Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Figure 8-45. High-Level SIGWX Chart – ICAO Area J Example
Figure 8-46. High-Level SIGWX Chart – ICAO Area M Example
Section 8: Forecast Charts Page 8-31
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
NEW GENERATION WEATHER PRODUCTS Collaborative Convective Forecast Product (CCFP) The CCFP is a graphical representation of forecast convective occurrence at 4-, 6-, and 8-hours after issuance time (Figure 9-1). Convection, for the purposes of the CCFP forecast, is defined as a polygon of at least 3,000 square miles containing all of the following threshold criteria:
• A coverage of at least 25 percent of echoes with at least 40 dBZ composite reflectivity,
• A coverage of at least 25 percent of echoes with echo top of FL250 or greater, and
• A forecaster confidence of at least 25 percent.
All three threshold criteria must be met for any area of convection 3,000 square miles or greater to be included in a CCFP forecast. This is defined as the minimum CCFP criteria. Any area of convection, which is forecasted to not meet all three of these criteria, is not included in a CCFP forecast.
The CCFP is intended to be used as a strategic planning tool for air traffic flow management. It aids in the reduction of air traffic delays, reroutes and cancellations due to significant convection. It is not intended to be used for tactical air traffic flow decisions, in the airport terminal environment, or for pilot weather briefing purposes. The graphical representation is subject to annual revision.
Figure 9-1. CCFP Example Section 9: New Generation Weather Products Page 9-1
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) Issuance The CCFP is issued by the Aviation Weather Center (AWC) from March through October for the 48-contiguous states. Canadian forecasts are included on the product and are available for southern Ontario and Quebec between April through September. This area is roughly from north of Wisconsin extending eastward to north of Maine.
The CCFP is issued every 2 hours, eleven times per day. Issuance times are from 08Z to 04Z during standard time and from 07Z to 03Z during daylight savings time. The product can be found on the AWC web page.
Collaboration The CCFP is produced from a collaborative effort between public and private meteorologists.
The collaboration occurs between meteorologists from the AWC, Center Weather Service Units (CWSU), Meteorological Services of Canada (MSC), commercial airlines offices, and other private weather companies.
Content Data graphically displayed on the CCFP consist of coverage of convection within a defined polygon, forecaster confidence of convective occurrence, and forecast movement of the convective areas. A data block also displays text information about coverage and confidence as well as forecast echo top and convective growth information.
Coverage The convective coverage within the forecast polygon is represented by the amount of fill within the polygon (Figure 9-2).
• Solid coverage, depicted by solid fill, means 75 to 100 percent of the polygon is forecast to contain convection.
• Medium coverage, defined by medium fill, indicates 40-74 percent of the polygon is forecast to contain convection.
• Sparse coverage, represented by sparse fill, means 25-39 percent of the polygon is forecast to contain convection.
A line of forecast convection, either within a forecast area or alone, is depicted by a solid purple line for solid (75 to 100 percent) or a dashed purple line for medium (40-74 percent) coverage.
For a line of convection to be forecast, it must meet the flowing criteria:
• Its length must be at least 100 miles long,
• The width of the line must be 40 nautical miles (NM) wide, and
• For a solid line, greater than 75 percent of the line must be expected to contain convection. For a medium line, 40 to 74 percent of the line must be expected to contain convection.
Section 9: New Generation Weather Products Page 9-2
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
Figure 9-2. CCFP Forecast Convective Coverage Confidence Confidence represents the subjective opinion of the forecasters that the polygon will meet the minimum CCFP threshold criteria. The forecaster’s confidence is represented by the color used to depict the polygon (Figure 9-2).
• A blue color represents high forecaster confidence (50-100 percent) the forecast convection will meet the minimum criteria.
• A gray color indicates low forecaster confidence (25-49 percent) the forecast convection will meet the minimum criteria.
Confidence is not to be associated with probability of occurrence.
Movement Forecast movement for each polygon or line is indicated with a gray or blue arrow (Figure 9-3).
The arrow points in the direction of forecast movement. A number at the tip of the arrow represents the speed in knots.
Figure 9-3. CCFP Forecast Convective Movement Section 9: New Generation Weather Products Page 9-3
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) Data Block A data block is located adjacent to every polygon forecast (Figure 9-4 and Figure 9-5). A thin line connects the data block to the associated forecast area. Each data block contains information about forecast maximum echo tops (TOPS) and convective growth rates (GWTH).
