Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) Prediction (NCEP) Central Operations (NCO). The Anchorage VAAC is managed by the AAWU. The areas of responsibility for each VAAC are:
• Washington VAAC
o FIRs in CONUS and adjacent coastal waters (Figures 6-1 and 6-18) o The Oakland Oceanic FIR over the Pacific Ocean (Figures 6-3 and 6-18) o The New York FIR over the western Atlantic Ocean (Figures 6-2 and 6-18) o FIRs over and adjacent to the Caribbean, and Central and South America north of 10 degrees south latitude (Figure 6-2 and 6-18)
• Anchorage VAAC o The Anchorage FIR (Figures 6-3 and 6-18).
o Russian FIRs north of 60 degrees north latitude and east of 150 degrees east longitude (Figure 6-18).
6.6.2 Volcanic Ash Advisory Statement (VAAS) A Volcanic Ash Advisory Statement (VAAS) provides information on hazards to aircraft flight operations caused by a volcanic eruption.
6.6.2.1 Issuance Volcanic Ash Advisory Centers (VAACs) are responsible for providing ash movement and dispersion guidance to Meteorological Watch Offices (MWOs) and neighboring VAACs. There are nine VAACs worldwide, two of which are located in the US (Figure 6-18). Each VAAC issues Volcanic Ash Advisory Statements and provide guidance to Meteorological Watch Offices (MWOs) for SIGMETs involving volcanic ash.
A VAAS may be issued within 6 hours of an eruption and every 6 hours thereafter. However, it can be issued more frequently if new information about the eruption is received.
6.6.2.2 Format A VAAS summarizes the known information about an eruption. It may include the location of the volcano, height of the volcano summit, height of the ash plume, a latitude/longitude box of the ash dispersion cloud, and a forecast of ash dispersion. The height of the ash cloud is estimated by meteorologists analyzing satellite imagery and satellite cloud drift winds combined with any pilot reports, volcano observatory reports, and upper-air wind reports.
6.6.2.3 VAAS Issued by the Washington VAAC Example
VOLCANIC ASH ADVISORY ISSUED: 2003JUL10/1300Z VAAC: WASHINGTON
VOLCANO: ANATAHAN 0804-20 LOCATION: N1621E14540 AREA: MARIANA ISLANDS
SUMMIT ELEVATION: 2585 FT (788 M)
ADVISORY NUMBER: 2003/251
INFORMATION SOURCE: GOES 9 IMAGERY. GFS MODEL WINDS FORECAST
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-58
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) ERUPTION DETAILS: ASH AND GAS EMISSIONS SINCE MAY 10.
OBS ASH DATE/TIME: 09/1202Z.
OBS ASH CLOUD: ASH NOT IDENTIFIABLE FROM SATELLITE DATA.
WINDS SFC/FL080 MOVING SW 10-15 KNOTS.
FCST ASH CLOUD +6H: SEE SIGMETS.
REMARKS: THE ASH PLUME OBSERVED IN VISIBLE IMAGERY IS TOO THIN AND DIFFUSE TO BE SEEN IN INFRARED AND MULTISPECTRAL IMAGAERY. ANY ASH UP TO FL080 SHOULD MOVE TOWARDS THE SW AT 10-15 KNOTS.
NEXT ADVISORY: WILL BE ISSUED BY 2003JUL10/1900Z.
6.6.3 Volcanic Ash Advisory (VAA) The Volcanic Ash Advisory (VAA) is advisory information on volcanic ash cloud issued in abbreviated plain language, using approved ICAO abbreviations and numerical values of self explanatory nature.
6.6.3.1 VAA Issuance Volcanic Ash Advisory Centers (VAACs) are responsible for providing ash movement and dispersion guidance to Meteorological Watch Offices (MWOs) and neighboring VAACs. There are nine VAACs worldwide, two of which are located in the US (Figure 6-18). Each VAAC issues Volcanic Ash Advisory Statements and provide guidance to Meteorological Watch Offices (MWOs) for SIGMETs involving volcanic ash.
VAAs are issued as necessary, but at least every six hours until such time as the volcanic ash cloud is no longer identifiable from satellite data, no further reports of volcanic ash are received from the area, and no further eruptions of the volcano are reported.
6.6.3.2 VAA Format The VAA format conforms to the “Template for advisory message for volcanic ash” included in ICAO Annex 3.
