final 12/13 Flashcards
1
Q
What are the 3 main ingredients for severe weather?
A
- instability
- moisture
- lifting mechanism
2
Q
What does CAPE stand for?
A
Convective Available Potential Energy
3
Q
How is CAPE measured?
A
J/kg
4
Q
For CAPE, how is 500-1500 measured?
A
unstable
5
Q
For CAPE, how is 1500-2500 measured?
A
very unstable
6
Q
For CAPE, how is >2500 measured?
A
extremely unstable
7
Q
What is the Lifted Index?
A
difference in temperature between environmental temperature and the parcel’s air temperature lifted adiabatically at 500 mb
8
Q
What are the ranges for Lifted Index’s instability?
A
stable, unstable, very unstable
9
Q
For LI, what is the range for stable?
A
> 0
10
Q
For LI, what is the range for unstable?
A
0 > LI > -6
11
Q
For LI, what is the range for very unstable?
A
< -6
12
Q
How are environmental lapse rates used to qualitatively measure instability?
A
when the environmental lapse rate exceeds the DALR, the atmosphere is considered unstable
13
Q
Be able to identify Absolutely Stable on a Skew T
A
ELR is to the right of the DALR and MALR
14
Q
Be able to identify Conditionally Unstable on a Skew T
A
ELR is between the DALR and MALR
15
Q
Be able to identify Absolutely Unstable on a Skew T
A
ELR is to the left of the DALR and MALR
16
Q
What are the two types of shear?
A
- speed shear
- directional sheer
17
Q
How does speed shear affect severe storms?
A
- allows thunderstorms to tilt with height (separating downdrafts from updrafts)
- crucial for tstorms to sustain themselves
18
Q
How does directional shear affect severe storms?
A
allows updrafts to spin
19
Q
What is the Bulk Richardson Number?
A
total amount of shear (kts) between two vertical levels
20
Q
What is Effective Shear?
A
amount of shear that is able to rotate with an updraft
21
Q
For Effective Shear, what is the range for weak shear?
A
0-20 kts
22
Q
For Effective Shear, what is the range for moderate shear?
A
20-40 kts
23
Q
For Effective Shear, what is the range for high shear?
A
40-60 kts
24
Q
For Effective Shear, what is the range for extreme shear?
A
> 60 kts
25
What is Storm Relative Helicity?
amount of potential spin (m^2/s^2) between two levels relative to an updraft
26
For Storm Relative Helicity, what is the range for rotating drafts to be unlikely?
0-100 m^2/s^2
27
For Storm Relative Helicity, what is the range for rotation possible?
100-250 m^2/s^2
28
For Storm Relative Helicity, what is the range for rotation likely? (aka tornados)
250-400 m^2/s^2
29
For Storm Relative Helicity, what is the range for strong rotation likely w violent tornados?
> 400 m^2/s^2
30
What is the Hodograph?
plots the wind vectors with height on a Cartesian Coordinate System
31
What kind of hodograph is favorable for tornados?
a clockwise rotating hodograph
32
What are the four lifting mechanisms?
- upper level divergence / PVA
- cold fronts
- warm fronts
- outflow boundaries
33
What is upper level divergence / PVA?
cause surface pressure to decrease and promote upward vertical motions across that pressure gradient, lifting the parcel
34
What are cold fronts?
- move very quickly, forcing air parcels to rise rapidly
- occasionally produce supercells, more often squall lines
35
High instability + low shear = _______ ?
squall line
36
High instability + high shear = _______ ?
supercells and/or squall line
37
Low instability + high shear = _______ ?
weak supercells and line segments
38
What are warm fronts?
- excellent at producing/maintaining supercells!
- associated with strong inversions that need to be broken for T-storms to develop
- low level shear is typically maximized along warm fronts
- move slowly
39
What are dry lines?
- marks the boundary between hot, dry air and warm, moist air
- advance during the day, then retreat at night
- an lead to convective initiation, which in turn can lead to storm development
40
What are outflow boundaries?
- cold pools from previous convection, such as previous diurnal effects or ongoing storm effects
- can serve as a mesoscale boundary promoting low level convergence
- can create more tstorms
41
What are the 4 main types of storms?
- ordinary tstorm
- mesoscale convective system (multi-cell)
- supercell
- derecho
42
Discuss an ordinary t-storm.
- most basic convective system
- has 1 main updraft that is lost to a downdraft when precip starts
- 30-50 minutes long
- found in environments with weak vertical wind shear
- very common on hot summer afternoons
- rarely severe, but can have stronger winds from downbursts
43
Discuss a mesoscale convective system (aka squall line).
- complex of organized single-cell storms
- *** most common severe storm type
- weak to moderate shear (usually just speed shear)
- can produce severe wind/marginal hail
44
Discuss a supercell.