Figure 9-4. CCFP Data Block
Figure 9-5. CCFP Data Block Example
9.1.3.4.1 TOPS The word, TOPS, is used to depict the forecast maximum echo tops, in thousands of feet MSL, specified by four selected layers listed in Table 9-1. The heights of the forecast echo tops must cover at least 25 percent of the polygon. The exact location of the highest echo top within the polygon cannot be determined.
Table 9-1. CCFP Tops
Section 9: New Generation Weather Products Page 9-4
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
9.1.3.4.2 Growth The contraction, GWTH, is used to depict the forecast average growth rate of the convection.
The growth rate applies to both the height and coverage of the echoes (Table 9-2).
Table 9-2. CCFP Growth
9.1.3.4.3 Confidence Confidence depicted on the chart is the confidence the depicted polygon will meet the minimum CCFP criteria (Table 9-3).
Table 9-3. CCFP Confidence
9.1.3.4.4 Coverage Coverage is used to depict the forecast convective coverage within the polygon (Table 9-4). The coverage represents the percentage of the area forecast to be covered by convection.
Table 9-4. CCFP Coverage
Strengths and Limitations The primary strength of the CCFP is it relies on the vital collaborative efforts between several meteorological units in the private and public sector. The process helps produce the best possible convective forecast to assist in strategic air traffic decision-making.
The limitation of the CCFP is it does not include a forecast for all convection. If the convection does not meet the threshold criteria, it is not included in the CCFP. It is not intended to be used as a tactical short-term decision tool.
Section 9: New Generation Weather Products Page 9-5
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) Use The CCFP is a strategic planning tool for air traffic flow management in the 4- to 8-hour forecast period.
The product is not intended to be used as a pilot weather briefing tool; however CCFP is available to pilots and aircraft dispatchers as an additional tool for strategic planning.
Extended Convective Forecast Product (ECFP) The ECFP Planning Tool (Figure 9-2) is a graphical representation of the forecast probability of thunderstorms. The product identifies graphically where in the United States thunderstorms are likely over the next 72 hours. It is intended to enhance the CCFP. The CCFP is only valid out to 8 hours. This graphical product will use CCFP-style graphics, to facilitate ease of interpretation and use by those already familiar with the CCFP. The product is not a CCFP forecast (it is not forecasting the exact CCFP criteria), but intended to support the long range planning for CCFP type of constraints in the National Airspace System (NAS).
Issuance The development of the ECFP planning tool was a response to Federal Aviation Administration (FAA) and Industry needs in planning for weather hazards, specifically convection, one to two days in advance. To meet these planning needs, and to support CCFP planning beyond 8 hours, the ECFP intends to provide traffic planners and collaborators a quick-look forecast of the greatest probability of convection/thunderstorms. By utilizing CCFP-style graphics, users familiar with CCFP can easily determine where traffic constraints are most likely to occur over the next 3 days.
Section 9: New Generation Weather Products Page 9-6
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
Figure 9-6. ECFP Example Content This automated graphical forecast is created from the Short Range Ensemble Forecast (SREF) Calibrated Thunderstorm guidance. Probability of Thunderstorm contours are depicted at 40, 60, and 80 percent probabilities, using CCFP-like shading. Hashed areas represent 40–59 percent probability, solid lined areas represent 60–79 percent probability, and solid blue filled areas represent greater than 80 percent probability.
Use The ECFP is intended for FAA Traffic Managers at Air Route Traffic Control Centers (ARTCC), FAA Air Traffic Control System Command Center (ATCSCC), airline and aviation industry dispatch and flight planners, as well as commercial weather information providers supporting airline/FAA.
Frequency The ECFP is available 24/7 with updates issued at 01:00, 07:00, 13:00, and 19:00 UTC each day.
Section 9: New Generation Weather Products Page 9-7
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) National Convective Weather Forecast (NCWF) The National Convective Weather Forecast (NCWF) is a near real-time, high resolution display of current and 1-hour extrapolated forecasts of selected hazardous convective conditions for the conterminous United States. The NCWF may be used in conjunction with the report and forecast information contained within Convective SIGMETs. The NCWF is available for use by General Aviation, aircraft dispatchers, and Traffic Management Units (TMU).
Issuance The NCWF is issued by the Aviation Weather Center (AWC) and is updated every 5 minutes.
The product is available on the Aviation Digital Data Service (ADDS) web page.
Content The NCWF displays current convective hazard fields, 1-hour extrapolated forecast polygons, forecast speed and directions, and echo tops. Previous performance polygons can also be selected for display (Figure 9-7).
