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2/21 - 2/22 MW/GL's System


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12z UK.... bizarrely weak, major outlier.

sn10_acc.us_mw.png

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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12z Euro

sn10_acc.us_mw.png

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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00z HRRR

snku_acc.us_mw.png

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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00z NAM/3kNAM.... they like the north band.

snku_acc.us_mw.png

snku_acc.us_mw.png

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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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00z RDPS

snku_acc.us_mw.png

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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00z GFS/GFSv16

snku_acc.us_mw.png

snku_acc.us_mw.png

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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00z GDPS

snku_acc.us_mw.png

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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00z UK

sn10_acc.us_mw.png

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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00z Euro

sn10_acc.us_mw.png

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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RAP pounds (for this system at least) W.IA and mby--- and would put some of those locations just W of DSM very near 5' for the season.snku_acc.conus.png

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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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3KM going nuts also. Would be sweet if this Warm air advection  event turns into a warning. Many people will be totally caught off guard. snku_acc.us_mw.png

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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DMX- thought about issuing warnings- but doesn't exactly know where heaviest bands will set up. Says areas of 3-5" will likely see pockets of 6-7".

#ontheroadto72"
.DISCUSSION.../Today through Saturday/
Issued at 358 AM CST Sun Feb 21 2021

Today:

Long-wave trough that been developing over the western CONUS is
beginning to split into two separate short-wave features with the
first jet streak ejecting into the central Plains, and the second
moving from the Four Corners Region into the Texas and Oklahoma
Panhandles. The northern jet streak and associated vorticity maxima
has resulted in surface lee cyclogenesis in the last 12-18 hours and
has phased well, allowing the surface cyclone to deepen. Ahead of
the cyclone, stronger WAA has been ongoing between the Missouri
River Valley and Mississippi River Valley, and isentropic ascent
will continue to strengthen this morning. With H5 height falls
ongoing across the forecast area, expect snow showers to begin
developing and expanding across western Iowa after 4am or so, being
aided by the isentropic ascent. As of 3am CST the OAX radar is
already showing snow shower activity in eastern Nebraska. Still
expecting the area with greatest snowfall accumulations to be along
the Interstate 80 corridor and northward, then eventually dropping
off north of Hwy. 18. There is a still a decent amount of
uncertainty for precipitation south of Interstate 80.

First, a discussion in the area with greater confidence in
accumulating snow. This area will be along a line from Atlantic
northeast to Ames to Waterloo. From a sounding perspective, snow
will be the dominant precipitation type as the DGZ remains saturated,
and the layer below maintains a RH above 85 percent with
temperatures below freezing. Along and north of Interstate 80, there
is no indication of a warm-nose above freezing. Further, there is
also decent lift through the DGZ in this area, with omega ranging
between -8 to -15. Interestingly, the 00z deterministic GFS/NAM do
not depict overly robust frontogenetical processes within the
deformation zone, as the surface cyclone center moves along the IA-
MO border. With the strength of this short-wave and synoptic
forcing, typically would expect there to be stronger frontogenesis.
00z deterministic ECMWF is similar. However, several of the 00z CAMs
do have a band of stronger frontogenesis around 750mb from Atlantic
to Waterloo. The HRRR for example produces multiple pockets of 6 to
7 inches within the wider swath of 4 to 6 inches along and north of
Interstate 80. Further, multiple members of the 00z GEFS also hint
at a wide swath of 4 to 6 inches, with pockets of 6 to 7 inches. The
00z HREF mean remains consistent with this swath of 4 to 6 and max
values of 6 to 7. Given the strength of the synoptic system, the
CAMs stronger frontogenesis bands within the deformation zone of the
cyclone are credible, and therefore a reasonable solution. However
while they have the general swath of heavier snow accumulations, the
HRRR, NSSL WRF, NAM Nest, and other CAMs are not in complete
agreement with where localized amounts of 6 to 7 inches may occur.
Because snowfall amounts of 6 to 7 inches will be isolated and
likely spaced apart by up to 30 miles in some instances, will
continue to just maintain the Winter Weather Advisory for today.
Trying to capture the locally higher amounts with a Winter Storm
Warning would result in an unnecessarily large warning with respect
to the areal extent of it. Instead, will simply highlight that the
areas forecast to have 3 to 5 inches could see a few pockets of 6 to
7 inches.
12z-18z will be the time of highest snowfall rates for
west-central and central Iowa, as HREF mean points to rates between
0.75-1.00 inch per hour.

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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Latest HRRR going bonkers in C.IA - and we are only talking 7-8-9 hours out--- keep increasing!!!   qpf_acc.us_mw.pngsn10_acc.us_mw.png

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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It's too bad that bulls-eye can't extend eastward into eastern Iowa.  3" would still be good, though.

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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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12z NAM/3kNAM

snku_acc.us_mw.png

snku_acc.us_mw.png

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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Winter Storm Warning

URGENT - WINTER WEATHER MESSAGE

National Weather Service Omaha/Valley NE

842 AM CST Sun Feb 21 2021

 

IAZ043-055-056-069-079-NEZ034-045-052-053-212245-

/O.UPG.KOAX.WW.Y.0012.000000T0000Z-210222T0000Z/

/O.NEW.KOAX.WS.W.0003.210221T1442Z-210222T0000Z/

Monona-Harrison-Shelby-Pottawattamie-Mills-Burt-Washington-

Douglas-Sarpy-

Including the cities of Onawa, Mapleton, Missouri Valley,

Woodbine, Logan, Dunlap, Harlan, Council Bluffs, Glenwood,

Tekamah, Oakland, Lyons, Decatur, Blair, Omaha, Bellevue,

Papillion, and La Vista

842 AM CST Sun Feb 21 2021

 

...WINTER STORM WARNING IN EFFECT UNTIL 6 PM CST THIS EVENING...

 

* WHAT...Heavy snow. Total snow accumulations of 4 to 8 inches.

 

* WHERE...Portions of east central Nebraska and southwest and

  west central Iowa.

 

* WHEN...Until 6 PM CST this evening.

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12z RDPS

snku_acc.us_mw.png

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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Not very good dendrites here for accumulation. Maybe an inch thus far but going to be hard pressed to get 3" out of this unless something changes. The warning I believe is mainly for areas just to my NW and N. Still time, but not looking like warning material 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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12z GFS/GFSv16/GDPS.... yes, we're into nowcast range, but after days of tracking it's nice to know each model's final prediction.

I think every model has 2.5-3.5" for Cedar Rapids.

snku_acc.us_mw.png

snku_acc.us_mw.png

snku_acc.us_mw.png

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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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  • Tom unpinned this topic

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