- consists of a single, steadily rotating updraft
- ***Mesocyclone!!***
- very organized internal structure.
- can last for several hours.
- very strong vertical wind shear (both speed and directional!)
- can produce very large hail, damaging winds and most common producer of tornadoes!!
45
Discuss a derecho.
- any family of downburst clusters that produce a widespread straight-line windstorm.
- usually form with an extremely high instability and weak to moderate shear
- NWS criteria - Severe wind gusts (greater than 57 mph) at most points along the storm path
46
How can you use shear/instability to differentiate between a supercell and a squall line on a Skew T?
look for strong vertical wind shear
47
What are the 4 main types of precipitation possible during the winter season?
- rain
- freezing rain
- sleet
- snow
48
What else is the "Rain/Snow line" called?
540 line
49
How can temperature advection effect precip type over time?
- WAA at 850 mb ahead of a warm front can produce freezing rain conditions, as the surface will remain cold under the rising warm air
- CAA can turn normal rain conditions to snow, freezing rain, or sleet depending on the structure of it’s advection
50
Be able to identify a precipitation type based on a given weather sounding.
just like midterm
51
What are Lake Effect Snow events?
localized, convective snow bands that occur in the lee of lakes when relatively cold air flows over warm water
52
When does Lake Effect Snow occur?
late fall/early winter months (November – January)
53
What are some important reasons that we forecast the weather?
- Transportation
- Trade
- Resource Availability
- Agriculture
- Construction
- Utility Response
54
What are the 3 main forecasting sectors?
- broadcast
- government
- private
55
(BROADCAST) What are their major roles, and how do they differ?
- 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
56
(GOVERNMENT) What are their major roles, and how do they differ?
- 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
57
(PRIVATE) What are their major roles, and how do they differ?
- 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
58
What % confidence under 24 hrs?
80%< confidence
59
What are the 4 Forecasting Methods?
- Method 1: Persistence / Trends
- Method 2: Climatology
- Method 3: Analog
- Method 4: Numerical Weather Prediction (consensus)
60
Which two methods are most useful? During which type of scenarios are they most useful?
- National Weather Prediction (PoP, models, numbers idk)
- Analog (forecasting precip type and synoptic scale patterns)
61
What is NWP?
a set (huge, thousands) of mathematical equations that describe how pressure, temperature, moisture, air density, and wind will change over time
62
What does NWP stand for?
Numerical Weather Prediction
63
What are two major factors that influence the accuracy of a model?
- the accuracy/quality of equations to predict atmospheric chaos
- the accuracy/quality of the observations
64
What are the 3 main American forecast models?
- Global Forecast System (GFS)
- North American Mesoscale (NAM)
- Rapid Refresh (RAP)
65
What are the strengths/weaknesses of the Global Forecast System?
- strengths: synoptic weather pattern and long-term forecasting, maritime regions
- weaknesses: topography worse than NAM, does not predict convection well
66
What is MOS?
a statistical model that combines the NWP data with other local variables and runs through a set of regression equations
67
What does MOS stand for?
Model Output Statistics
68
Be able to describe the differences and similarities between MOS and NWP.
- NWP too simplified
- MOS is NWP mixed with stats to make it harder, better, fast stronger (more accurate, detailed, and realistic)
69
What is the forecast funnel?
The Basic Breakdown you should follow when creating a forecast
70
Describe the Planetary Scale and what observations are taken with each.
Look at hemispheric (global) patterns and how they will affect your forecast
71
Why is the forecast funnel useful for forecasting?
helps streamline the thought process, and gives due consideration to the atmospheric dynamics
72
What type of Lake Effect Snow bands are there?
- Wind Parallel Bands
- Long-Lake axis parallel Bands
73
What ingredients are needed for Lake Effect Snow?
1) High/steep vertical temperature gradient
2) Unfrozen Lake
3) Large Fetch
74
What type of soundings produce rain?
all temps above freezing
75
What synoptic parameters can we look at to predict rain vs. snow?
- temperature
- humidity
- dew point
- fronts and/or low pressure systems
76
What are the typical characteristics with the upper levels of the atmosphere?
- jet stream & jet streaks
- vorticity & vorticity advection
77
How are these upper air observations taken? What products are useful in this analysis?
- radiosondes
- rawinsondes (wind speed and direction)
- soundings (weather balloons)
78
What are the 5 standard levels of analysis?
- 250mb
- 300mb
- 500mb
- 700mb
- 850mb
79
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
80
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
81
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
82
Subgeostrophic flow?
- occurs when the centrifugal force counters the PGF via the geostrophic balance model
- winds are expected to be SLOWER than geostrophic speed
83
What are the 2 main types of flow and their characteristics?
