CBM CBM Severe Weather and Hazardous Conditions 1 — Questions and Answers
Question 1: What is the minimum sustained wind speed (mph) that classifies a tropical cyclone as a Category 1 hurricane on the Saffir-Simpson scale?
- 64 mph
- 74 mph (Correct answer)
- 85 mph
- 96 mph
Correct answer: 74 mph
A Category 1 hurricane begins at sustained winds of 74 mph (64 knots), the threshold that distinguishes it from a tropical storm.
Question 2: What distinguishes a 'supercell' thunderstorm from an ordinary thunderstorm?
- Greater rainfall totals and wider coverage
- A persistent rotating updraft called a mesocyclone (Correct answer)
- More frequent cloud-to-ground lightning
- Formation exclusively along cold fronts
Correct answer: A persistent rotating updraft called a mesocyclone
The defining characteristic of a supercell is a deep, persistent rotating updraft (mesocyclone), which makes it capable of producing large hail, damaging winds, and strong tornadoes.
Question 3: What is 'storm surge' in a hurricane context?
- The rapid intensification of a hurricane within 24 hours
- An abnormal rise of water above normal tide level driven by a storm's winds and pressure (Correct answer)
- Heavy rainfall on the right side of a hurricane
- The forward speed acceleration of a tropical cyclone
Correct answer: An abnormal rise of water above normal tide level driven by a storm's winds and pressure
Storm surge is the abnormal coastal flooding caused by a hurricane's onshore winds and low pressure pushing ocean water inland, and it is historically the leading cause of hurricane deaths.
Question 4: A tornado WARNING (as opposed to a watch) means what?
- Conditions are favorable for tornado development in the area
- A tornado has been spotted or indicated by radar and is imminent or occurring (Correct answer)
- Strong thunderstorms are possible within the next 6 hours
- A tornado has been confirmed but has already dissipated
Correct answer: A tornado has been spotted or indicated by radar and is imminent or occurring
A tornado warning is issued when a tornado is indicated by radar rotation or confirmed by a trained spotter, requiring immediate shelter action.
Question 5: What minimum sustained wind speed (mph) is required for a tropical cyclone to be classified as a tropical storm?
- 25 mph
- 39 mph (Correct answer)
- 55 mph
- 64 mph
Correct answer: 39 mph
A tropical cyclone becomes a named tropical storm when sustained winds reach 39 mph (34 knots), at which point it receives a name from the seasonal list.
Question 6: What is a 'derecho'?
- A cold-core upper-level low causing prolonged thunderstorms
- A long-lived, fast-moving windstorm associated with a line of severe thunderstorms, producing straight-line winds (Correct answer)
- A tornado family outbreak spawned by a single supercell
- A tropical storm remnant moving inland
Correct answer: A long-lived, fast-moving windstorm associated with a line of severe thunderstorms, producing straight-line winds
A derecho is a widespread, long-lived wind event with damaging straight-line winds (≥58 mph) across a path at least 250 miles long, produced by a bow echo or QLCS.
CBM CBM Severe Weather and Hazardous Conditions 1
What is the minimum sustained wind speed (mph) that classifies a tropical cyclone as a Category 1 hurricane on the Saffir-Simpson scale?