulations.
Therefore, will have a snowfall forecast that lies in between the
HREF and GEFS members, but certainly could see some locally higher
amounts where frontogenesis is strong. The warmer temperatures and
melting are the reason to not go nearly as high as the 12z HREF
mean, but the frontogenesis and lift through the DGZ justifies being
higher than GEFS mean, and even the 12z deterministic GFS for that
matter. Other considerations with this will be snowfall rate. 12z
HREF was not overly robust with this, greatest 1 hr snowfall rates
only reach about half an inch per hour. With the high moisture
content, visibility could still drop to around 1 mile as the column
saturates. With wind gusts only forecast up to 25 MPH, blowing snow
is not expected to be a big issue.
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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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I guess not really concerned as I was about this rain being shown as snow in few hours which is not happening. Never was supposed. The defo band is what counts. Good Luck to all the winter weather weanies!!!

The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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Bud, I don't expect any accumulation here til after midnight.  It's good that it's changing over to snow in Dubuque.  It has to change there before here.

season snowfall: 52.5"

 

'19-20: 36.2"      '18-19: 50.2"      '17-18: 39.5"      '16-17: 17.9"      '15-16: 20.0"      '14-15: 30.4"      '13-14: 48.3"      '12-13: 34.1"

 

Average snowfall: ~30"

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Most models put my backyard right on the wrong side of the cutoff. Quite a consensus for that, so it is probably correct. 

Gonna go with 1.5" in downtown IC and 4.5" in Hiawatha.

2020-21 Snowfall: (Hiawatha)

TOTAL: 51.6"

(Oct. 18: 0.6") (Oct 19: 2.0") (Nov. ?: 1.5") (Dec. 12: 3.7") (Dec. 23: 0.5") (Dec. 27: 1.2") (Dec. 29: 9.2") (Jan. 15: 2.3”) (Jan 17. 1.1”)  (Jan. 24: 2.5”) (Jan. 26: 6.8") (Jan. 31: 8.5") (Feb. 4: 5.0") (Feb. 6: 0.5") (Feb. 8: 1.0") (Feb. 11: 1.2") (Feb. 13: 1.3") (Feb. 21: 2.7")

 

 

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