Department of Geosciences

DEPARTMENT OF EARTH & CLIMATE SCIENCES SAN FRANCISCO STATE UNIVERSITY Nov 29, 2016 ERTH 360 Test #2 Fall 2016 200 pts Each question is worth 4 points. Indicate your BEST CHOICE for each question on the Scantron Form. Turn in and and put your name on your Scantron Form. Part 1. Weather Forecast Products The portal website that we just have been using to access forecast weather maps is shown below. The selection chart from one of the models, known as the GFS, is reproduced below as Table 1. Assume that the choices indicate forecast weather maps for 24 hours in the future. Questions 1 through 5 refer to choices that appear in rows in Figure 1. Figure 1: Selection Choices for the GFS State which choice you would choose to find: 1. The wind conditions forecast for a level at approximately 32000 ft a. 300 mb b. 500 mb c. SLP/Thickness/Pcpn d. 700 mb/RH e. (a) and (b) both. 1 2. The Sea level weather (isobars) map a. 300 mb b. 500 mb c. SLP/Thickness/Pcpn d. 700 mb/RH e. (a) and (b) both. 3. The wind conditions at approximately 18000 ft a. 300 mb b. 500 mb c. SLP/Thickness/Pcpn d. 700 mb/RH e. (a) and (b) both. 4. The position of mid and upper tropospheric troughs and ridges. a. 300 mb b. 500 mb c. SLP/Thickness/Pcpn d. 700 mb/RH e. (a) and (b) both. 5. The model heading is GFS. This is an abbreviation of a. Guidance for Frontal Systems b. Graded Flight Selections c. Grouped Forecast Selections d. Gridded Forecast Solutions e. Global Forecast System Figure 2 is taken from the Documentary you watched on the El Reno OK May 31, 2013 tornado. Questions 6, 7, 8, and 9 ask you questions about the videos you watched. Figure 2: Screen capture from video on the El Reno OK tornado of 31 May 2016 6. On Figure 2, the yellow line a. shows the route of an airplane intercept of the El Reno tornado. b. shows the boundary of a Tornado Warning for the storm. 2 c. shows the path taken by a mobile mesonet in intercepting the storm. d. shows the track of a secondary subvortex circling the parent tornado that struck the vehicle in which Tim Samaras, Paul Samaras, and Karl Young were driving. e. is Interstate 40 in Oklahoma. 7. The closest position of the Reed Timmer team with respect to the Wray CO tornado was dangerous because a. the obvious tornado is often surrounded by tornado strength winds outside of visible funnel. b. the obvious tornado motion is often erratic and can double back, reverse, speed up on its own path. c. The team put itself at risk from being struck by any secondary tornado associated with the visible tornado. d. The team put themselves at risk because the diameter of the tornado can expand rapidly. e. all of the above. 8. The TWISTEX team made which of the following mistakes in their attempt to deploy instruments in the path of the El Reno tornado. a. The team was driving too fast and missed an important turn. b. The team made a navigational error that took them into the center of the parent tornado. c. The team put itself at risk from being struck by any secondary tornado associated with the visible tornado. d. The team put themselves at risk by sheltering from heavy rain in the wrong location. e. The team stopped to eat lunch and lost track of the tornado. 9. The closest position of the Brunin-Magowan team with respect to the Katie OK tornado was dangerous because a. the obvious tornado is often surrounded by tornado strength winds outside of visible funnel. b. the obvious tornado motion is often erratic and can double back, reverse, speed up on its own path. c. The team put itself at risk from being struck by any secondary tornado associated with the visible tornado. d. The team put themselves at risk because the diameter of the tornado can expand rapidly. e. all of the above. Part 2. Use and Interpretation of Weather Maps Figure 3 is the 300 mb chart for 06 UTC 31 October 2014. Note Lines A, B, C , D, and E and also note the Arrows Labeled 1, 2, 3, 4, and 5. Questions 10 through 13 refer to this figure. 3 Figure 3. 