- zonal (W to E)
- meridonal (N to S)
84
What is positive trough orientation?
- produce the least amount of severe weather
- just chillin'
85
What is a Jet Streak?
localized regions of intense winds
86
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
87
What is Vorticity?
the clockwise or counter-clockwise spin of the atmosphere in relation to a vertical axis
88
What two types of vorticity do we observe? What do they mean for surface features?
positive (cyclonic) and negative (anticyclonic)
89
How does vorticity relate to the Jet Stream Schematic?
vorticity (and also shear) is typically enhanced in the presence of jet streaks
90
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)
91
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
92
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
93
Discuss temperature advection and how it affects surface features.
- regions where isotherms cut across isohypses
- aka baroclinic environments
94
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 %
95
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?"
96
Describe the Mesoscale and what observations are taken with each.
Regionally, what features are going to effect the overall processes?
97
Describe the Local Scale and what observations are taken with each.
How will terrain and other features influence my forecast?
98
What are the strengths/weaknesses of North American Mesoscale?
- strengths: Weather Research and Forecasting (WRF) model, good rep of topography
- weaknesses: ??
99
What are the strengths/weaknesses Rapid Refresh?
- strengths: Weather Research and Forecasting (WRF) model, different parameterizations than NAM
- weaknesses: ??
100
how far out does the Global Forecast System forecast?
384 hours (16 days)
101
what kind of grid spacing does the Global Forecast System have?
13x13 km (for first 10 days, 27km after that)
102
how long does it take for the Global Forecast System to run?
four hours
103
how far out does the North American Mesoscale forecast?
84 hours
104
what grid spacing does the North American Mesoscale have?
12x12 km
105
how long does it take for the North American Mesoscale to run?
2.5 hours
106
how far out does the Rapid Refresh forecast?
18 hours
107
how often does the Rapid Refresh run?
hourly
108
what grid spacing does the Rapid Refresh have?
13x13 km
109
how long does it take for the Rapid Refresh to run?
a little over an hour
110
what is another version of the Rapid Refresh?
High-Resolution Rapid Refresh (HRRR)
111
Is the Global Forecast System hydrostatic or nonhydrostatic?
hydrostatic
112
Is the Rapid Refresh hydrostatic or nonhydrostatic?
nonhydrostatic
113
Is the North American Mesoscale hydrostatic or nonhydrostatic?
nonhydrostatic
114
What is the cutoff time for the Global Forecast System?
2 hr 45 min
115
What is the cutoff time for the Rapid Refresh?
1 hr
116
What is the cutoff time for the North American Mesoscale?
1 hr 15 min
117
Gridpoint architecture of Global Forecast System?
spectral
118
Gridpoint architecture of Rapid Refresh?
finite difference
119
Gridpoint architecture of North American Mesoscale?
finite difference
120
Boundary conditions for North American Mesoscale?
lateral boundary conditions based on previous GFS runs
121
Boundary conditions for Global Forecast System?
global = no boundaries
122
Boundary conditions for Rapid Refresh?
lateral boundary conditions based on previous GFS runs
123
What does 'finite' mean?
Solves basic equations for specific points
124
What does 'spectral' mean?
Forecast changes of amplitude in waves
125
What does ECMWF mean?
European Center for Medium-Range Forecasts
126
How far out does the European Center for Medium-Range Forecasts forecast?
240 hours (10 days)
127
How often does the European Center for Medium-Range Forecasts run?
twice a day (every 12 hrs)
128
What is the top competitor of the Global Forecast System?
European Center for Medium-Range Forecasts
129
for MOS, what is the DT Row?
tells you the day the model is looking at
130
for MOS, what is the HR Row?
the hours in UTC that the model is forecasting for
131
for MOS, what is the X/N Row?
max and min temperatures
132
for MOS, what is the TMP Row?
surface temperature
133
for MOS, what is the DPT Row?
dewpoint
134
for MOS, what is the CLD Row?
cloud cover
135
for MOS, what is the WDR Row?
wind direction
136
for MOS, what is the WSP Row?
wind speed
137
what unit is the wind speed in in a MOS?
knots
138
for MOS, what is the P06 Row?
probability of precipitation during that 6 hour period
139
for MOS, what is the P12 Row?
probabiluty of precip during that 12 hour period
140
for MOS, what is the Q06 Row?
quantitative precip forecast (QPF) for liquid equilivient during that 6 hour period
141
The GPF is based on an _______. (meaning 0 is nothing and 6 is the highest level)
intensity scale
142
for MOS, what is the Q12 Row?
