Aviation Weather Services, Advisory Circular 00-45F, Revision 1
•BRW LUR QTZ AFM *BTT *FYU ,амЕ • GAL • FAI ROUNK 60 CZF * MCG • TKA GKN ORT ALANC LEMM: AKA EHOM *MDO ASNP AÇADO •5AG
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• 5AB + SAE ADK + 5AD -180 -170 -160 -150 -140 45АC -130 Figure 7-12. Wind and Temperature Aloft Forecast Network - Alaska 22 LIH HNL ragG LNY 20
KOA ITO 160 - 158 156 Figure 7-13. Wind and Temperature Aloft Forecast Network - Hawaii AC 00-45F (July 2008) Section 7: Forecast Text Products Page 7-46
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 7: Forecast Text Products Page 7-47
Figure 7-14. Wind and Temperature Aloft Forecast Network - Western Pacific
Table 7-10. Wind and Temperature Aloft Forecast (FB) Periods Model Run Product Available 6 hour Forecast 12 hour Forecast 24 hour Forecast Valid For Use Valid For Use Valid For Use 0000Z ~0200Z 0600Z 0200-0900Z 1200Z 0900-1800Z 0000Z 1800-0600Z 0600Z ~0800Z 1200Z 0800-1500Z 1800Z 1500-0000Z 0600Z 0000-1200Z 1200Z ~1400Z 1800Z 1400-2100Z 0000Z 2100-0600Z 1200Z 0600-1800Z 1800Z ~2000Z 0000Z 2000-0300Z 0600Z 0300-1200Z 1800Z 1200-0000Z
7.4.4 Delayed Forecasts If the scheduled forecast transmission is delayed, the existing valid forecast based on the earlier 6-hourly data can be used until a new forecast is transmitted.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-1 8 FORECAST CHARTS
8.1 Short-Range Surface Prognostic (Prog) Charts Short-Range Surface Prognostic (Prog) Charts (Figure 8-1) provide a forecast of surface pressure systems, fronts and precipitation for a 2-day period. The forecast area covers the 48- contiguous states, the coastal waters and portions of adjacent countries. The forecasted conditions are divided into four forecast periods, 12-, 24-, 36-, and 48-hours. Each chart depicts a “snapshot” of weather elements expected at the specified valid time.
The Surface Prognostic (Prog) Charts are available at the Aviation Digital Data Services (ADDS) web site at: http://adds.aviationweather.noaa.gov/progs/.
Figure 8-1. Surface Prog Chart Example
Aviation Weather Services, Advisory Circular 00-45F, Revision 1
8.1.1 Content
COLD FRONT COLD FRONTOLYSIS
WARM FRONT WARM FRONTOLYSIS
STATIONARY FRONT STATIONARY
OCCLUDED FRONT FRONTOLYSIS
OCCLUDED FRONTOLYSIS
CHANGE OF FRONT TYPE
COLD FRONTOGENESIS HIGH PRESSURE CENTER
WARM FRONTOGENESIS LOW PRESSURE CENTER
STATIONARY TROPICAL (TRPL) WAVE
FRONTOGENESIS TROUGH (TROF) OR L xxx xXX TROPICAL DEPRESSION
OUTFLOW BONDARY (OUTFLOW BNDRY)
TRPCL STORM TROPICAL STORM
DRYLINE XXX
RIDGE HURCN HURRICANE
SQUALL LINE XXX Figure 8-2. Surface Prog Chart Symbols
8.1.1.1 Pressure Systems Pressure systems are depicted by pressure centers, troughs, isobars, drylines, tropical waves, tropical storms and hurricanes using standard symbols (Figure 8-2). Isobars are denoted by solid thin gray lines and labeled with the appropriate pressure in millibars. The central pressure
8.1.1.2 Fronts Fronts are depicted using the standard symbols in Figure 8-2.
8.1.1.3 Squal Lines Squall lines are denoted using the standard symbol in Figure 8-2.
8.1.1.4 Precipitation Rain (light, moderate, heavy) *** Snow (light,moderate, heavy) Thunder (with rain, snow,no precipitation) Shower (rain, snow) .. Drizzle ~ Freezing rain, Freezing drizzle Ice pellets/Sleet Fog (shallow, deep) 00 Haze AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-2
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-3 Figure 8-3. Surface Prog Chart Precipitation Symbols
Precipitation areas are enclosed by thick, solid, green lines (Figure 8-4). Standard precipitation symbols are used to identify precipitation types (Figure 8-3). These symbols are positioned within or adjacent to the associated area of precipitation. If adjacent to the area, an arrow will point to the area with which they are associated. A mix of precipitation is indicated by the use of two pertinent symbols separated by a slash (Figure 8-4). A bold, dashed, grey line is used to separate precipitation within an outlined area with contrasting characteristics (Figure 8-4). For instance, a dashed line would be used to separate an area of snow from an area of rain.
Figure 8-4. Surface Prog Chart Precipitation Example
Precipitation characteristic are further described by the use of shading (Figure 8-5). Shading or lack of shading indicates the expected coverage of the precipitation. Shaded areas indicate the precipitation is expected to have more than 50% (broken) coverage. Unshaded areas indicate 30-50% (scattered) coverage.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-4
Figure 8-5. Surface Prog Chart Precipitation Coverage
8.1.2 Issuance Short-Range Surface Prognostic (Prog) Charts are issued by the Hydrometeorological Prediction Center (HPC) in Camp Springs, MD. Table 8-1 provides the product schedule. The 12- and 24-Hour Surface Prognostic (Prog). Charts are issued four times a day and are termed “Day 1” progs. The 36- and 48- Hour Surface Prog Charts are issued twice daily and are termed “Day 2” progs. They are available on the HPC web site at:
http://adds.aviationweather.noaa.gov/progs/.
