Severe Weather Test 2

Front 1

Air mass 1

Back 1

Homogeneous body of air with relatively uniform temperature and moisture characteristics of thesource region

Front 2

Air mass 2

Back 2

Large volume of air over a relatively flat region acquire thermal and moisture properties consistent with the underlying surface for anextended period of time.

Front 3

Air mass 3

Back 3

Air over the Gulf of Mexico: Warm and humid

Front 4

Air mass 4

Back 4

Air over the Northern Canada: Frigid and bone-dry

Front 5

Classifying Air Masses 1

Back 5

cA continental Arctic

Front 6

Classifying Air Masses 2

Back 6

cP continental Polar

Front 7

Classifying Air Masses 3

Back 7

cT continental Tropical

Front 8

Classifying Air Masses 4

Back 8

mT maritime Tropical

Front 9

Classifying Air Mass 5

Back 9

mP maritime Polar

Front 10

Air Mass Characteristics 1 (1. Source Region, 2. Polar, 3. Tropical)

Back 10

1. Land or Continental

2. Cold

3. Hot

Front 11

Air Mass Characteristics 2 (1. Source Region, 2. Polar, 3. Tropical)

Back 11

1. Land or Continental

2. Dry

3. Dry

Front 12

Air Mass Characteristics 3 (1. Source Region, 2. Polar, 3. Tropical)

Back 12

1. Land or Continental

2. Stable aloft,

3. Unstable at surface

Front 13

Air Mass Characteristics 4 (1. Source Region, 2. Polar, 3. Tropical)

Back 13

1. Water or Maritime

2. Cool

3. Warm

Front 14

Air Mass Characteristics 5 (1. Source Region, 2. Polar, 3. Tropical)

Back 14

1. Water or Maritime

2. Moist

3. Moist

Front 15

Air Mass Characteristics 6 (1. Source Region, 2. Polar, 3. Tropical)

Back 15

1. Water or Maritime

2. Can be stable

3. Typically unstable.

Front 16

Air Mass Characteristics 7

Back 16

Air masses are 3-DNot all air masses are in contact with the ground

Front 17

Cold Front and the stability of the air 1

Back 17

The type of precipitation depends on the stability of the warm air ahead of the front.

Front 18

Cold Front and the stability of the air 2

Back 18

T-storm. Usually a line of T-stroms (squall line) along thefront. Sometime supercell T-storms with tornados, hail anddamaging wind.

Front 19

Cold Front and the stability of the air 3

Back 19

Light rain or no rain at all.

Front 20

Cold Front and the stability of the air 4

Back 20

Regardless of the cloud formations, cold front refers tocold air advancing, lifting warm air ahead of it

Front 21

Warm Front and the stability of the air 1

Back 21

The type of precipitation depends on the stability of the warm air.

Front 22

Warm Front and the stability of the air 2

Back 22

Wide spread of cloud will develop. The cloud are deepest near the front and becomethinner and higher away from the front.

Front 23

Warm Front and the stability of the air 3

Back 23

Pressure is heaviest closer to the frontal boundary, and lighter where cloud are shallow.

Front 24

Warm Front and the stability of the air 4

Back 24

T-storm, and the cloud is layered.

Front 25

Warm Front and the stability of the air 5

Back 25

Regardless of the cloud formations, warm front refersto cold air retreating and warm air advancing.

Front 26

Comparison of cold and warm fronts 1

Back 26

Cold fronts have steeper “slope” than warm fronts.

Front 27

Comparison of cold and warm front 2

Back 27

Cold fronts advances faster than warm front

Front 28

Comparison of cold and warm front 3

Back 28

Cold fronts cause more violent weather -cumulonimbus clouds

Front 29

Comparison of cold and warm front 4

Back 29

Cold fronts cause short, sharp showers, whereas warm fronts causedrizzle or steady rain

Front 30

Comparison of cold and warm front 5

Back 30

Warm fronts cover a wider area with clouds and precipitation

Front 31

Comparison of cold and warm front 6

Back 31

Cold air is always ‘the boss’—its movement relative to the frontdetermine the type of front.

Front 32

Occluded front 1

Back 32

Cold front meets the warm front ahead of it, that segmentbecomes occluded.

Front 33

Occluded front 2

Back 33

Usually occur on mature and dissipating stages of an extratropicalcyclone

Front 34

Stationary Front and the stability of the air 1

Back 34

A line of shower and thunderstorms may develop

Front 35

Stationary Front and the stability of the air 2

Back 35

Heavy precipitation may persist leading to flooding.

