midterm 10/25 Flashcards
1
Q
What are some important reasons that we forecast the weather?
A
- Transportation
- Trade
- Resource Availability
- Agriculture
- Construction
- Utility Response
2
Q
What are the 3 main forecasting sectors?
A
- broadcast
- government
- private
3
Q
(BROADCAST) What are their major roles, and how do they differ?
A
- share weather forecasts and related stories, as well as NWS advisories, watches and warnings
- Radio, TV, Internet, Apps
- mix between presentation and forecast information
- can be ratings driven
- funded by media corporations
4
Q
(GOVERNMENT) What are their major roles, and how do they differ?
A
- dissemination through NOAA Weather Radios, Internet, smartphone apps
- hazardous weather events with watches/warnings, short- and long-range forecasts, weather briefings/discussions
- branches: National Weather Service, Storm Prediction Center, Weather Prediction Center, National Hurricane Center, Climate Prediction Center, Military
5
Q
(PRIVATE) What are their major roles, and how do they differ?
A
- Forecast for businesses: utility companies, Renewable Energy Agencies, Insurance Companies, Agricultural Corporations
- Could be its own forecasting business!
- Makes use of apps: WeatherBug, AccuWeather, Weather Underground
6
Q
What % confidence under 24 hrs?
A
80%< confidence
7
Q
What % confidence in 24 hrs?
A
75%-80% confidence
8
Q
What % confidence in 48 hrs?
A
50-75% confidence
9
Q
What % confidence in 72 hrs?
A
<50% confidence
10
Q
What % confidence in +72 hrs?
A
you’ll likely be wrong
11
Q
What are the 4 Forecasting Methods?
A
- Method 1: Persistence / Trends
- Method 2: Climatology
- Method 3: Analog
- Method 4: Numerical Weather Prediction (consensus)
12
Q
Which two methods are most useful? During which type of scenarios are they most useful?
A
- National Weather Prediction (PoP, models, numbers idk)
- Analog (forecasting precip type and synoptic scale patterns)
13
Q
What is NWP?
A
A forecast model is a set (huge, thousands) of mathematical equations that
describe how pressure, temperature, moisture, air density, and wind will
change over time
14
Q
What does NWP stand for?
A
Numerical Weather Prediction
15
Q
What are two major factors that influence the accuracy of a model?
A
- the accuracy/quality of equations to predict atmospheric chaos
- the accuracy/quality of the observations
16
Q
What are the 3 main American forecast models?
A
- Global Forecast System (GFS)
- North American Mesoscale (NAM)
- Rapid Refresh (RAP)
17
Q
What are the strengths/weaknesses of the Global Forecast System?
A
- strengths: synoptic weather pattern and long-term forecasting, maritime regions
- weaknesses: topography worse than NAM, does not predict convection well
18
Q
What are the strengths/weaknesses of North American Mesoscale?
A
- strengths: Weather Research and Forecasting (WRF) model, good rep of topography
- weaknesses: ??
19
Q
What are the strengths/weaknesses Rapid Refresh?
A
- strengths: Weather Research and Forecasting (WRF) model, different parameterizations than NAM
- weaknesses: ??
20
Q
What is MOS?
A
a statistical model that combines the NWP data with other local variables and runs through a set of regression equations
21
Q
What does MOS stand for?
A
Model Output Statistics
22
Q
Be able to describe the differences and similarities between MOS and NWP.
A
- NWP too simplified
- it’s NWP mixed with stats to make it harder, better, fast stronger (more accurate, detailed, and realistic)
23
Q
What is the forecast funnel?
A
The Basic Breakdown you should follow when creating a forecast
24
Q
Describe the Planetary Scale and what observations are taken with each.
A
Look at hemispheric (global) patterns and how they will affect your forecast
25
Describe the Synoptic Scale and what observations are taken with each.
Looking more nationally, what systems may affect your forecast. "What is the problem of the day?"
26
Describe the Mesoscale and what observations are taken with each.
Regionally, what features are going to effect the overall processes?
27
Describe the Local Scale and what observations are taken with each.
How will terrain and other features influence my forecast?
