Northern Plains Blizzard 11/27/-11/28

It looks like eastern CO may finally get its first major snowstorm of the season Sunday into Monday :D , and it could be a real nasty one, at that.
From the CPC Hazardous Weather Assesment:
A strong storm is expected to hit the southern Alaska Panhandle and Pacific Northwest coast, while another cyclone intensifies over the southern Great Plains. This system is expected to produce heavy snow over the central Rockies and adjacent areas of the Plains, and also has the potential to trigger severe weather over eastern Texas and the lower Mississippi Valley, due to strong wind shear and good moisture inflow from the Gulf.

From the NWS BOU forecast discussion:
BY LATE SATURDAY INTO SUNDAY...THE UPPER TROUGH ALLOWS A
SURFACE CYCLONE TO DEVELOPS OVER SOUTHEASTERN COLORADO. THE UPSLOPE
WITH THIS FOR THE PLAINS LOOKS BETTER FOR THE PLAINS BY SUNDAY
MORNING. TO EARLY FOR SPECIFICS ON SNOWFALL AMOUNTS AND SPECIFIC
STRENGTH OF THE INCOMING FEATURES. HOWEVER...WITH MODELS SHOWING
THE CHANGE IN THE LONG WAVE PATTERNS NOW FOR THE LAST FEW RUNS
...LOOKS LIKE WE MAY ACTUALLY SEE SOME PRECIPITATION.

This same system is also progged to potentially produce significant severe weather in the Arklatex Region and Southern Plains.(See topic in Map Room for more on that angle of the storm)
Several of the latest model runs (GFS in particular) show the low rapidly deepening in the vicinity of Lamar, with very strong northeasterly upslope flow developing over northeast and north central CO/southwest NE/southeastern WY/northwest KS the morning of the 27th and persisting through midday on the 28th. It's a good setup for a classic High Plains blizzard! I hope we get a lot of snow(it's been very dry around here since the last storm in mid-October) and hope we get a snow day Monday. If it develops like it is forecast to it will be a double whammy: blizzard for the High Plains and Front Range; severe wx outbreak for the Arklatex and Southern Plains. It doesn't get any better than this in late November! :D
Thoughts and commentary on this developing weather situation welcome.
 
GFS has a sick amount of precip in eastern NE and eastern SD, mainly SD. That would be bad bad if most of it is snow.

http://www.nco.ncep.noaa.gov/pmb/nwprod/an...fs_p60_102m.gif

Good portion looks to be rain, but a good chunk should be snow. Bad news if that is all snow in SD.

http://www.nco.ncep.noaa.gov/pmb/nwprod/an...fs_ten_084m.gif

982 machine in western IA Monday morning.

Are there any snowfall outputs past 72hr for the GFS anywhere? Not that I really NEED to see them this far out, but I'm excited.
 
Definately looking forward to getting snowed out of work on Monday and taking some snow footage. Both NAM and GFS has been consistent with significant accumulations of snow from Sunday Night into Monday Night as well as strong winds likely resulting in Blizzard conditions. Still some difference on exactly when the changeover will occur but mostly likely sometime right after 12z for E SD. NAM also showing snow accumulations of over 15 inches in less than a 12 hour period in SC SD. At 12z Monday a 979mb Low is centered in NW Iowa and a 1034mb High between Montana/Idaho. Looks like somewhere around 10+ inches of snow between 6z Mon and 6z Tue and other areas likely higher. With a strong pressure gradient and resultant strong winds should easily make for a nice Blizzard.

Total snow accumulations for SC SD quite impressive for that short of a period:
http://grib2.wxcaster.com/wxcaster4/CONUS1...OWFALL_84HR.gif
Starting Sunday evening they start seeing snow accumulations well over 1"/hr
 
I was thinking about setting up my webcam outside so people could watch this weather event unfold. And then when I go out hooking it up in my car as I go out to shoot since I have good internet all around this area. Im wondering if anyone has any software/website reccomendations for going about this? If possible I'd add windspeeds from the local ASOS/Precip accum-rate and other pertinent information as well as posting high quality pictures throughout the day and commentary.
 
Originally posted by Mike Hollingshead
Are there any snowfall outputs past 72hr for the GFS anywhere? Not that I really NEED to see them this far out, but I'm excited.

The only thing I know of is the good ol' 12 to 1 ratio :D

Using that "algorithm", and using the 0C 850MB isotherm... That would give southeastern SD a solid 20 to +30 inches (of course, not taking any convective feedback issues into account). Central and eastern NE don't escape either, with 18-24 inches...

