Deck 13: Weather Forecasting

Question 1

It is possible to make a short-range weather prediction based on a surface weather map.

Answer 1

True

Question 2

Surface pressure systems tend to move in the same direction as the wind at 5500 m (18,000 ft)-the 500-mb level.The speed at which surface systems move is about double the speed of the winds at this level.

Answer 2

False

Question 3

A weather watch would probably be issued for which of the following conditions?

A)There is a chance for tornadoes tomorrow.
B)Presently,extremely high winds are occurring at mountain summits.
C)​A tornado has been sighted at the outskirts of town.
D)​Heavy snow has been falling over the forecast area.
E)​There is a chance of rain tomorrow.

Answer 3

A

Question 4

Computer forecast models make certain assumptions about the atmosphere that are not always correct.

Question 5

Probably the easiest weather forecast to make is a statistical forecast.

Question 6

Soundings $\underline { \text { only} }$ provide information that aids in the prediction of fog,air pollution alerts,and the downwind mixing of strong winds.

Question 7

A weather warning indicates that

A)the atmospheric conditions are favorable for hazardous weather over a particular region.
B)hazardous weather is either imminent or occurring within the forecast area.
C)​hazardous weather is likely to occur within the forecast area during the next 24 hours.
D)​hazardous weather is frequently observed in a particular region.
E)​hazardous weather is occurring in nearby areas.

Question 8

The ASOS system is designed to provide nearly continuous information about wind,temperature,pressure,cloud-base height,and runway visibility at various airports.

Question 9

A downside of high-resolution models is that,as the horizontal spacing between grid points decreases,the number of computations increases.When the distance is halved,there are 8 times as many computations to perform,and the time (and computational expense)required to run the model goes up by a factor of 16.

Question 10

Meteorologists interpret the weather patterns and then correct any errors that may be present.The final chart is referred to as a prediction.

Question 11

These days the precise location where a tornado will form can be predicted up to 7 days in advance.

Question 12

Suppose that it is presently warm and raining.A cold front will pass your area in 3 hours.Behind the front,it is cold and snowing.A persistence forecast would predict warm and rainy weather.

Question 13

Monthly and seasonal forecasts make specific predictions of rain or snow.

Question 14

Stating that the chance of rain is 60 percent means that there is a 60 percent chance that it will rain within the forecast area.

Question 15

Doppler radar is helpful for measuring precipitation,but not wind.

Question 16

Because the many weather variables are constantly changing,meteorologists have devised atmospheric models that describe the present state of the atmosphere.These are not physical models that paint a picture of a developing storm;they are,rather,mathematical models consisting of many equations that describe how atmospheric temperature,pressure,winds,and moisture will change with time.

Question 17

An anticyclone is moving slowly eastward.Southerly winds on the western side of the system will bring warmer and more humid air to the region.Therefore,afternoon temperatures will be warmer than those of the day before.

Question 18

A forecast that extends beyond three days is often called an outlook.

Question 19

Weather forecasts are commonly grouped according to how far into the future the forecast extends.

Question 20

According to the National Weather Service,the subjective term "fair" implies a rather pleasant weather situation.

Question 21

Automated Surface Observing Systems (ASOS)measure

A)wind speed and direction.
B)cloud patterns.
C)​sun angles.
D)​likelihood of flooding.
E)​likelihood of lightning strikes.

Question 22

A forecast method that compares past weather maps and weather patterns to those of the present is

A)persistence forecasting.
B)the analog method.
C)​the trend method.
D)​nowcasting.
E)​steady-state forecasting.

Question 23

For a forecast to show skill it must

A)be better than one based on persistence or climatology.
B)be accurate to within 2°C of the predicted temperature.
C)​be accurate for over more than 90 percent of the forecast area.
D)​use the analog method of forecasting.
E)​use a probability.

Question 24

A weather forecast for the immediate future that employs the trend method is called

A)nowcasting.
B)extrapolation.
C)​first order forecasting.
D)​linear forecasting.
E)​persistence forecasting.

Question 25

The forecasting technique that produces several versions of a forecast model,each beginning with slightly different weather information to reflect errors in the measurements,is called​

A)climatology forecasting.
B)redundancy analysis.
C)​persistence forecasting.
D)​ensemble forecasting.
E)​probability forecasting.

Question 26

What would be the least accurate forecast method of predicting the weather two days into the future during changeable weather conditions?

