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High Plains Drifter

disclaimer:  "The meteorological views/forecast thinking expressed are those solely of the author of this blog
and do not necessarily represent those of official National Weather Service forecast products,
therefore read and enjoy at your own risk and edification!"

January 31, 2011

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [7]

Filed under: 2011 Feb 1-2 — Mike U @ 10:51 pm

A historic cold & windy day expected in Dodge City tomorrow! Well we may not be catching the snow end of this storm, but Southwest Kansas will bear the brunt of the cold + wind aspect of this storm.  There is no missing out on this.  A very rare combination of a 1052mb arctic high and a dynamic 1000mb low will be positioned perfectly such that Southwest Kansas will be right in the middle of the two.  Arctic air is already in place, and as of the time of this writing, the temperature at Dodge City was 10°F (Fig. 1).  The temperature will continue to steadily fall on 30 to 40 mph north winds all night and through the day Tuesday.

It should be noted that it is very rare to see temperatures hovering around 0 to 5°F throughout the day in Dodge City.  It is even more rare to see 25 to 40 mph winds tied to these temperatures.  This is a very anomalous cold event.  Reaching wind chill advisory criteria (-15°F) is difficult enough as it is for Dodge City, let alone wind chill WARNING criteria (-25°F), given the new equation for Wind Chill Index.  I have never seen the wind chill, with the new equation, reach colder than -20°F in Dodge City.  The combination of wind and temperature should lead to wind chill index readings of -25°F on just sustained wind alone!  In gusts, the wind chill will likely get as cold as -32°F!!  See Figure 2 below showing the RUC forecast temperature and wind gusts for 15z (9am) tomorrow morning.  Quite amazing.

Figure 1.

Figure 2.

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [6]

Filed under: 2011 Feb 1-2 — Mike U @ 5:09 pm

A trace of snow in Dodge City this afternoon…heavier snow overnight. some low level snow showers developed this afternoon making the ground white in spots, but mainly what little snow has fallen is being blowing around on this afternoon’s 20-30mph north winds (Fig. 1).  Temperatures have fallen into the upper teens, and even colder air is on the way.  Winds will also increase overnight tonight as the low begins to take shape in Texas, along with the arctic high expanding across the northern High Plains.  Winds will increase to 25-35 mph with frequent gusts above 40 mph by early Tuesday morning.  Even if we get 1-2″ of snow, this will cause some problems.  The latest GFS, NAM, and RUC all suggest a 1-3″ snowfall potential for Dodge City.  Figure 2 shows the 19z run of the RUC model valid 10z (4am CST) tomorrow morning as the snow really ramps up across Oklahoma and southern Kansas.  By 13z, the RUC shows about 1.5″ of snow accumulation in DDC.  The HRRR has been showing the same kind of snowfall through that time as well.  Tomorrow morning should prove to be nasty in Dodge City and all of southern KS for that matter.  Figure 3 shows the Dodge City forecast with a high of 6°F tomorrow!  Blizzard warnings have been issued from central/northeastern Oklahoma through much of Missouri and into Illinois (Fig. 4)

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [5]

Filed under: 2011 Feb 1-2 — Mike U @ 11:53 am

Watch out for the warm layer aloft! The potential for heavy sleet will wreck snow accumulations for some folks.  I think the warm layer aloft, maximized around 800mb or so per the latest NAM, will extend as far northwest as my virtual chase target (Columbia, MO).  I think south-central Missouri to Saint Louis may see enough of a warm layer aloft from 775 to 825mb to see sleet.  In fact, far south central into southeast Missouri will likely experience quite an ice storm as maximum warm layer aloft temperatures may exceed +3°C.  The series of images below shows this morning’s 12z simulated reflectivity from the 12km NAM.  I also overlaid the 800mb critical temperatures, in 1°C intervals from -1C to +5C.  In pink is the NAM model 31-34°F surface temperature range.  Note the overlap of warm 800mb temperatures into the surface cold air with the precipitation moving across southeastern Missouri into far southern Illinois during the day Tuesday.