Table 8-1. Short-Range Surface Prog Charts Schedule Issuance Time (UTC) ~1720 ~2310 ~0530 ~0935 Valid Time (UTC) 12-Hour Surface Prog 0000 0600 1200 1800 24-Hour Surface Prog 1200 1800 0000 0600 36-Hour Surface Prog 0000 NA 1200 NA 48-Hour Surface Prog 1200 NA 0000 NA
8.1.3 Use Short-Range Surface Prognostic (Prog) Charts can be used to obtain an overview of the progression of surface weather features during the next 48 hours. The progression of weather is the change in position, size, and intensity of weather with time. Progression analysis is accomplished by comparing charts of observed conditions to the 12-, 24-, 36-, and 48-hour progs. Short-Range Surface Prognostic (PROG) Charts make the comprehension of weather details easier and more meaningful. For example, in Figures 8-6 through 8-9, the cold front located from the eastern Great Lakes to Missouri is forecast to move southeastward and the High pressure center just north of the Minnesota/North Dakota boarder is also forecast to move southeast and weaken.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 2-HR FOST FRONTS/PRESSURE AND WEATHER VALID: 000OZ FRI DEC 1' 7 2004 * * H H 1031 /TROF ZHEC ISSUED: 16317 THU DEC 16 2004 Figure 8-6. 12-hour Surface Prog Chart Example UrE AND WEATHER VALID: 12002 FRI DEC * * H Ø40 1042 TROF TROF DOC/NORA/NWS/NCEP/НРС ISSUED: 1632Z THU DEC 16 2004 Figure 8-7. 24-hour Surface Prog Chart Example AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-5
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 36-HR FCST OF FRONTS/PRESSURE AND WEATHER VALID: 12002 FRI DEC 17 2004 H H 1031 H 1043 840 ANCEP/HPC ISSUED: 06277 THU DEC 16 2004 Figure 8-8. 36-hour Surface Prog Chart Example AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-6
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 HR FOST OF FRONTS/PRESSURE AND WEATHER VALID: 0000Z SAT DEC 18 2004 *** 1030฿ jo d H TROF H 1029 /NORA/NKS/NCEP/НРС ISSUED: 06277 THU DEC 16 2004 Figure 8-9. 48-hour Surface Prog Chart Example AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-7
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-8
8.2 Low-Level Significant Weather (SIGWX) Charts The Low-Level Significant Weather (SIGWX) Charts (Figure 8-10) provide a forecast of aviation weather hazards primarily intended to be used as guidance products for pre-flight briefings. The forecast domain covers the 48 contiguous states and the coastal waters for altitudes 24,000 ft MSL (Flight Level 240 or 400 millibars) and below. Each chart depicts a “snapshot” of weather expected at the specified valid time.
Figure 8-10. 12-Hour Low-Level SIGWX Chart Example
8.2.1 Content Low-Level Significant Weather (SIGWX) Charts depict weather flying categories, turbulence, and freezing levels (Figure 8-11). Icing is not specifically forecast.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1
FLIGHT PLANNING ONLY
SEE TAF S FOR SPECIFIC
TERMINAL FORECAST
CETLSNEILESS IESS TAAN S MILESOR CEILING 1000-3000
AND/OR VISIBILITY
MODERATE OR GREATER
TURBULENCE
AVY FREEZING LEVEL AT SURFACE
- FREEZING LEVEL ABOVE MEAN SEA LEVEL _ MODERATE TURBULENCE *OP (Hundreds of feet MSL) _ SEVERE TURBULENCE 240/100 Base (Hundreds of feet MSL)
EXTREME TURBULENCE Figure 8-11. Low-Level SIGWX Chart Symbols
8.2.1.1 Flying Categories Instrument Flight Rules (IFR) areas are outlined with a solid red line, Marginal Visual Flight Rules (MVFR) areas are outlined with a scalloped blue line, Visual Flight Rules (VFR) areas are not depicted (Figure 8-12).
Figure 8-12. Low-Level SIGWX Chart Flying Categories Example
8.2.1.2 Turbulence Areas of moderate or greater turbulence are enclosed by bold, dashed, yellow lines (Figure 8-
13). Turbulence intensities are identified by standard symbols (Figure 8-11). The vertical extent of turbulence layers is specified by top and base heights separated by a slant. The intensity AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-9
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 8: Forecast Charts Page 8-10 symbols and height information may be located within or adjacent to the forecasted areas of turbulence. If located adjacent to an area, an arrow will point to the associated area.
Turbulence height is depicted by two numbers separated by a solidus /. For example, an area on the chart with turbulence indicated as 240/100 indicates the turbulence can be expected from the top at FL240 to the base at 10,000 feet MSL. When the base height is omitted, the turbulence is forecast to reach the surface. For example, 080/ identifies a turbulence layer from the surface to 8,000 feet MSL. Turbulence associated with thunderstorms is not depicted on the chart.
Figure 8-13. Low-Level SIGWX Chart Turbulence Forecast Example
8.2.1.3 Freezing Levels The freezing level at the surface is depicted by a blue, saw-toothed symbol (Figure 8-11). The surface freezing level separates above-freezing from below-freezing temperatures at the Earth's surface.
Freezing levels above the surface are depicted by fine, green, dashed lines labeled in hundreds of feet MSL beginning at 4,000 feet using 4,000 foot intervals (Figure 8-11). If multiple freezing levels exist, these lines are drawn to the highest freezing level. For example, 80 identifies the 8,000-foot freezing level contour (Figure 8-14). The lines are discontinued where they intersect the surface.
The freezing level for locations between lines is determined by interpolation. For example, the freezing level midway between the 4,000 and 8,000 foot lines is 6,000 feet.