COMET® Summer Severe Weather Distance Learning Course

Description:
This module provides a brief overview of Buoyancy and CAPE. Topics covered include the origin of atmospheric buoyancy, estimating buoyancy using the CAPE and Lifted Index, factors that affect buoyancy including entrainment of mid-level air, water loading, convective inhibition, and the origin of convective downdrafts. This module delivers instruction with audio narration, rich graphics, and a companion print version.

Objectives:
Terminal Objectives
By the end of this module you will be able to do the following:
1. Describe how buoyancy contributes to formation of a convective storm and its related updrafts and downdrafts
2. Define CAPE, LI, and CIN and describe how they can be used to forecast convective activity

Enabling Objectives
By the end of this module you will be able to do the following:
1. Define buoyancy and list factors that tend to increase buoyancy
2. Describe the life cycle of a convective storm
3. Define CAPE and describe how CAPE is determined on a skew-T/log-P diagram
4. Define Lifted Index (LI) and describe how LI is determined on a skew-T/log-P diagram
5. Describe how CAPE differs from Lifted Index
6. Define Convective Inhibition (CIN) and list factors that tend to increase CIN
7. Given 2 soundings, choose the soundings that will give the stronger updraft or downdraft

Estimated time to complete: 1 h

Description:
This module provides a basic understanding of how to plot and interpret hodographs, with application to convective environments. Most of the material previously appeared in the CD module, Anticipating Convective Storm Structure and Evolution, developed with Dr. Morris Weisman. Principles of Convection II: Using Hodographs includes a concise summary for quick reference and a final exam to test your knowledge. The module comes with audio narration, rich graphics, and a companion print version.

Objectives:
Terminal Objectives
1. By the end of this module you will be able to plot and use a hodograph to determine wind shear

Enabling Objectives
By the end of this module you will be able to do the following:
1. Given a vertical profile of wind speed and direction, plot a hodograph on a polar coordinate chart
2. Describe how to use a hodograph to determine the vertical wind shear between two levels
3. Given a hodograph, determine the total magnitude of vertical wind shear, the mean shear direction, and the mean wind and storm motion from a hodograph

Estimated time to complete: 60 min

Description:
This module discusses the role of wind shear in the structure and evolution of convective storms. Using the concept of horizontal vorticity, the module demonstrates how shear enhances uplift, leading to longer-lived supercell and multicell storms. The module also explores the role of shear in the development of mesoscale convective systems, including bow echoes and squall lines. Most of the material in this module previously appeared in the COMET modules developed with Dr. Morris Weisman. This version includes a concise summary for quick reference and a final exam to test your knowledge. The module comes with audio narration, rich graphics, and a companion print version.

Objectives:
Terminal Objectives
By the end of this module you will be able to describe the influence that vertical wind shear has on convective storm behavior

Enabling Objectives
By the end of this module you will be able to do the following:
1. Describe how and where interaction between a thunderstorm outflow (the cold pool) and the environmental wind shear lead to enhanced uplift and formation of new convective cells
2. Describe the vertical wind shear conditions that maximize the uplift along the downshear edge of the cold pool
3. Describe the origin of updraft tilt in a convective cell
4. Describe the different vertical shear characteristics for supercell storms and mesoscale convective systems (MCSs)

Estimated time to complete: 60 min

Description:
Mesoscale convective systems occur worldwide and year-round and are accompanied by the potential for severe weather and flooding. This module describes typical system evolution by examining squall line, bow echo, and MCC characteristics throughout their life cycles. This module has less emphasis on the physical processes controlling MCS structure and evolution than our previously released module, Mesoscale Convective Systems: Squall Lines and Bow Echoes. Instead, this newly updated module includes more material on tropical squall lines, MCC's, and on NWP’s ability to predict convective systems. The module starts with a forecast scenario and concludes with a final exam. Rich graphics, audio narration, and frequent interactions enhance the learning experience.

Objectives:
After completing this module, you should be able to do the following things.