6.6.3.3 Volcanic Ash Advisory (VAA) Example
FVAK21 PAWU 190615
VOLCANIC ASH ADVISORY ISSUED: 20030419/0615Z VAAC: ANCHORAGE VOLCANO: CHIKURACHKI, 900-36 LOCATION: N5019 E15527 AREA: KAMCHATKA NORTHERN KURIL ISLANDS SUMMIT ELEVATION: 7674 FT (2339 M) ADVISORY NUMBER: 2003-02 INFORMATION SOURCE: SATELLITE AVIATION COLOR CODE: NOT GIVEN ERUPTION DETAILS: NEW ERUPTION OCCURRED APPROX 190500 UTC.
HEIGHT IS ESTIMATED AT FL300. ESTIMATE IS BASED AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-59
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-60 ON OBSERVEDAND MODEL WINDS. MOVEMENT APPEARS TO BE E AT 75 KTS.
OBS ASH DATA/TIME: 19/0500Z OBS ASH CLOUD: VA EXTENDS FM NEAR VOLCANO EWD TO N50 E160.
FCST ASH CLOUD +6HR: 30NM EITHER SIDE OF LN FM NIPPI N49 E159 - N50 E175.
FCST ASH CLOUD +12HR: 30NM EITHER SIDE OF LN FM N50 E168 - N50 E180.
FCST ASH CLOUD +18HR: 30NM EITHER SIDE OF LN FM N51 E175 - N50 E185.
NEXT ADVISORY: 20030419/1500Z REMARKS: UPDATES AS SOON AS INFO BECOMES AVAILABLE.
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) 7 FORECAST TEXT PRODUCTS
7.1 Area Forecasts (FA) An Area Forecast (FA) is a forecast in an abbreviated plain language of specified weather phenomena covering a flight information region (FIR) or other area designated by the meteorological authority. The Area Forecast (in conjunction with AIRMETs, SIGMETs, Convective SIGMETs, CWAs, etc.), is used to determine forecast en route weather and to interpolate conditions at airports which do not have a Terminal Aerodrome Forecast (TAF). As such, it serves as a flight planning and pilot weather briefing aid for use by general aviation pilots, civil and military aviation operations and Federal Aviation Administration (FAA) weather briefers.
Note…Hazardous weather (e.g., IFR, icing, turbulence, etc.) meeting AIRMET or SIGMET criteria are not forecast in the CONUS or Hawaii FAs. Valid AIRMETs and SIGMETs must be used in conjunction with the FA to determine hazardous weather information for the flight.
All Area Forecasts are available on the Aviation Weather Center (AWC) web site at:
http://aviationweather.gov/products/fa/.
Alaska Area Forecasts can also be found on the Alaska Aviation Weather Unit (AAWU) web site at: http://aawu.arh.noaa.gov/areaforecasts.php
7.1.1 Area Forecast Issuance Area forecasts are issued by the following offices for the following areas:
• The Aviation Weather Center (AWC)
o Conterminous U.S (CONUS) - Six (6) FAs covering separate geographical areas of the CONUS, excluding the Gulf of Mexico coastal waters west of 85W (Figure 7-1).
o Gulf of Mexico: The northern Gulf of Mexico, including the Houston Oceanic FIR, the Gulf of Mexico portion of the Miami Oceanic FIR, and the coastal waters west of 85W longitude (Figure 7-1 and 7-2).
o Caribbean Sea: Portions of the Gulf of Mexico (south of the Houston Oceanic FIR to approximately 22N latitude), the Caribbean Sea and adjacent portions of the North Atlantic (Figure 7-3).
• The Alaskan Aviation Weather Unit (AAWU)
o Alaska: Seven (7) FAs covering separate geographical areas of Alaska and the adjacent coastal waters, including the Pribilof Islands and Southeast Bering Sea (Figure 7-5).
• WFO Honolulu, Hawaii
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-1
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) o Hawaii: The main Hawaiian Islands and adjacent coastal waters extending out 40 nautical miles from the coastlines (Figure 7-4).
Figure 7-1. AWC Area Forecast Regions- Contiguous U.S.