Front 36

The Dryline 1

Back 36

The dryline is a type of front. It is also termed the“dewpoint” front.

Front 37

The Dryline 2

Back 37

It marks the boundary between moist Gulf ofMexico air and dry, warm desert air from thesouthwest. There is usually not a temperaturechange across the dryline.

Front 38

The Dryline 3

Back 38

Most evident in south-central U.S. (TX, OK, KS)

Front 39

Fronts summary 1

Back 39

1. Cold

2. Warm

3. Occluded

4. Dryline

Front 40

Fronts summary 2

Back 40

Lower troposphere is comprised of air masses thatcontrast in T and/or humidity. Narrow transitionzone called fronts, border air masses.

Front 41

Fronts summary 3

Back 41

Cold air is always ‘the boss’—its movementrelative to the front determine the type of front. Airretreats ahead of a warm front, advances behind acold front, and moves parallel to a stationary front.Cold front catches up warm front lead to occludefront.

Front 42

Fronts summary 4

Back 42

Clouds and precipitation develop along the frontsonly when a significant density contrast existsbetween air masses.

Front 43

Fronts summary 5

Back 43

With little difference in T and humidity between airmasses, the front may pass virtually unnoticedexcept a shift in wind direction

Front 44

Identifying Fronts: What to look for on a surface weather map or from own observations 1

Back 44

Sharp temperature over a relatively short distance

Front 45

Identifying Fronts: What to look for on a surface weather map or from own observations 2

Back 45

Change in moisture content

Front 46

Identifying Fronts: What to look for on a surface weather map or from own observations 3

Back 46

Rapid shifts in wind direction (think about the center of lowpressure!)

Front 47

Identifying Fronts: What to look for on a surface weather map or from own observations 4

Back 47

Pressure changes

Front 48

Identifying Fronts: What to look for on a surface weather map or from own observations 5

Back 48

Clouds and precipitation patterns

Front 49

Extra-tropical Cyclones 1

Back 49

Form along the jet stream between about 30-70°latitude.

Front 50

Extra-tropical Cyclones 2

Back 50

They are the parent storms from which much of thesevere weather of the mid-latitudes develops.

Front 51

Extra-tropical Cyclones 3

Back 51

Entire life cycle can span several days to well overa week, but can reach maximum intensity (i.e.,lowest central pressure) in as little as 36-48 hr afterformation.

Front 52

Extra-tropical Cyclones 4

Back 52

These storms cover areas ranging from severalhundred to a thousand miles across.

Front 53

Extra-tropical Cyclone 5

Back 53

Winds blow counter-clockwise (cyclonically) in NH

Front 54

Extra-tropical Cyclone 6

Back 54

Winds spiral into low at surface

Front 55

Extra-tropical Cyclone 7

Back 55

It forms, exists at intersection of fronts

Front 56

Extra-tropical Cyclone 8

Back 56

Cold front to S and W, warm front to E of low

Front 57

Extra-tropical Cyclone 9

Back 57

Cold air “behind” low, warm air “ahead” of low – lows & highs bothmove in direction of jet stream winds

Front 58

Extra-tropical Cyclone 10

Back 58

Thunderstorms often ahead of cold front

Front 59

Extra-tropical Cyclone 11

Back 59

Steady precipitation ahead of warm front (ice storms)

Front 60

Extra-tropical Cyclone 12

Back 60

Cloud sequence of cirrus, cirrostratus, altostratus, nimbostratus

Front 61

Extra-tropical Cyclone 13

Back 61

Life cycle of low: looks like huge sideways version of breaking oceanwave (lifetime: days to about 1 week)

Front 62

Extra-tropical Cyclone 14

Back 62

Energy source: cold air ‘wants’ to be under warm air

Front 63

Extra-tropical Cyclone 15

Back 63

Each cyclone is different from all others!

Front 64

Extra-tropical Cyclone: View from Above 1

Back 64

A fully matureextratropical cyclone'scloud pattern looks like alarge “comma”.

Front 65

Extra-tropical Cyclone: View from Above 2

Back 65

Severe weather occursalong the "tail" of the"comma"

Front 66

Extra-tropical Cyclone: View from Above 3

Back 66

Heavy rain, snow, sleet,mixed precipitation occur withinthe "head" of the "comma"

Front 67

Extra-tropical Cyclone: View from Above 4

Back 67

Blizzards occur (in winter)in the northwest quadrantof the "head" of the"comma"

Front 68

Upper level wave and convergence/divergence 1

Back 68

Front 69

Upper level wave and convergence/divergence 2

Back 69

Front 70

Upper level wave and convergence/divergence 3

Back 70

Front 71

Cyclone Development Regions in NA 1

Back 71

just east of the Rockies in the central U.S. (particularly ineastern CO)

Front 72

Cyclone Development Regions in NA 2

Back 72

just east of the Rockies in the central Canada (Alberta clipper)

Front 73

Cyclone Development Regions in NA 3

Back 73

just off the TX-LA coastline along the Gulf Coast of the U.S.

