Southern Plains Major Winter Storm December 18-20

[brettjrob]

There's one guy from SE CO that I've seen post occasionally. Other than that, I don't know of any. That entire region (if we're talking N of the AMA area so it's excluded) has fewer people than a typical county in the Northeast.

[Jim Martin]

Good chances for a big snow as highlighted there in western Kansas/Oklahoma Panhandle.

[brettjrob]

NAM continues to pull back NW with the 19/00z run. Bullseye is Lamar, with the heavy snow axis running NE from there through Scott City, Hays, Clay Center, and St. Jo. Also has the unpleasant effect of shaving off a little more of W TX from major drought relief. Caveat: the 12z WRF-NNM and WRF-ARW were decidedly more southerly, whereas I somewhat expected to see them backing up the NAM in a situation where it disagrees with the global models.

[jcwxguy]

in me says ill get 5-6", but with the trend

im thinking

[Ed Lizard]

Top down, I'd guess Dalhart would be in transition around Noon tomorrow, but I don't think its smooth rain to snow. But it should be mostly snow not too long after, if I had to guess.

NAM 3 hour regional loop from PSU e-Wall

Over an inch precip in the Panhandle, even if half is not snow, I bet they'd be happy. Amarillo, mostly rain, but again, I bet they're happy enough.

[Amped]

Those are some nice looking cells in southern NM

[Thundersnow12]

[baroclinic_instability]

I am still not convinced at the relatively fast ejection of the deep upper low through the plains in the more progressive guidance. Given the strong westward warm advection trajectories and deep convection orientation, rapid intensification seems likely with a stalled system during peak intensification. 00z RGEM would seem to be the more realistic solution to me with a strong bent-back low and slower solution.

[baroclinic_instability]

That said convection is going to play a key role in how this cyclone develops. A close eye should be kept on timing and as well as the orientation of the convective squall to the upper level features. There is no guarantee a slower stalled solution is going to occur. DMC is going to be a key player here.

[baroclinic_instability]

Toss in the 0Z UKMET into the group of a nearly stalled cyclone. oZ ECMWF is nearly identical to the 12Z albeit a tick slower. The similarities to the April 15th blizzard are insane although that did feature a much more robust warm sector.

[Chicago Storm]

0z ECMWF Text Data...

AMA:

 
MON 12Z 19-DEC   7.9	 6.4    1009	  95	  84    0.09	 563	 556   
MON 18Z 19-DEC   8.3	 6.2    1006	  98	  90    0.42	 558	 553   
TUE 00Z 20-DEC   2.6	 0.5    1009	  93	  70    0.20	 549	 541   
TUE 06Z 20-DEC  -2.1    -5.7    1017	  82	  95    0.07	 550	 536   
TUE 12Z 20-DEC  -3.7    -7.8    1022	  75	  92    0.03	 553	 536

DDC:

 
MON 12Z 19-DEC   7.2	 6.9    1011	  93	  79    0.02	 564	 555   
MON 18Z 19-DEC   3.4	 2.9    1014	  90	  96    0.11	 563	 551   
TUE 00Z 20-DEC  -0.6    -3.9    1017	  94	  99    0.54	 558	 545   
TUE 06Z 20-DEC  -3.2    -6.7    1019	  93	 100    0.29	 552	 537   
TUE 12Z 20-DEC  -4.5    -8.8    1021	  90	  96    0.22	 550	 533   
TUE 18Z 20-DEC  -4.5    -7.4    1022	  85	  92    0.03	 551	 534

GUY:

 
MON 12Z 19-DEC   6.7	 5.7    1010	  92	  57    0.04	 564	 556   
MON 18Z 19-DEC   5.5	 3.1    1011	  97	  99    0.43	 560	 550   
TUE 00Z 20-DEC  -0.9    -4.2    1015	  93	 100    0.69	 552	 540   
TUE 06Z 20-DEC  -3.4    -7.1    1020	  91	 100    0.37	 550	 534   
TUE 12Z 20-DEC  -5.0    -8.8    1023	  87	  94    0.14	 551	 533   
TUE 18Z 20-DEC  -4.5    -8.0    1024	  81	  74    0.01	 554	 535