Meanwhile, towards MI... We are in a regime that *appears* to be a severe weather pattern covering everything from MI to the GoM. Upon looking at the snow outside and remembering today was a Thanksgiving-that-never-reached-20F-for-a-HIGH!, I then realize this storm will be mild (50's?), damp, cloudy, and generally a showery-type storm... With all of the snow to the northwest and all of the severe weather in the deep south... :x
 
The thread title was changed to reflect the geographical changes in the forecast since this was created. Please continue to discuss blizzard potential for these dates here; any further changes will result in modeification of the thread title. In the meantime, I also removed topic-unrelated posts specific to the blizzard (specifically the gripes over the changing of the thread).

Also, apologies to Mark as I accidentally deleted his second post in here thinking it was his third.
 
Latest ETA run

just a note that the latest ETA run puts the storm a little farther to the east., shifting the heaviest snowfall a tad east then the last run. This would put KSUX into the heavy snow for a longer period of time. Not sure how much I buy into this since alot of rapid deepening low pressure systems have a tendency to swing farther west...but it is a change from last run. Snowfall amounts and pressure gradient still look very impressive to say the least points west and north of the low center. Also, ETA not quite as deep as GFS with storm intensity.
 
Latest 12Z NAM would place a nice band of potentially convective and very heavy snows across MN... A nice TROWAL sets up with weakly stable / symmetrically unstable saturated theta-e surfaces, combined with strong forcing to actually get things going. Not to mention, the -10C isotherm reaches down to 850MB at that time, which may actually be TOO cold for big flakes, but then again... It could also provide a much higher snow to liquid ratio of 15 to 1, 20 to 1, higher possibly higher. Climatologically, I would say this storm would probably be a 18-24 incher... And we all know that climatology is very important in forecasting future events :lol:

As of now, if I were to "chase" this thing and take a flight from MI... It would definitely be to MPX right now, and then start from there - barring any significant changes (which usually occur with these souther plains "hookers" as their known :lol: )
 
18Z NAM is another 100 miles east of the 12Z SFC track during the 72HR timeframe... Or roughly 250 miles further east than the 06Z run. With the mains shortwave still offshore, I think the models will continue to have a difficult time.

Also, the models tend to do poorly when predicting phasing of shortwaves beyond 24 hours...

While the best threat for a snowstorm still appears to be the MN area, I wouldn't put areas further east out of the woods just yet...
 
Yeah im just going to ignore the 18z NAM right now and go with the GFS/ENSEMBLE of a slightly slower/western solution which is more favorable for significant snowfall here. The 18z NAM however still looks ripe for a significant snowfall in Minnesota.
 
Originally posted by Scott Olson
Yeah im just going to ignore the 18z NAM right now and go with the GFS/ENSEMBLE of a slightly slower/western solution which is more favorable for significant snowfall here. The 18z NAM however still looks ripe for a significant snowfall in Minnesota.

For what it's worth also, the GFS has been performing much better this fall/winter compared to the NAM...

With that said (peaking at the 18Z GFS), the 18Z GFS is a bit further eastward as well. All of the medium range models are further west though, which would be more inline with an intense storm... Then again, intense storms tend to carve their own paths...

The lead shortwave is now coming ashore per the latest WV loop, so the 00Z models should have a better handle on the situation...
 
Originally posted by rdewey+--><div class='quotetop'>QUOTE(rdewey)</div>
<!--QuoteBegin-Scott Olson
Yeah im just going to ignore the 18z NAM right now and go with the GFS/ENSEMBLE of a slightly slower/western solution which is more favorable for significant snowfall here. The 18z NAM however still looks ripe for a significant snowfall in Minnesota.

For what it's worth also, the GFS has been performing much better this fall/winter compared to the NAM...

With that said (peaking at the 18Z GFS), the 18Z GFS is a bit further eastward as well. All of the medium range models are further west though, which would be more inline with an intense storm... Then again, intense storms tend to carve their own paths...

The lead shortwave is now coming ashore per the latest WV loop, so the 00Z models should have a better handle on the situation...[/b]

Yeah and the NAM doesn't have very good contunity beyond 48hrs. The GFS is also superior IMO with phasing systems (maybe not as much as UKMET which I also like.) The NAM solution is really hit or miss for our area while the GFS does provide measurable amounts of QPF. My current thinking is that the bulk in our area may fall as rain at least until 12z Monday although it becomes possible after 6z based on what im seeing. That seems in line with the previous NAM and the current GFS.
Regardless however there should still be several inches of snow across E-SD and could be over ten inches in SE SD if it can turn to snow quicker. With very strong winds should still make for a good Blizzard. At least right now Minnesota looks like the place to be with both models indicating snow sooner and higher amounts of precipitation.

