Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Table 5-18. Alaska Weather Depiction Charts Precipitation Intensity Symbols Symbol Meaning Liaht (No symbol) Moderate Heavy
5.5.3 Use The Alaska Weather Depiction Charts provide an overview of weather flying categories and other adverse weather conditions for the chart valid time. The chart often does not completely represent the en route conditions because of terrain variations and the possibility of weather occurring between reporting stations. These charts should be used in addition to the latest METAR/SPECIs, pilot weather reports, and radar and satellite imagery for a complete look at the latest flying conditions.
33 33 * PLCAZ 42 _PASL 18 SPKPAZ PATK 36 43 PAVO PABY 999 ₫·0100 PAET PASY 75 27 50 SMCAZ 13 DOL 38 PREN 10 f 60 47 ; RUFAZ KNTUS PAWD NRBAZ 42 PAIL ILI SURFACE OBSERVATIONS PAHO? ISTNID 182 05/04/2005 10 PASO DEWPT(deg F) CIG 380 PAMO 48 IFR_MVFR VFR 30755 999 Figure 5-44. AAWU Alaska Weather Depiction Chart - South Central Alaska Example Section 5: Graphical Observations and Derived Products Page 5-45
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
5.6 Radar Summary Chart The Radar Summary Chart (Figure 5-49) is a computer-generated mosaic of radar echo intensity contours based on Radar Weather Reports (Section 2.3) over the contiguous U.S.
Possible precipitation types, cell movements, maximum tops, locations of line echoes, and remarks are plotted on this chart. Much of this information is often truncated due to space limitations. Severe thunderstorm and tornado watches are plotted if they are in effect when the chart is valid. The Radar Summary Chart is available on the National Weather Service (NWS) Fax Charts Web site at: http://weather.noaa.gov/pub/fax/QAUA00.TIF.
Figure 5-45. Radar Summary Chart Example
5.6.1 Issuance The chart is issued hourly. Figure 5-50 depicts the WSR-88D weather radar network from which the chart is produced.
5.6.2 Format The Radar Summary Chart depicts precipitation type, intensity, coverage, movement, echoes, and maximum tops.
5.6.2.1 Precipitation Type The precipitation type, determined by a computer model, is indicated on the chart by symbols located adjacent to the precipitation areas. These symbols (Table 5-20) are not in METAR Section 5: Graphical Observations and Derived Products Page 5-46
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) format. Freezing precipitation is not reported in Radar Weather Reports and, thus, not plotted on the Radar Summary Chart.
Table 5-19. Radar Summary Chart Precipitation Type Symbols
SYMBOL MEANING R Rain RW Rain shower S Snow SW Snow shower T Thunderstorms
5.6.2.2 Precipitation Intensity The six precipitation intensity levels coded in the Radar Weather Report are consolidated into three contour intervals for the Radar Summary Chart (Figure 5-47). Precipitation intensity is correlated only for liquid precipitation, not solid precipitation (e.g., snow).
CBW KOIX KMSK KGCW *KMBX Ở KMVX KDLH
OKIFX OKBIS KMAX KUDX KABR O КСИРУ КАЙ КАКУ, KCEB O KOKX КВОХ
KSEX KFSD O KBBX KLAX КмУХ KCYS KLAX KOAX O KOTTY 2) KLOT KI wx KCLEO KPBZ KcCK *DIX KDAX OKRCK CRUEX ÁL O OKILN KRIX
KFTGO O KGLD KIWXO OKEAX KIND KILLICIO OKAKQ © KHIK KESK KPUX O KDDCO ÖKIC OKSGF КРАН OKHES KVEX O KEYXO ÖKVTX © KNKX KYUX KIWA KF SX KARX KFDX QKLBB HUN KING OKFDR OKTLX OKSRX KLZK ксихо квих CANOA KHIN KMXX O kJEx OKCLX KHIK SKEPZ KMAF O KDYXO OKFWS OKSHV КРОЕ KJAN КЕОХО O KVAR O KJAX LPLA KCRK O KuXC КМОВ OKMLB
KOFY KEWE KHCX KTEWO
PAPD OKCEP „РНМО KBRO KEYX I CBR RKSG K (07 PHKM O
PHNA RODNE Figure 5-46. WSR-88D Weather Radar Network Section 5: Graphical Observations and Derived Products Page 5-47
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) ATC Weather Precipitation Reflectivity Radar Echo Description (dBZ) Terminology Light Trace to light rain <30 dBZ Moderate Light to moderate 30-40 dBZ rain Heavy Heavy rain; >40-50 dBZ possible small granules Extreme Very heavy rain; 50+ dBZ hail; pea/marble or greater size hail 450 Highest echo top in area in hundreds of feet MSL (45,000 feet MSL).