Front 74

Cyclone Development Regions in NA 4

Back 74

along the East Coast of the U.S.

Front 75

Cyclone Development Regions in NA 5

Back 75

over the Bering Sea and Gulf of Alaska in the Pacific Ocean

Front 76

Intensity Difference 1

Back 76

East and Gulf coast cyclones are often more intense that their (lee)Rocky Mountain counterparts.

Front 77

Intensity Difference 2

Back 77

Latent heat released during condensation in the clouds contributes more tostorm intensification; local moisture source in the warm Gulf of Mexico andin the warm Gulf Stream current.

Front 78

Intensity Difference 3

Back 78

Sensible heat from the ocean (gulf) surface acts to heat the atmosphere,contributing more to storm intensification; heat energy transferred directlyfrom water to air through conduction.

Front 79

Intensity Difference 4

Back 79

Strong thermal contrasts between the ocean (gulf) and land enhance and maintain a sharp thermal boundary (i.e., baroclinic zone) along the coastline; most pronounced in winter.

Front 80

Intensity Difference 5

Back 80

There is often more than one jetstreak acting to create upper-leveldivergence; the jetstreaks are found within two separate jetstreams (polar andsubtropical) and their "phasing" creates the strongest storms

Front 81

Intensity Difference 6

Back 81

Friction is smaller over the ocean, which lead to weaker air convergenceinto the low-pressure center, allowing the low to maintain a greater intensity.

Front 82

"Bomb"

Back 82

Explosive cyclogenesis is called a "bomb": When extratropical cyclone deepens rapidly. 24 mb in 24 hr period. e.g., one case of 60 mb decrease in central pressure in24 h ==> 2.5 mb/h

Front 83

Ice Storms 1

Back 83

Freezing rain and drizzle – freezes on surfacescausing glaze of ice.

Front 84

Ice Storms 2

Back 84

Impacts public safety, insurance, economy,environment, power, and transportation

Front 85

Ice storms 3

Back 85

Even minor events cause travel and walkingdifficulties.

Front 86

Ice storms 4

Back 86

Aloft can cause icing on wings of airplanes.

Front 87

Supercooled water 1

Back 87

Water melts at 0ºC, but does not necessarilyfreeze at this temp

Front 88

Supercooled water 2

Back 88

Difficult to transition from moving fluid tosolid lattice of ice

Front 89

Supercooled water 3

Back 89

Aerosols serve as ice nuclei in air

Front 90

Supercooled water 4

Back 90

Ice nuclei most effective around 5ºF, marginally effective 5-23ºF, and hardly effective 23-32ºF.

Front 91

Supercooled water processes 1

Back 91

Melting process – snow melts in warm layer,freezes on surface in shallow cold layer (deepclouds) => freezing rain

Front 92

Supercooled water processes 2

Back 92

Supercooled warm rain process – collision andcoalescence of cloud droplets createsprecipitation, snow not involved (shallowclouds) => freezing drizzle, fog, or mist

Front 93

Supercooled water processes 3

Back 93

Can also have freezing spray from water bodies.

Front 94

Vertical temperature profile and different type of precipitation

Back 94

Front 95

Cross section through a warm front 1

Back 95

Front 96

Cross section through a warm front 2

Back 96

Front 97

Cross section through a warm front 3

Back 97

Front 98

Freeze rain Climatology

Back 98

Front 99

Freeze drizzle Climatology

Back 99

Front 100

Lake-effect Snowstorms 1

Back 100

Great Lakes, GreatSalt Lake, Aral Sea,and even ocean-effectsnow (Cape Cod,Outer Banks)

Front 101

Lake-effect Snowstorms 2

Back 101

Within ~50 miles ofshoreline

Front 102

Lake-effect Snowstorms 3

Back 102

1-5 feet in extremeevents

Front 103

Lake-effect Snowstorms 4

Back 103

Can continue for days

Front 104

Synoptic Set-up 1

Back 104

Very cold air movesover lake

Front 105

Synoptic Set-up 2

Back 105

Extreme snow = verywarm lake temp. andvery cold air; tempgradient!

