CBM Numerical Weather Prediction and Forecast Models 3

Question 1

Which NWP model product provides probabilistic information about the likelihood of a specific weather event exceeding a threshold, such as winds over 35 mph?

Accepted Answer

Ensemble probability forecasts

Answer

Deterministic GFS 500 mb height map

Answer

Model sounding from a single NAM run

Answer

RAP hourly analysis

Question 2

The 'butterfly effect' in atmospheric predictability, attributed to Edward Lorenz, implies that:

Accepted Answer

Small errors in initial conditions can grow exponentially, limiting deterministic forecast skill

Answer

Tropical systems follow butterfly-shaped tracks

Answer

Models initialized at 00Z are always more accurate than 12Z runs

Answer

Ensemble spread always decreases beyond day 7

Question 3

When a broadcast meteorologist evaluates 500 mb geopotential height anomalies from model output, they are primarily assessing:

Accepted Answer

Large-scale atmospheric flow patterns and ridges or troughs affecting the weather forecast

Answer

Boundary-layer wind shear for tornado prediction

Answer

Sea-surface temperature anomalies in the Pacific

Answer

Low-level moisture convergence for precipitation

Question 4

Which statement best describes the concept of 'model spin-up' and why it matters?

Accepted Answer

The time required for a model's physical processes to adjust from initial conditions to a dynamically consistent state, which can degrade very short-range forecasts

Answer

The delay between data download and on-air graphics rendering

Answer

The period during which ensemble members diverge from the control run

Answer

The process of converting MOS output to user-readable text

Question 5

The North American Ensemble Forecast System (NAEFS) combines members from which two modeling centers?

Accepted Answer

NCEP (USA) and CMC (Canada)

Answer

NCEP (USA) and UKMET (United Kingdom)

Answer

ECMWF and NCEP

Answer

CMC (Canada) and ECMWF

Question 6

In model verification, the term 'bias' refers to:

Accepted Answer

A model's tendency to systematically over-forecast or under-forecast a specific variable

Answer

Random errors that vary from run to run with no consistent pattern

Answer

The difference between ensemble mean and ensemble median

Answer

The lag between model initialization and data availability

Question 7

For a broadcast meteorologist, what is the most important reason to cross-reference multiple NWP models rather than relying solely on one?

Accepted Answer

No single model is consistently superior in all situations; comparing models reveals uncertainty and highlights where confidence is higher or lower

Answer

Regulatory requirements mandate multi-model use for on-air forecasts

Answer

Different models are licensed for different geographic regions

Answer

Viewers expect to see multiple model graphics on screen simultaneously