Storm Hazards covered in this course

Transcription

1 Chasing Tornadoes (LG: 3a) A video Teaser, while students enter the classroom. Day3-60 Tornadoes of 2016 (16:05) Pecos Hank channel Watch on your own: 2016 and 2017 tornado videos by Pecos Hank tornadoes 9 May 2016 tornadoes 24 May 2016 tornado Day3-05 Classic tornado in Manitoba 26 June 2007 (2:41) Search on tornado by slair. 1 Storm Hazards covered in this course Thunderstorm Hazards lightning tornado today hail downpours (of rain) / local flooding downbursts (of air) / gustfronts Hurricane Hazards contain thunderstorms storm surge / coastal flooding high waves coastal erosion 2

2 Have you or a close friend or family member seen a tornado? Survey Question: (A) No (B) Yes, in the distance. (C) Yes, very close, but no damage to their property. (D) Yes, and it damaged their property. Wikipedia Commons 3 Road-map to Storm topics Learning Goals (LG): 1-5 Day Hazards Risk & Safety 1 Lightning 2 Rain Downpours, Air Downbursts 3 Tornadoes 4 Hail Fundamentals Appearance & Evolution Thunderstorm basics Supercells, mesocyclone. Observ.: radar, satellite Wall cloud, striations, Doppler radar Clouds at Tstorms: flanking line, mammatus Energy makes storms sun, radiation, surface heating moisture, condensation, latent heating heat to motion, forces, winds 5 Flooding, winds, waves, storm surge Hurricanes energy in warm ocean, Coriolis 4

3 Today s Learning Goals (LG: 3a-e) By the end of this period, you should be able to: 3a) describe tornado shapes, what makes them visible, and where they form relative to a thunderstorm. 3b) use photographs & videos to identify the tornado intensity on the enhanced Fujita scale. 3c) describe characteristics of tornado evolution, tornado outbreaks, and mesocyclones. 3d) explain tornado hazards and safety procedures, and times and locations of greatest risk. 3e) explain the difference between tornado watches and warnings, and appropriate safety responses. 5 The Turbulent Atmosphere (Storms) (LG: 3a-e) Prof. Roland Stull Today we will cover: Tornadoes 1. Recognizing tornadoes 2. Recognizing supercell rotation 3. Speeds and disaster scales 4. Tornado safety 5. Tornado risk 6. Tornado outbreaks 7. Tornado evolution 8. Forecasting tornadoes and public warnings 6

4 1. Recognizing Tornadoes (LG: 3a,c) Tornadoes are violently-rotating columns of air, in contact with the ground. Many different types of tornadoes exist. The most violent tornadoes come from supercell thunderstorms We will focus on tornadoes from supercells Illustration 2011 by Roland Stull, used with permission 7 1. Recognizing Tornadoes (LG: 3a) Most tornadoes are made visible by cloud-water droplets (the funnel cloud) and/or dust and debris from the ground (the debris cloud). Some tornadoes are invisible. weatherstock.com, used under license 8

5 Example of Strong Tornado (from a Supercell Thunderstorm) debris F5 tornado in Elie, Manatoba, Wikipedia Commons (LG: 3a) 9 Chasing Tornadoes (LG: 3a) Day3-20 Extreme close-up of tornado near Wray, CO (play first 30s and also last half a normal speed) Shows separate debris and funnel clouds in first 30 s, becoming 100% debris cloud later. Watch the remainder of this video on your own. 10

6 iclicker Question (LG: 3a-e) Which statement is TRUE regarding how you can see tornadoes? A) Tornadoes are always visible by eye. B) Tornadoes are sometimes visible due to cloud droplets. C) Tornadoes are sometimes visible due to dust & debris. D) Tornadoes are visible because of their slow rotation. E) Tornadoes can be anticipated by the large thunderstorm above them. 11 View Looking Down from Above Tornadoes are Attached to Thunderstorms Only a small percentage (20-30%) of supercell thunderstorms produce tornadoes. (LG: 3a) rain Anvil X In N. America, most Thunderstorms move from southwest (SW) toward northeast (NE). Supercell storms: strongest strong tornadoes are most likely associated with supercell storms. (images by Stull, used with permission) 12

7 a) View Looking toward NW Tornadoes are Attached to Thunderstorms (LG: 3a) Tornado b) View Looking Down from Above rain Best thunderstorms viewing is: off to the side of the storm path preferred side is to the southeast of the storm (at X) look at the storm toward northwest resulting supercell storm looks like sketch at upper left (images by Stull, used with permission) X 13 Tornadoes are attached to thunderstorms (LG: 3a) Overshooting Top or Dome top Anvil Mammatus base SW Flanking Line Wall Cloud Main Updraft Striations Rain Funnel Cloud or Tornado Illustration 2011 by Roland Stull, used with permission NE u 14