Figure 5-47. Radar Summary Chart Precipitation Intensity
5.6.2.3 Echo Coverage All of the shaded areas within the contours are assumed to contain precipitation. However, actual precipitation coverage is less. This is because only a fraction of a grid box needs to be covered with echoes for the entire grid box to be plotted as precipitation on the chart.
5.6.2.4 Line Echoes When precipitation echoes are reported as a LINE, a line will be drawn through them on the chart (see Table 5-21). Where there is 8/10ths or more coverage, the line is labeled as solid (SLD) at both ends.
Table 5-20. Radar Summary Chart Echo Configuration Symbols
SYMBOL MEANING SLD 8/10ths or greater coverage in a line.
Line of echoes.
ISLD Solid line of thunderstorms with intense to extreme precipitation.
5.6.2.5 Cell Movement Section 5: Graphical Observations and Derived Products Page 5-48
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Cell movement is the average motion of all cells within a configuration. An arrow indicates direction of cell movement. Speed in knots is entered near the arrowhead. LM identifies little movement. Movement of areas and lines can be significantly different from the motion of the individual cells that comprise these configurations.
Table 5-21. Radar Summary Chart Cell Movement Examples
SYMBOL MEANING Cell movement to the northeast at 35 knots Cell movement to the east at 24 knots Cell movement to the south at 18 knots Cell movement to the southwest at 12 knots LM Little cell movement
5.6.2.6 Maximum Top
Figure 5-48. Radar Summary Chart Maximum Top Example
A maximum top is the altitude of the highest precipitation echo as coded on a Weather Radar Report (Section 2.3). Altitudes are sometimes augmented by satellite data. Individual Radar Weather Reports should be used to determine if satellite data was used for precipitation echo tops.
Tops are plotted in 3-digit groups representing height in hundreds of feet MSL and are underlined. Where it is necessary to offset a top for reasons of insufficient space, a line is drawn from one end of the underline to a small black square which represents the location of the top.
Section 5: Graphical Observations and Derived Products Page 5-49
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Maximum echo top does not equal maximum cloud top. The maximum echo top is the altitude of the highest light precipitation echo, not highest cloud top. Also, all radar heights are approximations due to radar wave propagation variations depending on atmosphere conditions.
5.6.2.7 Weather Watch Areas Heavy dashed lines outline Tornado (WT) (Section 5.5.2) and Severe Thunderstorm (WS) Watch (Section 5.4.2) areas. The type of watch and the watch number are enclosed in a rectangle and positioned as closely as possible to the northeast corner of the watch. If there is no room at the northeast corner of the watch, the watch information is offset and connected to the watch by a thin line. The watch number is also printed at the bottom of the chart (in Mexico) together with the issuance time and expiration time under a label reading “WEATHER WATCH AREAS”. In case no weather watch is in effect, “NONE” is printed at the bottom of the chart.
Table 5-22. Radar Summary Chart Weather Watch Area Examples
SYMBOL MEANING
Severe Thunderstorm Watch number 210
Tornado Thunderstorm Watch number 457
5.6.2.8 Operational Contractions Radar sites which report PPINA, PPINE, and PPIOM in their Weather Radar Reports (Section
2.3.1.10) are abbreviated to NA, NE, and OM respectively and plotted over the radar sites on the chart.
