MetEd Winter Weather Distance Learning Course
2005/06 Season

Description:
In this Webcast, Dr. James Steenburgh, working for the Department of Meteorology and the NOAA Cooperative Institute for Regional Prediction at the University of Utah, takes a look at cool-season orographic storms in western North America. He provides a brief microphysics review, an overview of cool-season orographic precipitation processes in several mountain ranges, and a look at forecasting tools and techniques. This Webcast is based on a classroom presentation given in Boulder, CO in December 2002.

Objectives:
• Improve knowledge of orographic precipitation processes and their geographical, climatological, and storm-to-storm variability.
• Build or enhance your orographic precipitation forecasting tool chest.
• Illustrate the strengths and weaknesses of quantitative precipitation forecasts by high-resolutions models in complex terrain.

Estimated time to complete: 1 h

Description:
This Webcast is based on a COMET classroom presentation by Dr. Gary Lackmann at the 2nd MSC Winter Weather Course held in Boulder, Colorado on 22 February 2002. Dr. Lackmann reviews the basic thermodynamics of freezing and melting and how operational models represent these processes. He also touches upon the biases that occur in the models by looking at examples of melting snow aloft, melting snow at the surface, freezing aloft (ice pellets), and freezing rain. Dr. Lackmann is a faculty member in the Department of Marine, Earth, and Atmospheric Sciences at North Carolina State University.

Objectives:
1. Examine four thermodynamic scenarios closely, each of which produces a different precipitation situation.

2. Compare sounding, radar, and model signatures associated with these scenarios.

3. Compare the representation of these thermodynamic processes in operational models at and near the surface.

4. Become aware of potential problems with the model forecasts.

5. Examine the limiting processes and requirements for freezing rain.

Estimated time to complete: 35 min

Description:
This webcast is based on a presentation by Dr. Moore MSC/COMET Winter Weather Workshop in Boulder, CO, 4 December 2002. In it, he covers the definition of the TROWAL and its role in heavy snow production in the form of bands primarily located to the northwest of the surface low. The various conveyor belts associated with mature winter cyclones are emphasized. The roles of mid-level frontogenesis and conditional symmetric instability in these systems are discussed in the context of heavy snow development.

Objectives:
1. Examine the structure of a mature midlatitude cyclone from the conveyor belt standpoint.

2. Understand how areas where equivalent potential vorticity < 0 are conducive to conditional symmetric instability and snowbands.

3. Demonstrate the positive interaction between frontogenesis and zones favorable for CSI.

4. Compare these features in two CONUS case studies.

Estimated time to complete: 45 min

Description:
Precipitation frequently falls and accumulates in discrete bands with accumulations that vary markedly over short distances. This module examines several mechanisms that result in mesoscale banded precipitation, focusing primarily on processes at work in midlatitude cyclones. The module starts with a review of the Norwegian and conveyor belt cyclone models. Then several banding processes are examined in detail, including deformation/frontogenesis, the Trowal (Trough of Warm Air Aloft), frontal merger, CSI/slantwise convection, and melting/evaporation-induced circulations. The module concludes with discussions of the representation of banded precipitation by NWP models and the detection of banded precipitation with satellite sensors.

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


With regard to the general features of mesoscale banded precipitation:

* Recall the operational definition of a precipitation band

* Describe the relationship between instantaneous and accumulated bands of precipitation

* Recall the basic requirements for precipitation and the role of atmospheric stability


With regard to the association between midlatitude cyclones and mesoscale banded precipitation:

* Recall and describe the different types of fronts in the Norwegian cyclone model

* Describe the typical precipitation field associated with each kind of front

* Distinguish an anafront from a katafront in forecast products

* Distinguish a cold occluded front from a warm occluded front in forecast products

* Recall and describe the types of air streams in the conveyor belt model of midlatitude cyclones

* Describe the relationship between air streams and fronts

* Describe the relationship between air streams and mesoscale banded precipitation

* Recognize different air streams in satellite images and forecast products

* Recall what a trowal is and where it occurs

* Describe the relationship between the trowal and banded precipitation

* Describe the trowal signature in forecast products

* Locate a trowal on satellite images and forecast products


With regard to processes that lead to mesoscale banded precipitation.

