11/14/16 Aviation Weather Services AC 00-45H 5-60 A graphical (e.g., chart) version of the VAA is also produced and is sometimes referred to as VAG. The VAG contains the same information as in the VAA but in a four-panel chart format.
5.8.2.1 VAA Issuance.
Each VAAC issues VAAs to provide guidance to MWOs for SIGMETs involving volcanic ash.
VAAs are issued as necessary, but at least every 6 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.
VAAs in both text and graphical format are available from the Web sites of the VAAC.
5.8.2.2 VAA Format.
The VAA format conforms to the “Template for advisory message for volcanic ash” included in ICAO Annex 3, Meteorological Service for International Air Navigation.
5.8.2.3 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 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.
11/14/16 Aviation Weather Services AC 00-45H 5-61
5.8.2.4 Volcanic Ash Advisory Graphic Example.
Figure 5-34. Volcanic Ash Advisory in Graphical Format
5.9 Area Forecasts (FA).
An FA is an abbreviated plain language forecast concerning the occurrence or expected occurrence of specified en route weather phenomena. The FA (in conjunction with AIRMETs, SIGMETs, Convective SIGMETs, CWAs, etc.) is used to determine forecast en route weather over a specified geographic region. FAs cover an 18- to 24-hour period, depending on the region, and issued three to four times daily, depending on the region, and are updated as needed. The exact phenomenon contained in FAs also varies by region.
FAs are not intended for use as a substitute for a Terminal Aerodrome Forecast (TAF) for those air carrier operations that require weather forecasts at specific airports (i.e., origin, destination, and any alternate). In these operations, a TAF or equivalent forecast that is generated for the specific airport in question, is required to meet the Title 14 of the Code of Federal Regulations (14 CFR) regulatory requirements that specify certain weather conditions and minima at the origin, destination, and alternate airports.
5.9.1 FA—Gulf of Mexico, Caribbean, and Alaska.
5.9.1.1 FA Issuance.
The following offices issue FAs for the following areas:
11/14/16 Aviation Weather Services AC 00-45H 5-62
• The Aviation Weather Center (AWC):
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 (see Figure 5-35, AWC Area Forecast (FA) Region and WMO Header—Gulf of Mexico).
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 (see Figure 5-36, AWC Area Forecast (FA) Region and WMO Header—Caribbean).
• The Alaskan Aviation Weather Unit (AAWU):
o Alaska: Seven FAs containing a total of 25 zones (see Table 5-11), covering separate geographical areas of Alaska and the adjacent coastal waters, including the Pribilof Islands and Southeast Bering Sea (see Figure 5-37, AAWU Flight Advisory and Area Forecast (FA) Zones—Alaska).
Figure 5-35. AWC Area Forecast (FA) Region and WMO Header—Gulf of Mexico
11/14/16 Aviation Weather Services AC 00-45H Figure 5-36. AWC Area Forecast (FA) Region and WMO Header-Caribbean -20 FACA20 ın/Gulf/ tlantic -100 - 80 Figure 5-37. AAWU Flight Advisory and Area Forecast (FA) Zones-Alaska 02 03 08 07 60† 09 17 7-557 -25 15 20
- 180 -170 -160 -150 -140 FAAK47 FAAK48 FAAK49 FAAK57 FAAK58 FAAK59 FAAK68 5-63
11/14/16 Aviation Weather Services AC 00-45H 5-64 Table 5-11. AAWU Area Forecast (FA) 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
5.9.1.2 FA Standardization.
All FAs follow these standards:
• All heights or altitudes are referenced to MSL, 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 ft, the level is preceded by FL to represent FLs
(e.g., FL180). Tops are always referenced to MSL.
• 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 current edition of Order 7340.2 for domestic products and ICAO Document 8400 for 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).
5.9.1.3 FA Issuance Schedule.
FAs are scheduled products issued at the following times (see Table 5-12, Area Forecast (FA) Issuance Schedule).
11/14/16 Aviation Weather Services AC 00-45H 5-65 Table 5-12. Area Forecast (FA) Issuance Schedule Gulf of Mexico (UTC) Caribbean (UTC) Alaska (UTC) 1st Issuance 0130 0330 0415 (DT) 0515 (ST) 2nd Issuance 1030 0930 1215 (DT) 1315 (ST) 3rd Issuance 1830 1530 2015 (DT) 2115 (ST) 4th Issuance None 2130 None Note: DT—During Alaska Daylight Time, ST—During Alaska Standard Time, UTC—Coordinated Universal Time.
