NWP Group of modules
Exam 1
1. Spectral models use continuous wave function gradients, 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?