SPD:

 
MON 18Z 19-DEC  -1.0    -2.5    1017	  79	 100    0.13	 558	 544   
TUE 00Z 20-DEC  -3.4    -4.6    1019	  94	 100    0.67	 554	 538   
TUE 06Z 20-DEC  -5.3    -6.7    1025	  89	  99    0.48	 552	 532   
TUE 12Z 20-DEC  -6.0    -7.0    1024	  87	  93    0.21	 552	 533   
TUE 18Z 20-DEC  -5.4    -5.5    1023	  81	  84    0.01	 556	 537

[ksstormhunter]

My 06Z updated. Right now Dalhart is my highest threat, with onset of snow around 15-16Z. I have snowfall rates around 1.5" to about 22Z, visibilities near zero, and wind gusts up to 51 mph. Snowfall accumulation in and around the Dalhart area is projected at 12.1". Other cities working into my threat areas are Dodge City, Liberal, Garden City, Great Bend, and Hayes, KS. Also Guymon, OK. Full data updated http://smartwxmodel.net/Storm1.htm,'>http://smartwxmodel.net/Storm1.htm, also all the other cities for later on http://smartwxmodel.net/ Thoughts?

[baroclinic_instability]

This storm is going to be awesome tomorrow. But what will keep it from being truly epic is the direct connection of DMC through the WCB and directly connected to the upper divergent jet circulation aloft. The occlusion here is 5 hrs too fast...or the cyclone is 5 hrs too fast. The greatest cyclones feature a direct feed from DMC to the jet circulation aloft which drives extreme pressure/height falls...very non-synoptic scale ascent into the synoptic cyclone...one of the most effective rapid positive feedback mechanisms in cyclone development. Think Groundshog Day February 1, Boxing Day, April 15 th blizzard ( see sat image on page 1), epic New England Nor'easter last January, etc.

That said, this storm is going to be ripping tomorrow, and I bet this stalls much more than NCEP guidance suggests.

[earthlight]

NAM continues to pull back NW with the 19/00z run. Bullseye is Lamar, with the heavy snow axis running NE from there through Scott City, Hays, Clay Center, and St. Jo. Also has the unpleasant effect of shaving off a little more of W TX from major drought relief. Caveat: the 12z WRF-NNM and WRF-ARW were decidedly more southerly, whereas I somewhat expected to see them backing up the NAM in a situation where it disagrees with the global models.

Seeing the Euro remain steadfast with the farther south/southeast cutoff of the heavier precipitation was a red flag to me that the NAM's farther northwest extent of the precipitation shield was bogus. The new 06z/19 run trended south and east from the previous run with a slightly flatter height field. This is more in line with the latest GFS (which may, admittedly, be a hair too far south and east) and ECMWF. This run is also more in line with the latest SREF mean.

The cutoff is going to be rather sharp, so it's going to be really tough to try and dissect the model guidance over the next few cycles. One thing I will say, in my experience (both on the East coast and otherwise) the GFS and specifically the GEFS tend to perform fairly poorly with precipitation cutoffs. I'm not sure if this can be attributed to the resolution, but whatever it may be..it's something to look out for. In this case, it seems the GFS operational is fairly reasonable.

Here are the NAM total precipitation adjustments for comparative purposes.

06z http://www.meteo.psu...CENT_6z/f48.gif

00z http://www.meteo.psu...CENT_0z/f54.gif

[baroclinic_instability]

Seeing the Euro remain steadfast with the farther south/southeast cutoff of the heavier precipitation was a red flag to me that the NAM's farther northwest extent of the precipitation shield was bogus. The new 06z/19 run trended south and east from the previous run with a slightly flatter height field. This is more in line with the latest GFS (which may, admittedly, be a hair too far south and east) and ECMWF. This run is also more in line with the latest SREF mean.