28
Why is the forecast funnel useful for forecasting?
helps streamline the thought process, and gives due consideration to the atmospheric dynamics
29
What type of Lake Effect Snow bands are there?
- Wind Parallel Bands
- Long-Lake axis parallel Bands
30
what are Wind Parallel Bands?
- occur across the shorter width of the lake
- generally associated with strong surface winds and shear
31
What are LLAP (Long-Lake axis parallel) Bands?
- occur in the middle of the lake and stretch it’s length to the leeward shore
- usually associated with the strongest LES events
32
What ingredients are needed for Lake Effect Snow?
1) High/steep vertical temperature gradient
2) Unfrozen Lake
3) Large Fetch
33
What is fetch?
- the distance traveled by wind or waves across open water
- typically need a fetch length greater than 160 km (~100 miles)
34
What type of soundings produce rain?
all temps above freezing
35
What type of soundings produce freezing rain?
goes from freezing and then passes thru a "warm layer" before a light freezing again
36
How does sleet form while looking at a sounding?
after falling through a shallow warm layer aloft and a deep freezing layer at the surface
37
How does snow form when looking at a sounding?
the entirety of the atmosphere is below freezing
38
What synoptic parameters can we look at to predict rain vs. snow?
- temperature
- humidity
- dew point
- fronts and/or low pressure systems
39
What are the typical characteristics with the upper levels of the atmosphere?
- jet stream & jet streaks
- vorticity & vorticity advection
40
How are these upper air observations taken? What products are useful in this analysis?
- radiosondes
- rawinsondes (wind speed and direction)
- soundings (weather balloons)
41
What are the 5 standard levels of analysis?
- 250mb
- 300mb
- 500mb
- 700mb
- 850mb
42
What is the Jet Stream? What are its characteristics?
- high velocity river of low-density air that flows “completely” around the Earth at mid-latitudes
- weakest in summer
- strongest in winter
43
What can the Jet Stream provide in regards to our forecasts?
- steers major weather features at all levels of the atmosphere!
- a direct effect on atmospheric variables at every level down to the surface
44
What is Geostrophic flow? How does it relate to the Jet Stream?
- flow is assumed to be parallel to Isohypses
- steers major weather features at all levels of the atmosphere
45
Subgeostrophic flow?
- occurs when the centrifugal force counters the PGF via the geostrophic balance model
- winds are expected to be SLOWER than geostrophic speed
46
Supergeostrophic flow?
- occurs when the centrifugal force enhances the PGF
- winds are expected to be FASTER than geostrophic speed
47
Where would you find Subgeostrophic flow when analyzing upper air maps?
troughs
48
Where would you find Supergeostrophic flow when analyzing upper air maps?
ridges
49
What are the 2 main types of flow and their characteristics?
- zonal (W to E)
- meridonal (N to S)
50
What is positive trough orientation?
- produce the least amount of severe weather
- just chillin'
51
What is neutral trough orientation?
( literally not talked abt so idk )
52
What is negative trough orientation?
- strong low pressure system (mature)
- wind shear aids in the formation of supercell thunderstorms
53
What is a Jet Streak?
localized regions of intense winds
54
What can Jet Streaks signify in regards to a forecast?
- areas of strong convergence and divergence
- typically the primary weather makers in a trough
- capable of amplifying/weakening troughs and ridges
55
What is Vorticity?
the clockwise or counter-clockwise spin of the atmosphere in relation to a vertical axis
56
What two types of vorticity do we observe? What do they mean for surface features?
positive (cyclonic) and negative (anticyclonic)
57
What does positive (cyclonic) vorticity mean for surface features?
rising air and falling geopotential heights
58
What does negative (anticyclonic) vorticity mean for surface features?
sinking air and increasing geopotential heights
59
How does vorticity relate to the Jet Stream Schematic?
vorticity (and also shear) is typically enhanced in the presence of jet streaks
60
shortwave features?
- a “kink” in the height contours is typically indicative of a shortwave flow pattern
- usually great areas of temperature advection (especially with troughs/fronts)
61
longwave features?
- typically >1000 km
- warmer under ridges, cooler under troughs
- pay attention to the axis of orientation (mostly for troughs)
- tighter gradient, faster progress (typically W→E)
62
analyze Vertical Velocities.