5.9.1.4 FA Amendments.
Amendments are issued whenever the weather significantly improves or deteriorates based upon the judgment of the forecaster. 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.
5.9.1.5 FA Corrections.
FAs 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.
5.9.1.6 FA—Gulf of Mexico (FAGX).
FAs issued for the Gulf of Mexico (FAGX) cover the airspace between the surface and 45,000 ft MSL and include the following elements with each geographical section having an entry, even if it is negative:
• Synopsis: This is a brief discussion of the significant synoptic weather affecting the FAGX area during the entire 24-hour valid period.
• Significant Clouds and Weather: This is a description of the significant clouds and weather for the first 12 hours, including the following elements:
o Cloud amount (SCT, BKN or OVC) for clouds with bases below FL180.
o Cloud bases and tops associated with the above bullet.
o Precipitation and thunderstorms.
o Visibility below 7 sm and obstruction(s) to visibility.
o Sustained surface winds greater than or equal to 20 kts.
o 12- to 24-hour categorical outlook (LIFR, IFR, MVFR or VFR).
11/14/16 Aviation Weather Services AC 00-45H 5-66
• Icing and Freezing Level: Moderate or severe icing and freezing level.
• Turbulence: Moderate or greater turbulence.
5.9.1.6.1 FA—Gulf of Mexico (FAGX) Example.
FAGX20 KKCI 091812 (ICAO product header) OFAGX (NWS AWIPS Communication header) SYNOPSIS VALID TIL 101900Z FCST...091900Z-100700Z OTLK...100700Z-101900Z
INTERNATIONAL OPERATIONS BRANCH
AVIATION WEATHER CENTER KANSAS CITY MISSOURI .
CSTL WATERS FROM COASTLINE OUT TO HOUSTON OCEANIC FIR AND GLFMEX MIAMI OCEANIC FIR AND W OF 85W. HOUSTON OCEANIC FIR AND GLFMEX MIAMI OCEANIC FIR.
.
TS IMPLY SEV OR GTR TURB SEV ICE LLWS AND IFR CONDS. HGTS MSL.
.
01 SYNOPSIS...HIGH PRES OVR NRN GLFMEX.
.
02 SIGNIFICANT CLD/WX...
.
CSTL WATERS...
SCT020. OTLK...VFR.
.
HOUSTON OCEANIC FIR… SCT020. OTLK...VFR.
.
GLFMEX MIAMI OCEANIC FIR...
SCT020. OTLK...VFR.
.
03 ICE AND FRZLVL...
CSTL WATERS…SEE AIRMETS ZULU WAUS44 KKCI AND WAUS42 KKCI.
HOUSTON OCEANIC FIR… NO SGFNT ICE EXP OUTSIDE CNVTV ACT.
GLFMEX MIAMI OCEANIC FIR…NO SGFNT ICE EXP OUTSIDE CNVTV ACT.
FRZLVL…140 THRUT.
.
04 TURB...
CSTL WATERS…SEE AIRMETS TANGO WAUS44 KKCI AND WAUS42 KKCI.
HOUSTON OCEANIC FIR… NO SGFNT TURB EXP OUTSIDE CNVTV ACT.
GLFMEX MIAMI OCEANIC FIR…NO SGFNT TURB EXP OUTSIDE CNVTV ACT.
5.9.1.7 FA—Caribbean (FACA).
FAs issued for the Caribbean (FACA) cover the airspace between the surface and 24,000 ft MSL and include the following elements. Each geographical section will have an entry even if it is negative.
• Synopsis: A brief discussion of the synoptic weather affecting the FACA area during the 24-hour valid period.
• Significant Clouds and Weather: A description of the significant clouds and weather for the first 12 hours, including the following elements.
o Cloud amount (SCT, BKN, or OVC) for cloud bases below FL180.
o Cloud bases and tops associated with the above bullet.
11/14/16 Aviation Weather Services AC 00-45H 5-67 o Precipitation and thunderstorms.
o Visibility below 7 sm and obstruction(s) to visibility.
o Sustained surface winds greater than or equal to 20 kts.
o 12- to 24-hour categorical outlook (IFR, MVFR or VFR).
• Icing and Freezing Level: A moderate or greater icing and freezing level.
• Turbulence: A moderate or greater turbulence.
