Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
5.5 Weather Depiction Chart The Weather Depiction Chart (Figure 5-39) contains a plot of weather conditions at selected METAR stations and an analysis of weather flying category. It is designed primarily as a briefing tool to alert aviation interests to the location of critical or near-critical operational minimums at terminals in the conterminous US and surrounding land areas. The chart can be found at: http://weather.noaa.gov/pub/fax/QGUA00.TIF
Figure 5-39. Weather Depiction Chart Example
5.5.1 Issuance The Weather Depiction chart is issued eight times daily at the following times:
Table 5-13. Weather Depiction Charts Issuance Schedule Valid Time (UTC) 01 04 07 10 13 16 19 22
5.5.2 Station Plot Model METAR elements (Section 2.1) associated with weather flying category (visibility, present weather, sky cover, and ceiling) are plotted for each station on the chart (Figure 5-41). The station is located at the center of the sky cover symbol. Most stations are not plotted due to space limitations. However, all reporting stations are used in the weather flying category analysis.
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-42
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 5-40. Weather Depiction Chart Station Plot Model
5.5.2.1 Visibility When visibility is 5 miles or less, it is entered to the left of the station. Visibility is entered in statute miles and fractions of a mile.
5.5.2.2 Present Weather Present weather symbols are entered to the left of the station. If the present weather information is obtained by an automated system, the right bracket symbol ( ] ) is plotted to the right of the station.
When several types of weather and/or obstructions to visibility are reported, the most significant weather element is plotted. This is the first weather element coded in the METAR report (Section 2.1) and is usually the highest coded number in the Present Weather Symbols guide (Appendix I).
5.5.2.3 Sky Cover Sky cover represents the summation total of the sky condition element from the METAR report.
For example, if the METAR sky condition element was SCT030 BKN060 OVC090, the sky cover would be overcast. Sky cover symbols are listed in Figure 5-41.
5.5.2.4 Ceiling Ceiling is the height from the base of the lowest layer aloft covering more than one-half the sky to the ground. Additionally, vertical visibility into a total surface-based obscuration is defined as a ceiling. For a METAR report, the first broken (BKN) or overcast (OVC) layer is the ceiling.
For example, if the METAR sky condition element is SCT030 BKN060 OVC090, the ceiling is 6,000 feet.
For stations with broken to overcast layers, the ceiling height is plotted below the station.
Ceilings are reported as hundreds of feet above ground level (AGL).
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-43
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) For a total surface-based obscuration, no ceiling is plotted and the METAR must be consulted.
Partial obscurations are not identified.
• For a partial obscuration with no layer above, the sky cover symbol will be plotted as missing (Figure 5-41).
• For a partial obscuration with a layer above, the sky cover and ceiling height will be plotted for the cloud layer only.
The METAR report should be consulted to identify the partial obscuration.
If the sky cover is clear, few, or scattered, no ceiling is plotted.
5.5.3 Weather Flying Category Analysis Instrument Flight Rules (IFR) indicated on the Weather Depiction Chart represents ceilings less than 1,000 feet and/or visibility less than 3 statute miles and IFR operations must be in place.
IFR areas are outlined on the chart with a solid line and are shaded. IFR areas are typically shaded red in colorized versions of the chart.
Marginal Visual Flight Rules (MVFR) indicated on the Weather Depiction Chart represents ceiling 1,000 to 3,000 feet and/or visibility 3 to 5 statute miles and VFR operations can take place. MVFR areas are outlined with a solid line, but the area is not shaded. MVFR areas are typically shaded blue in colorized versions of the chart.
Visual Flight Rules (VFR) indicated on the Weather Depiction Chart represents a ceiling greater than 3,000 feet or clear skies and visibility greater than 5 statute miles and VFR operations can take place. VFR conditions are not analyzed. This does not necessarily imply that the sky is clear.
5.5.4 Use The Weather Depiction Chart is an ideal place to begin flight planning or to prepare for a weather briefing. This chart provides an overview of weather flying categories and other adverse weather conditions for the chart valid time. The chart, though, may not completely represent the en route conditions because of terrain variations and the possibility of weather occurring between reporting stations. This chart should be used in addition to the current METAR reports, pilot weather reports, and radar and satellite imagery for a complete look at the latest flying conditions.
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-44
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
5.6 Alaska Weather Depiction Charts The Alaska Weather Depiction Charts (Figure 5-43) display color coded station plots which show: temperature, dew point, ceiling, visibility and wind direction/speed. A key to the station plots is found on each map.
