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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 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.

2 Comments »

  1. This is the part I hate… the waiting game. Glued to my computer for 60 hours watching every single model run. Watching the system is kind of like watching a bowling ball, shouting “further to the left, further to the left… no, too far! go right, go right! damn it!”

    Comment by Robert Dewey — January 30, 2011 @ 3:23 pm

  2. bout time!

    Comment by Stephanie Dunten — January 30, 2011 @ 6:24 pm

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