Department of Earth & Climate Sciences Spring
2018
Meteorology 260 Name
_____________________
Laboratory #11: Joplin Tornado Day
Subsynoptic, Thermodynamic,
and Wind Shear Setting
Due Date: Friday 4 May
Part A: 2200
UTC Midafternoon Surface Chart Subsynoptic Analyses (100 pts)
Part B:
1200 UTC Sounding Analyses (100 pts)
Part C:
1200 UTC CAPE Analyses (100
pts)
Part D:
1200 UTC Hodograph Analyses (100 pts)
Purpose
of this Assignment:
á
Operational
and Practical Purposes:
o
To
study the subsynoptic, thermodynamic, and wind shear environments in which the
Joplin tornadic thunderstorm developed;
á
Skills
and Techniques Learned or Applied
o
To
have the students apply the techniques they have learned in the SkewT/log P
Sounding and hodograph analyses part of the class;
o
To
give students an opportunity to visualize how instability manifests itself in
the morning environment in severe weather settings;
o
To
show students how severe weather meteorologists estimate afternoon instability
by transforming the morning sounding;
o
To
show students how to evaluate the instability graphically, and computationally;
o
To
introduce students to the finite difference approximation of summation;(integration)
graphically and computationally;
Part A:
2200 UTC Surface Chart Subsynoptic Analyses
Fig. 1: Surface plot with isobars, 2200 UTC 22
May 2011
Figure 1 is the 2200 UTC
surface chart on 22 May 2011.
Isobars are drawn at two millibar intervals, with two labeled. You are also provided a separate clean
copy of this chart for your final analyses. You have the 1200 and 1600 UTC analyzed surface
charts from Lab 9 (100 pts)
1. On the copy above, draw
blue, brown, green, and red streamlines, as we have have done in class many
times to help find important boundaries (10 pts);
2. On the copy ablove, label
lows and highs (if present) using the correct color convention, shade in the area in which dew points
are 60F or greater in light green (10 pts);
3. On the copy above, note
that the isobars are strongly kinked away from low pressure in certain locations. It turns out that isobars are strongly
kinked usually in areas in which they cross boundaries. Using this knowledge, and your results
in (1) above, now draw in all the boundaries, using correct symbols and color
conventions. (40 pts)
4. Transfer all that youÕve
done above to the final clean copy.
This is what you will turn in and what will be graded. Neatness counts here. (10 pts for Neat
Analysis)
5. How does your analysis conform
to the prethunderstorm environment generally considered to be associated with
severe weather in the Great Plains (30 pts)
Part B:
1200 UTC Sounding Analyses (100 pts)
You are provided with two color copies of Fig. 1
below, the Springfield MO sounding
and hodograph for 12 UTC 22 May 2011
Fig.
1: KSGF Sounding and Hodograph, 12
UTC 5/22/11
1.
Determine the morning stability at KSGF (Springfield, MO) by
analysis of one of the copies of the morning sounding for 1200 UTC 22 May 2011
by completing the following tasks:
a.
Estimate the height (in millibars) of the Lifting
Condensation Level, Level of Free Convection, 500 mb Lifted Index, Equilibrium
Level. Be sure to indicate the
parcel ascent curve, LCL, LFC and EL right on the diagram. And shade in the
areas of CAPE and CIN with proper colors; (30 pts)
b.
Is the sounding absolutely unstable, absolutely stable or
conditionally unstable for a surface lifted parcel. Explain your answer in several
sentences. (20 pts)
2.
On the second copy of the sounding for for 1200 UTC 22 May
2011 (second copy), estimate the afternoon stability at KSGF (Springfield, MO
by completing the following tasks:
a.
Estimate the Convective Temperature, Convective Condensation
Level and determine if the sounding is potentially unstable. Indicate the Convective Temperature (CT),
Convective Condensation Level (CCL), and ÒafternoonÓ parcel ascent curve,
positive area on sounding (CAPE) (shaded red), and negative area on sounding
(CIN) (shaded blue); (30 pts)
b.
Is the sounding you modified for afternoon surface heating
potentially stable or unstable for a surface lifted parcel. Explain your answer in several
sentences. (20 pts)
Part C: Calculation of CAPE
1.
Calculate
the CAPE from the morning sounding using the method discussed in
class. You'll be
approximating the CAPE crudely (explained in class) by summing up the
indidividual contributions of layers approximately 1500 m thick. The table
below should get you started. (95 points)
2.
Using
the results from (1) above, calculate the maximum vertical velocity at the EL
in the morning. (Started in class) (5
points)
Pressure (mb) 
Elevation AGL (m) 
Temp Env (K) 
Temp Parcel (K) 
Diff 
(LFC) ~700 
~3000 