Introduction to MCS Characteristics

• Recall the definition of an MCS
• Recall common types of MCS organization, especially squall lines and bow echoes
• List the potential weather hazards most likely associated with MCSs
• Identify key features associated with MCS initiation and evolution
• Recognize a likely MCS in radar imagery

Squall Lines

• Identify the various forms and compositions of squall lines
• Locate key squall line structures, including the cold pool, leading gust front, and rear-inflow jet
• Recall evolution of the surface pressure pattern during the lifetime of a squall line
• Explain the types of squall line formation
• Identify the phases of squall line evolution
• Using satellite and radar imagery, recognize the type and phase of a squall line
• Explain what determines if a squall line will be weak-to-moderate or moderate-to-strong
• Quantify low-level shear and identify which vertical wind shear most controls squall line strength
• Recall movement of long lines versus short lines, and movement of cells within a line
• Identify line back building and recognize conditions which support it
• Describe a line echo wave pattern and identify one from radar data
• List the differences between tropical and extratropical squall lines

Bow Echoes

• Define bow echoes and identify weather patterns conducive to their development
• Explain what a rear-inflow notch is and how to assess it with the MARC technique
• Discuss the factors that contribute to bow echoes being an especially severe form of MCS
• Describe the most likely time of onset and location of damaging winds from a bow echo
• Describe the characteristics of a derecho

Mesoscale Convective Complexes (MCCs)

• Recall how MCCs are defined via satellite imagery
• Describe where MCCs usually occur
• List the potential weather hazards associated with MCCs
• Explain what an MCV (or MVC) is and its relationship to an MCC
• Recognize the signature of an MCV from satellite imagery
• Recall why it is important to monitor an MCV

MCSs and Numerical Weather Prediction (NWP)

• List model convection issues and describe their impact on forecast elements
• Describe the difference between a model with convective parameterization and one without
• List the relative strengths and weaknesses of using a model with higher resolution (10 km WRF) versus one with lower resolution (22 km Eta)
• Describe common NWP limitations and errors related to forecasting large-scale convection
• Explain how model output should be applied to forecasting MCS occurrence

Estimated time to complete: 2-4 h

Description:
This Webcast features NWS forecaster Matthew J. Bunkers presenting the results of a study originally presented at the 19th AMS Conference on Severe Local Storms and published in the February 2000 issue of the AMS journal Weather and Forecasting. It is delivered as a streaming audio lesson with accompanying text and graphics.

In this presentation Mr. Bunkers presents a statistically superior method for predicting supercell motion regardless of the shape or location of the shear profile on the hodograph plot. The method is a modification of the method presented by Dr. Morris Weisman in the COMET Program CD module, Anticipating Convective Storm Structure and Evolution, and was developed based on 225 actual supercell events.

Estimated time to complete: 30 min

Description:
This module presents current conceptual models of several MCS types and provides explanations for the structures and behavior of MCSs based on the physical processes underlying their evolution. An understanding of the physical processes and conceptual models of MCSs will help forecasters to predict the most likely locations of severe weather within existing systems and to forecast the longevity, areal extent, and path of the system.

Accompanied by conceptual animations, numerical simulations, and case studies, Mesoscale Convective Systems: Squall Lines and Bow Echoes presents strategies with which the forecaster can identify the potential for long-lived MCSs and attendant severe weather.

Estimated time to complete: 4-6 h

Description:
In order to help forecasters build a strategy for anticipating convective storm structures, their evolution, and the potential for severe weather, A Convective Storm Matrix provides learners the opportunity for extensive exploration of the relationship between a storm's environment and its structure.

The matrix is composed of 54 four-dimensional numerical simulations based on the interactions of 16 different hodographs and 4 thermodynamic profiles. By comparing animated displays of these simulations, learners are able to discern the influences of varying buoyancy and vertical wind shear profiles on storm structure and evolution.

