SKYWARN Storm Spotter Training 2021 Metro Skywarn NWS Twin Cities Agenda • General Information • Updraft Features • Question and Answer • Break • Downdraft Features • Assess storm strength/potential • Determine storm motion and safety of your location • Report critical information • Question and Answer • Class Wrap Up • Amateur radio reporting (Metro Skywarn Nets) We Don't Recommend Chasing We owe a great deal to storm chasers. • Knowledge, • Images for Best Training Materials, • Minnesota Severe Storms Conference, and • Metro Skywarn Training. Metro Skywarn classes do not teach storm chasing skills • We do not dispatch spotters to particular locations. • Storm Chasing is a highly advanced skill. • We teach the basics of storm spotting and safety. • You are spotting at your own risk. Part 1: Role of Storm Spotters Spotters provide reports of what is actually happening Radar © Michael Thompson Spotter Mtsoutdoorsimages.com Part 1: Role of Storm Spotters What you see What radar sees © Bill Reid SPC Convective Outlooks • Storm Prediction Center outlooks the risk for severe weather across the country, as far out as 7 days in advance • www.spc.noaa.gov SPC Convective Outlooks SPC Convective Outlooks NWS’ Website • weather.gov/twincities • Get an hourly forecast for your city/zip code • Weather story of the day Weather Story • Main weather story of the day in one graphic • Also posted on Facebook and Twitter -@NWSTwinCities Area Forecast Discussion • Reasoning behind each forecast • Highlights timing, areas of greatest impact, and forecast uncertainty • www.weather.gov/twincities • Forecasts-Forecast Discussion Hazardous Weather Outlook weather.gov/twincities/ehwo SPC Mesoscale Discussions • Issued up to several hours before an event. May also be a progress report. • Heads-up that a tornado/severe thunderstorm watch may be imminent Severe Weather Watches • Issued when weather conditions are favorable for the development of severe weather • Usually issued 1-3 hours before severe weather occurs. Sometimes before storms even develop • “Spotters Get Ready” Severe Weather Warnings • Severe weather is imminent or occurring • Polygon-based. Anyone in the warning is at risk • We need your reports! Severe Weather Warnings • Our warnings are “Impact-Based” • Highlight the severity of the hazard expected, and potential impacts to life and property Warning Dissemination • Use multiple methods in case one method fails Wireless TV/Radio NWS Mobile Emergency Widget Alerts Hazard County Internet/ Communication Mobile Apps Warning Systems NOAA Weather Radio Weather Apps Wireless Emergency Alerts (WEA) County Boundary • Cell towers relay warning message to mobile devices • Certain Hazards • Tornado • Flash Flood Warning Polygon • Non-Weather Emergencies NOAA Weather Radio • Constant feed of NWS forecast products and alerts • Tone alerts can be programmed by county and hazard type • Available online or at major retailers for $20-$40 Part 3: Step By Step Storm Spotting • 4 Ingredients needed for Severe Storms • Moisture • Lift • Instability • Wind Shear © Tyler Olson Severe Storm Ingredients: Moisture • No moisture = no clouds • Water vapor condensing into clouds ultimately fuels the developing storm • Dew Points greater than 60-65 °F are ideal Severe Storm Ingredients: Lift • Must have a forcing mechanism to cause air to rise. • Look for: surface boundaries, low pressure systems, daytime heating, elevated terrain Severe Storm Ingredients: Instability • An “unstable atmosphere” means warm & humid air near the surface, with cooler & drier air aloft • Allows for air not only to rise, but accelerate upwards. • Updrafts can exceed 100 mph in the strongest © Brad Nelson thunderstorms Severe Storm Ingredients: Wind Shear • Winds change speed and direction at different levels in the atmosphere • Allows for more intense and longer-lived thunderstorms • Vast majority of significant severe weather comes from rotating storms (supercells) Step By Step Storm Spotting: Overview • Step 1: Identify updraft and downdraft features • Step 2: Assess storm strength/potential • Step 3: Determine storm motion and safety of your location • Step 4: Report critical information Updrafts and Downdrafts • Updrafts = Rising Air • Warm, humid air that fuels the storm • Thick, puffy, billowy clouds indicate a healthy updraft • Downdrafts = Sinking Air • Rain-cooled air that rushes out underneath the storm • Frequently contain heavy rain and possibly hail • The interaction between the updraft and downdraft is crucial in determining thunderstorm strength, longevity, and severity Thunderstorm Evolution • Thunderstorm evolution depends on the updraft & downdraft • Function of the 4 ingredients mentioned previously Supercell Schematic Supercell With Tornado © Bill Doms Updraft