Inclass Exercise and Homework 4 -- CAPE

Due Wednesday 5 May 2011.

(a) Plot the sounding for 12 UTC 21 April 2010 for Salt Lake City, Utah (KSLC) on the FSL interactive sounding site: http://www-frd.fsl.noaa.gov/mab/soundings/java/

i. Determine the elevation (in mb) of the LCL, LFC (if present) and EL (if present). (15 pts)

ii. What is the value of CAPE for this sounding? What is the value of CIN for this sounding? (10 pts)

(b) Examine the geographic plot of surface based CAPE for that is roughly coincident in time with the above sounding.

i. Describe whether the pattern shown in the Salt Lake City area is roughly consistent with your results above.(10 pts)

ii. What is the value of the vertical velocity at the Equilibrium Level for the CAPE value shown near Park City, Utah (that CAPE value is 450 J/kg)? (5 pts)

(c) The Day 1 Convective Outlook from SPC for 4/25/10 is given here. Note the red highlighted text in the discussion for the mid Missisippi River Valley.

".. STRONG SOUTHEASTERLY LOW LEVEL WINDS WILL TRANSPORT MOISTURE NORTHWARD AND HELP TO DESTABILIZE PARTS OF MO/IL/IND/KY AHEAD OF THE SURFACE LOW...."

Illustrate the point the forecaster was trying to make by doing the following:

(i) The 1400 UTC surface chart with two isobars drawn on it is given here.

  1. Isobars are drawn on standard synoptic charts at 4 millibar intervals. Draw the 1004, 1008, 1012, and 1016 isobars.
  2. Draw some streamlines on the 1400 UTC surface chart (arrows tangent to the instantaneous wind direction);

(ii) Here is the map showing surface-based CAPE and CIN for 1400 UTC. Using this chart and the surface chart you just analyzed, illustrate the statement the forecaster was making.