Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) FROM 30SSE CLT-160SE ILM-140ENE OMN-60E TLH-ABY-30SSE CLT AREA SEV EMBD TS MOV FROM 21015KT. TOPS ABV FL450.
TORNADOES...WIND GUSTS TO 60KT POSS.
TS ASSOCD WITH TROPICAL STORM ALBERTO.
.
OUTLOOK VALID 211555-211955 FROM 30E RDU-180SE ECG-140SSE ILM-180E PBI-40SE PBI-40S EYW-90SW EYW-70W SRQ-50N CTY-40N MCN-30NW SPA-30E RDU REF WW 475.
WST ISSUANCES EXPD. REFER TO MOST RECENT ACUS01 KWNS FROM STORM PREDICTION CENTER FOR SYNOPSIS AND METEOROLOGICAL DETAILS. REFER TO MOST RECENT WTNT21 KNHC FROM TROPICAL PREDICTION CENTER FOR DETAILS ON TROPICAL STORM ALBERTO.
Convective SIGMET bulletin for the eastern region of the conterminous U.S.(WSUS31) issued by the Meteorological Watch Office (Aviation Weather Center) in Kansas City, Missouri (KCCI) on the 21st day of the month at 1355 UTC. The National Weather Service AWIPS communication header for this product is SIGE.
Convective SIGMET (WST) for the eastern region of the conterminous U.S. issued by the Aviation Weather Center in Kansas City, Missouri (MKCE) on the 21st day of the month at 1355 UTC. Convective SIGMET 1E is the 1st Convective SIGMET issued for the eastern region of the conterminous US on the 21st day of the month. Valid until 1555 UTC. States affected are North Carolina (NC), South Carolina (SC), Florida (FL), Georgia (GA) and adjacent coastal waters.
Within an area bounded from 30 nautical miles south-southeast of Charlotte, North Carolina (CLT) to 160 nautical miles southeast of Wilmington, North Carolina (ILM) to 140 nautical miles east-northeast of Ormond Beach, Florida (OMN) to 60 nautical miles east of Tallahassee, Florida (TLH) to Albany, Georgia (ABY) to 30 nautical miles south-southeast of Charlotte, North Carolina (CLT). An area of severe embedded thunderstorms moving from 210 degrees at 15 knots. Cumulonimbus tops above flight level 450 (approximately 45,000 feet MSL) Tornadoes and surface wind gust to 60 knots are possible. The thunderstorms are associated with Tropical Storm Alberto.
The outlook portion of the Convective SIGMET bulletin is valid from the 21st day of the month at 1555 UTC to the 21st day of the month at 1955 UTC. Within an area bounded from 30 nautical miles east of Raleigh-Durham, North Carolina (RDU) to 180 nautical miles southeast of Elizabeth City, North Carolina (ECG) to 140 south-southeast of Wilmington, North Carolina (ILM) to 180 nautical miles east of (PBI) to 40 nautical miles southeast of West Palm Beach, Florida (PBI) to 40 nautical miles south of Key West, Florida (EYW) to 90 nautical miles southwest of Key West, Florida (EYW) to 70 nautical miles west of Sarasota, Florida (SRQ) to 50 nautical miles north of Cross City, Florida (CTY) to 40 nautical miles north of Macon, Georgia (MCN) to 30 nautical miles northwest of Sparta, Georgia (SPA) to 30 nautical miles east of Raleigh-Durham, North Carolina (RDU). Refer to Weather Watch Notification Message 475.
Convective SIGMET issuances are expected. Refer to the most recent Day 1 Convective Outlook (ACUS01 KWNS) from the Storm Prediction Center (SPC) for a synopsis and meteorological details. Refer to the most recent Tropical Cyclone Forecast/Advisory (WTNT21 KNHC) from the Tropical Prediction Center (TPC) for details on Tropical Storm Alberto.
6.1.5 SIGMET – Outside the Conterminous U.S. (O-CONUS)
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-13
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.1.5.1 SIGMET Issuance Criteria – Outside the Conterminous U.S. (O-CONUS) SIGMETs outside the Conterminous U.S. (O-CONUS SIGMETs) are issued when any of the following is occurring or expected to occur affecting an area greater than 3,000 square miles or, in the judgment of the forecaster, an area having the potential to have a significant effect on the safety of aircraft operations.