A)trend method
B)​persistence forecast
C)​analog method
D)​prediction by weather types
E)​numerical weather prediction

Question 27

By examining a surface map,the movement of a surface low pressure area can be predicted because

A)low-pressure areas tend to move parallel to isobars of the warm sector.
B)lows tend to move toward the area with the greatest pressure.
C)​movement is the same as it was during the previous 24 hours.
D)​once a low is established it always moves toward the east at double the original speed.
E)​current weather in the region will remain the same.

Question 28

An analysis is a

A)forecast chart that shows the atmosphere at some future time.
B)forecast chart that compares past weather maps with those of the present.
C)​surface or upper-level chart that interprets the present weather patterns.
D)​forecast method used in long range weather prediction.
E)​method used to determine skill in predicting the weather.

Question 29

A persistence forecast could be quite accurate when

A)a frontal system approaches your location at constant speed.
B)you are positioned in the middle of a large,stationary air mass.
C)​the weather has been unusually cold for several days.
D)​upper level winds blow straight from west to east.
E)​when a warm front is approaching.

Question 30

Predicting the weather by weather types employs which forecasting method?

A)probability
B)steady-state
C)​analog
D)​persistence
E)​guess

Question 31

An accurate forecast

A)always shows skill.
B)may or may not show skill.
C)​never shows skill.
D)​requires complex computer equipment.
E)​can only be accomplished after many years of experience.

Question 32

Which forecasting method assumes that weather systems will move in the same direction and at the same speed as they have been moving?

A)persistence forecast
B)probability forecast
C)​weather type forecast
D)​climatological forecast
E)​steady state (trend)forecast

Question 33

Weather forecast that predicts that the future weather will be the same as the present weather is called

A)a steady-state forecast.
B)the trend method.
C)​a persistence forecast.
D)​the analogue method.
E)​an extended weather forecast.

Question 34

Suppose that where you live,the middle of January is typically several degrees warmer than the rest of the month.If you forecast this "January thaw" for the middle of next January,you would have made a

A)forecast based on the analogue method.
B)persistence forecast.
C)​forecast based on weather types.
D)​probability forecast.
E)​climatological forecast.

Question 35

The greatest improvement in forecasting skill during the past 30 years has been made in forecasting

A)snowstorms along the eastern seaboard.
B)the development of middle latitude cyclones in the Pacific Ocean.
C)​severe storm warnings for hurricanes and tornadoes.
D)​the movement of warm and cold fronts.
E)​maximum and minimum temperature 6 to 10 days into the future.

Question 36

With the ____ method,a forecaster might look at a prog and say "I've seen this weather situation before,and so and so happened,so I think the same thing will happen here."

A)historical
B)seasonal
C)​persistence
D)​analog
E)​predictive

Question 37

A probability forecast that calls for a "40 percent chance of rain" means that​

A)there is a 40 percent chance that it will not rain within the forecast area.
B)there is a 40 percent chance that any random place in the forecast area will receive measurable rain.
C)​it will rain on 40 percent of the forecast area.
D)​it will rain during 40 percent of the time over the forecast area.
E)​it will definitely rain.

Question 38

A prog is

A)a chart that interprets the current state of the atmosphere.
B)an instrument that draws lines on an upper-level chart.
C)​a new method of forecasting the weather.
D)​a forecast chart that shows the atmosphere at some future time.
E)​another name for a probability forecast.

Question 39

A forecast of an extended period of dry weather would be made for a region beneath

A)an upper-level trough.
B)the polar jet stream.
C)​a cold pool of air aloft.
D)​an upper-level ridge.
E)​a shortwave trough.

Question 40

The forecasting of weather by a computer is known as​

A)weather type forecasting.
B)climatology forecasting.
C)​extended weather forecasting.
D)​analog prediction.
E)​numerical weather prediction.

Question 41

A comma cloud is

A)an organized band of clouds that looks like a comma on a satellite photograph.​
B)a large cumulonimbus cloud whose anvil is in the shape of a comma.
C)​a high wispy cirrus cloud that takes on the shape of a comma.
D)​the spiraling arms of a hurricane.
E)​a band of high cirrus clouds blown by the jet stream.

Question 42

​Which of the following is the least likely to be a forecaster's rule of thumb?