* Define the terms: deformation, frontogenesis, frontolysis

* Describe how deformation leads to frontogenensis

* Describe the vertical motions associated frontogenesis

* Describe how frontogenesis leads banded precipitation

* Recognize and diagnose deformation and frontogenesis in forecast products

* Describe circulations induced by melting and evaporation in the lower tropsphere

* Describe the relationship between melt/evaporation-induced circulations, frontogenesis, and banded precip

* Recognize and diagnose banded precipitation forced by melt/evaporation-induced circulations in forecast products

* Define frontal merger

* Describe the difference between frontal merger and frontal occlusion

* Describe a typical synoptic setting for frontal merger and its relationship with midlatitude cyclones

* Describe the relationship between frontal merger and banded precipitation

* Recognize and diagnose frontal merger in forecast products

* Describe the relationship between CSI and slantwise convection

* Describe the atmospheric conditions conducive to CSI

* Describe what atmospheric conditions lead to low inertial stability

* Recognize and diagnose CSI and slantwise convection with cross-sectional analysis.


With regard to the simulation of mesoscale banded precipitation by NWP models:

* Given the grid spacing determine the grid resolution

* Describe the characteristics of a hydrostatic atmosphere

* State why high-resolution NWP models need to be non-hydrostatic

* Describe the need for parameterization in NWP models

* Describe the pros and cons of parameterization versus explicit treatment of processes

* Describe the difference between prognostic and diagnostic moisture physics and the benefits of each

* Characterize COAMPS and NOGAPS


With regard to the detection of mesoscale banded precipitation by satellite sensors:

* Describe the benefits and drawbacks of satellite estimates of precipitation

* Recall at least 4 satellite sensors that measure precipitation

* Describe the benefits and drawbacks of the GOES Precipitation Index

* Describe the benefits and drawbacks of precipitation estimates derived from microwave sensors

* Describe how a blended precipitation product is derived

Estimated time to complete: 3 h

Description:
This interactive case exercise covers a 24-hour forecast period that
includes the challenge of precipitation type forecasting. The case
exercise provides an overview of precipitation type forecasting based on
model algorithms, partial thickness analysis, and the top-down method.

Objectives:
• Understand the limitations of NWP models in precipitation type forecasts.
• Apply partial thickness analysis for forecasting precipitation type.
• Apply the top-down Method for forecasting precipitation type.

Estimated time to complete: 27-90 min

Description:
This module, the latest in our series on Numerical Weather Prediction, covers the theory and use of ensemble prediction systems (EPSs). The module will help forecasters develop an understanding of the basis for EPSs, the skills to interpret ensemble products, and strategies for their use in the forecast process. It contains six sections: an Introduction that briefly presents background theory; Generation, which describes how ensemble systems are constructed; Statistical Concepts, which provides a brief refresher on knowledge required for ensemble product interpretation; Summarizing Data, which describes common ensemble forecast products; Verification, which discusses how EPSs performance is assessed and documented; and Case Applications, which provides links to a number of forecast cases illustrating the use of EPSs in the forecast process. Questions and Exercises are offered throughout to help you test your learning and provide practical examples. The module also includes a pre-assessment and module final quiz.

Objectives:
Explain the basis for NWP ensemble prediction, and what we mean when we say that the atmosphere is chaotic (i.e. sensitive to initial conditions).

Describe the variety of methods used to generate the ensemble members of an ensemble prediction system, including perturbation of initial conditions, boundary conditions, and model configurations.

Understand the basic statistical concepts and methods used in the development of ensemble products, including probability distributions and their middleness, variability, and shape characteristics.

Recognize and interpret the variety of ensemble forecast products, including spatial and point forecast graphics, and including those that account for flow regimes (RMOP) and reveal NWP model bias and errors.