• Thunderstorm - of type below *
o Obscured (OBSC TS)
o Embedded (EMBD TS)
o Widespread (WDSPR TS)
o Squall line (SQL TS)
o Isolated severe (ISOL SEV TS)
• Severe Turbulence (SEV TURB)
• Severe Icing (SEV ICE)
o With Freezing rain (SEV ICE (FZRA)
• Widespread Duststorm (WDSPR DS)
• Widespread Sandstorm (WDSPR SS)
• Volcanic Ash (VA)
• Tropical Cyclone (TC)
NOTE: Obscured, embedded, or squall line thunderstorms do not have to reach 3,000 square miles criteria.
*Tornado (TDO), Funnel Cloud (FC), Waterspout (WTSPT), and Heavy Hail (HVY GR) may be used as a further description of the thunderstorm as necessary.
6.1.5.2 SIGMET Issuance Time and Valid Period – Outside the Conterminous U.S. (O- CONUS) A SIGMET is an unscheduled product issued any time conditions reaching SIGMET criteria are occurring or expected to occur within a 4-hour period. A SIGMET outside the conterminous U.S. (O-CONUS) can have a valid period up to, but not exceeding, four (4) hours, except for volcanic ash (VA) and tropical cyclone (TC) which can be valid up to six (6) hours. SIGMETs for continuing phenomena will be reissued at least every 4 (or 6) hours as long as SIGMET conditions continue to occur in the area for responsibility.
6.1.5.3 SIGMET Format – Outside the Conterminous U.S. (O-CONUS) O-CONUS SIGMETs contain the following information, related to the specific phenomena and in the order indicated:
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-14
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
• Phenomenon and its description (e.g., SEV TURB).
• An indication whether the information is observed, using OBS and/or FCST. The time of observation will be given in UTC.
• Location of the phenomenon referring, where possible to latitude and longitude, and flight levels (altitude) covering the affected area during the SIGMET valid time.
SIGMETs for volcanic ash cloud and tropical cyclones contain the positions of the ash cloud, tropical cyclone center and radius of convection at the start of the validity time of the SIGMET.
• Movement towards or expected movement using sixteen points of the compass, with speed in knots, or stationary, if appropriate.
• Thunderstorm maximum height as FL.
• Changes in intensity; using as appropriate, the abbreviations Intensifying (INTSF), Weakening (WKN), or No Change (NC).
• Forecast position of volcanic ash cloud or the center of the tropical cyclone at the end of the validity period of the SIGMET message.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-15
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-7. SIGMET Outside the Conterminous U.S. Decoding Example
Table 6-3. Decoding a SIGMET Outside of the Conterminous U.S. (O-CONUS) Line Content Description 1 WSPA07 ICAO communication header PHFO Issuance MWO 010410 Issuance UTC date/time 2 SIGPAT NWS AWIPS communication header 3 KZOA Area Control Center SIGMET Product type TANGO SIGMET series 2 Issuance number VALID 010410/010800 Valid period UTC date/time PHFO Issuance office 4 OAKLAND OCEANIC FIR Flight Information Region (FIR) FRQ TS OBS AND FCST WI 200NM N3006 W14012 - N2012 W15016 CB TOP FL400 MOV W 10KT WKN.
Phenomenon description
The SIGMET in Figure 6-7 is decoded as the following:
(Line 1) The WMO product header is WSPA07. Issued by the PHFO on the 1st day of the month at 0410 UTC.
(Line 2) The NWS AWIPS communication header is SIGPAT.
(Line 3) For the Oakland (KZOA) Area Control Center. This is the 2nd issuance of SIGMET Tango series, valid from the 1st day of the month at 0410 UTC until the 1st day of the month at 0800 UTC, issued by the Honolulu Meteorological Watch Office.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-16
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) (Line 4) Concerning the Oakland Oceanic Flight Information Region (FIR), frequent thunderstorms observed and forecast within 200 nautical miles of 30 degrees and 6 minutes north; 140 degrees and 12 minutes west; to 20 degrees and 12 minutes north, 150 degrees and 16 minutes west, cumulonimbus tops to flight level 400 moving west at 10 knots, weakening.
