High Plains Drifter

Peak of the storm has passed for Kansas City as snow rates decrease. As of 1:30am, I measured an average depth of somewhere between 4 and 4.5″ around the yard at my parent’s house in Overland Park.  Since then, I am estimating the average snowfall rate based on radar to be on the order of 1/2″ to 3/4″ per hour, therefore the estimated depth as of 5:45am is probably 6 to 7″.  At first light, I will go out and measure, however during blizzard conditions, the snow compacts faster, and the true snowfall may not be entirely representative by the current average depth.  Here is a photo of me and my brother’s vehicle in my parent’s driveway with a drift in front of my Jeep at 1:30am:

Below is a surface map at 1:00am CST showing the observations during the height of the storm as it was affecting Kansas City.  Note the surface wind vorticity center over northeastern Missouri.  A 987mb surface low between Kirksville (IRK) and Columbia (COU):

Freezing rain and 30°F in Johnson County, KS. The storm appears to be on track.  Blizzard conditions continue to spread northeast along with the mixed precipitation/snow line.  As of 18z (Noon), Topeka was having a sleet/snow mix, Lawrence was sleet, and it was freezing rain here in Overland Park.  Below is a cool graphic showing the national radar mosaic along with the model depiction of the radar picture for the same time from the 12z run of the high-resolution NMM-WRF model:

Blizzard conditions ongoing/developing across southeastern TX Panhandle and southwestern OK. There is widespread snow and mixed precipitation across much of northwest TX into Oklahoma with the mix/snow line still west of Oklahoma City, but blizzard conditions are developing rapidly and spreading deeper into Oklahoma.  This will continue through the day and spread into southeastern KS late this afternoon.  Blizzard/near blizzard conditions are still expected in the Kansas City metro with the height of the storm sometime around 8pm tonight to 8am Friday morning.  The official NWS forecast for Kansas City metro is for 4-7″ with frequent wind gusts in the 30 to 40 mph range.  This is blizzard criteria.  I would not be surprised to see a whole slew of blizzard warnings issued later on today along the track of the yellow area in the surface chart I annotated:

Another snow bust in Dodge City.  I am now in KC with the family for Christmas…and more??! Well, the southern elongated PV anomaly in the mid levels I talked about in the previous posts actually developed into a decent, but small closed low, instead, but farther south…and moved straight east after it closed off over New Mexico.  As of 1:00am CST on Christmas Eve morning, the storm center was over West Texas with an impressive precipitation area across West Texas into Southwest Oklahoma.  This area, denoted in yellow in the image below, is the area to watch for the Kansas City metro tomorrow into tomorrow night for heavy snow.  Yes, the 00z models had backed off a little bit, however, the satellite and radar presentation across West Texas is impressive, and this is the beginning of the cyclogenesis event for tomorrow and tomorrow night as this storm tracks across the Ozarks and then eventually into the midwest states.  There will be a period of Freezing Rain in the KC metro as the arctic air filters into the area first at the surface.  Eventually, though, the entire column will be below zero, probably sometime in the 4-7pm time frame in the KC area.  Then after that, periods of heavy snow should occur during the evening into overnight hours, which is also when the winds will really kick in.

Another dud for Dodge?! Round one of the event is over and done with.  We had around a tenth of an inch of freezing rain topped off with a little bit of sleet and snow (which measured to around 0.1″ depth here at my house).  I’m letting my 4-inch rain gauge thaw out to find out the exact measurement at the house.  The main storm over AZ and NM will be moving almost due east today…with the main PV anomaly likely remaining far enough south to keep Dodge City out of the mix for decent precip rates today and tonight.  I think over the next 18 hours or so we may run up a total of 2 or maybe 3″ or so, but at this point, based on my latest thinking, I am not impressed.  The wind on Thursday.  That’s another story.  More on that in another blog post perhaps.

Ironic that I was supposed to leave this morning for Overland Park, but I postponed that trip due to the weather affecting Dodge City.  It now appears that Overland Park (southwest suburb of KC) may bear the brunt of that southern storm when it kicks out north on Thursday/Thursday night and bombs out as it does so.  The cyclogenesis as it lifts north will be tremendous — especially once the arctic air becomes involved and that northern High Plains system becomes involved and ultimately merges with the southern storm.  Here is the portion of the official Area Forecast Discussion I wrote at work earlier this morning spelling out all the meteorological insight:

EVEN AT THIS LATE HOURLY LEADING UP TO THE EVENT...STILL MANY  
QUESTIONS...PARTICULARLY AROUND SNOWFALL AMOUNTS AND WHERE  
HEAVIEST SNOW WILL FALL. BY IN LARGE...THIS SYSTEM APPEARS TO BE  
TURNING INTO A BIG DUD FOR SOUTHWEST KANSAS...FROM A SNOW  
STANDPOINT. THE FREEZING DRIZZLE/FREEZING RAIN EVENT SINCE LATE  
LAST NIGHT HAS BEEN THE MAIN HAZARD UP TO THIS POINT...AND ROADS  
HAVE BECOME SLICK AND HAZARDOUS AREAWIDE. THE WIND AND SNOW...MOST  
LIKELY LIGHT SNOW...WILL BE THE SECOND PHASE OF THIS EVENT...LATER  
ON TODAY, TONIGHT, AND INTO THE FIRST PART OF THURSDAY.  