Table 5-23. Radar Summary Chart Operational Contractions
SYMBOL MEANING NA Not available NE No echoes OM Out for maintenance Section 5: Graphical Observations and Derived Products Page 5-50
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
5.6.3 Use The Radar Summary Chart aids in preflight planning by identifying areas of precipitation and highlighting its characteristics. This chart displays precipitation only; it does not display clouds, fog, fronts, or other boundaries. Therefore, the absence of echoes does not equal clear weather.
Cloud tops will be somewhat higher than precipitation tops detected by radar. The chart must be used in conjunction with other charts, reports, and forecasts.
The radar summary chart is for preflight planning only and should always be cross-checked and updated by current WSR-88D images. Once airborne, the pilot must evade individual storms by in-flight observations. This can be done by using visual sighting or airborne radar as well as by requesting weather radar information from En route Flight Advisory Service “Flight Watch” briefers at Automated Flight Service Station (AFSS). AFSS Flight Watch briefers have access to current weather radar imagery.
Figure 5-49. Radar Summary Chart Example Section 5: Graphical Observations and Derived Products Page 5-51
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
5.7 Alaska Initial Geopotential Heights and Winds Charts The Alaska Initial Geopotential Heights and Winds Charts (Figure 5-54) display an analysis of the observed height contours and winds at selected constant pressure surfaces (flight levels).
Figure 5-50. Alaskan Initial Geopotential Heights and Winds Chart Example
Table 5-24. Pressure Altitudes of Alaska Initial Geopotential Heights and Winds Charts
CHART PRESSURE ALTITUDE (Feet, MSL)
PRESSURE ALTITUDE (Meters, MSL) 200 MB 39,000 ft 12,000 m 300 MB 30,000 ft 9,000 m 500 MB 18,000 ft 5,500 m 700 MB 10,000 ft 3,000 m 850 MB 5,000 ft 1,500 m
5.7.1 Issuance The charts are issued twice daily with valid times of 00z and 12z and can be found on the Alaska Aviation Weather Unit (AAWU) Web site at: http://aawu.arh.noaa.gov/upperwinds.php.
Section 5: Graphical Observations and Derived Products Page 5-52
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
5.7.2 Analysis The analysis of both height contours and winds are based on output from the North American Mesoscale (NAM) computer forecast model.
5.7.2.1 Height Contours Height contours are lines of constant height referenced to MSL and are used to map the height variations of constant pressure surfaces. They identify and characterize pressure systems on constant pressure charts.
Contours are drawn as solid lines and labeled in meters. The intervals at which the contours are drawn are 60 meters on all of the charts.
5.7.2.2 Winds Wind is plotted in increments of 5 knots (kts). The wind direction is referenced to “true” north and is depicted by a stem (line) pointed in the direction from which the wind is blowing. Wind speed is determined by adding the values of the flags (50 kts), barbs (10kts), and half barbs (5 kts) found on the stem.
A single circle over the station with no wind symbol indicates a calm wind.
Figure 5-51 contains some examples wind symbols.
Figure 5-51. Alaskan Initial Geopotential Heights and Winds Chart Wind Plotting Model
Section 5: Graphical Observations and Derived Products Page 5-53
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
5.7.3 Use The Alaska Initial Geopotential Heights and Winds Charts are used to provide an overview of heights, pressure patterns and winds at specified pressure altitudes. Pressure patterns cause and characterize much of the weather. Typically, lows and troughs are associated with bad weather, clouds and precipitation, while highs and ridges are associated with good weather.
Figure 5-52. Alaskan Initial Geopotential Heights and Winds Chart – 200MB Winds and Contours Chart Example
Figure 5-53. A laskan Initial Geopotential Heights and Winds Chart – 300MB Winds and Contours Chart Example Section 5: Graphical Observations and Derived Products Page 5-54
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
Figure 5-54. Alaskan Initial Geopotential Heights and Winds Chart – 500MB Winds and Contours Chart Example
Figure 5-55. Alaskan Initial Geopotential Heights and Winds Chart – 700MB Winds and Contours Chart Example Section 5: Graphical Observations and Derived Products Page 5-55
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010)
Figure 5-56. Alaskan Initial Geopotential Heights and Winds Chart – 850MB Winds and Contours Chart Example Section 5: Graphical Observations and Derived Products Page 5-56