Series of 6-hr interval images from the this morning’s (12z Jan 31) 12km NAM model valid from 12z Tuesday 2/1 through 06z Wednesday 2/1

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [4]

Filed under: 2011 Feb 1-2 — Mike U @ 1:49 am

Virtual Winter Storm Chase Target……Columbia, MO. The global spectral model solutions have settled down enough to a point that it’s time to investigate some potential subsynoptic aspects of this storm and try to figure out where the best probability for 20 inches of snow will be.  20+ inches of snow from one synoptic storm in the central United States without any topographic or lake effect influence is rare.  It takes the perfect combination of the golden three:  1) intense, deep tropospheric baroclinicity 2) very abundant Gulf of Mexico moisture, and 3) jet stream winds to manifest this baroclinic instability and moisture into one major-league, robust storm.  See Figure 2 for the latest surface map showing the arctic air to the north and the Gulf of Mexico moisture ready to come back north.  In essence, all great mid latitude cyclones, by nature, need to have all of these properties in order to produce such a large-scale, tremendous output of precipitation as can bee seen in Figure 1.  Anyway, I wish I had the time off work to experience this one, seeing as we’ll miss out here in Dodge City, because there is a very good chance that a few locations will see 20-24″ of snow.  The trick is trying to figure out where exactly that will occur.  Model QPF fields give a nice clue, but QPF fields tend to be quite unstable run-to-run when it comes down to the details of figuring out where will be the greatest probability of the most snowfall.  Cyclogenesis, cyclogenesis, cyclogenesis!  It’s important to determine when the most mature phase of the storm will be (during what time frame is the 500-700mb lows deepening the most?).  Ageostrophic motions in the atmosphere are most pronounced at times of cyclone deepening, when the atmosphere is really out of balance.

The GFS and the Canadian GEM models both suggest the most vigorous development during the day Tuesday with a 700mb low really deepening substantially by 00z Wednesday 2/2.  It will be doing this over central/eastern Missouri.  This is where I believe is the best probability for 20+ inches of snow.  I believe this will extend from roughly Lake of the Ozarks to Columbia, MO to Bloomington, IL.  Columbia is a nice middle ground, and it’s along Interstate 70, so thus the reason for choosing this as my virtual target.  The GFS shows the 700mb Theta-E axis really maturing and bending back to the west into the cold air (Figure 3), with development of the inverted theta-e ridge (commonly known as the “TROWAL” in meteorological circles) by late in the day Tuesday.  There will be 2 to 3+” per hour snowfall rates for a sustained period of time along the nose of the 700mb Theta-E ridge in the cold air.  Upward vertical motion should be through the roof with all the sub-synoptic forcing for ascent and all the available moisture to work with.

Wind is another interesting facet of this system.  Check out the forecast MSLP gradient in the 48-hr Canadian GEM model forecast!! (Figure 4).  If that gradient does actually become realized, then blizzard conditions will exist.  It’s shaping up to be a hell of a storm for eastern Oklahoma, pretty much all of Missouri, and Illinois.

A huge area of the central and eastern U.S. is forecast to receive more than an inch of liquid equivalent precipitation Feb 1-3
Figure 1.

Surface map as of 11pm on 2001 Jan 30
Figure 2.

48hr fcst of GFS valid 00z Feb 2
Figure 3.

48hr fcst of Canadian GEM valid 00z Feb 2
Figure 4.

January 30, 2011

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [3]

Filed under: 2011 Feb 1-2 — Mike U @ 2:01 pm

This morning’s model runs suggest a trend to the north and west with heavy snow axis. The new 12z runs of the NAM, GFS, and even the Canadian GEM support a scenario which includes areas like Wichita and Kansas City for heavy snow.  The mid level PV anomaly is now expected to lift out in a more northerly direction given the very cold upstream disturbance digging south in its wake which will act to pivot the main lead wave out sooner and in a more northerly direction.  In fact, the 12z runs may still be playing catch up to what may eventually happen, and if that’s the case, then the main lead PV anomaly will undergo development even quicker and lift out north-northeasterly into Kansas!  If this does happen, then development at 700mb will occur faster and farther west, which is good for decent accumulating snow in Dodge City.  The trends look “up” right now for portions of southwest and especially south-central Kansas.  It still looks like the real major heavy snow axis will be across the eastern Great Plains into the Mid-Mississippi Valley, but this heavy snow axis will likely be farther north and a bit west than what Post #2 indicated.  Major snowfall of 12″ or greater will occur in the heavy snow axis, which at this time, now looks to include Kansas City and points northeast of there through Quincy, MO and up to Chicago.  The heavy snow axis of 5 to 8″ may begin as far southwest as Northwestern Oklahoma, which is getting closer to Dodge City, and there is still time for the westward trend to continue to perhaps include Dodge City.  Right now, I am expecting 1 to 3″ in Dodge City, but that is with very low confidence given the instability in the model depiction of heavy QPF axes.