WATER VAPOR LOOP SHOWED THE CYCLONE CLOSING OFF ALONG THE AZ/NM  
BORDER AS OF 09Z. WILL FOLLOW THE BROAD H7 LOW CENTER AND H7 RH>90  
PERCENT FIELDS FOR WHERE SNOW WILL TRACK. FRONTOGENESIS FORCING IS  
HARD TO FIND AT H7, SO AM NOT EXPECTING ANY HEAVY PRECIPITATION  
FOR THE REMAINDER OF THE EVENT...JUST A LARGE SPATIAL AREA OF LOW  
ACCUMULATION RATE SNOW NEAR THE H7 VORT AXIS AS IT TRACKS ACROSS  
SOUTHWEST KANSAS. THE 06Z NAM DOES HINT AT SMALL PV ANOMALY  
EJECTING NORTHEAST INTO NORTHWEST OKLAHOMA AND SOUTH CENTRAL KS BY  
THIS EVENING WHICH MAY HELP BOOST PRECIPITATION RATES...BUT IT IS  
REALLY THE ONLY MODEL SHOWING THIS. THAT BEING SAID...ANY HINT AT  
H7 CONVERGENCE NEAR THE H7 LOW WILL PROMOTE INCREASED  
FRONTOGENESIS AND SUBSEQUENT SNOWFALL RATES...BUT THIS IS GOING TO  
BE DIFFICULT TO ACHIEVE SINCE IT NOW APPEARS THAT THE MAJOR MID  
LEVEL PV ANOMALY WILL BE TRACKING WELL TO THE SOUTH INTO NORTH  
TEXAS...THEN LIFTING NORTH-NORTHEAST ACROSS THE OZARKS.  
MEANWHILE...THE MONTANA/WYOMING VORT WILL MOVE SOUTH-  
SOUTHEAST...WHICH WILL INFLUENCE THE TRACK OF THE SOUTHERN  
VORT...WHILE SOUTHWEST KANSAS REMAINS IN BETWEEN THE TWO. FOR SNOW  
AMOUNTS...AM JUST GOING TO GO WITH A GENERAL 2 TO 4 INCH FORECAST  
ACROSS THE WHOLE AREA...BUT IF THE 06Z NAM12 IS ON TO SOMETHING  
REGARDING THE MESOSCALE DETAILS...THEN SOME HIGHER AMOUNTS WILL BE  
SEEN ACROSS THE EASTERN FA.   

WE WILL NOT MISS OUT ON THE WIND. THANKS TO THE NORTHERN  
VORT...SURFACE ANTICYCLOGENESIS WILL BE VERY GOOD ACROSS NORTHERN  
MONTANA WITH 1036MB HIGH. THE SOUTHERN STREAM WAVE WILL PROVIDE  
THE GREAT LOWER TROPOSPHERIC CYCLONIC RESPONSE WITH A DEEPENING  
SUB 995MB LOW ACROSS THE OZARKS. IN BETWEEN...THE GRADIENT WILL BE  
VERY STRONG...AND THESE WINDS ARE EXPECTED TO COMMENCE LATE  
THURSDAY NIGHT...STRONGEST OCCURRING MIDDAY THURSDAY. EVEN WITH  
JUST AN INCH OF ADDITIONAL SNOWFALL THURSDAY...BLIZZARD OR NEAR  
BLIZZARD CONDITIONS WILL BE QUITE POSSIBLE AS SUSTAINED WINDS WILL  
LIKELY REACH 30 TO 35 KNOTS AT TIMES...WITH GUSTS WELL INTO THE 40  
TO PERHAPS 50 KNOT RANGE DURING THE HEIGHT OF THE WIND EVENT.  
FRESH, NON-COMPACTED SNOWFALL WILL WHIP AROUND SUBSTANTIALLY  
CAUSING PERHAPS SEVERE BLOWING AND DRIFTING WITH JUST ONE INCH OF  
ACCUMULATION. EVEN IF LITTLE ADDITIONAL SNOW FALLS DURING THE WIND  
EVENT THURSDAY...GROUND BLIZZARD CONDITIONS WILL BE POSSIBLE IN  
THE AREAS THAT SEE 3 OR MORE INCHES OF SNOW. THIS IS THE REASONING  
FOR CONTINUING WITH THE BLIZZARD WATCH...WITH ONE MORE SHIFT TO  
RE-EVALUATE BEFORE UPGRADING TO A BLIZZARD WARNING FOR PORTIONS OF  
THE DDC FA OR DROPPING THE WATCH IF THE SNOW DOES NOT MATERIALIZE.   

