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Flashcards in Exam II Deck (160)
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1

Under which of the following circumstances do errors in model physics have the highest impact?

A) When dynamic forcing is strong
B) When physical processes are strong
C) When dynamic forcing is weak
D) When physical processes are weak

B & C

2

Which of the following elements help forecasters add value over NWP?



A) Continuous MetWatch
B) Use of MOS for rare events
C) Regular use of verification
D) Forecaster experience

A, C, & D

3

Which of the following elements help forecasters add value over NWP?

A) Continuous MetWatch
B) Use of MOS for rare events
C) Regular use of verification
D) Forecaster experience

A, C, & D

4

Which of the following tools help forecasters perform the continuous meteorological watch (MetWatch)?

A) Radar reflectivity and velocity
B) Medium-range NWP forecasts
C) Satellite depictions
D) Surface analyses

A, C, & D

5

True or False:
Model analysis and forecaster experience have a direct impact on the final forecast issued by meteorologists.

True

6

Which of the following situations present opportunities to improve on the NWP forecast?

A) Forecasting severe weather in the short range when convection is initiating
B) Forecasting precipitation for a landfalling hurricane
C) Forecasting temperature in the medium range when your area is in a stable block
D) Forecasting temperature in areas of rugged terrain

A,B, & C

7

Which of the following statements about MOS guidance are correct? (Choose True or False for each option)
A) Data sets are seasonally stratified.
B) Model guidance will lead to a good forecast if environmental conditions are typical for the event.
C) Model guidance is skillful in forecasting atypical events.
D) Regional parameterization affects MOS guidance.
E) MOS guidance corrects for systemic errors in the NWP models.

A) True
B) True
C) False
D) False
E) True

8

Choose the best answer.

A major snowstorm is to occur on the 10th of October at a station in Nebraska. The GFS MOS report has the following October 9-15 GFS Extended MOS forecasts for maximum and minimum temperature:
KLBF GFSX MOS GUIDANCE 10/08/xxxx 1200 UTC
Forecast Hour:
24 36 48 60 72 84 96 108 120 132
Max/Min Temperature:
30 57 26 31 17 33 27 43 33 48
Snow is rarely observed in early October at this location, and the air mass accompanying and following the storm is unusually cold. Forecast 850-hPa temperatures are expected to be at least 3 standard deviations below normal, which statistically is expected only 1% of the time. Based on this information, how would you adjust the forecast temperatures for Monday 12 October (day 4)?

A) I would use them as presented because MOS removes systematic bias.
B) I would use them as presented because MOS predicts extreme events well.
C) I would lower them because of the unusual snow cover and cold air mass.
D) I would raise them because of the unusual snow cover and cold air mass.

C

9

Choose all that apply.
You are a TV meteorologist on a network 10 p.m. newscast in the Philadelphia, PA area. Your main concern is the potential for snow during rush hour (7 a.m. to 9 a.m. EST, or 12 to 14 UTC) of the next morning.

At 5 p.m. EST (22 UTC) your time, you reviewed the previous hour’s radars, surface observations, and corresponding forecasts of simulated composite radar reflectivity and lowest level reflectivity from the 18 UTC NAM/WRF-NMM run that day.

Given the data in these afternoon graphics, how would you assess the NAM forecast from 18 UTC valid at 21 and 22 UTC?

A) The observations indicate that the NAM is correctly developing precipitation in south-central Virginia.
B) The composite radar reflectivity indicates that the NAM is too fast developing precipitation in south-central Virginia
C) The observations indicate that the NAM is too slow developing precipitation in south-central Virginia.
D) The composite radar reflectivity indicates that the NAM is too slow developing precipitation in eastern North Carolina

C & D

10

Choose all that apply.
Now you want to develop your forecast for the late evening news. The following 10 p.m. EST (03 UTC) data for observations and level 1 NAM/WRF-NMM 18 UTC run of simulated reflectivity valid at the same time are available. After viewing these graphics, answer the question below.

How do the observations now compare to the NAM/WRF-NMM observations in the mid-Atlantic states?

A) The advance of precipitation into central Maryland is too slow in the NAM.
B) The advance of precipitation into central Maryland is accurately predicted in the NAM.
C) The advance of precipitation into central Maryland is too fast in the NAM.
D) The forecast precipitation in the NAM shows signs of becoming banded.

