Advanced Spotter Training: Anticipating Severe Weather Threats Professor Paul Sirvatka College of DuPage Meteorology Preparing for Severe Weather • Preparedness involves understanding the probable and potential threats. • Understanding the forecast • Understanding the atmosphere • Understanding the storm • Understanding the potential danger • Where do we gain this understanding? • Learning is a process and takes time and perseverance • Many available resources Advanced Spotter Training 2014 Professor Paul Sirvatka Sources of Wx Info and Education • First, we need to know where to look. • NEXLAB – weather.cod.edu • NWS LOT - www.crh.noaa.gov/lot • www.crh.noaa.gov/lot/?n=severe_briefing • www.nws.noaa.gov/om/severeweather/index.shtml • Storm Prediction Center - www.spc.noaa.gov/ • SKYWARN - skywarn.org/ • Spotter Network - http://www.spotternetwork.org/ Advanced Spotter Training 2014 Professor Paul Sirvatka NEXLAB http://weather.cod.edu HWO Hazardous Weather Outlook AFD Area Forecast Discussion ACUS Convective Outlook MCD Mesoscale Discussion SPS Special Weather Statement SVS Severe Weather Statement LSR Local Storm Report WW Weather Watch WU Severe Thunderstorm Warning WF Tornado Warning AdvancedCernan Earth Spotter and Training Space Center 2014 at Triton College ProfessorProfessor Paul Paul Sirvatka Sirvatka NEXLAB http://weather.cod.edu HWO – Hazardous Weather Outlook AFD – Area Forecast Discussion ACUS – Convective Outlook MCD – Mesoscale Discussion SPS – Special Weather Statement SVS – Severe Weather Statement LSR – Local Storm Report WW – Weather Watch WU – Severe Thunderstorm Warning WF – Tornado Warning AdvancedCernan Earth Spotter and Training Space Center 2014 at Triton College ProfessorProfessor Paul Paul Sirvatka Sirvatka NEXLAB http://weather.cod.edu You do not have to know everything! You just have to be willing to grow in your understanding and stay situationally aware! AdvancedCernan Earth Spotter and Training Space Center 2014 at Triton College ProfessorProfessor Paul Paul Sirvatka Sirvatka Thunderstorms Advanced Spotter Training 2014 Professor Paul Sirvatka Let’s Make a Thunderstorm! Let’s take a look at the ingredients needed for severe thunderstorms: • Lift • Moisture • Instability • Vertical Wind Shear Most discussions focus around these ingredients. AdvancedCernan Earth Spotter and Training Space Center 2014 at Triton College ProfessorProfessor Paul Paul Sirvatka Sirvatka Lift – Forcing the air to move upwards We need a physical mechanism to get the air moving upwards AdvancedCernan Earth Spotter and Training Space Center 2014 at Triton College ProfessorProfessor Paul Paul Sirvatka Sirvatka Do not confuse lift with instability Very rarely will the atmosphere be warmed so that deep convection occurs with only surface heating. Advanced Spotter Training Professor Paul Sirvatka What does that mean for you? • Fronts and outflow • Be aware of the boundaries not only closeness of a front to initiate thunderstorms, you – strong changes but can modify in temperature, a thunderstorms that change in wind interact with them. direction. Any big Some boundaries play change that is a role in tornado expected may signal production. the onset of severe storms. Advanced Spotter Training 2014 Professor Paul Sirvatka Moisture - Save the Dew Point! • As the dew point goes up, so do the chances for severe weather. • 50’s – Getting there. • 60’s – Juicy! • 70’s – Sweaty! And big storms if storms form. Flood potential too. • Boundary layer or surface. That is what you should watch for! Advanced Spotter Training 2014 Professor Paul Sirvatka What does that mean for you? • Be aware of trends in the moisture – use the dew point, not relative humidity. • Watch for cloud base heights. Higher cloud bases (LCL’s) mean more evaporation, more cooling when rain falls, and a lower tornado threat. AdvancedAdvanced Spotter Spotter Training Training 2014 2014 ProfessorProfessor Paul Paul Sirvatka Sirvatka Instability • Most commonly used • 0-1000 J/kg parameter is CAPE Marginally unstable. (Convective Available • 1000-2500 J/kg Potential Energy.) Moderately unstable. Measures in Joules/kg. Can be expressed as • 2500-4000 J/kg SBCAPE (surface –based) Very unstable. MLCAPE (mean, or mixed, • 4000+ J.kg layer CAPE) of MUCAPE Extremely unstable. (most unstable) CAPE. • Lifted