Figure 9-7. NCWF Example Section 9: New Generation Weather Products Page 9-8
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) Current Convective Hazard Fields The current convective hazard field is a high-resolution display that identifies selected hazards associated with convective precipitation. The field is created from WSR-88D national reflectivity and echo-top mosaics and cloud-to-ground lightning data.
WSR-88D radar reflectivity data are filtered to identify locations having significant convective precipitation. Reflectivity data with echo tops of less than 17,000 feet MSL are eliminated from the data. This process removes ground clutter and anomalous propagation as well as significantly reduces the amount of stratiform (non-convective) precipitation from the data. Most stratiform precipitation tops are below 17,000 feet. The filter also removes shallow convection with tops below 17,000 feet. Shallow convection is often short-lived but can contain conditions hazardous to aviation and may be embedded in stratiform convection.
Frequencies of cloud-to-ground lightning are added to the filtered radar data to provide a more accurate picture of current hazardous convective conditions.
Current convective hazard fields are color coded according to the convective hazard scale for display on the NCWF (Figure 9-8).
Figure 9-8. NCWF Current Convective Hazard Fields Example
9.3.2.1.1 Convective Hazard Field Scale The convective hazard field scale uses six hazard levels (Figure 9-9) to characterize hazardous convection conditions.
The six hazard levels are determined by two factors:
• Intensities and maximum tops of WSR-88D reflectivity data, and
• Frequencies of cloud-to-ground lightning.
Higher hazard levels are associated with higher radar reflectivity intensities and higher frequencies of lightning strikes.
The six hazard levels are reduced to four-color codes for display on the NCWF. The relationships between the six hazard levels and four-color codes are summarized in Figure 9-9.
Section 9: New Generation Weather Products Page 9-9
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
Figure 9-9. NCWF Hazard Scale One-Hour Extrapolated Forecast Polygons One-hour extrapolated forecast polygons are high-resolution polygons outlining areas expected to be filled by selected convective hazard fields in 1 hour. Extrapolated forecasts depict new locations for the convective hazard fields based on their past movements. Extrapolation forecasts do not forecast the development of new convective hazard conditions or the dissipation of existing conditions. Forecasts are provided only for convective hazard scale levels 3 or higher. The forecast polygons do not depict specific forecast hazard levels. On Figure 9-10, the light blue polygon denotes the location of the 1-hour forecast convective hazard field.
Forecast Speed and Direction Forecast speed and direction are assigned to current convective hazard fields having a 1-hour extrapolated forecast. A line (or arrow on the AWC JavaScript product) is used to depict the direction of movement (Figure 9-10). The speed in knots is depicted by the first group of two numbers located near the current convective hazard field. The second group of three numbers identifies echo tops.
Forecast speed and direction is only updated every 10 minutes. The larger update time-interval (compared to five-minute updates for the NCWF) smooths erratic forecast velocities. On Figure 9-10, the forecast direction (depicted by an arrow) is pointing to the southeast and the speed is 25 knots.
Echo Tops Echo tops are assigned to current convective hazard fields having a 1-hour extrapolated forecast. Echo tops are depicted by a group of three numbers located near the current convective hazard field and is plotted in hundreds of feet MSL (Figure 9-10). The first number of the group identifies forecast speed of movement. On Figure 9-10, the echo tops are 45,000 feet MSL.
Section 9: New Generation Weather Products Page 9-10
Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
Figure 9-10. NCWF One-Hour Extrapolated Forecast Polygon, Forecast Movement Velocity, and Echo Tops Example Previous Performance Polygons Previous performance polygons are magenta polygons displaying the previous hour’s extrapolated forecast polygons with the current convective hazard fields. A perfect forecast would have the polygons filled with convective hazard scale levels 3 or higher data. Levels 1 and 2 would be outside the polygons. The display of previous performance polygons allows the user to review the accuracy of the previous hour’s forecast.
Figure 9-11 depicts current convective hazard fields and previous performance polygons (magenta) valid at 1500Z. The previous performance polygons are the 1-hour extrapolated forecasts made at 1400Z. Although the polygons do not perfectly match the current level 3 and higher hazard fields, the forecasts are still fairly accurate.
Newly developed convective hazard levels 3 and higher do not have previous performance polygons. Extrapolated forecasts do not forecast developing hazardous convective.
Section 9: New Generation Weather Products Page 9-11