6.1.5.4 SIGMETs for Volcanic Ash A SIGMET for volcanic ash cloud is issued for volcanic eruptions. A volcanic eruption is any volcanic activity including the emission of volcanic ash, regardless of the eruption’s magnitude.
Initial Volcanic Ash SIGMETs may be issued based on credible pilot reports in the absence of a Volcanic Ash Advisory (VAA), but are updated once a VAA is issued. Volcanic ash SIGMETs will continue to be issued until the ash cloud is no longer occurring or expected to occur over the area of responsibility.
SIGMETs for volcanic ash cloud are valid up to six (6) hours and provide an observed or forecast location of the ash cloud at the beginning of the SIGMET. A six-hour forecast position for the ash cloud, valid at the end of the validity period of the SIGMET message, is also included. SIGMETs are reissued at least every six (6) hours while the volcanic ash cloud hazard exists or is expected to exist.
6.1.5.5 SIGMETs for Tropical Cyclone A SIGMET for a tropical cyclone may be issued for non-frontal synoptic-scale cyclones meeting the following criteria.
• Originates over tropical or sub-tropical waters with organized convection and definite cyclonic surface wind circulation.
• Wind speeds reach 35 knots independent of the wind averaging time used by the Tropical Cyclone Advisory Center (TCAC).
SIGMETs for tropical cyclones will be valid up to six (6) hours. SIGMETs for tropical cyclones will include two positions. The first position included will be the TCAC advisory position. The second position will be the forecast position valid at the end of the SIGMET period.
In addition to the two storm positions, SIGMETs will include associated convection when applicable. SIGMETs will be reissued at least every six (6) hours while the tropical cyclone wind remains or are expected to remain above 34 knots.
6.1.5.6 SIGMET Cancellation– Outside the Conterminous U.S. (O-CONUS) SIGMETs are cancelled when the phenomena is no longer occurring or expected to occur in the area of responsibility.
6.1.5.7 SIGMET Amendments– Outside the Conterminous U.S. (O-CONUS) SIGMET amendments will NOT be issued. Instead, the next SIGMET in the series is issued to accomplish the update. The valid time of the new SIGMET is reset to reflect the new 4-hour valid period (6-hour for VA and TC SIGMETs).
6.1.5.8 SIGMET Corrections– Outside the Conterminous U.S. (O-CONUS) Corrections to SIGMETs are issued as necessary. This is done by issuing a new SIGMET in the series which advances the SIGMET number and cancels the previous SIGMET.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-17
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.1.5.9 SIGMET Example– Outside the Conterminous U.S. (O-CONUS)
WSPA07 PHFO 010358 SIGPAT KZOA SIGMET TANGO 1 VALID 010400/010800 PHFO- OAKLAND OCEANIC FIR. EMBD TS OBS BY SATELLITE WITHIN AREA BOUNDED BY N2055 W15000 - N1950 W14945 - N1922 W15130 - N2027 W15048 – N2055 W15000. CB TO TOP FL400. MOV W 10KT. WKN.
SIGMET (SWPA07) issued by the Meteorological Watch Office (Weather Forecast Office) in Honolulu, Hawaii (PHFO) on the 1st day of the month at 0358 UTC. The National Weather Service AWIPS communication header for this product is SIGPAT. This SIGMET concerns the Oakland Oceanic FIR. This is the first (1) issuance of SIGMET series Tango valid from the 1st day of the month at 0400 UTC until the 1st day of the month at 0800 UTC. Within the WFO Honolulu portion of the Oakland Oceanic FIR, embedded thunderstorms observed by satellite within an area bounded by 20 degrees/55 minutes north, 150 degrees/00 minutes west to 19 degrees/50 minutes north, 14 degrees/45 minutes west to 19 degrees/22 minutes north, 151 degrees/30 minutes west to 20 degrees/27 minutes north, 150 degrees/48 minutes west to 20 degrees/55 minutes north, 150 degrees/00 minutes west. Cumulonimbus tops to flight level 400 (approximately 40,000 feet MSL). The thunderstorms are moving west at 10 knots and weakening.