8 iclicker Question (LG: 3a-e) Strong tornadoes are A) not connected to thunderstorms B) within the strongest downdraft region of the thunderstorm C) usually connected to supercell thunderstorms D) often under the updraft region of thunderstorms E) often associated with mesocyclones 15 Tornado Shapes (LG: 3a,b) Many shapes are possible for tornadoes from supercell Thunderstorms. Shape is independent of intensity classification (i.e., Fujita or Torro scale) Illustration 2011 by Roland Stull, used with permission 16

9 (A) (LG: 3a) Tornado Shapes Q: Which image shows a wedge tornado? (C) (B) weatherstock.com, used under license (D) (E) wikipedia commons Recognizing supercell rotation: striations around the mesocyclone a rotating wall cloud (LG: 3a, c) Overshooting Top or Dome top Anvil Mammatus base Flanking Line Main Updraft Striations (Striations were shown in previous class.) u Rain Illustration 2011 by Roland Stull, used with permission SW Wall Cloud NE Illustration 2011 by Roland Stull, used with permission 18

10 Mesocyclone Rotation (LG: 3a, c) Day3-25 Supercell Crazy by Stephen Locke. Time lapse of many mesocyclone (5:34) (play at 2x speed, show first half only) Watch the remainder of this video on your own. 19 Wall Cloud (LG: 3a, c) rain-free thunderstorm base A wall cloud is an isolated lowering of cloud base... beneath rising cumulus towers... on SW flank of the storm... outside of (SW of) the precipitation region. Tornadoes come from rotating wall clouds in supercells. rain Wikipedia commons wall cloud rain rain-free thunderstorm base wall cloud Wikipedia commons 20 Illustration 2011 by Roland Stull, used with permission

11 Excellent Wall Cloud Example (LG: 3a, c) Day3-30 Wall cloud near Amber, OK Search on tornado wall cloud Amber gopro. (1.35, show all). (already time lapse) 21 (LG: 3a, c) Q: As a tornadic thunderstorm approaches you, the sequence of events you experience over your location (not far away) is: wikipedia commons (A) tornado, downpour, rainbow, lightning, anvil (B) anvil, gust front, lightning, downpour, tornado (C) downpour, gustront, anvil, tornado, lightning (D) supercell, tornado, mesocyclone, wall cloud, lightning (E) (none of the above) 22

12 3. Speeds and Disaster Scales (LG: 3b, d) Horizontal Movement (Translation) of the Center of the Tornado usually from SW toward NE in N. America (but movement toward any direction has been observed) translation speeds of center of tornado = 0 and 100 km/hr most move at speeds near middle of that range If in your car, you can easily drive away from most tornadoes. (Take a road perpendicular to the tornado path.) 23 Tornado Rotation Speeds & Disaster Scales (LG: 3b) Rotational (tangential) speeds around tornado center are much faster than translation speeds. These rotational winds cause the damage. Classified by: Enhanced Fujita Scale (used in N. America) determined by amount of damage to buildings. EF0 = very weak tornado -> might break a few windows. EF5 = exceptionally strong tornado -> totally destroy whole buildings TORRO Scale determined by wind speed. (Europe) 24

13 Effective Apr 2013 in Canada. Speed is max 3-second gust. Wikipedia commons For more details, see efscale/ef-scale.html (LG: 3b) Enhanced Fujita tornado damage scale. (stats updated 2014) Scale Rotation (mph) Rotation (km/hr) Damage % of torn. in Canada EF Light or Gale 66% EF Moderate 26% EF Significant 6.5% EF Severe 1.3% EF Devastating 0.3% EF5 > 200 > 322 Incredible 0.05% 25 Review this on your own (LG: 3b) 26

14 Day3-50. Video showing examples EF0-EF5 damage. Pecos Hank (5:30) (LG: 3b) Tornado Outbreak of 3 May F5 Damage 27 NWS Photos by Mike Branick (LG: 3b) Q: Based on damage to the wood-frame house in the foreground, the Fujita tornado intensity is: (A) EF1 (B) EF2 (C) EF3 (D) EF4 (E) EF5 28

15 (old) (LG: 3b) National Weather Service 29 Chased by Tornadoes (LG: 3d) Tornadoes vs. Cars & Trains Day3-40 Car sucked into tornado. (1:00) Day3-45 Tornado derails train in Illinois in 2008 (1:00) 30

16 Don t Cheat iclicker responses count toward a grade. Operating 2 or more iclickers (for yourself and friends) is cheating. Giving your iclicker for a friend to operate for you in this class is cheating. By UBC policy, cheating in class can earn you an F, or can result in you being expelled from UBC. Don t cheat. 31 My Research Numerical Weather Prediction (Using big computers to forecast the weather for W. Canada.) Clean Energy Transportation Weather Disasters Special Projects We produce weather forecasts for many locations: (see example on next screen for UBC) 32

17 My Research Weather forecasts for UBC. location=3510 We produce weather forecasts for Whistler. location= ATSC Applied Meteorology. (3 cr) (Totally online) Weather for Sailing, Flying & Snow Sports Flying and Soaring Weather 1. Clouds, ceiling, visibility & fog 2. Pressure, temperature, winds & wind shear 3. Turbulence & Icing 4. Thunderstorms & aviation weather services Winter Weather for Snow Sports 5. Winter weather 6. Mountain weather in winter 7. Snow conditions Sailing Weather 8. Wind and waves 9. Large-scale winds 10. Local winds and gusts 11. Marine weather services 34

