Figure 2. MetGen AIRMET Preparation Tool on the WFO-Advanced Workstation Display.
Advances in forecast models, algorithms, and techniques offer opportunities to enhance forecast products with higher precision and temporal resolution (Hudson and Mosher, 1999). To exploit these advances, forecaster productivity tools must be provided which unburden the forecaster from some nonmeteorological tasks, while allowing the direct application of newly developed algorithm output to the forecast preparation process.
The Aviation Gridded Forecast System (AGFS) Product Development Team (PDT) is tasked by the Federal Aviation Administration Aviation Weather Research Program to develop forecaster productivity tools for the Aviation Weather Center (AWC). These tools, being developed as extensions of the AWIPS meteorological display system, will provide several capabilities to assist in the preparation of AIRMETs (Airmen's Meteorological Advisories), domestic, convective, and international SIGMETs (Significant Meteorological Advisories), and convective SIGMET outlooks.
The goals of this development are to provide new capabilities and improve upon existing forecast preparation techniques employed at the AWC. Recent NWS decisions to integrate AWIPS into National Centers' operations provided an unambiguous development path. The meteorological display component of AWIPS, the WFO-Advanced workstation, provides hooks that allow software developers to incorporate additional functionality. Wilson et al. (1999) describes the technical aspects of the development of these tools, including the high-level structure, the programming languages used, and the technical limitations of developing within the WFO-Advanced architecture.
Several requirements were identified as necessary to achieve improvements in the production of the advisories named in Section 1. Foremost among these requirements is the ability to directly apply new PDT-developed and AWC operational model-derived gridded guidance products to the forecast preparation process. The integrated display capabilities of WFO-Advanced, enhanced with displays of AWC-specific data and the tools described in Section 3, enable the forecaster to graphically delineate advisory areas, lines, or points (operationally referred to as from-lines) on image and graphic displays of observational and model data. Currently, AWC forecasters use several display systems, each good at a particular category of data display (e.g., VDUC for satellite imagery, N-AWIPS for gridded model fields). The integrated displays possible with WFO-Advanced allow the forecaster to view and assimilate data and guidance more efficiently. The productivity tools will then allow the forecasters to delineate advisories on these displays, adjusting the guidance fields (based on current observations and experience) by the placement of from-lines.
An equally important requirement is to reduce the nonmeteorological tasks associated with routine forecast issuance. This is necessary to free the forecaster to devote more time to meteorological diagnosis, to utilize the ever-increasing volume of data, and to achieve the goal of adding detail and resolution to the forecasts. Our approach involves developing software tools to minimize the typing required, provide advisory navigation information of from-line vertices (anchor points), and maintain logs of forecast issuance. Typing can be reduced by software which:
An additional requirement of this development is to produce the forecast in two formats for dissemination: conventional text format, and a 3-dimensional grid representation consistent with the operational text product. The gridded representations of AWC's advisories are intended to be disseminated via the Internet on the Aviation Digital Data Service (ADDS) Web page as part of planned grid display capabilities (Sherretz and Thompson, 1999).
Detailed requirements for the structure and layout of the tools were developed through frequent visits by PDT team members to AWC and extensive input from AWC forecasters and Operations Support Branch developers.
A starting point in our requirements development is documenting the existing forecast preparation procedure in full detail. Then the PDT team designs software approaches to automate or simplify the procedure wherever possible. Figure 1 illustrates a portion of the current convective SIGMET preparation process. Details of the text editing and unscheduled issuance processes are not shown in this example, but the figure serves to illustrate the number of discrete steps involved in convective SIGMET preparation. The flow chart is used to document and understand the current process, identify the parts of the process that may be handled more efficiently by software, and identify which parts of the process are common to the other advisories.
The suite of tools under development is referred to as MetGen (Meteorological Advisory Generator). As development progresses and the tools increase in number and complexity, individual GUIs will be created for each type of advisory. Selectors will be provided for A-Gen (AIRMET tool, including domestic SIGMET selectors), I-Gen (international SIGMET tool), C-Gen (convective SIGMET tool), and O-Gen (convective SIGMET Outlook tool). Each of these products share certain characteristics. Each one is delineated graphically by points, lines, complex lines, and/or polygons. They also share similar message header structure. Underlying interactive graphics and inter-process communication software serves all of the advisories, yet there are enough differences in the format and terminology of each to justify separate GUIs.