A & D

11

Choose the best answer.
The graphics here show the forecast of precipitation from the 18 UTC run of the NAM/WRF-NMM for the hours covering rush hour the next morning. Assume that temperatures will support snow throughout the Philadelphia PA area. The Short-Range Ensemble Forecasts (not shown) support the precipitation forecast of the NAM/WRF-NMM.

Use this information and graphics above to answer the question.

Based on these 1-hour precipitation graphics and verification of the movement of the precipitation shield from the previous two questions, what would your 10 p.m. forecast be for the next morning rush hour (7-9 a.m. EST, 12-14 UTC) in the Philadelphia PA area?

A) Snow will start before the beginning of the rush hour in the entire Philadelphia area.
B) Snow will start after the end of rush hour in the entire Philadelphia area.
C) Snow will not reach the Philadelphia area before, during, or after the morning rush hour.
D) Snow will overspread the Philadelphia area from south to north during the rush hour.

D

12

Choose the best answer.
When assessing the certainty of a forecast using EFS products, which EFS limitation needs to be taken into consideration?

A) The greater uncertainty of initial conditions due to EFS initialization and perturbation methods.
B) The high resolution of EFSs and their ability to offer detailed information for high impact weather events.
C) The availability of detail for onset time of convection.
D) The probability of exceeding a forecast threshold.

A

13

Determine whether each of the following options would be considered an advantage of EFSs when compared to deterministic models. Choose True or False for each option.
A) Information on the probability of a weather event.
B) Details about the degree of certainty in a forecast.
C) Improved spatial resolution.
D) Meteorological details for forecasts from 0 to 72 hours.

A) True
B) True
C) False
D) False

14

Are each of the following an advantage of deterministic models when compared to EFSs? (Choose True or False for each option)
A) Resolution of mesoscale features.
B) Details about the location and amount of rainfall.
C) Details about wind speeds.
D) Details about the certainty of a forecast.

A) True
B) True
C) True
D) False

15

What are 3 primary errors in data and quality control?

1. Instrument Errors
2. Representativeness Errors
3. Converting remotely-sensed data into high-quality observations to be integrated with other data

16

What are 3 types of representativeness errors?

1. Vertical
2. Horizontal
3. Temporal

17

What are 2 primary model initialization problems?

1. First guess can sometimes overwhelm actual data.
2. First guess may result in good observations being ignored.

18

What will poor analysis typical lead to in models?

Huge forecast errors.

19

What are some of the most common atmospheric variables that are not routinely measured?

1. Longwave & Shortwave Radiation
2. Cloud Water & Ice Content
3. Surface roughness of the ocean
4. Turbulence

20

What is the model's initial impression of the atmosphere's current condition?

The first guess (an earlier forecast)

21

Where is the model's first guess most easily modified?
Where is it least easily modified?

data-rich areas (CONUS)
data-poor areas (oceans)

22

What are some ways to check the model's first guess influence on the analysis?

1) Compare different model analyses to each other.
2) Compare model analyses to satellite, radar, and other real-time information.

23

What are some common sources of error in the model?

1) Equations of motion are incomplete
2) Errors in the numerical approximation
3) Boundary conditions

24

What is the horizontal resolution of an NWP model related to for grid point models?
For spectral models?

- the spacing between grid points
- the number of waves that can be resolved

25

What does 'resolution' represent in a grid point model?
In a spectral model?

- the average area depicted by each grid point
- the number of waves used

26

Why is it important to know the amount of area between grid points?

Because atmospheric processes and events occurring over areas near to or smaller than this size will not be included in the model.

27

In spectral models, what is the horizontal resolution designated by?
What does this variable indicate?

- "T" number
- It represents the number of waves used by a spectral model

28

What does the "T" stand for in "T-number?"
What does it indicate?

- Triangular Truncation
- The particular set of waves used by a spectral model

29

What equation is the wavelength of the smallest wave in a spectral model represented as?

minimum wavelength = 360 degrees/N, where N is the total number of waves (the "T" number)

30

What is the equation used to represent the approximate grid spacing with the same accuracy as a spectral model?

delta-X = 360 degrees/3N