- Negative = Sinking Motion (Regions of surface CAA)
- Positive = Upward Motion (Regions of surface WAA, low level convergence)
- correlates with jet streaks and vorticity advection similar to upper levels
63
analyze Dewpoint Depressions.
- difference between the air temperature and dew point of an area (the smaller the value, the greater the RH)
- can be indicative of instability
- saturation of mid-levels
- upward vertical motion + high RH (low DPD) = cumulus clouds
- horizontal motion (limited vertical motion) + high RH (low DPD) = stratus clouds
64
Discuss temperature advection and how it affects surface features.
- regions where isotherms cut across isohypses
- aka baroclinic environments
65
Identify and discuss Low Level Jets and their role in Low Pressure development.
- a channel of increased winds near the surface located in the warm sector of a mid-latitude cyclone (between a SE High and a NW low)
- efficient in transporting warm, moist air northward
- may also increase severe wx %
66
how far out does the Global Forecast System forecast?
384 hours (16 days)
67
what is Baroclinic?
- a region with a distinct difference in air masses (a separation of warm/cold air)
- surface frontal boundaries usually present (typically with troughs and developed low pressure systems)
- will likely amplify the ridge/trough
68
what is Barotropic?
- a region of uniform temperature distribution
- a lack of fronts
- weather features remain fairly static (typically with ridges/zonal flow)
69
what kind of grid spacing does the Global Forecast System have?
13x13 km (for first 10 days, 27km after that)
70
how long does it take for the Global Forecast System to run?
four hours
71
how far out does the North American Mesoscale forecast?
84 hours
72
what grid spacing does the North American Mesoscale have?
12x12 km
73
how long does it take for the North American Mesoscale to run?
2.5 hours
74
how far out does the Rapid Refresh forecast?
18 hours
75
how often does the Rapid Refresh run?
hourly
76
what grid spacing does the Rapid Refresh have?
13x13 km
77
how long does it take for the Rapid Refresh to run?
a little over an hour
78
what is another version of the Rapid Refresh?
High-Resolution Rapid Refresh (HRRR)
79
Is the Global Forecast System hydrostatic or nonhydrostatic?
hydrostatic
80
Is the Rapid Refresh hydrostatic or nonhydrostatic?
nonhydrostatic
81
Is the North American Mesoscale hydrostatic or nonhydrostatic?
nonhydrostatic
82
What is the cutoff time for the Global Forecast System?
2 hr 45 min
83
What is the cutoff time for the Rapid Refresh?
1 hr
84
What is the cutoff time for the North American Mesoscale?
1 hr 15 min
85
Gridpoint architecture of Global Forecast System?
spectral
86
Gridpoint architecture of Rapid Refresh?
finite difference
87
Gridpoint architecture of North American Mesoscale?
finite difference
88
Boundary conditions for North American Mesoscale?
lateral boundary conditions based on previous GFS runs
89
Boundary conditions for Global Forecast System?
global = no boundaries
90
Boundary conditions for Rapid Refresh?
lateral boundary conditions based on previous GFS runs
91
What does 'finite' mean?
Solves basic equations for specific points
92
What does 'spectral' mean?
Forecast changes of amplitude in waves
93
What does ECMWF mean?
European Center for Medium-Range Forecasts
94
How far out does the European Center for Medium-Range Forecasts forecast?
240 hours (10 days)
95
How often does the European Center for Medium-Range Forecasts run?
twice a day (every 12 hrs)
96
What is the top competitor of the Global Forecast System?
European Center for Medium-Range Forecasts
97
for MOS, what is the DT Row?
tells you the day the model is looking at
98
for MOS, what is the HR Row?
the hours in UTC that the model is forecasting for
99
for MOS, what is the X/N Row?
max and min temperatures
100
for MOS, what is the TMP Row?
surface temperature
101
for MOS, what is the DPT Row?
dewpoint
102
for MOS, what is the CLD Row?
cloud cover
103
for MOS, what is the WDR Row?
wind direction
104
for MOS, what is the WSP Row?
wind speed
105
what unit is the wind speed in in a MOS?
knots
106
for MOS, what is the P06 Row?
probability of precipitation during that 6 hour period
107
for MOS, what is the P12 Row?
probabiluty of precip during that 12 hour period
108
for MOS, what is the Q06 Row?
quantitative precip forecast (QPF) for liquid equilivient during that 6 hour period
109
The GPF is based on an _______. (meaning 0 is nothing and 6 is the highest level)
intensity scale
110
for MOS, what is the Q12 Row?