5.9.1.7.1 FA—Caribbean (FACA) Example.
FACA20 KKCI 121530 (ICAO product header) OFAMKC (NWS AWIPS Communication header)
INTERNATIONAL OPERATIONS BRANCH
AVIATION WEATHER CENTER KANSAS CITY MISSOURI VALID 121600-130400 OUTLOOK...130400-131600 .
ATLANTIC S OF 32N W OF 57W...CARIBBEAN...GULF OF MEXICO BTN 22N AND 24N.
.
TS IMPLY SEV OR GTR TURB SEV ICE LLWS AND IFR CONDS. SFC TO 400 MB.
.
SYNOPSIS...WK CDFNT EXTDS FM NR 28N60W TO 23N63W TO THE MONA PASSAGE. CDFNT WL MOV EWD AND WKN TODAY. EXP NARROW BAND OF CLDS WITH ISOL SHRA INVOF CDFNT.
.
SIGNIFICANT CLD/WX...
ERN MONTERREY FIR...NRN MERIDA FIR SCT025 SCT060. OTLK...VFR.
.
ATLC SWRN NEW YORK FIR...SAN JUAN FIR NW OF CDFNT...SCT025 SCT060. LYR OCNL BKN. TOP 120. ISOL SHRA.
OTLK...VFR.
VCNTY CDFNT...SCT025 BKN060. OCNL BKN025. TOP 120. WDLY SCT SHRA. ISOL TSRA TIL 20Z. OTLK...VFR SHRA.
SE OF CDFNT...SCT025 SCT060. ISOL SHRA. OTLK...VFR.
.
ATLC MIAMI FIR SCT025 SCT060. LYR OCNL BKN. TOP 120. ISOL SHRA. OTLK...VFR.
.
WRN PIARCO FIR...NRN MAIQUETIA FIR...CURACAO FIR BTN 61W-63W...SCT025 BKN060. OCNL BKN025. TOP 120. WDLY SCT SHRA. OTLK...VFR SHRA.
RMNDR...SCT025 SCT060. ISOL SHRA. OTLK...VFR.
.
SANTO DOMINGO FIR...PORT-AU-PRINCE FIR SCT025 SCT060. LYR OCNL BKN. TOP 120. ISOL SHRA. OTLK...VFR.
.
NRN BARRANQUILLA FIR...NRN PANAMA FIR SCT025 SCT060. ISOL SHRA. SFC WND NE 20-25KT. OTLK...VFR.
.
KINGSTON FIR...NERN CNTRL AMERICAN FIR...HABANA FIR SCT025 SCT060. ISOL SHRA. OTLK...VFR.
.
ICE AND FRZLVL...
NO SGFNT ICE EXP OUTSIDE CNVTV ACT.
FRZLVL... 145-170.
.
11/14/16 Aviation Weather Services AC 00-45H 5-68 TURB...
NO SGFNT TURB EXP OUTSIDE CNVTV ACT.
5.9.1.8 FA—Alaska.
FAs issued for Alaska cover the airspace between the surface and 45,000 ft MSL and include the following elements:
• Synopsis: A brief description of the significant synoptic weather affecting the FA area during the first 18 hours of the forecast period.
• Clouds and Weather: A description of the clouds and weather for each geographical zone during the first 12 hours of the forecast period, including the following elements:
o AIRMET information for IFR ceiling and visibility, mountain obscuration, and strong surface winds.
o Cloud amount (SCT, BKN, or OVC) with bases and tops.
o Visibility below 7 sm and obstruction(s) to visibility.
o Precipitation and thunderstorms.
o Surface wind greater than 20 kts.
o Mountain pass conditions using categorical terms (for selected zones only).
o 12- to 18-hour categorical outlook (VFR, MVFR and IFR).
• Turbulence: A description of expected turbulence conditions, including the following elements:
o AIRMET information for turbulence or LLWS.
o Turbulence not meeting SIGMET or AIRMET criteria during the 6- to 12-hour period.
o If no significant turbulence is forecast, NIL SIG will be entered.
• Icing and freezing level: A description of expected icing conditions including the following elements:
o AIRMET information for icing and freezing precipitation.
o Icing not meeting SIGMET or AIRMET criteria during the 6- to 12-hour period.
o Freezing level.
o If no significant icing is forecast, NIL SIG will be entered, followed by the freezing level.
11/14/16 Aviation Weather Services AC 00-45H 5-69
5.9.1.8.1 FA—Alaska Example.
FAAK47 PAWU 222010 (ICAO product header) FA7H (NWS AWIPS Communication header) JNUH FA 222015 (Area forecast region, product type, issuance date/time) EASTERN GULF COAST AND SE AK...