So pal Pan SCYPC 45 PASC39 48 15Ф CYUB 999 „CYU SS "CYEV PARD 15 240m _PAKP 59' CYOC 54 CZFM PAOT, 54 PAFM Y 1999 35¢ • 210 ı20 DE 38) 110 / 58 'CZFN 19" 80; 10@PFYU 2 6799СКА2 PAUN S4 Ø150i PAEM 16 9999 1530 999 991999 ¡ PATK 799 PAS· 5115419KILA2 999 /PACV.
SO PREM -42 158, PAKN GAILSO 999™ 19 999 _ PAHO- 3_90 18. 70 49 54 PAJN 5E 460 IÇWDL 10( 999 SO PAST 15 _ PAWG РАРН MP(des SoW DEWPT (deg F) | CIG 172 07/14/2005
IFR MYFRAYFR 190 Figure 5-41. AAWU Alaska Weather Depiction Chart Example Thirteen charts cover Alaska (except for the Aleutians) and adjacent areas of Canada.
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-45
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Table 5-14. AAWU Alaska Weather Depiction Charts Coverage Chart Coverage Scale Entire State of Alaska (1:12 million) All of Southeast Alaska (1:5 million) Southern Southeast Alaska (1:3 million) Northern Southeast Alaska (1:3 million) North Gulf Coast (1:5 million) South Central Alaska (1:5 million) Cook Inlet/Susitna Valley (1:2 million) Southwest Alaska (1:6 million) Western Interior (1:5 million) Central Interior (1:5 million) Northern Alaska (1:6 million) Southwest British Columbia (1:7 million) Yukon Territory/Northern British Columbia (1:8 million)
5.6.1 Issuance The charts are issued hourly and can be found on the Alaska Aviation Weather Unit (AAWU) web site at: http://aawu.arh.noaa.gov/Sigwx.php. The charts will first appear at about 10 minutes past the hour, with a second update at about 25 minutes past the hour.
5.6.2 Legends The Alaska Weather Depiction Charts depict numerous parameters including the flying category, sky cover and wind.
5.6.2.1 Flying Category Each station plot is color-coded according to the weather flying category reported (Table 5-16).
Red indicates instrument flight rules (IFR), blue indicates marginal visual flight rules (MVFR), and black is plotted for stations reporting visual flight rules (VFR).
Table 5-15 AAWU Alaska Weather Flying Categories and Criteria FLYING CATEGORY CEILING (feet) VISIBILITY (miles) VFR (black) Greater than 3,000 feet Greater than 5 miles MVFR (blue) 1,000 to 3,000 feet 3 to 5 miles IFR (red) Less than 1,000 feet Less than 3 miles
5.6.2.2 Station Plot METAR elements are plotted for each station on the chart (Figure 5-45). Some stations are not plotted due to space limitations, notably on the chart which covers the entire state of Alaska.
Figure 5-42. AAWU Alaska Weather Depiction Chart Station Plot Legend AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-46
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
5.6.2.3 Sky Cover The sky cover symbol is plotted at the station location and is filled according to the summation total of the sky condition element from the METAR report. For example, if the METAR sky condition element was SCT030 BKN060 OVC090, the sky cover would be overcast. Sky cover symbols are listed in Figure 5-41.
5.6.2.4 Station Identifier (STNID) The four-letter ICAO station identifier is entered to the upper right of the station.
5.6.2.5 Wind 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.
Some sample wind symbols are shown on Figure 5-46.
Figure 5-43. AAWU Alaska Weather Depiction Chart Wind Symbols
5.6.2.6 Temperature (TMP deg F) Temperature in degrees Fahrenheit is plotted to the upper left of the sky cover symbol.
5.6.2.7 Visibility (VIS) Visibility in statute miles is plotted to the left of the sky cover symbol. Decimals are used to represent tenths of miles when necessary.
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-47
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
5.6.2.8 Dew Point Temperature (DEWPT deg F) Dew point temperature in degrees Fahrenheit is plotted to the lower left of the sky cover symbol.
5.6.2.9 Ceiling (CIG) Ceiling is the height from the base of the lowest layer aloft covering more than one-half the sky.
Additionally, vertical visibility into a total surface-based obscuration is defined as a ceiling. For a METAR report, the first broken (BKN) or overcast (OVC) layer is the ceiling. For example, if the METAR sky condition element is SCT030 BKN060 OVC090, the ceiling is 6,000 feet.