QPF precip amount for that 12 hour period
111
for MOS, what is the T06 Row?
probability of thunderstorms/conditional probability of severe storms during that 6 hour period
112
for MOS, what is the T12 Row?
probability of thunderstorms/severe thunderstorms during that 12 hour period
113
for MOS, what is the POZ/POS Row?
- probability of freezing (POZ)
- probability of snow (POS)
114
for MOS, what is the TYP Row?
verbal representation of the predicted precip
115
for MOS and the TYP Row, what does R represent?
rain
116
for MOS and the TYP Row, what does S represent?
snow
117
for MOS and the TYP Row, what does Z represent?
mixed
118
for MOS, what is the SNW Row?
snowfall forecast for a 24-hour period
119
for MOS, what is the CIG Row?
ceiling height forecast
120
for MOS, what is the VIS Row?
visibility forecast
121
for MOS, what is the OBV Row?
obstruction to vision (fog, haze, etc.)
122
for MOS, what is the GFSX?
- global model forecast
- combines hourly forecast into 2 concise forecasts per day
- wind direction is removed
- timeframes are in 12 and 24 hour increments
123
This general indicator of winter precipitation is a measure of the 1000-500mb thickness.
540 Line
124
This type of force can act to destabilize or ruin a lake effect snow event, but is crucial for supercell storms to form.
Directional Shear
125
This type of force can enhance convergence on the lee side of the lake during a lake effect snow event, leading to a much stronger event.
Friction/Orographic forcing
126
What is supercooled water?
stays in liquid form, even below freezing temperatures
127
This forecasting method is used when a changing weather variable will continue to change at a similar rate.
trending forecasting
128
What is the National Weather Service statement?
“We will provide weather, water, and climate data, forecasts and warnings for the protection of life and property, and the enhancement of the national economy."
129
How much time (generally) is covered by a MOS forecast product?
3 days
130
What input on the OBV row would be used if sand was obstructing the view near the tower?
BL
131
What force is not considered when evaluating for geostrophic flow aloft?
friction
132
What type of vorticity occurs in the right exit region of a jet streak?
Cyclonic / Positive Vorticity
133
This trough orientation can signify the beginning or the end of a Mid-Latitude Cyclone.
positive
134
This type of environment is associated with uniform temperature distribution, with atmospheric features remaining fairly static.
barotropic
135
These types of clouds can form as a result of weak/positive vertical velocities in conjunction with high relative humidity values.
status clouds
136
This forecasting method involves the use of computer forecasts and models, including PoP forecasts.
Probability/Statistical method
137
This forecast model is the only model that operates on the global scale.
Global Forecast System
138
This weather forecast model is generally better at forecasting along coastal areas, and does worse comparatively in areas of topographic features.
Global Forecast System
139
For MOS on the CLD row, what cover is CL?
no clouds
140
For MOS on the CLD row, what cover is FW?
1/8-2/8 cover
141
For MOS on the CLD row, what cover is SC?
3/8-1/2 cover
142
For MOS on the CLD row, what cover is BK?
5/8-7/8 cover
143
For MOS on the CLD row, what cover is OV?
8/8 full cover
144
what do you look for at the 250/300mb level?
- jet stream (Rossby waves)
- jet streaks
145
what is looked for at the 500mb level?
vorticity (specifically the advection)
146
what to look for at the 700mb level?
- shortwave vs longwave
- vertical velocity
- RH and dewpoint depressions
147
what to look for at the 850mb level?
- temperature advection
- low level jet (LLJ)
148
what does the 850mb level represent?
the top (or near the top) of the Planetary Boundary Level (PBL)
149
what become better defined at the 850mb level?
surface high/low pressure centers
150
Draw the jet streak diagram.
ok
151
Draw the sea breeze diagram.
ok
152
Draw the land breeze diagram.
ok