Interpret ensemble verification products, and apply them in using ensemble forecasts.

Estimated time to complete: 4-5 h

Description:
This Webcast features Phil Schumacher, NWS Sioux Falls, South Dakota discussing the conditions that dictate the location of precipitation relative to inverted troughs. Phil presents a composite case study based on collaborative research with Dr. R. Weisman and others, as well as two examples of inverted trough events in the Central Plains. This presentation is based on his presentation at the MSC Winter Weather Course, December 2002, in Boulder, Colorado. The webcast is accompanied by a case exercise, Inverted Trough Case Exercise.

Objectives:
1. Describe inverted troughs and their associated precipitating features.
2. Present the results of a composite inverted trough study, based on the differences between inverted troughs that produce precipitation ahead vs. behind the trough.
3. Demonstrate the use of isentropic techniques in diagnosing important inverted trough features.
4. Look at several case studies demonstrating the impact of inverted troughs on precipitation distributions.

Estimated time to complete: 60 min

Description:
This exercise follows the progression of a winter weather event across the Central Plains states beginning 1200 UTC on 7 March 1999. Each forecast question is accompanied by Eta model data and includes a forecast discussion by Phil Schumacher, NWS Sioux Falls, South Dakota. This exercise compliments the Webcast, Inverted Troughs and their Associated Precipitation Regimes, based on a presentation by Phil Schumacher at the MSC Winter Weather Course, December 2002, in Boulder Colorado.

Objectives:
1. Identify whether precipitation will be primarily ahead or behind an inverted by applying the conceptual model of inverted trough precipitation organization.

2. Use isentropic analysis to view the affect inverted troughs have on moisture transport and the implied lift associated with inverted troughs.

3. Use the conceptual model of inverted trough precipitation organization to determine the approximate beginning and ending time for significant precipitation associated with inverted troughs.

Estimated time to complete: 45 min

Description:
This Webcast, presented by Dr. Jim Moore of St. Louis University, covers the advantages and applications of diagnosis and visualization of large-scale flow and vertical motion on surfaces of constant potential temperature. The movement of moisture along these surfaces is emphasized, as is the diagnosis of the components of vertical motion. Background mathematical concepts are presented, then illustrated with soundings, cross sections, and plan view analyses of data from multiple cases.

Objectives:
1. Understand the concepts of pressure advection and system relative flow.

2. Understand dynamic destabilization and associated environmental moistening.

3. Diagnose static stability, upper fronts and CSI in this framework.

4. Examine at frontogenesis and transverse jet streak circulations on vertical cross sections with analyzed potential temperature fields.

5. Examine the components of vertical motion in an isentropic framework.

6. Compare the advantages and disadvantages of isentropic analysis.

7. Examine a wintertime case study utilizing isentropic analysis.

Estimated time to complete: 1 h

Description:
This exercise examines an event that took place in the 24 hour time period beginning at 18Z, Dec 31, 2000 in southern British Columbia, Canada and northern Washington/Idaho, United States. This is a companion piece to the COMET Webcast, Slantwise Convection: An Operational Approach.

Objectives:
• Apply techniques for assessing and forecasting conditional symmetric instability and associated slantwise convection

Estimated time to complete: 45 min

Description:
This Webcast is a recreation of a presentation on slantwise convection given by Kent Johnson in February, 2002 in Boulder, Colorado. It focuses on assessing the release of conditional symmetric instability as slantwise convection. It provides an overview of the characteristics and theory of CSI, assessment of CSI and slantwise induced precipitation in complex terrain, and operational challenges to assessing CSI.

Objectives:
1. Show that the atmosphere can be intertially and gravitationally stable, but unstable to a slantwise displacement when near or at saturation.

2. Demonstrate the vertical-cross section approach in diagnosing the potential for conditional symmetric instability (CSI).

3. Examine ways to improve forecasts that involve a potential slantwise convection situation.

4. Examine the typical characteristics of CSI in complex terrain.

5. Apply a slantwise convection analysis to a real world situation.

Estimated time to complete: 40 min