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8.4.1.9 Volcanic Eruption Sites Volcanic eruption sites are identified by a trapezoidal symbol (Figure 8-38). The dot on the base of the trapezoid identifies the location of the volcano. The name of the volcano, its latitude, and its longitude are noted adjacent to the symbol.
Figure 8-38. High-Level SIGWX Chart Volcanic Eruption Site Example
8.4.1.10 Widespread Sandstorms and Dust storms Widespread sandstorms and dust storms are labeled with the appropriate symbol (Appendix I).
The vertical extent of sand or dust is specified by top and base heights, separated by a horizontal line. Sand or dust which extends below the lower limit of the chart (FL240) is identified with XXX (Figure 8-39).
Figure 8-39. High-Level SIGWX Chart Widespread Sandstorm and Dust Storm Example
8.4.2 Issuance In accordance with the World Meteorological Organization (WMO) and the World Area Forecast System (WAFS) of the International Civil Aviation Organization (ICAO), High-Level significant weather (SIGWX) forecasts are provided for the en-route portion of international flights. The National Weather Service (NWS) Aviation Weather Center (AWC) in Kansas City, MO provides a suite of SIGWX forecast products for the World Area Forecast Center (WAFC) in Washington, D.C. The charts are available for different ICAO areas around the world as defined in Table 8-7.
The charts are not amended.
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Table 8-7. High-Level SIGWX Chart Issuance Schedule – WAFC Washington ICAO Area Chart Type Chart Area Valid Times (UTC) Issued 0800 Issued 1400 Issued 2000 Issued 0200 A Americas Mercator
0000 0600 1200 1800 B1 Americas/ Africa Mercator
0000 0600 1200 1800 F Pacific Mercator
0000 0600 1200 1800 H N America/ Europe Polar Stereographic
0000 0600 1200 1800 I N Pacific Polar Stereographic
0000 0600 1200 1800 J S Pacific Polar Stereographic
0000 0600 1200 1800 M Pacific Mercator
0000 0600 1200 1800
The WAFC in London, England also issues High-Level Significant Weather (SIGWX) Charts for other geographical areas of the world. Both Washington and London WAFC charts are available online at: http://aviationweather.gov/iffdp/sgwx.shtml
8.4.3 Use High-Level Significant Weather (SIGWX) Charts are provided for the en route portion of international flights. These products are used directly by airline dispatchers for flight planning and weather briefings before departure and by flight crew members during flight.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 PGEE07 KKCI 230000 WAFC WASHINGTON 4{270 340 340 FIXED ICAO PR250-6STG KX TIME FORECAST CHART VALID 00 UTC 24 OCT 2006 340 340 340 [390 300 [390| 500 500 EMBO "PAUL" 530 530 530 530 T. 5598-40 [530 530 530 530 500 500 20 450 340 450 370 450 XXX 400 XXX 390 L31 130/631 [FL330 270 340 Figure 8-40. High-Level SIGWX Chart - ICAO Area A Example AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-30
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Figure 8-41. High-Level SIGWX Chart - ICAO Area B1 Example
Figure 8-42. High-Level SIGWX Chart - ICAO Area F Example
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Figure 8-43. High-Level SIGWX Chart - ICAO Area H Example
Figure 8-44. High-Level SIGWX Chart - ICAO Area I Example
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-33
Figure 8-45. High-Level SIGWX Chart - ICAO Area J Example
Figure 8-46. High-Level SIGWX Chart - ICAO Area M Example
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 9: Supplementary Products Page 9-1 9 SUPPLEMENTARY PRODUCTS
9.1 Collaborative Convective Forecast Product (CCFP) The Collaborative Convective Forecast Product (CCFP) is a graphical representation of forecast convective occurrence verifying at 2-, 4 -, and 6-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 tops 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
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9.1.1 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 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 two 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 at http://aviationweather.gov/products/ccfp/.
9.1.2 Collaboration The CCFP is produced from a collaborative effort between public and private meteorologists.
The collaboration occurs between meteorologists from the Aviation Weather Center (AWC), Center Weather Service Units (CWSU), Meteorological Services of Canada (MSC), commercial airlines offices, and other private weather companies.
9.1.3 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 tops and convective growth information.
9.1.3.1 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 50-74 percent of the polygon is forecast to contain convection.
Sparse coverage, represented by sparse fill, means 25-49 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 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 40NM wide, and
75 percent of the line must be expected to contain convection.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 9: Supplementary Products Page 9-3
Figure 9-2. CCFP Forecast Convective Coverage
9.1.3.2 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 9-3).
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.
Figure 9-3. CCFP Forecast Confidence
9.1.3.3 Movement Forecast movement for each polygon or line is indicated with a gray or blue arrow (Figure 9-4).
The arrow points in the direction of forecast movement. A number at the tip of the arrow represents the speed in knots.
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Figure 9-4. CCFP Forecast Convective Movement
9.1.3.4 Data Block A data block is located adjacent to every polygon forecast (Figure 9-5 and Figure 9-6). A thin line connects the data block to the associated forecast area. Each data block contains information about forecast maximum echo tops (TOPS), convective growth rates (GWTH), forecaster confidence (CONF), and convection coverage (CRVG).
Figure 9-5. CCFP Data Block
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 9: Supplementary Products Page 9-5
Figure 9-6. 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 three 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 FL250 – FL310 Flight level 250 to flight level 310 FL310 – FL370 Flight level 310 to flight level 370 370+ Above flight level 370
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 areal coverage of the echoes (Table 9-2).
Table 9-2. CCFP Growth ++ Fast positive growth + Moderate positive growth NC No change in the growth
- Negative Growth
9.1.3.4.3 Confidence The contraction, CONF, depicted on the chart is the confidence the depicted polygon will meet the minimum CCFP criteria (Table 9-3).
Table 9-3. CCFP Confidence LOW 25 to 49 percent HIGH 50 to 100 percent
9.1.3.4.4 Coverage The contraction, CVRG, 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.
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Table 9-4. CCFP Coverage 25 – 49% Sparse 50 – 74% Medium 75 –100% Solid
9.1.4 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.
9.1.5 Use The CCFP is to be used as a strategic planning tool for air traffic flow management in the 2- to 6-hour forecast period.
The product is not intended to be used as a pilot weather briefing tool.