11/14/16 Aviation Weather Services AC 00-45H 5-56
• Erroneous motion vectors are occasionally assigned to storms; and
• Convective hazard field scales are not identified within the forecast polygons.
5.6.5.4 Uses of the NCWF.
The purpose of the NCWF is to produce a Convective hazard field diagnostic and forecast product based on radar data, echo top mosaics, and lightning data. The target audience includes the FAA and other government agencies, pilots, aircraft dispatchers, aviation meteorologists, and other interested aviation users in the general public.
5.7 Products for Tropical Cyclones.
The NWS issues SIGMETs, Convective SIGMETs, and CWAs to inform the aviation community about the potential or existence of tropical cyclones. These above-listed products are the primary source of information. The NWS also issues other products pertaining to tropical cyclones. Tropical cyclones have a sustained wind speed of 34 kts or greater and are called tropical storm, hurricane, typhoon, and cyclone, depending on their intensity or region of the world.
5.7.1 Tropical Cyclone Advisory (TCA).
The TCA is intended to provide tropical cyclone forecast guidance, through 24 hours, for international aviation safety and routing purposes. TCAs are issued by the World Meteorological Organization’s (WMO) TCACs for all ongoing tropical cyclone activity in their respective AORs. There are seven TCACs worldwide, with two in the United States, the NWS’ National Hurricane Center (NHC) in Miami, Florida, and the NWS’s Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii.
The NHC is responsible for all ongoing tropical cyclone activity in the Atlantic and eastern Pacific, north of the equator, while the CPHC is responsible for the central Pacific, north of the equator. TCAs are available on their respective Web sites.
5.7.1.1 Issuance.
The NHC and CPHC issue TCAs at 0300, 0900, 1500, and 2100 UTC and are valid from the time of issuance until the next scheduled issuance or update.
The forecast position information in the TCA is interpolated from the official forecast data, which is valid at 0000, 0600, 1200, and 1800 UTC.
5.7.1.2 Content.
TCAs list the current tropical cyclone position, motion, and intensity, and 6-, 12-, 18-, and 24-hour forecast positions and intensities. It is an alphanumeric text product produced by hurricane forecasters and consists of information extracted from the official forecasts.
This forecast is produced from subjective evaluation of current meteorological and oceanographic data as well as output from Numerical Weather Prediction (NWP) models, and is coordinated with affected NWS offices, the NWS National Centers, and the Department of Defense (DOD).
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5.7.1.3 Format.
The format of the Aviation Tropical Cyclone Advisory is as follows:
FKaa2i cccc ddhhmm (ICAO communication header) (TROPICAL CYCLONE TYPE) (NAME)ICAO ADVISORY NUMBER ## (ISSUING OFFICE CITY STATE) BBCCYYYY time UTC day of week mon dd yyyy TEXT $$
5.7.1.4 Aviation Tropical Cyclone Advisory (TCA) Example.
FKNT25 KNHC 210900 TCANT5 TROPICAL STORM ICAO ADVISORY NUMBER 27 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092007 0900 UTC SUN OCT 21 2007
TC ADVISORY DTG: 20071021/0900Z TCAC: KNHC TC: ERNESTO NR: 027 PSN: N3000 W08012 MOV: N 13KT C: 0998HPA MAX WIND: 045KT FCST PSN + 06 HR: 211200 N3106 W07951 FCST MAX WIND + 06 HR: 045KT FCST PSN + 12 HR: 211800 N3206 W07930 FCST MAX WIND + 12 HR: 050KT FCST PSN + 18 HR: 220000 N3321 W07903 FCST MAX WIND + 18 HR: 045KT
11/14/16 Aviation Weather Services AC 00-45H 5-58 FCST PSN + 24 HR: 220600 N3436 W07836 FCST MAX WIND + 24 HR: 040KT
RMK THE FORECAST POSITION INFORMATION IN
THIS PRODUCT IS INTERPOLATED FROM OFFICIAL FORECAST DATA VALID AT 0000...
0600...1200...AND 1800Z.
NXT MSG: 20071021/1500Z $$
5.7.1.5 Additional Tropical Cyclone Information Products.
The NHC, CPHC, and select WFOs issue many public tropical storm and hurricane/typhoon information products. Many are in Web-based graphic format. For more information on these public forecasts, see the Web sites of NHC, CPHC, WFO Guam, and WFOs along the Gulf Coast and the East Coast.
5.8 Volcanic Ash Forecasts.
In addition to SIGMETs, the NWS issues forecasts to notify the aviation community of volcanic ash clouds.
5.8.1 Volcanic Ash Advisory Center (VAAC).
A VAAC is a meteorological office designated by an ICAO regional air navigation agreement to provide advisory volcanic ash information to MWOs, World Area Forecast Centers (WAFC), area control centers, flight information centers, and international operational meteorological (OPMET) data banks regarding the lateral and vertical extent and forecast movement of volcanic ash in the atmosphere following a volcanic eruption.
There are nine VAACs worldwide (see Figure 5-33, Volcanic Ash Advisory Centers (VAACs)). The duties of a VAAC include:
• Monitoring relevant geostationary and polar-orbiting satellite data to detect the existence and extent of volcanic ash in the atmosphere in the area concerned;
• Activating the volcanic ash numerical trajectory/dispersion model in order to forecast the movement of any ash cloud that has been detected or reported; and
• Issuing advisory information regarding the extent and forecast movement of the volcanic ash cloud.
11/14/16 Aviation Weather Services AC 00-45H 5-59 Figure 5-33. Volcanic Ash Advisory Centers (VAACs)
AORs for VAACs include Anchorage, Montreal, Washington. Wellington (New Zealand), Buenos Aires (Argentina), London, Toulouse (France), Tokyo, and Darwin.
The United States has two VAACs with responsibilities defined in ICAO Annex 3, Meteorological Service for International Air Navigation. The Washington VAAC is jointly managed by the National Environmental Satellite, Data, and Information Service (NESDIS) Satellite Analysis Branch (SAB) and the NWS National Centers for Environmental Prediction (NCEP) Central Operations (NCO). The Anchorage VAAC is managed by the NWS’s AAWU. The AORs for each VAAC are:
• Washington VAAC.
o FIRs in CONUS and adjacent coastal waters.
o The Oakland Oceanic FIR over the Pacific Ocean.
o The New York FIR over the western Atlantic Ocean.
o FIRs over and adjacent to the Caribbean and Central and South America north of 10 degrees south latitude.
• Anchorage VAAC.
o The Anchorage FIR.
o Russian FIRs north of 60 degrees north latitude and east of 150 degrees east longitude.
5.8.2 Volcanic Ash Advisory (VAA).
The VAA is advisory information on volcanic ash cloud issued in abbreviated plain language, using approved ICAO abbreviations and numerical values of self-explanatory nature.
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:
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• 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.
.