Figure 7-2. AWC Area Forecast Region and WMO Header - Gulf of Mexico
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-2
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 7-3. AWC Area Forecast Region and WMO Header - Caribbean
Figure 7-4. WFO Honolulu Area Forecast Region and WMO header - Hawaii
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-3
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 7-5. AAWU Flight Advisory and Area Forecast Zones - Alaska
Table 7-1. AAWU Area Forecast Zones – Alaska 1 Arctic Coast Coastal 14 Southern Southeast Alaska 2 North Slopes of the Brooks Range 15 Coastal Southeast Alaska 3 Upper Yukon Valley 16 Eastern Gulf Coast 4 Koyukuk and Upper Kobuk Valley 17 Copper River Basin 5 Northern Seward Peninsula-Lower Kobuk Valley 18 Cook Inlet-Susitna Valley 6 Southern Seward Peninsula-Eastern Norton Sound 19 Central Gulf Coast 7 Tanana Valley 20 Kodiak Island 8 Lower Yukon Valley 21 Alaska Peninsula-Port Heiden to Unimak Pass 9 Kuskowim Valley 22 Unimak Pass to Adak 10 Yukon-Kuskowim Delta 23 St. Lawrence Island-Bering Sea Coast 11 Bristol Bay 24 Adak to Attu 12 Lynn Canal and Glacier Bay 25 Pribilof Islands and Southeast Bering Sea 13 Central Southeast Alaska
7.1.2 Area Forecast Standardization All Area Forecasts follow these standards:
• All heights or altitudes are referenced to above mean sea level (AMSL), unless otherwise noted (i.e., prefaced by AGL or CIG), and annotated using the height in hundreds of feet, consisting of three digits (e.g., 040). For heights at or above 18,000 AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-4
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) feet, the level is preceded by FL to represent flight levels (e.g., FL180). Tops are always referenced to AMSL.
• References to latitude and longitude are in whole degrees and minutes following the model: Nnn[nn] or Snn[nn], Wnnn[nn] or Ennn[nn] with a space between latitude and longitude and a hyphen between successive points. Example: N3106 W07118 – N3011 W7209
• Messages are prepared in abbreviated plain language using contractions from the Federal Aviation Administration (FAA) Order 7340.1Z for domestic products and International Civil Aviation Organization (ICAO) document 8400 for international products issued for Oceanic FIRs. A limited number of non-abbreviated words, geographical names and numerical values of a self-explanatory nature may also be used.
• Weather and obstructions to visibility are described using the weather abbreviations for surface weather observations (METAR/SPECI). See the Federal Meteorological Handbook (FMH) No. 1 – Surface Observations or Section 3.1 of this document.
Note…For AWC FAs, “CSTL WTRS” refer to water areas that extend from the coastline to the FIR boundary. “CSTL SXNS” refer to land areas along and near the coastline.
Note: Refer to Appendix A for definitions of common terms used in Area Forecasts.
7.1.3 Area Forecast Issuance Schedule Area forecasts are scheduled products issued at the following times.
Table 7-2. Area Forecast (FA) Issuance Schedule Boston and Miami (UTC) Chicago and Fort Worth (UTC) San Francisco and Salt Lake City (UTC) Gulf of Mexico (UTC) Caribbean (UTC) Hawaii (UTC) Alaska (UTC) 1st Issuance 0845 DT 0945 ST 0945 DT 1045 ST 1045 DT 1145Z ST 0130 0330 0340 0145 DT 0245 ST 2nd Issuance 1745 DT 1845 ST 1845 DT 1945 ST 1945 DT 2045Z ST 1030 0930 0940 0745 DT 0845 ST 3rd Issuance 0045 DT 0145 ST 0145 DT 0245 ST 0245 DT 0345 ST 1830 1530 1540 0145 DT 1445 ST 4th Issuance 2130 2140 1945 DT 2045 ST Note: DT – Daylight Time, ST – Standard Time, UTC – Coordinated Universal Time
7.1.4 Area Forecast Amendments Amendments are issued whenever the weather significantly improves or deteriorates based upon the judgment of the forecaster. These updates are those required to keep forecasts of non-AIRMET conditions representative of existing or expected conditions. “AMD” is included after the date/time group on the FAA product line. The date/time group on the WMO and FAA lines is updated to indicate the time of the correction. The ending valid time remains unchanged.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-5
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
7.1.5 Area Forecast Corrections Area Forecasts containing errors will be corrected. “COR” is included after the date/time group on the FAA product line. The date/time group on the WMO and FAA lines is updated to indicate the time of the correction. The ending valid time remains unchanged.
7.1.6 Area Forecast Format – Conterminous U.S. (CONUS) Area forecasts issued for the conterminous U.S. (CONUS) cover the airspace between the surface and 45,000 feet AMSL and include the following forecast sections:
• Synopsis : A short description of significant synoptic weather systems affecting the area during the 18 hour valid period. This includes the location and movement of pressure systems and fronts. Air mass descriptions may be used in the absence of significant weather systems. References to low ceilings and/or visibilities, strong winds, or any other phenomena that the forecaster considers useful may also be included.