The cutoff is going to be rather sharp, so it's going to be really tough to try and dissect the model guidance over the next few cycles. One thing I will say, in my experience (both on the East coast and otherwise) the GFS and specifically the GEFS tend to perform fairly poorly with precipitation cutoffs. I'm not sure if this can be attributed to the resolution, but whatever it may be..it's something to look out for. In this case, it seems the GFS operational is fairly reasonable.

Here are the NAM total precipitation adjustments for comparative purposes.

06z http://www.meteo.psu...CENT_6z/f48.gif

00z http://www.meteo.psu...CENT_0z/f54.gif

Also note the already slower progression of the wave. Noticeable already. They still have a ways to go.

[baroclinic_instability]

Edit. I was wrong, the 06Z is faster lol. They have even farther to go.

[ksstormhunter]

14Z Update, Dalhart, Garden City, and Liberal, KS are in the highest threat. Through 01Z, looking for 3.2" of snow for Dalhart region, with the heaviest snow starting from 19Z-01Z. Snowfall rates up to 1.2" per hour. Winds will be pushin in excess of 50mph across the area also. Other cities that are starting to work they way up in the threat areas are Dodge City, Hays, Great Bend, Dodge City, Newton City, and Salina, KS. All data points uploaded http://smartwxmodel.net/Storm1.htm'>http://smartwxmodel.net/Storm1.htm or http://smartwxmodel.net

[Srain]

13Z surface analysis suggest the cold front lies from Raton, New Mexico NE to Hays, Kansas. The H5 low is near Carlsbad, New Mexico moving ENE. There sould be some interesting webcam shot from Dumas later today.

[Ed Lizard]

New NAM delays the change to snow in Dalhart, Amarillo is mostly rain, and the real drought denting >1 inch precip is confined to the Northern Panhandle. The forecast emagram, which suggested DHT was changing to snow at 18Z, now suggests surface temps too warm, and all rain at that time.

Garden City is my blizzard pick city. (Southwest Colorado gets a little more snow, so my pick city is flexible) I think they can get 30 knot plus winds at least in gusts.

[Srain]

The Rapid Refresh Meso models are keying in on SE Colorado/NE New Mexico for the highest totals...

[brettjrob]

Would love to be somewhere between Lamar and Tribune this evening. AMA and DDC look to get fringed, with perhaps a nice 4-8" consolation prize at least for the latter.

[Srain]

AMA Update:

UPDATE...

MAIN CHANGES TO THE FORECAST WERE TO PUSH BACK THE TIMING OF THE

SNOW AND ADJUST SNOWFALL TOTALS.

DISCUSSION...

HEADLINES ARE STILL IN GOOD SHAPE SO NO CHANGES PLANNED IN THAT

REGARD. COLD FRONT IS CURRENTLY LOCATED FROM NEAR ADRIAN TO WEST OF

GUYMON. UPSTREAM OBSERVATIONS AND THE 1200 UTC SOUNDING AT KDDC

SUGGEST A RELATIVELY DEEP FRONTAL INVERSION ABOVE THE SURFACE.

OBSERVATIONS SHOW THE RAIN TO SNOW TRANSITION HAS TAKEN ABOUT 2 HOURS

AFTER THE FRONTAL PASSAGE. BASED ON THIS...WE DELAYED THE ARRIVAL OF

THE FRONT AND THE COLDER AIR FARTHER SOUTH AND EAST. THINK ALL RAIN

WILL BE LIKELY SOUTH AND EAST OF A LINE FROM BEAVER TO HEREFORD.