QPF precip amount for that 12 hour period
143
for MOS, what is the T06 Row?
probability of thunderstorms/conditional probability of severe storms during that 6 hour period
144
for MOS, what is the T12 Row?
probability of thunderstorms/severe thunderstorms during that 12 hour period
145
for MOS, what is the POZ/POS Row?
- probability of freezing (POZ)
- probability of snow (POS)
146
for MOS, what is the TYP Row?
verbal representation of the predicted precip
147
for MOS and the TYP Row, what does R represent?
rain
148
for MOS and the TYP Row, what does S represent?
snow
149
for MOS and the TYP Row, what does Z represent?
mixed
150
for MOS, what is the SNW Row?
snowfall forecast for a 24-hour period
151
for MOS, what is the CIG Row?
ceiling height forecast
152
for MOS, what is the VIS Row?
visibility forecast
153
for MOS, what is the OBV Row?
obstruction to vision (fog, haze, etc.)
154
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
155
What is fetch?
- the distance traveled by wind or waves across open water
- typically need a fetch length greater than 160 km (~100 miles)
156
What is neutral trough orientation?
( literally not talked abt so idk )
157
What is negative trough orientation?
- strong low pressure system (mature)
- wind shear aids in the formation of supercell thunderstorms
158
What does positive (cyclonic) vorticity mean for surface features?
rising air and falling geopotential heights
159
What does negative (anticyclonic) vorticity mean for surface features?
sinking air and increasing geopotential heights
160
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)
161
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
162
what is Barotropic?
- a region of uniform temperature distribution
- a lack of fronts
- weather features remain fairly static (typically with ridges/zonal flow)
163
What type of soundings produce freezing rain?
goes from freezing and then passes thru a "warm layer" before a light freezing again
164
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
165
How does snow form when looking at a sounding?
the entirety of the atmosphere is below freezing
166
what are Wind Parallel Bands?
- occur across the shorter width of the lake
- generally associated with strong surface winds and shear
167
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
168
This general indicator of winter precipitation is a measure of the 1000-500mb thickness.
540 Line
169
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
170
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
171
What is supercooled water?
stays in liquid form, even below freezing temperatures
172
This forecasting method is used when a changing weather variable will continue to change at a similar rate.
trending forecasting
173
Supergeostrophic flow?
- occurs when the centrifugal force enhances the PGF
- winds are expected to be FASTER than geostrophic speed
174
Where would you find Subgeostrophic flow when analyzing upper air maps?
troughs
175
Where would you find Supergeostrophic flow when analyzing upper air maps?
ridges
176
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."
177
How much time (generally) is covered by a MOS forecast product?
3 days
178
What input on the OBV row would be used if sand was obstructing the view near the tower?
BL
179
What force is not considered when evaluating for geostrophic flow aloft?
friction
180
What type of vorticity occurs in the right exit region of a jet streak?
Cyclonic / Positive Vorticity
181
This trough orientation can signify the beginning or the end of a Mid-Latitude Cyclone.
positive
182
This type of environment is associated with uniform temperature distribution, with atmospheric features remaining fairly static.
barotropic
183
These types of clouds can form as a result of weak/positive vertical velocities in conjunction with high relative humidity values.
status clouds
184
This forecasting method involves the use of computer forecasts and models, including PoP forecasts.
Probability/Statistical method
185
This forecast model is the only model that operates on the global scale.
Global Forecast System
186
This weather forecast model is generally better at forecasting along coastal areas, and does worse comparatively in areas of topographic features.
Global Forecast System
187
For MOS on the CLD row, what cover is CL?
no clouds
188
For MOS on the CLD row, what cover is FW?
1/8-2/8 cover
189
For MOS on the CLD row, what cover is SC?
3/8-1/2 cover
190
For MOS on the CLD row, what cover is BK?
5/8-7/8 cover
191
For MOS on the CLD row, what cover is OV?
8/8 full cover
192
what do you look for at the 250/300mb level?
- jet stream (Rossby waves)
- jet streaks
193
what is looked for at the 500mb level?
vorticity (specifically the advection)
194
what to look for at the 700mb level?
- shortwave vs longwave
- vertical velocity
- RH and dewpoint depressions
195
what to look for at the 850mb level?
- temperature advection
- low level jet (LLJ)
196
what does the 850mb level represent?
the top (or near the top) of the Planetary Boundary Level (PBL)
197
what become better defined at the 850mb level?
surface high/low pressure centers
198
What % confidence in 24 hrs?
75%-80% confidence
199
What % confidence in 48 hrs?
50-75% confidence
200
What % confidence in 72 hrs?
<50% confidence
201
What % confidence in +72 hrs?
you'll likely be wrong
202
Draw the jet streak diagram.
ok
203
Draw the sea breeze diagram.
ok
204
Draw the land breeze diagram.
ok