6.1.5.9.1 SIGMET for Volcanic Ash Example
WVNT06 KKCI 082030 TJZS SIGMET FOXTROT 2 VALID 082030/090230 KKCI- SAN JUAN FIR VA FROM SOUFRIERE HILLS LOC 1642N06210W VA CLD OBS AT 2030Z SFC/060 WI N1730 W06400 - N1700 W06300 - N1650 W06300 - N1710 W06400 - N1730 W06400. MOV W 15KT. FCST 0230Z VA CLD APRX N1730 W06500 - N1700 W06300 - N1650 W06300 - N1710 W06500 - N1730 W06500.
The ICAO communication header for this product is WVNT06. It is a SIGMET issued by the Aviation Weather Center (KCCI) in Kansas City, Missouri on the 8th day of the month at 2030 UTC. This is the second (2) issuance of SIGMET series Foxtrot valid from the 8th day of the month at 2030 UTC until the 9th day of the month at 0230 UTC. Within the San Juan Oceanic FIR, volcanic ash from Soufriere Hills volcano located at 16 degrees/42 minutes north, 62 degrees/10 minutes west. Volcanic ash cloud observed at 2030 UTC from the surface to 6,000 feet MSL within an area bounded by 17 degrees/30 minutes north, 64 degrees/00 minutes west to 17 degrees/00 minutes north, 63 degrees/00 minutes west to 16 degrees/50 minutes north, 63 degrees/00 minutes west to 17 degrees/10 minutes north, 64 degrees/00 minutes west to 17 degrees/30 minutes north, 64 degrees/00 minutes west. Moving to the west at 15 knots.
Forecast at 0230 UTC, volcanic ash cloud located approximately at 17 degrees/30 minutes north, 65 degrees/00 minutes west to 17 degrees/00 minutes north, 63 degrees/00 minutes west to 16 degrees/50 minutes north, 63 degrees/00 minutes west to 17 degrees/10 minutes north, 65 degrees/00 minutes west to 17 degrees/30 minutes north, 65 degrees/00 minutes west.
6.1.5.9.2 SIGMET for Tropical Cyclone Example
WSNT03 KKCI 081451 SIGA0C AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-18
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) KZNY SIGMET CHARLIE 11 VALID 081500/082100 KKCI- NEW YORK OCEANIC FIR TC KYLE OBS N3106 W07118 AT 1500Z CB TOP FL500 WI 120NM OF CENTER MOV WSW 5 KT NC FCST 2100Z TC CENTER N3142 W07012
The ICAO communication header for this product is WSNT03. It is a SIGMET issued by the Aviation Weather Center (KCCI) in Kansas City, Missouri on the 8th day of the month at 1451 UTC. The National Weather Service AWIPS communication header for this product is SIGPAT.
This is the eleventh (11) issuance of SIGMET series Charlie valid from the 8th day of the month at 1500 UTC until the 8th day of the month at 2100 UTC. Within the New York Oceanic FIR, Tropical Cyclone Kyle observed at 31 degrees/6 minutes north, 71 degrees/18 minutes west at 1500 UTC, cumulonimbus tops to flight level 500 (approximately 50,000 feet MSL), within 120 nautical miles of the center, moving from west-southwest at 5 knots, no change in intensity is forecast, at 2100 UTC the tropical cyclone center will be at 31 degrees/42 minutes north, 70 degrees/12 minutes west.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-19
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.2 Airmen’s Meteorological Information (AIRMET) An AIRMET is a concise description of the occurrence or expected occurrence of specified en route weather phenomena which may affect the safety of aircraft operations, but at intensities lower than those which require the issuance of a SIGMET. AIRMETs are intended for dissemination to all pilots in flight to enhance safety and are of particular concern to operators and pilots of aircraft sensitive to the phenomena described and to pilots without instrument ratings. AIRMETs are issued by the responsible Meteorological Watch Office (MWO) to give notice to operators and aircrews of potentially hazardous en route conditions.