A)For short time intervals,mid-latitude cyclonic storms and fronts tend to move in the same direction and at approximately the same speed as they did during the previous six hours.
B)Low pressure areas tend to move in a direction that parallels the isobars in the warm air sector.
C)​Lows tend to move toward the region of greatest pressure drop.
D)​Highs tend to move toward the region of greatest pressure drop.
E)​A "chance of rain" means that the chance of rain is 30-50 percent.

Question 43

An ensemble forecast goes further and further into the future,the forecast lines can become scrambled.Such a chart is often referred to as a​

A)spaghetti plot.​
B)chaos chart.
C)​multilinear plot.
D)​filament chart.
E)​shifting plot.

Question 44

Warm advection occurs when the​

A)wind veers (changes direction in a clockwise manner)with height.
B)wind backs (changes direction in a counterclockwise manner)with height.
C)​isotherms are parallel to the winds.
D)​wind veers with height and the isotherms are parallel to the winds.
E)​Sun angle is 90 degrees.

Question 45

A forecast of "chance of precipitation" means the probability of precipitation is

A)between 0 and 20 percent.
B)between 30 and 50 percent.
C)​between 50 and 60 percent.
D)​between 60 and 70 percent.
E)​greater than 80 percent.

Question 46

Modern computer forecasting models have increasingly smaller grid spacing.This presents which of the following problems?

A)Mesoscale weather features can be predicted.
B)Small-scale weather features can be resolved by the models.
C)​Many more computations are needed.
D)​The vast amount of information makes it difficult to make a prediction.
E)​It takes too long to make a prediction.

Question 47

Lines connecting points of equal pressure change are called

A)isobars.
B)isograds.
C)​contours.
D)isotherms.​
E)​isallobars.

Question 48

Suppose there are two cloud layers above you.The lower cloud layer is moving from a westerly direction,while the higher cloud layer is moving from a northwesterly direction.From this observation you conclude that the wind is ____ with height and ____ advection is occurring between the cloud layers.

A)backing;cold
B)backing;warm
C)​veering;cold
D)​veering;warm
E)​backing;no

Question 49

Thickness charts help forecasters

A)identify cloud patterns.
B)locate stratospheric disturbances.
C)​predict the length of sunshine on a day.
D)​predict whether falling precipitation will be rain or snow.
E)​provide information on Sun angles in specific locations.

Question 50

The principle that "surface weather systems tend to move in the same direction and at approximately the same speed as they have been moving" forms the basis of which type of forecasting method?

A)persistence forecast​
B)analogue method
C)​steady-state forecast
D)​ensemble forecast
E)​nowcast.

Question 51

Very short-range forecasts often utilize which of the following forecast methods?

A)steady-state or trend method
B)pattern recognition method
C)​ensemble method
D)​both the steady-state (trend method)and ensemble methods
E)​both the steady-state (trend method)and pattern recognition methods

Question 52

In the short-range weather forecasts of this chapter,we assumed that the pressure systems and fronts were ____.​

A)moving at a constant rate
B)accelerating along a random curve
C)​stable and unchanging
D)​moving towards zero
E)​exactly identical

Question 53

Conditions such as high wind speeds,cold air moving southward,warm air moving northward,and a shortwave moving into a longwave trough-will typically manifest themselves as a(n)____ of a longwave trough.

A)dissipation
B)stabilization
C)​weakening
D)​deepening
E)​receding

Question 54

Warm advection is most likely to occur​

A)in the center of a cut-off low.
B)from the surface up to the 500 mb level ahead of an advancing warm front.
C)​behind a cold front.
D)​where the winds back with height.
E)​on the western side of a shortwave trough at the 500 mb level.

Question 55

Which below is least likely to be a condition associated with an omega high?

A)It is in the shape of the Greek letter "omega."
B)It is known as a "blocking high."
C)​It forms when the flow aloft is zonal.
D)​It tends to persist in the same geographic area for many days.
E)​It keeps troughs in their positions.

Question 56

If you wanted to make a persistence forecast of minimum and maximum temperatures for a particular city,which type of chart would be most helpful?

A)surface chart
B)meteogram
C)​500 mb chart
D)​adiabatic chart
E)​Doppler radar display

Question 57

Which of the following can cause errors in forecasts made by numerical weather prediction models?

