1. Given the attached temperature sounding for Vancouver, valid at noon local time yesterday. Also, given the following weather observation at 3 PM local time on that same day:
METAR CYVR 082300Z 14015KT 5SM TSRA BKN082 40/20 A2953

a. (7 points) What is the 3 PM relative humidity near the surface? ___________%

b. (5) How high is the tropopause over Vancouver on this day? ________ kPa

c. (8) At 3 PM, assume the noon sounding is unchanged, except for the new surface
temperature. To what altitude (i.e., pressure) must surface air be lifted by a trigger
mechanism to initiate a thunderstorm? ____________ kPa

d. (8) The top of the thunderstorm reaches what altitude (i.e., pressure) on this day? __________ kPa

e. (3) The name for this top part of the thunderstorm is ________________________________ .

f. (5) The hydrometeors at the top of this particular storm are likely to be (circle one:
ice only , ice and supercooled water , liquid only )

2. (15) The local weather radar in Aldergrove observes a peak reflectivity
of 50 dBZ in the storm. This would be associated with a heating rate of ____________________ .
This drives the “heat engine” of the thunderstorm.

3. The precipitation pattern on the ground is sketched
in the map at right. In that map, sketch the likely
locations of the:
a. (3) gust front (indicate with a curved line),
b. (3) rear flank downdraft (label with “RFD”),
c. (3) main updraft (label with “U”).
d. (2) Also, what is the name of the line that
surrounds the heavy precip
area in the map at right? _________________

4. The Doppler radar (“R”) at Aldergrove detects
a tornado at location “T” in the map at right.
a. (8) Sketch the “tornado vortex signature”
on this map, using different shading or colours
to indicate regions with different signs.

b. (10) A max Doppler shift of delta nu = 1600 s–1
is measured by the 10 cm radar. What is
the likely Fujita intensity classification? F______

5. (20) Suppose that “precipitation drag” works oppositely, such that falling hydrometeors force the surrounding air upwards. How would thunderstorms and associated phenomena be different, if at all? (Write your response in the answer book)

Attachment: Sounding (plotted on a thermo diagram).

P (kPa)	T (C)
20	-20
40	-20
60	5
75	20
80	11
100	30