600 
~4500 



500 
~6000 



400 
~7500 



300 
~9000 



(EL) 240 
~10500 



Table 1:
Temperature Information Obtained from Sounding Analyses (completed in
Part B) for KSGF 12 UTC 5/22/11
Part D: 1200 UTC Hodograph
Analyses (100 pts)
Table
1 shows the wind directions and speeds observed in the Springfield sounding 12
UTC 22 May 2011. Figure 2 is a
blank diagram called a ÒhodographÓ .
It allows us to visualize the way wind directions and speeds vary with
height.
Table 1: Winds and pressures observed in KSGL
radiosonde launch, 12 UTC 22 May 2011
Figure 2: Blank hodograph pape
Pressure (mb) 
Height (m) AGL 
Direction (deg) 
Speed (kts) 
962 
0 


925 
340 


850 
1071 


700 
2709 


500 
5361 


479 
5704 


Table 2: Wind Directions (deg) and speeds (kts)
at selected pressure levels
StormRelative Helicity (m^{2}/s^{2}) 
Midlevel Mesocyclone Strength 
Meets Strength Threshold for Categorization as
Supercell 
100 
Weak 
No 
150 
Moderate 
Yes 
250 
Strong 
Yes 
>350 
Violent 
Yes 
Table 3: Storm Relative Helicity and Mesocyclone
Strength
1. Fill in Table 2 with the
wind directions and speeds extracted from the radiosonde information in Table 1;
(2 pts each for 24 points)
2. Plot the hodograph as
follows:
a. Plot an arrow (vector) for
each level given in Table 2, as shown in class. Label each arrow near its end
with the appropriate level (for example, Sfc). (2 pts each for a total of 10
pts)
b. Put a black dot at the tip
of each arrow; (2 pts each for a total of 10 pts)
c. Draw (neatly) straight line
segments connecting each dot. (2 pts each for a total of 10 pts)
3. In plain english describe
how the the wind in the lowest 6 km, as visualized by the hodograph you just
constructed, varied with height. (4
pts)
4. In plain english describe
if this is consistent with your answer in Part A, #5(4 pts)
5. Storm motions:
a. Using the method discussed
in class, plot a Yellow Circle for the initial storm motion. (4 pts)
b. Using the method discussed
in class, plot Red Circles for the motion of the left and right moving
supercells; (4 pts)
6. The 03 km storm relative
helicity (SRH) calculated for this hodograph can be found in the box on the
upper right of the sounding.
Positive values of this parameter indicate that inflow air entering the
updraft of any developing thunderstorm would be rotating. Answer in complete sentences.
a. Using the information given
in Table 3, categorize the potential strength of the midlevel mesocyclone of
any developing thunderstorm; (10
pts)
b. How do your values in Table
2 and the plotted hodograph conceptually indicate that the updraft of any
developing thunderstorm on this cay would be helical (rotating)? (10 pts)
7. Table 4 contains the values
of various parameters for all tornadoes in the Great Plains since 2008 that
occurred with the prototype severe weather pattern in the Great Plains AND a
loaded gun sounding. The row
highlighted in yellow contains the parameters for the Joplin Tornado.
Table 4: Parameters Associated with All Tornado
Occurrences in the southern Great Plains since 2008 that occurred with the
prototype severe weather pattern discussed in class and a Loaded Gun Sounding. (from Davies, J. M., 2017: Meteorological
setting for a catastrophic event: The deadly Joplin tornado of 22 May 2011. Electronic
J. Severe Storms Meteor., 12 (3), 1Ð23.)
Comment on the relationship
between the value of EHI and tornado strength that you can deduce from the
information in this table. (20
points)