Front 106

Synoptic Set-up 3

Back 106

Behind cold front withhigh pressure movingin

Front 107

Synoptic Set-up 4

Back 107

Late fall and earlywinter (lakes warm andice free with cold airmasses)

Front 108

Synoptic Set-up 5

Back 108

Concept of Delta-T

Front 109

Development - Wind 1

Back 109

Air approaching lake is 23 to -13ºF.

Front 110

Development - Wind 2

Back 110

Air accelerates over lake (less friction)

Front 111

Development - Wind 3

Back 111

Divergence at upwind shore and convergence at downwindshore

Front 112

Development - Wind 4

Back 112

Sinking air and clear skies upwind and rising air and clouds/precip. downwind

Front 113

Development - Moisture 1

Back 113

Air warms and moistens over lake (capacityincreases as temp. increases), rapid evaporation

Front 114

Development - Moisture 2

Back 114

Air at lake surface can warm up to 36ºF!

Front 115

Development - Moisture 3

Back 115

Above warm surface layer, air remains cold => rapiddestabilization

Front 116

Climatology 1

Back 116

Usually within 50 miles (80 km) of shore

Front 117

Climatology 2

Back 117

Warm lake and cold air => LES

Front 118

Climatology 3

Back 118

Large lake-air temp. difference => LES

Front 119

Climatology 4

Back 119

T-diff > 10C, otherwise, the E and destabilizationare generally insufficient for lake-effect snow todevelop.

Front 120

Climatology 5

Back 120

Frozen lake shuts off LES

Front 121

Blizzards: Why the Plains? Unique geography 1

Back 121

Mountains block moderate Pacific air

Front 122

Blizzards: Why the Plains? Unique geography 2

Back 122

Endless night produces bitter cold air that sweepsdown from Canada

Front 123

Blizzards: Why the Plains? Unique geography 3

Back 123

Lee Cyclones bring wind and drag cold air down

Front 124

Blizzards: Why the Plains? Unique geography 4

Back 124

Gulf of Mexico moisture fuels snow

Front 125

Ingredient - Cold Air 1

Back 125

Originates on plains of west-central Canada inwinter

Front 126

Ingredient - Cold Air 2

Back 126

Snow covered – radiates infrared energy, reflectssunlight

Front 127

Ingredient - Cold Air 3

Back 127

Long winter nights

Front 128

Ingredient - Cold Air 4

Back 128

Clear skies => radiational cooling

Front 129

Ingredient - Cold Air 5

Back 129

Strong surface high develops => pressuregradient for wind

Front 130

Ingredient - Cold Air 6

Back 130

-30 to -50 ºF

Front 131

Ingredient - Arctic Front 1

Back 131

Leading edge of shallow, bitter cold air mass

Front 132

Ingredient - Arctic Front 2

Back 132

Second surge of cold air behind polar front

Front 133

Ingredient - Arctic Front 3

Back 133

Cyclones drag cold air southward

Front 134

Ingredient - Arctic Front 4

Back 134

Colorado lows = more snow and wind; biggerstorms!

Front 135

Ingredient - Arctic Front 5

Back 135

Alberta Clippers = colder temps.; dusting of snow.

Front 136

Ground Blizzards 1

Back 136

Caused only by blowing snow

Front 137

Ground Blizzards 2

Back 137

Skies may be clear

Front 138

Ground Blizzards 3

Back 138

Frequent in Plains (usuallylocalized)

Front 139

Ground Blizzards 4

Back 139

Drifting covers roads

Front 140

Ground Blizzard 5

Back 140

Poor visibility

Front 141

Ground Blizzard 6

Back 141

“Black ice”

Front 142

Ground Blizzard 7

Back 142

Unexpected and dangerous

Front 143

Blizzard Safety 1

Back 143

Drive carefully !!! Try not to get stranded or covered

Front 144

Blizzard Safety 2

Back 144

Dress warmly

Front 145

Blizzard Safety 3

Back 145

Beware of carbon monoxide

Front 146

Blizzard Safety 4

Back 146

Fires, falling through ice, heart attacks

Front 147

Blizzard Safety 5

Back 147

Winter storm survival kit in vehicle (blanket, flashlight,batteries, first aid kit, knife, food, water, dry clothes, potty(coffee can w/ lid), etc.)

Front 148

Blizzard safety 6

Back 148

Winter supplies (sand, cat litter, shovel, booster cables,tools, etc.)

Front 149

Blizzard safety 7

Back 149

STAY with vehicle !!!

Front 150

Blizzard safety 8

Back 150

Carry cell phone.