Index can also be used. The more negative, the more unstable. Advanced Spotter Training 2014 Professor Paul Sirvatka What does that mean for you? • Instability has influence • Instability regulates over convection but is how strong updrafts sometimes over- (hail) and downdrafts emphasized in (damaging winds) may importance. Some be. Increasing severe thunderstorms temperatures and occur with minimal increasing moisture instability. More content will increase instability however the amounts of usually means storms instability. will be intense. Advanced Spotter Training 2014 • Professor Paul Sirvatka Speaking of instability… Gilbert, being still single, looks toward space to find a spouse. Advanced Spotter Training 2014 Professor Paul Sirvatka Caps and Convective Inhibition • Sometimes the release • When CIN is high, of instability is limited storms cannot form. Or by a layer of stable air if they already exist, called a “cap.” This is they will have a lower also known as tornado threat. Convective Inhibition • CIN, like CAPE, can (CIN). be SBCIN (surface based) or MLCIN (mean or mixed layer.) Advanced Spotter Training 2014 Professor Paul Sirvatka Vertical Wind Shear Vertical wind shear is the way the speed and/or direction of the winds changes as you go higher up into the atmosphere. It is perhaps the most important factor in understanding the threat for severe weather. Advanced Spotter Training 2014 Professor Paul Sirvatka Vertical Wind Shear Vertical wind shear leads to – • Longer-lived storms • A better ability to generate new storms in a multicell system • Stronger amounts of vertical shear lead to the development of rotation within thunderstorms (that is, the mesocyclone.) Such storms with strong and persistent rotation are called supercells. Supercells are almost always severe and are responsible for most tornadoes and almost all of the strong and violent (EF 2-5) tornadoes. Advanced Spotter Training 2014 Professor Paul Sirvatka Terms to pay attention to • SRH – Storm Relative Helicity Values greater than 150 J/kg are significant • 0-6 km (deep layer) shear Values greater than 30-40 kts usually indicate supercell potential • Unidirectional shear may lead to splitting storms that become supercells • Unidirectional winds may lead to “training of storms • Strong directional changes, especially near the surface, pose the greatest threat for tornadoes. Advanced Spotter Training 2014 Professor Paul Sirvatka What does that mean for you? • Shear matters the most. Be hyper aware anytime shear values get in the supercell range. Watch for words that indicate very strong shear such as “long- lived supercells” or “violent or long-tracked tornadoes” • Advanced Spotter Training 2014 Professor Paul Sirvatka Tornado Climatology There are more than 1200 tornadoes in the US per year. Advanced Spotter Training 2014 Professor Paul Sirvatka College of DuPage Meteorology • Most comprehensive community college meteorology program in the nation. • Courses include: • Intro to Meteorology • Severe and Unusual Weather • Forecasting • Intermediate Meteorology • Mesoscale Meteorology • Severe Weather Analysis • Thunderstorm Lab • Climate and Global Change • Hazardous Weather and Preparedness Advanced Spotter Training 2014 Professor Paul Sirvatka Weather Hazards and Preparedness • The course Weather Impacts and Preparedness, Earth 1119, is designed to help you sort through all the meteorology and terminology of weather that impacts your community, including winter weather, floods and droughts, heat waves and fire weather. • The Weather Hazards and Preparedness Certificate include looking at bigger issues, including emergency management, weather forecasting, climate change and severe weather analysis tools. Advanced Spotter Training 2014 Professor Paul Sirvatka Storm Chasing - Thunderstorm Laboratory Taking a storm chase is the best way to get hands- on experience with severe weather concepts and storm spotting. We still have a number of spot open this year in spring and summer. Please check weather.cod.edu/chasing for all the information you need. Advanced Spotter Training 2014 Professor Paul Sirvatka Just remember to keep growing! Advanced Spotter Training 2014 Professor Paul Sirvatka Thank you! Paul Sirvatka Professor of Meteorology College of DuPage Weather [email protected] .