.
AIRMETS VALID UNTIL 230415 CB IMPLY POSSIBLE SEV OR GREATER TURB SEV ICE LLWS AND IFR CONDS.
NON MSL HEIGHTS NOTED BY AGL OR CIG.
.
SYNOPSIS VALID UNTIL 231400 989 MB LOW 275 NM SE KODIAK IS WILL MOV SE WARD TO ABOUT 350 NM S PASI BY 14Z WHILE FILLING TO 998 MB. ASSOCD OCFNT ARCING E AND SE FM LOW WILL MOV ONSHR SE AK AND DSIPT BY END OF PD.
.
LYNN CANAL AND GLACIER BAY JB...VALID UNTIL 230800 ...CLOUDS/WX...
FEW025 SCT050 BKN100 TOP 120.
OTLK VALID 230800-231400...VFR.
PASSES...WHITE...CHILKOOT...VFR.
...TURB...
NIL SIG.
...ICE AND FZLVL...
NIL SIG. FZLVL 020.
.
CNTRL SE AK JC...VALID UNTIL 230800 ...CLOUDS/WX...
FEW025 SCT050 BKN100 TOP 120.
AFT 03Z ISOL BKN050 -SHRA.
OTLK VALID 230800-231400...VFR.
...TURB...
AFT 05Z SW PAFE ISOL MOD TURB BLW 040.
...ICE AND FZLVL...
NIL SIG. FZLVL 025.
.
SRN SE AK JD...VALID UNTIL 230800 ...CLOUDS/WX...
FEW025 SCT050 BKN100 TOP 120.
AFT 00Z OCNL BKN050 -RA. ISOL BKN025 -RA.
11/14/16 Aviation Weather Services AC 00-45H 5-70 AFT 03Z SFC WND SE 25G35KT.
OTLK VALID 230800-231400...VFR.
...TURB...
AFT 02Z CLARENCE STRAIT SW ISOL MOD TURB BLW 040.
...ICE AND FZLVL...
AFT 02Z OUTER CST PAHY S ISOL MOD ICEIC 040-100. FZLVL 025.
.
5.10 Alaskan Graphical Area Forecasts (FA).
NWS’s AAWU produces a series of graphical forecasts to complement the text-based FA for Alaska (see paragraph 5.9.1). These forecasts are available from the AAWU’s Web page under Graphical FA.
• Flying Weather.
• Surface Forecast.
• Icing Forecast.
• Turbulence Forecast.
• Convective Outlook.
Additional products may be available. Some of these may be labeled experimental and, thus, the contents and format are subject to change.
5.10.1 Issuance.
The AAWU issues the Alaskan Graphical FAs. The flying weather, icing, and turbulence forecasts are issued three times a day, approximately at 0530, 1330, and 2130 UTC during Alaska Standard Time (AKST), and 0430, 1230, and 2030 UTC during Alaska Daylight Time (AKDT). Surface Forecasts are issued four times a day, approximately at 0315, 0915, 1530, and 2130 UTC during AKST, and 0215, 0815, 1430, and 2030 UTC during AKDT. The Convective Outlook is a seasonal product and only issued from May 1 through September 30 at 1230 UTC with updates at 0430 UTC.
All forecasts are amended as needed.
11/14/16 Aviation Weather Services AC 00-45H 5-71
5.10.2 Content.
5.10.2.1 Flying Weather.
The Flying Weather graphic (see Figure 5-38, Alaskan Graphical Area Forecast (FA)—Flying Weather Example) illustrates areas of prevailing Marginal VFR (MVFR) or IFR conditions, strong winds (30 kts sustained or greater), and any active volcano in Alaska. This product consists of two 6-hour forecasts valid for a total of 12 hours. Each forecast specifies where such conditions can be expected within the 6-hour valid time.
Areas of occasional or continuous MVFR/IFR are represented by shaded regions (red for IFR, blue for MVFR), whereas areas of predominately VFR weather are not shaded. MVFR/IFR conditions are possible outside these shaded regions, but only isolated in coverage. Strong surface winds are shown in a circle hatch overlay. Active volcanoes are denoted by a volcano symbol at the location of the volcano.
Note: This forecast is also referred to as IFR/MVFR graphic on their Web site.
Figure 5-38. Alaskan Graphical Area Forecast (FA)—Flying Weather Example