For a total surface-based obscuration, no ceiling is plotted and the METAR must be consulted.
If the sky cover is clear, few, or scattered, no ceiling is plotted.
The ceiling is plotted to the lower right of the station circle. Ceilings are reported as hundreds of feet above ground level (AGL). If no ceiling is present, the code 999 will be plotted.
5.6.2.10 Present Weather (WX) Present weather symbols are entered to the left of the station. Note that the older Surface Aviation Observation (SAO) code is used instead Surface Analysis Chart symbols or the modern METAR code.
Table 5-16 Alaska Weather Depiction Charts Precipitation Symbols Table 5-17 Alaska Weather Depiction Charts Obstruction to Visibility Symbols Symbol Meaning Symbol Meaning T Thunderstorm BD Blowing Dust R Rain BN Blowing Sand RW Rain Shower BS Blowing Snow L Drizzle BY Blowing Spray ZR Freezing Rain D Dust ZL Freezing Drizzle F Fog A Hail GF Ground Fog IP Ice Pellets H Haze IPW Ice Pellet Showers IF Ice Fog S Snow K Smoke SW Snow Showers SP Snow Pellets SG Snow Grains IC Ice Crystals Table 5-18 Alaska Weather Depiction Charts Precipitation Intensity Symbols Symbol Meaning
- Light (No symbol) Moderate + Heavy
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-48
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
5.6.3 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 43 PLERZ 45 PAFK 3QФ 999 A PACK 45 _PASW 36 PAZk 43 40 48 PAAG PAER 19 PS BABY 999 PASY 27 SMCAZ PALV |44 SORT _PAWR PAEN 10• 60 RUFAZ 38
45. PAL. *KNTUS 36®50 NABAZ 19945 42 PAIL ILI SURFACE OBSERVATIONS PAHO? IMP(devISOWX ISTNID 182 05/04/2005 IFR_MVFR VFR DEWPT(deg F) _ CIG Figure 5-44. AAWU Alaska Weather Depiction Chart - South Central Alaska Example AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-49
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
5.7 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 0920Z MON 13 JUN 2005 RADAR SUMMARY SD095- 220 NE 220
NE NE NE 28 RW NE ¿ NE NE
• NE
NE NE R 190 NEVA NE NE 260 NE NA NET 137 NE NE NE NE -NE.
NE NA NE NE NE NE NA NE NE NE LEGEND. NE ECHO AREAS INTENSITIES 1-3-5 NE NE
WEATHER WAT START END S ¡ PRECIPITATION SPEED NOAA/NUS/NCEP WASHINGTỔN IS DEPT OF COMMERCE NCEP + 09202 MON 13 JUN 2005 RADAR SUMMARY SD09 Figure 5-45. Radar Summary Chart Example
5.7.1 Issuance The chart is issued hourly. Figure 5-50 depicts the WSR-88D weather radar network from which the chart is produced.
5.7.2 Format The Radar Summary Chart depicts precipitation type, intensity, coverage, movement, echoes, and maximum tops.
5.7.2.1 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 AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-50
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) 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
5.7.2.2 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).
KOT· KMSX KGGW * KMBX O KNVY KULI OKIEX ÖKBIS KELA KABR O КМРУ KCEB :
КМАХ KUDK KF SDO KARY KHKX KBCI
KDYN A KLOT KOLEO ALŘx KCTS курх FOAK O KIWx TO KUX KDAX KFTCO O KELD KIWXO CKLEX KIL O in St KIND OKIN
OKIE KPUX O KODCO OESGF OKHPE KEYXO OEVIX кРУх KAEX. KUND KIN
• CECAF OKNEX YO KIWA KYDS OKIBB IDE CRAMA CATLE KIZK ксио квих KYUX KHỐX КИАГ OKFYS OKSHV КРОЕ EJAN KFOXO O EVA KGEK O PAPD POTA C Figure 5-46. WSR-88D Weather Radar Network AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-51
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 5-47. Radar Summary Chart Precipitation Intensity
5.7.2.3 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.
5.7.2.4 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
8/10ths or greater coverage in a line.
Line of echoes.
Solid line of thunderstorms with intense to extreme precipitation.
5.7.2.5 Cell Movement 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 AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-52
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) 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
5.7.2.6 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.
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.
AC 00-45F, CHG 2 Section 5: Graphical Observations and Derived Products Page 5-53