NWP Group of modules
Exam 1
1. Spectral models use continuous wave functiongradients, while grid point models use discrete grid boxes to define meteorological fields. The implication of these differences is that ______models tend to have a better representation of global fields and gradients, while ______models lend themselves better to limited-area applications and tend to have a better representation of the effect of physical processes on the evolution of the weather.
2. Complete the following statement that defines a primary difference between hydrostatic and non-hydrostatic models.
______models can explicitly forecast vertical motion, whereas ______models only diagnose vertical motion fields.
3. A spectral model is preferable for forecasting which of these phenomenon?
a. Precipitation patterns near complex terrain with topographic resolution coarser than 10 km
b. Planetary wave pattern for the next 7 days
c. Development and evolution of a mesoscale convective system
d. Outflow boundary propagation
e. 24-hr boundary layer wind forecast
f. QPF for the next 5 days along the West Coast
4. When selecting a vertical coordinate system for an NWP model, what are two of the most important considerations (assuming unlimited computational resources)?
5. Match each vertical coordinate system (Sigma, Eta, or Isentropic) to its primary disadvantage in NWP models for depicting weather. (Choose the best match below, then click Done.)
a. May not correctly portray weather events in lee of mountains
b. May not represent the boundary layer with sufficient resolution over elevated terrain
c. Not allowed to represent superadiabatic conditions in the boundary layer
6. Which of the following are effects of inadequate model terrain on weather elements?
7. Using the graphic below, determine the feature(s) that you would expect precipitation schemes using inferred clouds to be able to reasonably represent in a model with grid spacing of 80 km.
8. If the convective parameterization scheme does not properly remove the instability, what effect(s) might the resulting heating profile have on other model forecast variables?
9. Which of the following statements about convective precipitation schemes are true?
10. Assume that model output shows a lot of "grid-scale" precipitation and very little or no convective precipitation in a convective situation affecting your area of forecast responsibility (underactive CP). What adjustments might you have to make?
11. You are the lead forecaster for the nighttime shift during the month of June. Upwind of your location, a mesoscale convective complex (MCC) is dying out, leaving a considerable amount of mid-level cloudiness or "debris," which can be seen on IR satellite imagery. After examining the initial conditions of the forecast models, it is clear that the MCC has not been analyzed in the RH fields and that the associated RH field will not be resolved. The models indicate that the next day will feature full sun with some afternoon airmass convection developing at the same time that the debris should be advecting over your area. You estimate that, in reality, it will take most of the day for the MCC-generated cloudiness to clear your area. How would you modify the model forecast for the following parameters?
12. You are the lead forecaster for the daytime shift during December, downwind from Lake Erie. The first lake-effect snow event of the year (not adequately predicted by the operational forecast models) occurred last night, depositing 6 to 12" of snow in your area. The forecast for today is for full sun, as high pressure moves over your area and cold advection and onshore winds abate. While the models use datasets derived from satellite data to determine the existence of snow cover, snow depth data was unavailable and the model was initialized with diagnosed model snow depth from the previous model run. The model surface albedo for snow is reduced toward the characteristic albedo of the underlying surface for any snow depth less than 2". This morning's model snow depth is only about 1". How, if at all, would you modify the model forecast for the following parameters?
13. If snow cover were tuned as indicated below, what forecast errors would likely result for model 2-m temperature, 2-m RH, PBL height, and the chance of convective precipitation?
14. In what kinds of situations would you expect statistical guidance to perform well?
15. Under the influence of which of the following would you expect MOS NOT to be reliable?
16. When diagnosing near-term model performance on the local level, would you expect weekly averaged measures to be more useful than monthly measures and why?
17. After ingesting new high quality data and generating a forecast, should a model's analysis closely resemble a skilled hand analysis?
18. Data voids in an observing network can cause (Click your choice):
19. In what situations is the DA system most likely to fail?
20. In which of the following situations are observations unlikely to impact the model's forecast favorably during the data assimilation process?