EDIT: DAMN! The new NAM is so slow to move the system north resulting in almost no QPF over SD. Still looks good for SC C MN.
-Scott
 
Man the GFS remains reather impressive. By midnight the 850 0c line moves east to the MO river while the sfc low bombs out in w IA. Has a 982 low east of Omaha at midnight from 988 at 6pm. Takes it down to 980 by morning in nc IA. I'm sure just how that wrap around band sets up won't be very certain till it is actually happening. What seems sure is that near midnight it'll be changing to snow and from there on it will probably be damn windy. For what it is worth in a 6 hour period in the a.m. on Monday it shows it putting down 12-18 inches at 12/1 ratio in se SD. That is right below a 60-65knt low level jet. It keeps plastering that area.
 
NAM continues to show highest snow rates in Minnesota extending in as far north as Canada. But the GFS which still has known better continuity and verification of QPF from this range shows a beautiful 20+ inches of snow occuring in SE SD making the rapid changeover to snow (6z) (TEMP 31.1 Surface, 850mb T -1.1) and accumulating an IMPRESSIVE amount of it in a 3 hr period with a steady but declining amount throughout the day. Most likely all but finished by 0z Tue. Though with the strong winds and 20 inches it'll be hard to tell the difference. The stronger/slightly slower GFS has support from other global models some of which show even a slightly more amplified system. The AFWA MM5 looks like the NAM solution but split between exact location of best lift.

Im actually quite impressed with the contunity of the GFS as it was indicating roughly (within 40 miles) the same area to recieve Blizzard like conditions almost a week ago.) While the NAM which has been in pretty decent agreement but has remained too weak and has made significant shifts to the path of the system.

And if the GFS output didn't look enough like a kicker for the Dakotas take a look at this from our friends at the Hydrometeorological Prediction Center:

\"OTHER RECENT GUIDANCE SUGGESTS THAT THIS SYSTEM WILL UNDERGO RAPID DEEPENING EARLIER THAN EITHER THE NAM OR THE GFS...WITH A SLOWER PROGRESSION NEWD. RECOMMEND FOLLOWING THE 00Z CANADIAN GEM MASS FIELDS AROUND F48...THEN THE 00Z UKMET FOR F60 AND BEYOND. \"

From the look at the UKMET & GEM both deepen this system quite quickly and take it a little more direct NE direction through Omaha into NW IA. A look at the ECMWF yields support for this as well. This all appears even more favorable for significant snow than the GFS is indicating.

NAM 12z Just came in and it looks like its coming around! Looks to be well over ten inches of snow with areas along MO river even higher. NAM not in so much of a rush to move system East as before and looks to continue snow potiental longer than GFS even does.

15-20" Snow (Those are 10:1). Indicated along and in between James & Missouri River

http://grib2.wxcaster.com/wxcaster4/CONUS_...OWFALL_72HR.gif

Snow/Liquid ratio looks most likely 10:1 with the Sanders Ensemble showing 85-95% precentage in the 9:1 average category. Climatologically SD's snow to liquid ratio is 13:1. With the bottom 25 percentile at 10:1.
 
Based on the 12Z models, I'm thinking areas between Pierre and Huron SD will see the heaviest band. The 12Z NAM snow algorithm outputs 20-30 inches in that area, and it also appears that they stay on the western side of the 850MB -3C isotherm...

I expect the comma head to be begin developing between 21Z and 03Z, with significant vertical velocities and high RH values through the entire column. A nice TROWAL structure sets up as well across the Pierre/Huron region, thought looking at cross sections - I don't really see much CSI, but there is a *hint* of convective instability over far southeastern SD, but it's rather shallow and probably insignificant. Either way, with very intense vertical velocities through the entire saturated column- particularly between 12-21Z tomorrow, a few bursts of thundersnow aren't out of the question...

Overall, I think the NAM snow algorithm is pretty much on target.
 
latest.gif


I wonder if that is snow right there. O'Neill is reporting snow so it could be. That area right there I think is going to get completely hammered. There is a lot of moisture and a looooong way to go.

I'm working out a way/vehicle to get up there now and will be getting a motel room up there tonight.
 
Hmm, that's pretty interesting H... I'm getting around 3C at 850MB over that region, so it seems that it would clearly be rain... But, ONL is reporting snow as you observed. Local RUC soundings over that heavier band shows a >0C layer between 2K-5K FT, but right under that temps fall from 3C to -3C - so some refreezing of melted precipitation may be occuring. I think we are looking at "bright banding".

The profile is saturated, so there won't be any more evaporational cooling - but cold air descending from aloft as well as an CAA that starts up should help to cool the profile later today.
 
Hmmm spc meso page has 0c line at 850 running right through the middle of whatever it is(as of 18z).
 
Are you sure it isn't the 6 isotherm? I see that it is covered up bu the dewpoint line and looks like a 0. The 0 line looks to be near KANW. That's still 3-4C @850 at KONL where snow was being reported.
 
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