Advanced Spotter Training: Anticipating Severe Weather Threats. Professor Paul Sirvatka College of DuPage Meteorology

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1 Advanced Spotter Training: Anticipating Severe Weather Threats College of DuPage Meteorology

2 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

3 Sources of Wx Info and Education First, we need to know where to look. NEXLAB weather.cod.edu NWS LOT Storm Prediction Center - SKYWARN - skywarn.org/ Spotter Network -

4 NEXLAB HWO AFD ACUS MCD SPS SVS LSR WW WU WF Hazardous Weather Outlook Area Forecast Discussion Convective Outlook Mesoscale Discussion Special Weather Statement Severe Weather Statement Local Storm Report Weather Watch Severe Thunderstorm Warning Tornado Warning Advanced Cernan Earth Spotter and Training Space Center 2014 at Triton College

5 NEXLAB 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 Advanced Cernan Earth Spotter and Training Space Center 2014 at Triton College Professor Professor Paul Paul Sirvatka Sirvatka

6 NEXLAB You do not have to know everything! You just have to be willing to grow in your understanding and stay situationally aware! Advanced Cernan Earth Spotter and Training Space Center 2014 at Triton College

7 Thunderstorms

8 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. Advanced Cernan Earth Spotter and Training Space Center 2014 at Triton College

9 Lift Forcing the air to move upwards We need a physical mechanism to get the air moving upwards Advanced Cernan Earth Spotter and Training Space Center 2014 at Triton College

10 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

11 What does that mean for you? Fronts and outflow boundaries not only initiate thunderstorms, but can modify thunderstorms that interact with them. Some boundaries play a role in tornado production. Be aware of the closeness of a front to you strong changes in temperature, a change in wind direction. Any big change that is expected may signal the onset of severe storms.

12 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!

13 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. Advanced Advanced Spotter Spotter Training Training Professor Professor Paul Paul Sirvatka Sirvatka

14 Instability Most commonly used parameter is CAPE (Convective Available Potential Energy.) Measures in Joules/kg. Can be expressed as SBCAPE (surface based) MLCAPE (mean, or mixed, layer CAPE) of MUCAPE (most unstable) CAPE J/kg Marginally unstable J/kg Moderately unstable J/kg Very unstable J.kg Extremely unstable. Lifted Index can also be used. The more negative, the more unstable.

15 What does that mean for you? Instability regulates how strong updrafts (hail) and downdrafts (damaging winds) may be. Increasing temperatures and increasing moisture content will increase the amounts of instability. Instability has influence over convection but is sometimes overemphasized in importance. Some severe thunderstorms occur with minimal instability. More instability however usually means storms will be intense.

16 Speaking of instability Gilbert, being still single, looks toward space to find a spouse.

17 Caps and Convective Inhibition Sometimes the release of instability is limited by a layer of stable air called a cap. This is also known as Convective Inhibition (CIN). When CIN is high, storms cannot form. Or if they already exist, they will have a lower tornado threat. CIN, like CAPE, can be SBCIN (surface based) or MLCIN (mean or mixed layer.)

18 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.

19 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.

20 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 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.

21 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 longlived supercells or violent or long-tracked tornadoes

22 Tornado Climatology There are more than 1200 tornadoes in the US per year.

23 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

24 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.

25 Storm Chasing - Thunderstorm Laboratory Taking a storm chase is the best way to get handson 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.

26 Just remember to keep growing!

27 Thank you! Paul Sirvatka Professor of Meteorology College of DuPage Weather