18 4. Tornado Safety (LG: 3d,e) Tornadoes are short lived (usually minutes) Typical damage path narrow (usually width of a house, up to size of city block). damage paths often one to tens of kilometers long. Rarely last for hours, or have damage paths 1 km or more wide, or have paths of a 100 of km long. 35 Safest places to be: If indoors: below ground, in a basement or storm cellar (LG: 3d,e) get out of mobile homes (worse place to be in tornado) If outdoors on foot: get into a ditch or hole place your body below "line of fire" of fast moving debris Photos by Mike Branick If in car: drive away from tornado on best convenient road preferably to right or left of translation direction of tornado. Do NOT hide under highway bridge or overpass. 36

19 5. Tornado Risk (LG: 3d) Oklahoma, the center of Tornado Alley 37 Wikipedia commons Tornado Frequency vs. Intensity in Canada (LG: 3d) photo courtesy of EC 38

20 Tornado Risk in Canada (LG: 3d) Greatest tornado frequency in Canada photo courtesy of EC 39 iclicker Question (LG: 3a-e) A risky place to be, regarding tornadoes, is A) under a rotating wall cloud B) in tornado alley C) in a car driving away from a tornado D) in a mobile home in a tornado E) in a basement or cellar under a tornado, due to falling debris 40

21 6. Tornado Outbreaks (LG: 3c,d) Tornado Outbreak = 6 tornadoes in one day and one region, or many tornadoes during about a week. Outbreaks occur almost every year in N. America. Some recent examples: Aug 2005 Hurricane Katrina: 44 tornadoes in SE USA. Apr & May 2011: 2 outbreaks: 336 & 180 tornadoes, killed Apr 2014: outbreak 84 tornadoes in mid USA, killed Jan 2017: outbreak 81 tornadoes in SE USA, killed and they continue. Don t memorize all these. Just note that there are many tornado outbreaks. 41 Squall Line: a line of thunderstorms (LG: 3a-e) Radar image of a squall line from Dec 2017 Tornado outbreaks are often associated with squall lines. Squall lines often form along cold fronts. As the cold front moves toward the southeast, the thunderstorms along the front move toward the northeast. NWS 42

22 (LG: 3a,c,d) N Tstorm cells as viewed by radar Tornado Damage Tracks in an outbreak 43 (LG: 3c) Tornado Outbreak of Apr

23 (LG: 3c) Tornado Outbreak of 3 May Tornado Outbreak of 3 May Radar (LG: 3c) (LG: 2c) National Weather Service 46

24 iclicker Question (LG: 3a-e) Tornado outbreaks A) are rare B) happen almost every day in North America C) happen almost every year in North America D) are usually caused by a single strong supercell storm E) often cause parallel damage tracks along the ground 47 (LG: 3c) (LG: 2c) Hook Echo in Radar Reflectivity Image Tornado Vortex Signature in Doppler Velocity Image National Weather Service 48

25 7. Tornado Evolution (from supercells) (LG: 3c) thunderstorm wall cloud dust whirl dust whirl funnel cloud mature tornado decaying rope stage dissipating Illustration 2011 by Roland Stull, used with permission Forecasting Tornadoes is Very Difficult (LG: 3e) Tornado Watch 6 to 12 hour forecast a broad region within which tornadoes are favorable or likely later in day you can continue your normal activities you should monitor emergency announcements on news or weather radio. Stull & wife vs. Tornado Tornado Warning tornado actually detected now ( nowcast ), by either - Doppler radar sees tornado vortex signature or TVS, or - human spotter or other government official actually sees a tornado nowcast warning tells you: - where tornado is - where it is moving - warning is for specific towns or counties within the expected path - tornado sirens activated in those towns warnings come only 15 minutes or less prior to a tornado hitting you, so you MUST immediately terminate normal activities and go to tornado shelter or other area of refuge. 50

26 (LG: 3c-e) Which statement is TRUE? F5 tornado in Elie, Manatoba, Wikipedia Commons (A) Tornadoes always move toward the northeast in N. America. (B) It is safe to be in a car in a tornado. (C) Tornado warnings are issued 6 to 12 hours in advance. (D) Mobile homes attract tornadoes. (E) Tornado size and shape can be used to estimate tornado intensity. 51 The Turbulent Atmosphere Day3-50 One last YouTube recommendation to watch on your own if you plan to chase storms: Pecos Hank Tornado Death Traps. (11:40) Summary of Day 3 Tornadoes 1. Recognizing tornadoes 2. Recognizing supercell rotation 3. Speeds and disaster scales 4. Tornado safety 5. Tornado risk 6. Tornado outbreaks 7. Tornado evolution 8. Forecasting tornadoes and public warnings Next Class: From Heat to Motion Hail Prof. Roland Stull 52