00z/Jan30 run of GFS valid 12z 2/1 at 700mb
Figure 1. Last night’s GFS run did not show much development at 700mb south of Dodge City.  The wind fields did not show a tremendous amount of convergence and/or deformation which is necessary for good upward vertical motion.

12z/Jan30 run of GFS valid 12z 2/1 at 700mb
Figure 2. This morning’s GFS run, however, does show better development at 700mb south of Dodge City, which is directly tied to better jet streak dynamics and a more robust development at 500mb

12z/Jan30 run of GFS valid 06z 2/1 at 500mb
Figure 3. 500mb Temperature and Wind forecast from this morning’s GFS run.  White arrows depict the individual jet streaks at 500mb.  Check out the cold air at 500mb across the northern Rockies — a very anomalous -40C in eastern Montana!  This will lead to stronger cold advection into the base of the trough and subsequently more vigorous mid level cyclonic development.  The track of the mid level PV anomaly is in yellow as per the GFS.  The Canadian model is very similar with this track.  Heavy snow almost always occurs just north of the mid level PV track, which is where frontogenesis and westward extension of the warm conveyor (a.k.a. the “TROWAL”) sets up.  If this track pans out, heavy snow is most likely from Northwest Oklahoma through south-central Kansas to east-central Kansas — major cities like Wichita and Kansas City being in this track.

12z/Jan30 run of GFS snow accumulation
Figure 4.

12z/Jan30 run of NAM snow accumulation
Figure 5.

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [2]

Filed under: 2011 Feb 1-2 — Mike U @ 3:07 am

An I-44 & Ohio Valley Special! The Feb 1-2 storm coming up will be rather impressive.  Actually really impressive.  It’s a classic meet-and-greet of very cold, arctic air and an unrestricted, rich Gulf of Mexico moisture source.  A true “Clash of the Airmasses”.  (Yes, this is the worst pseudo-meteorological idiom ever).  At any rate, this storm is interesting enough to me to blog about, despite it not really affecting Southwest Kansas much.  I usually only blog about the western Great Plains storms, but given the dearth of winter precipitation events out here this season, I was itching to write about something.  At least we’ll see the cold air component here in Dodge City (as was the focus of post #1 of this series), and perhaps an inch of snow.  But the real story will be farther east…where areas like Tulsa, Springfield MO, Saint Louis, Indianapolis, and Cincinnati will see some rather phenomenal winter precipitation whether it be heavy snow, sleet, or freezing rain (or a combination of the three to some degree).  There should be a 50-100 mile wide swath of potentially very damaging icing from eastern Oklahoma through northern Arkansas into portions of southeastern Missouri and then northeast along the Ohio River (give or take).  This is the classical corridor for major ice storms.  Immediately north of the sleet/freezing rain, both the NAM and GFS indicate the potential for heavy snow accumulation of 15 to 24 inches.  It is interesting that, even at 60-72 hours out, both the models show a similar storm total snow axis and magnitude.  See Figures 1 and 2 below.  In Figure 3, I created a composite chart using IDV (Integrated Data Viewer) and GFS grids showing the forecast warm layer aloft, centered roughly around 850mb (the salmon and red shading area) along with surface temperature isotherms of 22, 28, 32, 35°F which reveals the forecast overlap of these fields indicating the best area for sleet/freezing rain (model uncertainties at this time frame understood, of course).  It looks like my friends and family in Kansas City will be on the northwestern fringes of this storm, but it wouldn’t take much of a shift to the north… and for the storm to mature faster… to bring Kansas City into play for some serious accumulating winter precipitation.

NAM run total snowfall from the 00z/Jan30 run
Figure 1.

GFS total snowfall through 00z/Feb03 from the 00z/Jan30 run
Figure 2.

Composite chart showing ice storm potential from the 72-hour GFS forecast valid 00z/Feb02
Figure 3.

January 29, 2011

Central U.S. Winter Storm and Cold Air Outbreak 2011 February 1-2 [1]

Filed under: 2011 Feb 1-2 — Mike U @ 11:11 pm

Dramatic changes coming to the Central/Southern Plains, Mid-Mississippi Valley region. A substantial arctic air intrusion is expected next Tuesday and Wednesday.  In addition, a decent portion of the Central U.S. will see some major winter precipitation, including freezing rain, sleet, and snow.  A mid-latitude cyclone will mature at the boundary of the arctic airmass leading to a widespread winter storm event.  It looks like the most substantial winter precipitation will extend from Oklahoma through Missouri and east toward the Ohio Valley/lower Great Lakes region.  We saw a high of 71 in Dodge City on Friday, January 28th, which was only a few degrees from a record high for the date.  4-days later, on Tuesday, February 1, the late afternoon temperature in Dodge City will likey be around 10°F!