• VFR Clouds/Weather : A 12-hour specific clouds and weather forecast, followed by a 6-hour categorical outlook giving a total forecast period of 18 hours. This section gives a general description of clouds and weather which cover an area greater than 3,000 square miles and are significant to VFR flight operations. The forecasts are referenced to states or geographic areas. States are presented in the order listed within the header of the FA, however, portions of adjacent states may be grouped together when they are forecast to have similar conditions. The following weather elements, if applicable, are included in the following order for each 12-hour specific forecast:
o Sky condition (coverage, cloud base, and tops) if bases are higher than or equal to 1,000 feet AGL and at or below FL180. Heights are referenced to MSL unless preceded by AGL or CIG. Sky condition is not repeated for each new time group unless it is forecast to change.
o Surface visibilities and associated obstructions when visibility is between 3 and 5 statute miles and coverage is 3,000 square miles or greater. When no visibility value is forecast, it is implied to be greater than 5 statute miles.
o Weather (precipitation, including thunderstorms, fog, haze, blowing dust, etc.) if it results in visibilities of 3 to 5 statute miles.
o Significant wind information (direction and speed) if the surface wind is sustained at 20 knots or greater and/or gusts are greater than or equal to 25 knots.
A 6-hour categorical forecast follows the 12-hour specific clouds and weather forecast.
At a minimum, the category of the expected prevailing condition (IFR, MVFR, VFR) is stated in the outlook. If IFR or MVFR, the cause is listed (e.g., CIG, FG, BR, etc.). VFR stands alone except for wind (WND), thunderstorms (TSRA) and precipitation types (without intensities). The contraction “WND” is appended to any category if the sustained surface wind is expected to be 20kts or more or surface wind gusts are expected to be 25 knots or more during the majority of the 6-hour outlook period.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-6
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 7-6. Area Forecast – CONUS Communication and Product Header Example
Table 7-3. Decoding a CONUS Area Forecast Communication and Product Header Line Content Description 1 DFW Area Forecast region identifier C Indicates VFR clouds and weather forecast FA Product type 120945 Issuance and beginning of valid date/time (UTC) 2 SYNOPSIS AND VFR CLDS/WX Statement of weather information contained in this forecast message 3 SYNOPSIS VALID UNTIL 130400 Synopsis valid date and time 4 CLDS/WX VALID UNTIL 122200…OTLK VALID 122200-130400 The clouds and weather section valid time. The valid date and time of the outlook.
5 OK TX AR TN MS AL Description of the area for which the FA is valid.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-7
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 7-7. Area Forecast - Clouds and Weather Element Example
The “Clouds and Weather” section above is decoded as follows:
South central and southeast Texas:
Scattered to broken bases at 1,000 feet above ground level (AGL). Tops at 3,000 feet above mean sea level (MSL). Visibility 3 to 5 statute miles in mist. Between 1400 and 1600 UTC…clouds bases becoming scattered at 3,000 feet AGL. 1900 UTC…scattered bases at 5,000 feet AGL. 12 to 18 hour categorical outlook…VFR.
Oklahoma:
Panhandle and northwest…scattered bases at 3,000 feet AGL, scattered to broken bases at 10,000 feet AGL. Tops at flight level 20,000 feet MSL. 1500 UTC…scattered bases at 4,000 feet AGL, scattered bases at 10,000 feet AGL. After 2000 UTC…scattered thunderstorms with rain showers developing..a few possible severe. Cumulonimbus tops to flight level 45,000 feet MSL. Outlook…VFR.
Remainder of the state…Ceilings broken at 2,000 feet AGL. Tops at 5,000 feet MSL.
Visibilities 3 to 5 statute miles in mist. 1400 UTC…scattered to broken bases at 4,000 feet AGL.
Tops at 10,000 feet MSL. 1800 UTC…ceilings broken 6,000 feet AGL. Tops to flight level 18,000 feet MSL. 2200 UTC…scattered thunderstorm with rain showers developing…a few possibly severe. Cumulonimbus tops above flight level 45,000 feet MSL. 12-18 hour categorical outlook…VFR.