AFTER 3 PM...EXPECT RAIN TO BECOME MIXED WITH SNOW FOR AREAS

INCLUDING AMARILLO...BORGER...PERRYTON...AND BEAVER. ALL RAIN IS

EXPECTED ACROSS THE SOUTHEAST TEXAS PANHANDLE THROUGH 6 PM. THINK THE

RAIN WILL TURN TO ALL SNOW AT AMARILLO BETWEEN 4 AND 5 PM. THE TIME

FRAME FOR HEAVIEST SNOWFALL AT AMARILLO APPEARS TO BE BETWEEN 4 PM

THIS AFTERNOON AND 6 AM TUESDAY.

INCREASED SNOWFALL AMOUNTS SLIGHTLY ACROSS THE FAR NORTHWEST

PANHANDLES WHERE ALMOST 4 INCHES OF SNOW HAS ALREADY ACCUMULATED AT

TEXLINE. ACROSS THE SOUTHEAST HALF OF THE PANHANDLES...SNOW AMOUNTS

WERE LOWERED DUE TO THE SOAKING RAINS THIS MORNING AND THE DELAYED

ARRIVAL OF THE COLDER AIR. HOWEVER...BASED ON THE EXPECTED STRENGTH

OF THE WINDS...STILL THINK BLOWING AND DRIFTING SNOW WILL PRODUCE

NEAR WHITEOUT TO WHITEOUT CONDITIONS AT TIMES ACROSS THE BLIZZARD

WARNING AREA. IN ADDITION...THE RAIN WILL LIKELY FREEZE ON THE

ROADWAYS LATER THIS AFTERNOON AND EVENING BEFORE THE SNOW

ACCUMULATES ON TOP OF THE GLAZE. THEREFORE...EXTREMELY HAZARDOUS

TRAVEL CONDITIONS ARE STILL EXPECTED ACROSS THE PANHANDLES THROUGH

TUESDAY MORNING. UNLESS IT IS AN EMERGENCY...WE ADVISE AGAINST ANY

TRAVEL THROUGH AT LEAST TUESDAY MORNING...ESPECIALLY NORTH AND WEST

OF A LINE FROM AMARILLO TO CANADIAN. THIS BLIZZARD/WINTER STORM HAS

THE POTENTIAL TO BE LIFE-THREATENING IF YOU ARE CAUGHT OUTSIDE OR

BECOME STRANDED IN YOUR CAR.

[baroclinic_instability]

This storm is putting the hurt on portions of NM. A few random twitter snow pics for those who love snow.

Surface low still sitting across NM. Sick already on satellite. This beauty is going to be insanity tonite on WV.

[Eskimo Joe]

Enjoy it fellas, what a storm this looks to be!

[ksstormhunter]

18Z SmartCast Update. Right now highest threats are Liberal, Garden City, Hayes, KS areas and Dalhart, TX. Through 05Z tracking snow accumulations of 3-5", with strongest winds zoning in on the Liberal-Dalhart-Garden City areas, with wind gusts up to 45-50 mph. Full threat list is posted http://smartwxmodel.net or http://smartwxmodel.net/Storm1.htm Switching to hourly outputs on my program.

[EasternUSWX]

This storm is putting the hurt on portions of NM. A few random twitter snow pics for those who love snow.

Surface low still sitting across NM. Sick already on satellite. This beauty is going to be insanity tonite on WV.

Last picture you post is just dear lord!!

[Thundersnow12]

This storm is putting the hurt on portions of NM. A few random twitter snow pics for those who love snow.

Surface low still sitting across NM. Sick already on satellite. This beauty is going to be insanity tonite on WV.

haha found that same picture at the bottom!

[baroclinic_instability]

Geez don't tease me Taos, NM. I would do anything to be skiing right now.

[Thundersnow12]

[baroclinic_instability]

Not poo pooing on this storm because it it sick, but that vis shot tells it all. If this bad boy came 5 hours later convection along that bulging front would have been feeding the center of this cyclone some highly non-synoptic UVV's straight through the WCB. Would have been explosive.