2/1 - 2/3 FCST S. PLAINS/MIDWEST/GL/NE STORM

[DWest]

Newest GFS run is reverting to a more southerly path, which includes snow for parts of Oklahoma that weren't getting much in the last day's worth of runs. The 00z isn't putting down the same quantity that the old 06z did, but it's still very respectable if it materializes. For my part I'm simply glad it didn't keep pushing things further north!

 

[Rocky Rascovich]

Been overdue to chime in on my favourite type of weather .. I'm liking the latest trends on raising the QPF values on both the GFS and especially NAM.. think this may just barely pan out if enough moisture gets entrained into this system. If you believe the NAM, TUL will get almost an entire winter's normal snowfall with this .. (8-10") while the OUN area may get up to 4", probably from my farm on northwest to northeast (I live 5 NW of Piedmont). Will be interesting to see the trends over the next 48 hours, if this continues to increase the snow amounts .. or decrease. I suspect winter storm watches will be issued tomorrow for the Mon. night/Tue. time frame. Looking at forecasted skew T's.. think ice will be the greatest concern along the I-40 corridor here in central OK. maybe not as much toward TUL. All in all, we DESPERATELY need the moisture where I live. Have only had 3.5" of rain since September 1 according to a neighbour up the road who has a rain gauge.

Further down the road, looks like the first half of February look much colder than normal with opportunities for some snow/ice. Lets hope we catch up some on the moisture for our wheat crop which is in poor shape.

 

[Chris Carter]

It seems like most weather stations in Nebraska are dismissing the GFS as the outlier. The euro has been the steady choice with the GEM and NAM mixing for an extended light snow event, sounds kind of like the light snow storm we got earlier this month. Sounds like anywhere from 3 to 6 inches will be quite common but with still some uncertainty. The hpc has piggybacked onto the idea of this.

 

[Mike Smith]

I would be extremely skeptical of the dry slot the 12Z NAM is showing into central Kansas. With both the surface low and 500mb low predicted by the same model to track well to the south, there is no reason to believe there will be an intrusion of dry air as shown.

It is very odd this year (and this was certainly the case with this week's East Coast blizzard) that the models seem to get it more or less correct 5 days out, then get muddy at days 3 and 4, then get really good at days 1 and 2. We may be seeing that now. While I believe someone in the central U.S. will get very heavy snow, I'm holding off on a location until the system in the Pacific gets over land so it can be better sampled.

 

[DWest]

It seems like most weather stations in Nebraska are dismissing the GFS as the outlier. The euro has been the steady choice with the GEM and NAM mixing for an extended light snow event, sounds kind of like the light snow storm we got earlier this month. Sounds like anywhere from 3 to 6 inches will be quite common but with still some uncertainty. The hpc has piggybacked onto the idea of this.

The 00z UKMET actually has stronger low pressure than the GFS does, which would indicate to me faster return of arctic air as the system moves by. It also keeps the high pressure center over S. Dakota at around 1045 millibars; if anything that would shift the freezing precip line slightly further southeast than even the GFS has it.

The ECMWF is a bit different as you mentioned, and even more extreme - placing the ejecting low at 999 mb and the S. Dakota high at 1052 mb at the point it crosses over the Missouri bootheel area. While the center of high pressure seems to be based a bit further west with this model, the demarcation line for the 1044-1045 contour is still well into S. Dakota. I may be wrong here, but wouldn't this model actually call for greater snow totals across an even larger geographical area? I think that while the low is a bit further west as well, the stronger pressure systems would probably make up for the adjustment in the snow line in that the cold air might filter in faster.

[00z UKMET valid 00z Feb 2]



[00z ECMWF valid 00z Feb 2]



Of course, I could be (and probably am) completely wrong - but that's my amateur take on those models.

 

[Patrick Marsh]

It is very odd this year (and this was certainly the case with this week's East Coast blizzard) that the models seem to get it more or less correct 5 days out, then get muddy at days 3 and 4, then get really good at days 1 and 2. We may be seeing that now.

I wouldn't keep the disclaimer of "this year". Several of us (in Norman) have been commenting for awhile now that this has been true with respect to southern plains winter storms. A trend we've noticed for a couple of years now is that the models are good about 5 days out, then jump wildly in one direction. After this the models continue to trend back toward the original 5 day forecast, being "correct" about 36 hours out. Then inside of 36 hours, the models "over-correct".

Regardless, I don't care what the models predict in the coming days...as long as I end up with "shovable" snow.

 

[Mike Smith]

I wouldn't keep the disclaimer of "this year".

Patrick,
We at WeatherData have noticed the same thing but it seems even more pronounced this year. I have no clue as to why that might be. That is why I am cautioning people that model details at this point are likely incorrect, especially since the 500mb pattern doesn't support some of those details (i.e., a dry slot in KS nearly all the way to CNK).
Mike

 

[jshields]

mmmm, interesting update on the hpc website today about an hour ago. looks like they are preferring the 0Z euro and UKMET at this point. major model initialization errors with the gfs...

MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1219 PM EST SAT JAN 29 2011

VALID JAN 29/1200 UTC THRU FEB 02/0000 UTC


...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z NAM/GFS EVALUATION INCLUDING THE NEW CANADIAN AND PREFERENCES

...UPPER TROUGH FORMING ACROSS THE INTERMOUNTAIN WEST/ROCKIES
THROUGH THE PERIOD...

PREFERENCE: UKMET

THE NAM AND GFS HAVE POTENTIALLY SIGNIFICANT INITIALIZATION ERRORS
OVER BRITISH COLUMBIA...
WITH THE NAM TOO WEAK AND NORTHEAST WITH THE CENTER OF THE
DEVELOPING SHORTWAVE TROUGH...
AND GFS TOO STRONG AND SOUTH. THESE DIFFERENCES CONTRIBUTE TO
GROWING SOLUTION DIFFERENCES OVER TIME...WITH THE GFS LESS
AGGRESSIVE IN DIGGING THE TROUGH INTO THE ROCKIES...A SOLUTION
WHICH IS DISCOUNTED DUE TO INITIALIZATION ERRORS AND ITS RELATIVE
POSITION WITHIN THE GUIDANCE ENVELOPE. MEANWHILE...THE
NAM...ALTHOUGH WITH INITIALIZATION ISSUES OF ITS OWN BUT NOT AS
MUCH AS THE GFS...PRODUCES A FORECAST CLOSE TO THE MODEL CONSENSUS
INCLUDING ENSEMBLES...AND THUS IS CONSIDERED REASONABLE.
OTHERWISE...THE NEW UKMET HAS TRENDED TOWARD THE 00Z ECMWF BUT IS
NOT AS FAR WEST NOR AS DEEP WITH THE UPPER LOW BY 84 HRS...AND
GIVEN ITS MORE RECENT AND MORE ACCEPTABLE
INITIALIZATION...PRODUCES THE MOST PREFERRED SOLUTION.


i sense lots of changes possible yet to come!!

 

[David Reimer]

MOD: Can we please have TX added to this thread?

It looks like the 12Z model runs have come in colder as a whole for the Tuesday event, with the NAM showing a large swath of 6+ inches of snow across Oklahoma. Meanwhile, the GFS is showing 0.50+ inches of ice across portions of Southeast Oklahoma for the event. I'm also keeping in mind that this storm is not yet onshore, thus the national upper-air grid hasn't gotten any good data on this storm yet. I'm playing it conservative here for North Texas, but cautiously optimistic that the models are having difficulties with the shallow arctic air at the surface and are keeping it too far north. While HPC is advising the 12Z NAM/GFS may have issues (remind anyone of the boxing day blizzard in the mid-atlantic?) my comments here are still pretty much valid.

I've just posted my first discussion over on the TexasStormChasers.com website. For those interested, you can read it at http://www.texasstormchasers.com/2011/01/29/212011-winter-storm-potential-discussion-1/

 

[Chris Vagasky]

MEANWHILE...THE
NAM...ALTHOUGH WITH INITIALIZATION ISSUES OF ITS OWN BUT NOT AS
MUCH AS THE GFS...PRODUCES A FORECAST CLOSE TO THE MODEL CONSENSUS
INCLUDING ENSEMBLES...AND THUS IS CONSIDERED REASONABLE.
OTHERWISE...

If that's the case, Oklahoma's looking at a huge snowfall with lots of blowing and drifting. (IMG from Barker's site)

 

[Chris Carter]

Winds have not been discussed too much, but it is a reality. I would as far as this is probably the first legit widespread blizzard potential for the plains so far this winter season.

 

[Robert Dewey]

MOD: Can we please have TX added to this thread?

I think they're going to need to add a whole lot of states to the title. Might be easier to say "PLAINS TO GREAT LAKES."

 

[jshields]

the new 12Z euro is out and has shifted way south to the same general path as the nam/gfs. it has the surface low over northeast tx at hr 72(tuesday 12Z) and flies it all the way up to ohio at hour 96(12Z wed).

 

[DWest]

Winds have not been discussed too much, but it is a reality. I would as far as this is probably the first legit widespread blizzard potential for the plains so far this winter season.

I took a look at winds earlier - I don't see much potential, at least according to the forecasted pressure gradients, for anything over 35 mph - there is the pretty good chance of having over 20kts for many areas, but alas that doesn't meet blizzard criteria requirements.

If that's the case, Oklahoma's looking at a huge snowfall with lots of blowing and drifting.

Did you pull that graphic from Earl Barker's site? Seems to have more detail as if it's some sort of placefile.

 

[Chris Vagasky]

Yea, that's from Barker's.