A series of questions guides the exploration and helps to reveal key storm/environment relationships evident in the matrix. A synopsis of the physical processes that control storm structure, as well as the current conceptual models of key convective storms types, is included for reference.

Subject matter expects for A Convective Storm Matrix: Buoyancy/Shear Dependencies include Mr. Steve Keighton, Mr. Ed Szoke, and Dr. Morris Weisman.

Note: This module was originally published on CD-ROM in March 1996 (v1.1) and re-released in 2001 as v1.3 for Microsoft Windows users only. CD-ROM version 1.3 works fairly well with Windows 98/ME/NT4/2000 but has reported to be problematic with Windows XP. Users of version 1.1 should obtain the patch located at http://www.comet.ucar.edu/help/ModuleSupport/matrix_problem.htm or use the new, Web-based module.

Estimated time to complete: 3-4 h

Description:
This module includes an interactive MCS Matrix of numerical simulations illustrating the physical processes controlling MCS evolution, as well as an archive of the entire Web module, Mesoscale Convective Systems: Squall Lines and Bow Echoes.

Patterned after the CD Module A Convective Storm Matrix, the new MCS Matrix provides learners the opportunity for extensive exploration of the relationship between a MCSs environment and its structure. The matrix is composed of 21 four-dimensional numerical simulations based on the interactions of 10 different hodographs with a common thermodynamic profile. By comparing animated displays of these simulations learners are able to discern the influences of vertical wind shear and the Coriolis Force on MCS structure and evolution.

A series of questions guides the exploration and helps to reveal key storm/environment relationships evident in the matrix.

The subject matter expert for this module is Dr. Morris Weisman.

Note: This module was originally published 5/28/99 as a CD-ROM (v1.0) as dual module along with a local copy of the Web module Mesoscale Convective Systems: Squall Lines and Bow Echoes (v3.0). The CD-ROM version of An MCS Matrix (1.0) works fairly well with Windows 98/ME/NT4/2000 but has reported to be problematic with Windows XP. Windows XP Users of version 1.0 should use the new, Web-based module.

Estimated time to complete: 3-4 h

Description:
This module is currently only available on CD-ROM. For more information on ordering a copy of this module on CD-ROM, please visit: http://meted.ucar.edu/about_contact.htm#buy

The primary purpose of the Anticipating Convective Storm Structure and Evolution module is to provide forecasters a strategy for anticipating storm structures, their evolution, and the potential for severe weather, based on an understanding of the physical processes that control their development. Because convective storms develop rapidly, having the right set of expectations of what is possible and probable within the storm environment will allow forecasters to better manage their activities during a convective event.

A traditional approach to teaching about convective storms has been to discuss several classic storm types that reveal distinctive structural elements. However, these classic storm types are not the norm. In nature, thunderstorms exist along a continuous spectrum of possible structures rather than always falling into discrete categories. Storms often exhibit qualities of more than one classic type or evolve from one type into another during their life cycle. For this reason, this module examines convective storms based on the predominant physical processes involved in their development that tend to place them in a particular region of the spectrum.

Because forecasters also need to accurately monitor the evolution of convective storms in order to issue timely weather warnings and statements, this module will also demonstrate methods for monitoring storm evolution through the available data (in particular, modern radar data), based on a thorough understanding of the current conceptual models of convective storms. Numerous interactions and a set of summary exercises are included. Summary Page--Key Points to Remember are available online at http://meted.ucar.edu/convectn/mod8sumpag.pdf.

Subject matter expects for Anticipating Convective Storm Structure and Evolution include Dr. Morris Weisman, Steve Keighton, and Ed Szoke.

Estimated time to complete: 8-10 hours

This NWS Storm Prediction Center (SPC) page features numerous technical fields that are commonly used at the SPC to determine the potential for severe thunderstorms and tornadoes. There is a description available for each field/indices found by clicking on the "Overview" located on the left hand side of the page. These fields and parameters aid forecasters in mesoscale forecasting and monitoring of current conditions.

Estimated time to complete: varies