National Weather Service Professional Development Series Professional Competency Unit

Description of Job Duty Competency to be Achieved

Assess and forecast those features of the mesoscale environment that determine the icing type and the potential severity of an icing event.

Description of Need

To determine icing type and severity, forecasters must assess the mesoscale features that influence the formation of icing. To perform such assessment, forecasters must:

Specific Job Task Skills and Knowledge

1. Demonstrate and utilize knowledge of the physical theoretical concepts and parameters related to icing type and severity (i.e., liquid water content (LWC), cloud processes/type/extent, temperature, droplet size, and precipitation) in the development of an icing forecast.

2. Using observational tools (skew-T, PIREPS, satellite data and derived products) evaluate parameters such as cloud cover and type, temperature, and location of supercooled liquid water (SLW) for the purpose of locating possible icing and determining icing severity.

3. Using national mosaic, local radar data, satellite data, and surface observations, evaluate parameters such as precipitation location, precipitation type, and cloud cover for the purpose of locating areas of freezing precipitation and likely areas of supercooled large droplets (SLDs) aloft.

4. Using numerical model output determine the current and future state of parameters such as SLW, precipitation, and location of subfreezing layers for the purpose of estimating locations of icing and icing severity.

5. Integrate the diagnostic icing algorithms into the forecasting process to further evaluate the icing environment.

Instructional Components

Instructional Component 6.1: Icing Type and Severity: This Web-based module presents the various types and severity categories of aircraft icing and outlines the main factors, physical processes, and mesoscale environments that combine to create hazardous icing conditions. The module also includes recent research findings in the area of supercooled large drop (SLD) clear icing and a supplementary section with forecast methods for diagnosing and predicting SLD clear icing conditions. [COMET]

Instructional Component 6.2: Icing Assessment and Forecast Tools: A series of short web-based lessons that demonstrate the use of various diagnostic tools to evaluate the mesoscale atmospheric parameters pertinent to icing type and severity. These lessons expand upon concepts and methods introduced in the first web-based module (6.1) by providing in-depth demonstration and intensive practice.

1. 6.2.1 Icing Assessment Using Soundings and Wind Profiles: This web-based lesson demonstrates patterns and methods for identifying temperature and wind profiles favorable for icing. Includes numerous practice exercises allowing learners to improve their skills in icing assessment using these basic observational tools. [COMET]

2. 6.2.2 Icing Assessment Using Observations and Pilot Reports: This web-based lesson demonstrates patterns and methods for finding areas and layers with favorable icing conditions. Includes numerous practice exercises allowing learners to improve their skills in icing assessment using these basic observational tools. [COMET]

3. 6.2.3 Icing Assessment with Satellite Imagery: Demonstrates patterns and methods for identifying icing threats using visible and infrared (3.9, 6.7, and 10.7 micron) imagery and derived products. Includes practice exercises allowing learners to improve their familiarity and skill with satellite data analysis. Part of the content to be presented in this instructional component are provided in the multimedia CD-ROM 6.9, GOES IR Imagery Including Winter and Icing Applications.

4. 6.2.4 Icing Assessment with Radar Imagery: Demonstrates patterns and methods for identifying bright bands and other icing signatures using both local radar and national mosaic imagery and derived products. Includes practice exercises allowing learners to improve their familiarity and skill with radar data analysis.

Instructional Component 6.3: Numerical Models: Demonstrates the integration of numerical model output (to possibly include ETA 29 km, MM5, RAMS, RUC, and NOGAPS) with observational data (as in 6.2) to aid in the diagnosis and forecasting of icing severity and location on the mesoscale.

Instructional Component 6.4: Data Integration: Demonstrates the integration of data sources presented in 6.2 and 6.3 with diagnostic icing algorithms stovepipe, temperature/RH) to aid in the diagnosis and forecasting of icing type and severity at the mesoscale level.

Instructional Component 6.5: Interactive session where participants engage in a series of exercises integrating the physical and theoretical concepts of icing with use of data and diagnostic tools to make a diagnoses of the atmospheric conditions relevant to estimating icing type and severity. Use of the satellite products and diagnostic icing algorithms will be addressed in the diagnosis of the icing environment. [teletraining]

Instructional Component 6.6: Interactive session where participants engage in a series of exercises that incorporate and integrate all data sources, model output, satellite products, observational data, and diagnostic icing algorithms to make diagnoses and forecasts for icing type and severity. [teletraining]

In February and March, 1998, the COMET Program with Marcia Politovich of NCAR presented two video-teletraining sessions on Forecasting Aviation Icing to Navy forecasters. The bulk of the presentation was based on material derived from the COMET Program Web-based module 6.1 on icing type and severity.

Instructional Component 6.7: The Icing Event of 6 March 1996: A Resource Data Set: This CD-ROM contains a comprehensive data set of over 3300 images, graphics, text products, and derived products portraying an icing event that occurred over the continental United States on 6 March 1996. An application for viewing and exploring the data set is included. This CD-ROM will serve as a companion to the Web-based lessons 6.2.1-3, and may also be utilized by other future Web-based lessons in this Professional Development Series. This hybrid approach takes advantage of the strengths of both Web and CD-ROM technologies. With Web-based lessons, learners are able to access up-to-date training materials on the Internet. With CD-ROM-based data sets, learners can browse and display thousands of data products without the delays imposed by slow Internet connections.

Instructional Component 6.8: Supplementary Resource Data Sets: Like the first resource data set CD, this CD-ROM will contains comprehensive data sets of images, graphics, text products and derived products protraying two icing events: one produced by warm-layer processes and a second produced by collision-coalescence processes. This CD will include numerous Doppler radar products and imagery, so that companion web-modules may focus on radar interpretation for the assessment of icing type and severity. An application for viewing and exploring the data set will be included. This CD-ROM will serve as a companion to the Web-based lessons and may also be utilized by other future Web-based lessons in this Professional Development Series.

Instructional Component 6.9: GOES IR Imagery Including Winter and Icing Applications: This CD contains a mini-case study in which 3.9 micron imagery is applied to forecasting a major icing outbreak over the midwestern U.S. This caselet also covers how to use the conventional infrared and visible imagery in a potential icing situation. There two other winter storm case studies which emphasize satellite imagery. The rest of the module contains basic backgrounsysinformation on all of the spectral channels.

Instructional Component 6.10: Aviation Icing Compilation: This CD-ROM will be a compilation of information contained in the Web-based components 6.1-4 and may also include the case study data sets provided on CD-ROM 6.7 and 6.8.

Instructional Component 6.11: Agency-specific procedures and requirements for incorporating icing type and severity into the various agencies' products (DD175-1, AIRMET, SIGMET, etc.).

Instructional Component 6.12: Training officers and SOOs will provide training on local mesoscale model usage and biases that pertain to diagnosing and forecasting icing type and severity.

Instructional Component 6.13: An online bibliography that identifies some of the key subject matter-related references for this particular unit.

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