Examples Updraft Base Updraft Examples Updraft Examples © Theresa Caspers Visual Cues To Storm Strength • Strong • Weak • Sharp, crisp cloud edges • Fuzzy cloud edges • Visible upward motion • Weak upward motion • Well-defined updraft/downdraft • Ill-defined storm structure regions • Little to no visible rotation • Visible rotation • Mammatus clouds underneath anvil Updraft/Downdraft Examples Updraft/Downdraft Examples Updraft/Downdraft Examples © Brad Nelson Updraft Features: Wall Cloud • Develops under the updraft base, indicates rotation • Area of strongest rotation and inflow in updraft • Visible upward motion • Typically a first step towards tornadogenesis… sometimes • Usually tilted downwards towards the rainfall/downdraft Updraft Features: Wall Cloud Updraft Base Updraft Features: Wall Cloud Updraft Features: Wall Cloud Updraft Features: Wall Cloud © Michael Thompson Updraft Features: Wall Cloud Is My Wall Cloud Tornadic? • Look for persistent rotation. Watch the storm for a few minutes. • Is rotation speeding up/slowing down? How fast is it? • How low is the wall cloud to the ground? • Descending wall clouds are a sign of developing tornadogenesis • How strong is the inflow into the storm? • Increasing inflow into the storm is a sign of developing tornadogenesis • Are there any signs of a developing funnel cloud? • Look for enhanced areas of rotation and lowering Tips For Identifying Rotation • In general, strong rotation will be obvious • Watch the storm for at least several minutes • Be sure you are looking at the updraft base • Watch for rotation along a vertical axis, not a horizontal one • If you’re still not sure, rotation is likely weak or non-existent Updraft Features: Tornadoes • Rapidly rotating column of air, in contact with the wall cloud or updraft base AND the ground • Typically preceded by a wall cloud and then a funnel cloud • Funnel cloud may not be visible even as tornadic circulation is on the ground • Will often initially be evident as rotation/debris at the ground Funnel or Tornado? © Scott Woelm Funnel or Tornado? Funnel or Tornado? © Brad Nelson Funnel or Tornado? • Report only what you see • Other spotters may have a better view © Michael Thompson Break Time $5 Recommended Donation • Check - send to Metro Skywarn PO Box 131895 St. Paul, MN 55113 • Click “Donate” on MetroSkywarn.org It’s tax deductible! We’re a 501(C)(3) organization Downdraft Features • Review: All storms contain updrafts and downdrafts • Downdrafts appear dark • Rain/hail/strong winds coming out of storm (outflow) • Updraft/downdraft balance determines the strength and longevity of a storm Downdrafts On Radar Downdraft Features Downdraft Features Downdraft Features © Bill Doms Downdraft Features: Shelf Cloud • Occur on the leading edge of downdrafts (Gust Front) • Strong winds often follow immediately after the shelf cloud • Most common with a squall line or linear storm systems • No vertical rotation, but may exhibit rotation © Bill Doms along a horizontal axis Downdraft Features: Shelf Clouds © Scott Woelm Shelf Cloud © Scott Woelm Shelf Cloud © Scott Woelm Roll Cloud Shelf Cloud or Wall Cloud? © Brad Nelson Shelf Clouds vs Wall Clouds Wall Cloud Shelf Cloud • Updraft/inflow • Downdraft/outflow • Vertical rotation • Horizontal rotation • Attached to inflow base • Moves along outflow • Associated with tornadoes • Often followed by damaging wind gusts • Typically a feature of supercell thunderstorms • Typically a feature of squall lines Shelf Cloud or Wall Cloud? Shelf Cloud or Wall Cloud? © Bill Doms Shelf Cloud or Wall Cloud? © Brad Nelson Supercell Structure: Radar Advanced Feature: Rear Flank Downdraft (RFD) • Area of sinking air that wraps around the back of the updraft/rain free base • May observe a pronounced clear slot develop in the back of the updraft base/wall cloud • Can bring strong winds • Does NOT necessarily mean a tornado will form Squall Lines • Group of storms organized in a line • Can be hundreds of miles long, but typically only 10-20 miles wide • Pose the greatest risk for damaging winds • “Derechos” are intense squall lines that can produce damaging winds over 80-90 mph over a large area • In certain cases, tornadoes can be embedded in squall lines • “Quasi-Linear Convective Systems” • Very difficult for spotters Part 4: Storm Spotter Safety • Your safety is of the utmost importance • Situational Awareness is key • What is the storm motion? • Are you at a safe distance? • Are there other storms in the area? • Are you safe from lightning? Hail? Flooding? • Do you have an escape route? Place of shelter? • Visibility often degraded around storms Storm Motion • Most storms generally exhibit a west to east component of motion • Supercells typically exhibit deviant motion • Tend to move slower