-UMSCHEID  

Blizzard conditions appear more likely in Dodge City — particularly in the 12am to 12pm Christmas Eve day time frame.  The new 00z NAM model is in and it appears more favorable for blizzard conditions around western Kansas.  Now that we are zeroing in on this storm as it is within the CONUS RAOB network, the models should finally begin to lock into a solution — which favors 850 to 700mb cyclogenesis over southern/eastern Kansas.  Frontogenesis fields also look more favorable to the west of the low, thanks to the arctic air intrusion from the surface to 700mb from Montana and Wyoming.  The position of the 1036+ High and the sub-1000mb Low is classic when compared to historic western Kansas blizzard events.  I’ve done some research on this subject, and tomorrow I’ll show a composite chart of MSLP pattern of 20 Central High Plains blizzard cases dating back to 1948. See the chart below:

My driveway is already slick! I didn’t expect the light freezing drizzle to develop this soon, but it has.  That low level warm advection atop the shallow cold layer is already underway, and it’s just going to get worse.  Temperature in Dodge is now 28°F.  It appears the 3-6″ is still on track as the latest numerical model prediction continues to keep the 500mb vorticity stream south of southwest Kansas as it undergoes a hard-to-predict re-orientation from an east to west configuration to more of a meridional north-south configuration.  See the cartoon below:

As it is doing this, the storm undergoes cyclogenesis in the low levels.  How fast will this occur?  How much will the whole storm itself translate east is it re-orients itself.  How is the northern PV anomaly up in Montana going to affect this??  This is an unusual time when the global spectral models are still very volatile even at 36-60 hours!  Below is the numerical prediction of 500mb Height/Vorticity from the GFS and ECMWF global models valid for 6am CST Christmas Eve morning Dec 24:

I am expecting 3-6″ here in Dodge City.  Currently, it is 30°F and foggy in Dodge City as of Noon. Well, this is my second attempt at this post, so this will be brief.  Numerical models are really struggling with the phasing of the southern stream storm and a second northern stream system dropping south out of Canada into the Rockies in the 60-84 hr time frame.  This all has impacts on the mid level and low level cyclogenesis and tracks of the lows.  Let’s look at some REAL DATA though.  Here is the surface chart as of 11am:

The dashed line in the image above is the subjectively analyzed axis of surface vorticity and baroclinicity.  This is where the surface low will form and track as the upper system approaches tonight and tomorrow.  A West Texas through Childress, TX through Central OK track is ideal for decent snow in Dodge City.  This is promising!  Below is the water vapor image from late this morning:

The southernmost PV anomaly (denoted in yellow X) will take a track close to the white arrow.  This PV track is also favorable for accumulating snow in Southwest Kansas including Dodge City.  I’ll write more later this afternoon.  -Mike U

…Potentially major, long duration blizzard to affect portions of Kansas and Nebraska!…

I decided to blog about this event since there will likely be impacts in Dodge City…including at least 3-6 hours of blizzard (or at least near-blizzard) conditions.  I am working 10pm to 6am forecast shifts right now at WFO Dodge City — my last one being Wednesday morning.  This is going to be a very, very close call for Dodge City regarding major blizzard impacts.  It is still 60 to 72 hours from the major impacts from this storm, so there is plenty of time for models to change…but there is now VERY solid agreement among the major models regarding this storm… which will be a TRUE blizzard…for a good portion of the Central Plains.  Below are a few charts to start off this meteorological documentation of this event:

Water vapor image showing the mid level moist and dry regions that correspond to areas of lift and subsidence.  Black arrows denote the upper level jet cores.  I highlighted the subjectively analyzed Potential Vorticity (PV) stream in red.  This is the making of the storm.  This PV stream will continue to dig south-southeast…reaching a base somewhere over Arizona tomorrow, December 22nd.  Cyclogenesis will then begin as the mid level jet streak rounds the base of the carved out trough.

Here is a sample of some of the major model predictions on what to do with the mid level vorticity and height pattern once the PV stream reaches its southernmost point.  Timing is still a huge issue, and history has taught us High Plains winter forecasters that “slower and deeper” is the way to go.  Right now, that would be the UKMET model.  It is farthest southwest with the main PV and 500mb low center valid 00z Thursday Dec 24.

And then there was the wind.  The ECMWF and UKMET models are depicted here valid 12z Thursday Christmas Eve morning.  A ~998mb low vs. a 1034mb high from the southeast Plains to the far northern High Plains is a classic SLP pattern for western Plains blizzards historically.  The yellow dot on the two charts above denote Dodge City — firmly in the SLP gradient at this valid time.

More later.  I go into work at 10pm, and while I am at work I will not blog since I have to do my professional forecasting of this event for the 27 counties of Southwest Kansas we are responsible for.  Next update will likely be early in the morning or perhaps one more before I go into work this evening.  -Mike U