7.1.6.1 Area Forecast – Conterminous U.S. (CONUS) Examples
7.1.6.1.1 Area Forecast – BOS Example
FAUS41 KKCI 081745 (ICAO product header) FA1W (NWS AWIPS Communication header) BOSC FA 081745 (Area forecast region, product type, issuance date/time)
SYNOPSIS AND VFR CLDS/WX SYNOPSIS VALID UNTIL 091200 AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-8
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) CLDS/WX VALID UNTIL 090600...OTLK VALID 090600-091200
ME NH VT MA RI CT NY LO NJ PA OH LE WV MD DC DE VA AND CSTL WTRS .
SEE AIRMET SIERRA FOR IFR CONDS AND MTN OBSCN.
TS IMPLY SEV OR GTR TURB SEV ICE LLWS AND IFR CONDS.
NON MSL HGTS DENOTED BY AGL OR CIG.
.
SYNOPSIS...18Z CDFNT 30N PQI-40E MPV-ALB-20N JHW LN. STNR FNT 20N JHW-ECK LN. STNR FNT EWC-ROD-IND LN. TROF 210SE SIE-170SE ECG LN CONTG SWD. HIGH WRN NC. 12Z STNR FNT FM LOW NR FWA ALG 20N CLE- JHW-ALB-30NNE BOS LN. CDFNT 30NNE BOS-120SE BGR LN. CDFNT FM LOW NR FWA ALG PXV-50SE FAM LN CONTG SWWD. HIGH NR ODF.
.
ME NH VT NRN ME...SCT040 BKN060 TOP FL250. OCNL BKN040. SCT -SHRA/ISOL -TSRA. CB TOP FL350. 21Z BKN040. ISOL -SHRA. WND W G25KT. 03Z SKC. OTLK...VFR.
VT/NRN NH/RMNDR ME MTNS...SCT-BKN040 BKN060 TOP FL250. SCT SHRA/ISOL TSRA. CB TOP FL350. 03Z BKN040. OCNL VIS 3-5SM BR.
OTLK...MVFR CIG BR.
SRN NH/RMNDR ME...SCT040 BKN100 TOP FL250. OCNL BKN040 IN WDLY SCT -SHRA/ISOL -TSRA BECMG AFT 19Z SCT TSRA. TS POSS SEV. CB TOP FL400. 04Z BKN020. WDLY SCT -SHRA. OTLK...MVFR CIG SHRA BR.
.
MA RI CT CT CSTL PLAIN/RI/SERN MA...SKC. 21Z SCT040. ISOL TSRA. CB TOP FL400. 03Z SKC. OCNL VIS 3-5SM BR. OTLK...IFR CIG BR.
RMNDR...SCT100. 19Z SCT040 BKN100 TOP 160. SCT TSRA POSS SEV. CB TOP FL450. 02Z BKN040. WDLY SCT SHRA. OTLK...MVFR CIG BR.
.
NY LO LO/N CNTRL-NERN NY...SCT-BKN040 BKN060 TOP 160. SCT SHRA/ISOL TSRA. CB TOP FL350. 03Z BKN040. WDLY SCT -SHRA. OTLK...MVFR CIG SHRA.
WRN-S CNTRL NY...BKN040 OVC060 TOP 160. SCT -TSRA. CB TOP FL450.
03Z BKN030. SCT SHRA. OTLK...MVFR CIG SHRA.
EXTRM SERN NY-LONG ISLAND...SKC. 21Z SCT040. ISOL TSRA. 03Z SKC.
OCNL VIS 3-5SM BR. OTLK...IFR CIG BR.
RMNDR NY...BKN050 TOP 160. SCT TSRA POSS SEV. CB TOP FL450. 03Z BKN040. SCT SHRA. OTLK...MVFR CIG SHRA.
.
PA NJ WRN-N CNTRL PA...BKN040 OVC060 TOP FL220. SCT TSRA. CB TOP FL400.
03Z BKN060. SCT SHRA NWRN/N CNTRL PA. OTLK...VFR SWRN PA...MVFR CIG SHRA NWRN/N CNTRL PA.
S CNTRL-NERN PA...BKN060 TOP FL220. ISOL TSRA BECMG AFT 20Z SCT TSRA. CB TOP FL400. 03Z OVC060. SCT SHRA NERN PA. OTLK...MVFR CIG SHRA NERN PA. MVFR CIG BR S CNTRL PA.
SERN PA-NRN NJ...SCT060. AFT 21Z ISOL TSRA. CB TOP FL400. 03Z SKC OR SCT CI. OTLK...VFR.
SRN NJ...SKC OR SCT CI. OTLK...VFR.
.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-9