A)computers cannot predict the short-range future
B)the model captures too many fine scale details
C)​there is too much data to predict the weather
D)​inadequate representation of pertinent meteorological processes
E)​too many different types of data are assimilated in a model

Question 58

Suppose a computer model uses more closely spaced grid points and a greater number of data points,and thus has better resolution.What would this model be particularly useful in forecasting?​

A)large scale winds
B)a ​vorticity maximum
C)​longwave directions
D)​temperatures at the surface
E)​the relative position of highs and lows

Question 59

Which weather advisory is issued when falling or blowing snow and winds of at least 35 miles per hour restrict visibility to less than 1/4 mile for several hours?

A)tornado warning
B)hurricane warning
C)​snow advisory
D)​blizzard warning
E)​snow warning

Question 60

In one forecast,west of San Francisco,the flow is meridional with a cut-off warm,upper high situated just south of Alaska.To the south,both east and west of the high are troughs.Because the shape of this flow around the high resembles the Greek letter ____,the high and its accompanying ridge are known as a(n)____ high.​

A)theta
B)gamma
C)​omega
D)​beta
E)​alpha

Question 61

You are in Calgary,Alberta,Canada,100 km (62 mi)east of the Rockies in January.The current wind is from the north.Looking at a prog for tomorrow,you see that the wind will be from the west,hence tomorrow's temperature will be ____ today.​

A)warmer than​
B)colder than
C)​the same as
D)​colder and drier
E)​the same but more humid than

Question 62

The routine daily forecasting of weather by computers using mathematical equations has come to be known as ____________________.

Question 63

The ____________________ describes the steps used by forecasters to steer their attention from large scales to smaller scales and from short time frames to longer periods.​

Question 64

____________________,which includes more than 175 nations-is responsible for the international exchange of weather data and certifies that the observation procedures do not vary among nations.

Question 65

A forecast based on the climate of a particular region is known as a(n)____________________.​

Question 66

The ____________________ is a chart that shows how one or more weather variables has changed at a station over a given period of time.​

Question 67

In the course of a single workday,a typical forecaster may examine and compare ____ individual weather maps.

A)five
B)seven
C)​ten
D)​dozens of
E)​thousands of

Question 68

Another aid in weather forecasting is the use of ____________________-a two-dimensional vertical profile of temperature,dew point,and winds.​

Question 69

Predicting the weather by weather types employs the ____________________.​

Question 70

A weather ____________________ indicates that atmospheric conditions favor hazardous weather occurring over a particular region during a specified time period.A weather ____________________,on the other hand,indicates that hazardous weather is either imminent or actually occurring within the specified forecast area.Advisories are issued to inform the public of less hazardous conditions caused by wind,dust,fog,snow,sleet,or freezing rain.

Question 71

A long-range forecast is a forecast that extends beyond about​

A)8.5 years.
B)8.5 months.
C)​8.5 weeks.
D)​8.5 days.
E)​8.5 hours.

Question 72

____ tend to steer the movement of surface pressure systems.

A)Cumulus clouds
B)Doppler radar
C)​Winds aloft
D)​Ensemble forecasts
E)​Stationary fronts.

Question 73

Suppose that where you live,the middle of January is typically several degrees warmer than the rest of the month.If you forecast this "January thaw" for the middle of next January,what type of a weather forecast will you have made?

A)ensemble forecast
B)common forecast
C)​seasonal outlook
D)​nowcast
E)​probability forecast

Question 74

A weather forecast for up to a few hours (usually not more than 6 hours)is called a(n)____________________ forecast,or ____________________.

Question 75

A blocking high is a

A)high pressure system and accompanying ridge that changes location quickly.
B)high pressure system and accompanying ridge that persists in the same location for many days.
C)​high pressure system and accompanying ridge that produces torrential rains.
D)​ridge associated with a low pressure system.
E)​trough associated with a low pressure system.

Question 76

Surface weather information is provided by more than ____ land-based stations and hundreds of ships and buoys providing surface weather information at least four times a day.

A)100
B)10,000
C)​100,000
D)​1,000,000
E)​10,000,000

Question 77

The analog method is often referred to as ____________________.

Question 78

Given a map with isallobars,high pressure systems tend to move where the isallobars indicate ____________________ values,and low pressure systems move where the isallobars are ____________________.

Question 79

If low clouds at an elevation of 3000 ft above you are moving from the southeast,and clouds about 8000 ft higher are moving from the southwest ____________________ advection is taking place between the cloud layers.

Question 80

The analysis of a(n)____ can be especially helpful when making a short-range forecast that covers a relatively small area,such as the mesoscale.​

A)sounding
B)meteogram
C)​Doppler radar image
D)​thick chart
E)​index