NAM 3-hr Surface temperature forecast for 3pm 1/28
Figure 1. Surface map as depicted by the 3-hr NAM forecast showing the 70s in Southwest Kansas on Friday, 1/28

NAM 69-hr Surface temperature forecast for 3pm 2/1
Figure 2. Surface map as depicted by the 69-hr NAM forecast showing temperatures in the teens in Southwest Kansas on Tuesday afternoon, 2/1

NWS Forecast for Dodge City, Kansas City, Springfield MO, Norman OK from Saturday evening 1/29/2011
Figure 3. Official NWS forecasts for Dodge City, Kansas City, Springfield MO, and Norman OK for the upcoming winter weather event for next week.  A winter storm watch is already in effect for Kansas City and Springfield MO.

January 17, 2011

Mid-winter convection in western Kansas

Filed under: General Weather & Forecasting — Mike U @ 9:07 pm

Mid-winter convection! An unstable airmass, by mid-January standards, greeted western Kansas on January 17th, providing for some low-topped convective updrafts in the northwest flow.  Temperatures rose into the upper 50s to near 60 at Garden City and Dodge City with dewpoints rising into the lower to mid 40s.  I drove north up toward the Horse Thief Reservoir about 15 miles north-northwest of my house to photograph one of the small convective cells.  It certainly felt more like an early spring day instead of the dead of winter!

January 9, 2011

Southwest Kansas Winter Weather Event January 9-10 [post 2]

Filed under: 2011 Jan 10 — Mike U @ 10:09 pm

The “haves” and the “have nots” — The storm is coming out across the Rockies in pieces — not good for heavy snow in Dodge City. My updated thinking is 1-3″ in Dodge City for this event.  We’ve started to get some very light snow here at my house just north of town, but only a dusting of accumulation so far.  The expected cyclogenesis from the surface to about 700mb just isn’t going to take shape like earlier expected, and as such, only periods of light (maybe moderate at times) snow will occur through Monday.  Since the storm will  not be as developed for southwest Kansas, the winds behind the low will not be as strong, so the blowing and drifting component will also likely be less than I previously thought.  Unless radar echoes blossom in the area highlighted in Figure 2 (associated with the “x” near the Colorado-Utah border as shown in Figure 1) through the night, then this just isn’t going to happen for most of Southwest Kansas along and south of Highway 50.  The Hays and Wakeeney areas have already seen an inch or two of snow with the first little mesoscale wave while we were left high and dry in Dodge for the most part.  Yet another “blah” event it would appear.

Figure 1

Figure 2

Meanwhile, the real excitement isn’t even occurring across the Central Plains, but in the Southeast.  A major ice and snow storm is underway across much of the Gulf Coast/Southeast region (except for near the coast where it’s warm enough for all rain):

Figure 3

Figure 4

January 8, 2011

Southwest Kansas Winter Storm January 9-10 [post 1]

Filed under: 2011 Jan 10 — Mike U @ 9:15 pm

Accumulating snow, strong winds, and cold temps headed for Southwest Kansas. We are within 30 hours of the beginning of a winter storm to affect western Kansas. I have been working midnight shifts working this event at the Dodge City NWSFO, but the time has come to begin blogging a little bit about the storm. I think we’ll see 5 to 7″ of snow in Dodge City… that is my own personal prediction at this point based on the latest forecast track/strength of the approaching storm from various model inputs. Figure 1 shows the MSLP and surface wind pattern. Note the surface circulation from near Gage, OK to Childress, TX. This good for moderate/heavy snow for much of Southwest Kansas. This low level development is going to form in the left exit region of an upper level jet streak, which is shown in blue in Figure 2. The jet streak dynamics will be quite good. Winds will shift at the surface from southeast to northeast Monday morning…then to the north and increasing 20-30 mph by midday in Dodge City. Substantial blowing and drifting snow will occur across much of Southwest Kansas. The ECMWF model has pegged this for a number of runs now, and the NCEP models are finally trying to catch up with the ECMWF regarding the magnitude of wind and cold behind the front. Monday will be quite brutal around Dodge City.

Figure 1

Figure 2

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