• AIRMETs are available for the conterminous U.S. (CONUS) on the Aviation Digital Data Service (ADDS) web site at: http://adds.aviationweather.noaa.gov/airmets/
• AIRMETs are available for Alaska on the Alaska Aviation Weather Unit (AAWU) web site at:
http://aawu.arh.noaa.gov/
• AIRMETs are available for Hawaii on the NWS WFO Honolulu web site at:
http://www.prh.noaa.gov/hnl/pages/aviation.php
6.2.1 AIRMET Issuance AIRMETs are issued from the three Meteorological Watch Offices (MWO) located at the Aviation Weather Center (AWC), the Alaska Aviation Weather Unit (AAWU), and the Weather Forecast Office (WFO) in Honolulu. Their areas of responsibility are:
• AWC: The conterminous U.S. and adjacent coastal waters (CONUS) (Figure 6-8)
• AAWU: Alaska and adjacent coastal waters (Figure 6-9)
• WFO Honolulu: Hawaii and adjacent waters (Figure 6-10)
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-20
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-8 AWC AIRMET Areas of Responsibility – Conterminous U.S.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-21
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-9. AAWU Flight Advisory and Area Forecast Zones - Alaska
Table 6-4. AAWU Flight Advisory and 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
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-22
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-10. WFO Honolulu AIRMET Areas of Responsibility - Hawaii
6.2.2 AIRMET Issuance Criteria An AIRMET may be issued when any of the following weather phenomena are occurring or expected to occur over an area of at least 3,000 square miles:
• Ceiling less than 1,000 feet and/or visibility less than 3 statute miles (IFR)
o Weather phenomena restricting the visibility including, but not limited to, precipitation (PCPN), smoke (FU), haze (HZ), mist (BR), fog (FG), and blowing snow (BS).
• Widespread mountain obscuration (MTN OBSCN)
o Weather phenomena causing the obscurement are included, but limited to clouds (CLDS), precipitation (PCPN), smoke (FU), haze (HZ), mist (BR), and fog (FG).
• Moderate turbulence (MOD TURB)
o Top and bottom of MOD TURB layer are specified.
• Sustained surface wind greater than 30 knots (STG SFC WND)
• Moderate icing (MOD ICE)
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-23
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) o Top and bottom of MOD ICE are specified.
o The range of freezing level altitudes is given when the bottom altitude of MOD ICE is the freezing level (FRZLVL).
o Areas with multiple freezing levels are specified.
o Range of freezing levels over the area is specified.
o Lowest freezing levels above ground level (AGL) at intervals of 4,000 feet AMSL (or SFC as appropriate) are specified.
• Non-convective low-level wind shear potential below 2,000 feet AGL (LLWS POTENTIAL).
6.2.3 AIRMET Standardization All AIRMETs follow these standards:
• All heights or altitudes are referenced to above mean sea level (AMSL), unless otherwise noted, and annotated using the height in hundreds of feet, consisting of three digits (e.g., 040). For heights at or above 18,000 feet, the level is preceded by FL to represent flight levels (e.g., FL180).
• Messages are prepared in abbreviated plain language using contractions from the Federal Aviation Administration (FAA) Order 7340.1Z. A limited number of nonabbreviated 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: Refer to Appendix A for definitions of common terms used in AIRMETs.
6.2.4 AIRMET Bulletins, Issuance Times, and Valid Period AIRMETs are issued as bulletins containing one or more AIRMET messages following the schedule listed below. Unscheduled AIRMETs are issued when conditions are occurring or expected to occur, but were not forecast.
Table 6-5. AIRMET Issuance Schedule 1st Scheduled Issuance (UTC) 2nd Scheduled Issuance (UTC) 3rd Scheduled Issuance (UTC) 4th Scheduled Issuance (UTC) CONUS 0245 0845 1445 2045 Alaska 0145 (DT)/ 0245 (ST) 0745 (DT)/ 0845 (ST) 1345 (DT)/ 1445 (ST) 1945 (DT)/ 2045 (ST) Hawaii 0400 1000 1600 2200 Note: DT - Daylight Time, ST - Standard Time
AIRMETs are valid for no more than 6 hours. The valid period of an AIRMET message cannot exceed the valid time of the AIRMET bulletin. However, note that each AIRMET contains remarks concerning the continuance of the phenomenon during the six (6) hours following the AIRMET ending time. Also, AIRMET bulletins can contain a separate outlook when conditions AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-24