300 mb Chart for 0600 UTC 31 October 2014 10. On Fig. 3, a ridge is at Line(s) a. B and A (both) b. A and E (both) c. C d. D e. A 11. On Fig. 3, a (surface dynamic high would be located at a. A and E (both) b. D and E (both) c. C d. D e. B 12. On Fig. 3, divergence is probably occurring at Location a. A b. B c. C d. D e. E 13. On the basis of your interpretation of Fig. 3, the arrow which best shows the position of the polar jet stream is a. 1 b. 2 c. 3 d. 4 4 e. 5 Figure 4 is the surface chart for 12 UTC 9 November 2011. Note the pressure systems at A and B and the frontal lines at locations a, b and c. Questions 14 through 16 refer to this figure. Figure 4. Surface Chart, 1200 UTC 9 November 2011 14. On Fig. 4, the pressure system at A is a. a warm core low b. a dynamic low c. a dynamic high d. a wave cyclone e. b. and d. 15. On Fig. 4, Line a is a(n) a. Occluded Front b. Stationary Front c. Cold Front d. Warm Front e. Dry Line 16. On Fig. 4, Line c is probably a 5 a. Occluded Front b. Stationary Front c. Cold Front d. Warm Front e. Dry Line Figure 5 is the Meteogram for Saint Louis, 2000 UTC 8 to 2000 UTC 9 November 2011. Questions 17 through 19 refer to this figure Figure 5. Meteogram for Saint Louis, 2000 UTC 8 to 2000 UTC 9 November 2011 17. The direct evidence (seen on the meteogram given in Fig. 5) of a frontal passage at Saint Louis is a. the wind shift between 8 UTC and 9 UTC. b. the lowest pressure that occurred around 8 to 9 UTC. c. the rainfall that occurred between 9 UTC and 14 UTC d. a., b., and c. above. e. sharp temperature drop between 9 UTC and 14 UTC 18. The indirect evidence (seen on the meteogram given in Fig. 5) of a frontal passage at Saint Louis is a. the wind shift between 8 UTC and 9 UTC. b. the lowest pressure that occurred around 8 to 9 UTC. c. the rainfall that occurred between 9 UTC and 14 UTC d. a., b., and c. above. e. sharp temperature drop between 9 UTC and 14 UTC 19. The evidence (seen on the meteogram given in Fig. 5) suggests that the front passing Saint Louis was 6 a. a cold front. b. a warm front. c. a stationary front. d. an occluded front. e. no front passed Saint Louis. Part 3. Statistical Measures Important in Characterizing the Climate of an Area 20. The term “normal” (in the context of “normal” rainfall or “normal” temperature) is a. the usual rainfall or temperature expected in an area. b. defined as the average rainfall or temperature for the whole period of record. c. defined as the mean for the 30 yr period ending in the last year of the last decade (currently1981-2010) d. a measure of correlation. e. the standard deviation expressed as a percentage. 21. Correlation measures the degree to which a. the given relationship between the events is not due to chance alone and there is a systematic reason for the relationship. b. the average rainfall or temperature for the whole period of record does not change. c. the mean for the 30 yr period ending in the last year of the last decade (currently 1981- 2010) reflects the long term mean. d. the occurrence of one event is linked, by statistical test to the occurrence of another event. e. the standard deviation is expressed as a percentage. 22. Which of the following measures the range (either as a number or a ratio) of precipitation values relative to the average that can be expected 67% of “the time” (meaning, 67% of the years in the long term record will have rainfall values within the range) a. standard deviation b. correlation coefficient. c. coefficient of variation d. extreme values. e. (a) and (c) above. 23. In the context of correlation, the given relationship between the events is not due to chance alone and there is a systematic reason for the relationship is the definition for a. average or mean value. b. correlation coefficient. c. coefficient of variation d. statistical significance e. standard deviation Part 4. California Rainfall Variability Refer to Figure 6, a diagram that shows the seasonal rainfall for the period for the period of record for Downtown San Francisco. Questions 24 through 26 refer to this chart. 7 Figure 6. Seasonal Rainfall, San Francisco, Downtown, Period of Record 24. The term seasonal rainfall implies a. that the rainfall shown is only for the winter season. b. that the rainfall shown is only for the summer season. c. that the rainfall shown comes seasonally. d. that the rainfall shown is calculated for the period July 1 of one year to June 30 of the next.

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