Forecasters interact with MetGen in two ways: with interactive graphics, and with the GUI. The tool is invoked by selecting its name from the main menu bar of the WFO-Advanced workstation. The GUI appears on the display for the forecaster to initiate the forecast preparation process. The GUI, a window containing menu bars, buttons, and selection lists providing various functionality, allows the forecaster to specify details of the advisory. Within the GUI, the forecaster may select forecast type, issuance type (e.g., scheduled, amendment, special, etc.), geographic region, vertical extent of the advisory, and appropriate text strings. Text strings available on the GUI are descriptors of frequency, intensity, and conditions. The vertical extent selector allows assignment of an altitude for base, top, or affected layer of an advisory. The selector is labeled in pressure (25-mb resolution) and flight level (in hundreds of feet, rounded to the nearest 500 ft.). Text output incorporates flight level information. Grid output requires pressure as the vertical coordinate in 25-mb resolution.
After analyzing the weather situation and determining the need for an advisory, the forecaster selects the forecast region (for header and log information) and prepares one or more from-lines, or selects a phrase stating that an advisory is not required. MetGen provides editable shapes in latitude/longitude space, which can be annotated, created, moved, edited, and deleted on the display using the mouse pointer. Vertices may be added or deleted as necessary. The forecaster may also retrieve, display, and edit from-lines from the previous advisory issuance. In the case of outlooks, for example, minor adjustment of the from-line may be all that is required to update the forecast for the current issuance. MetGen "snaps" anchor points to even distance and azimuth increments, identifies anchor point locations with respect to aviation references, lists affected states, and displays this information on the GUI so the forecaster has instantaneous feedback on from-line location. From-lines may be created over plan-view displays of image and graphic data. As each from-line is completed, header and navigation information and selected text is passed to a word processor, on which the forecaster can add free-form text and issue the completed bulletin. A GRIB-format grid file is created using the anchor point and vertical information.
The MetGen GUI is shown in Figure 2, with a from-line and affected states visible on the WFO- Advanced display. In this example, an AIRMET advisory preparation process is simulated. The "look and feel" of the GUIs for the other advisories will be very similar. In this simulated icing AIRMET for the Chicago Region the MetGen text output, displayed in the lower portion of the GUI for forecaster inspection, is:
CHIZ WA 020245
AIRMET ZULU FOR ICE AND FRZLVL VALID UNTIL 030300
.
AIRMET ICE..WI KS MN ND IA MO NE CO WY MT
80NE DIK TO 110SW DLH TO 70W DEC TO 80ESE PWE TO 100NNE LBF
TO 90NE GUC TO 60NNW CPR TO 80NE DIK
MOD ISOL SEV RIME/MXD ICGICIP BTWN 100 AND FL200
.
Figure 2. MetGen AIRMET Preparation Tool on the WFO-Advanced Workstation Display.
Current emphasis is on completion of the convective SIGMET, convective SIGMET outlook, and international SIGMET tools by the convective season of 1999. A prototype of this suite of tools is undergoing thorough evaluation by forecasters at AWC, and a complete tool allowing end-to-end forecast preparation of these advisories will incorporate feedback and bug fixes identified during this evaluation. Subsequent development during the remainder of Fiscal Year 1999 will be the completion of MetGen enhancements for end-to-end AIRMET and domestic (non-convective) SIGMET forecast preparation.
The authors wish to thank Craig Hartsough and Jennifer Mahoney for their thoughtful review of this manuscript. Forecasters at AWC contribute greatly to these efforts and their contribution to the requirements specification and design of these tools is essential and appreciated. The efforts of William Carle, Richard Kerr, Horace Hudson, and Michael Weinrich are of particular importance. This research is in response to requirements and funding by the Federal Aviation Administration. The views expressed are those of the authors and do not necessarily represent the official policy or position of the US Government.
Hudson, H. R. and F. R. Mosher, 1999: An operational thunderstorm forecast experiment designed for use in real time aircraft routing. 8th Conference on Aviation, Range, and Aerospace Meteorology, Dallas, TX, Amer. Meteor. Soc., paper 8.8.
Sherretz, L., and G. Thompson, 1999: Overview of the Aviation Digital Data Service. 8th Conference on Aviation, Range, and Aerospace Meteorology, Dallas, TX, Amer. Meteor. Soc., paper J1.2.
Wilson, A., D. M. Rodgers, and U. H. Grote, 1999: Adding productivity tools to the WFO-Advanced meteorological workstation. 15th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology, Dallas, TX, Amer. Meteor. Soc., paper 11.4.