Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.4 Additional Products for Convection The National Weather Service (NWS) in addition to the SIGMETs, Convective SIGMETs, and CWAs already discussed, offers a few more products informing the aviation community about the potential for convective weather.
6.4.1 Convective Outlooks (AC) The NWS Storm Prediction Center (SPC) issues narrative and graphical convective outlooks to provide the contiguous U.S. NWS Weather Forecast Offices (WFOs), the public, media and emergency managers with the potential for severe (tornado, wind gusts 50 knots or greater, or hail 3/4 inch diameter size or greater) and non-severe (general) convection and specific severe weather threats during the following three days. The Convective Outlook defines areas of slight risk (SLGT), moderate risk (MDT) or high risk (HIGH) of severe thunderstorms for a 24-hour period beginning at 1200 UTC. The Day 1 and Day 2 Convective Outlooks also depict areas of general thunderstorms (GEN TSTMS), while the Day 1, Day 2, and Day 3 Convective Outlooks may use SEE TEXT for areas where convection may approach or slightly exceed severe criteria. The outlooks are available on the SPC web site at:
http://www.spc.noaa.gov/products/outlook/.
6.4.1.1 Issuance Convective Outlooks are scheduled products issued at the following times:
Table 6-8. Convective Outlook Issuance Schedule Convective Outlook Issuance Time (UTC) Valid Period (UTC) Day 1 0600 1200 – 1200 1300 1300 – 1200 1630 1630 – 1200 2000 2000 – 1200 0100 0100 – 1200 Day 2 0730 (Daylight Savings Time) 0830 (Standard Time) Day 2/1200 – 1200 1730 Day 2/1200 – 1200 Day 3 1100 Day 3/1200 – 1200
SPC corrects outlooks for format and grammatical errors and amends outlooks when the current forecast does not or will not reflect the ongoing or future convective development.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-37
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-15. Day 1 Categorical Convective Outlook Graphic Example
6.4.1.2 Format of the Categorical Convective Outlook Narrative
SPC AC ddhhmm [SPC - issuing office, AC – product type, ddhhmm – date and time the product was issued
DAY (ONE, TWO OR THREE) CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK time am/pm time zone day mon dd yyyy
VALID DDHHMM – DDHHMMZ
THERE IS A (SLIGHT, MODERATE, HIGH) RISK OF SEVERE THUNDERSTORMS TO
THE RIGHT OF LINE (LIST OF ANCHOR POINTS AND DIRECTION AND DISTANCE IN STATUTE MILES FROM THE LINE). THE LINE WILL ENCLOSE THE AREA OF RISK.
THERE MAY BE ONE OR MORE AREAS OF RISK AT THE APPROPRIATE LEVEL OF RISK. WHEN A MODERATE OR HIGH RISK IS FORECAST, THE INDIVIDUAL STATES ARE ALSO LISTED WITH THE TWO LETTER POSTAL STATE IDENTIFIERS.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM (LIST OF ANCHOR POINTS AND DIRECTION AND DISTANCE IN STATUTE MILES FROM THE LINE). THERE MAY BE ONE OR MORE AREAS OF GEN TSTMS LISTED.
…AREA OF CONCERN #1… AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-38
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
AREAS OF HIGHEST RISK ARE DISCUSSED FIRST (HIGH SEVERE RISK,
MODERATE SEVERE RISK, SLIGHT SEVERE RISK, APPROACHING SEVERE LIMITS). THE FORECAST PROVIDES A NARRATIVE TECHNICAL DISCUSSION.
…AREA OF CONCERN #2…
NARRATIVE TECHNICAL DISCUSSION
$$
…FORECASTER NAME… MM/DD/YY
6.4.2 Watch Notification Messages The NWS Storm Prediction Center (SPC) issues Watch Notification Messages to alert the aviation community, NWS offices (WFOs), the public, media and emergency managers to organized thunderstorms forecast to produce tornadic and/or severe weather in the conterminous U.S.
SPC issues three types of Watch Notification Messages: Aviation Watch Notification Message, Public Severe Thunderstorm Watch Notification Message and Public Tornado Watch Notification Message. They are available on the SPC web site at:
http://www.spc.noaa.gov/products/watch/.
6.4.2.1 Aviation Watch Notification Message SPC issues Aviation Watch Notification Messages to alert the aviation community to organized thunderstorms forecast to produce tornadic and/or severe weather as indicated in Public Watch Notification Messages.
6.4.2.1.1 Format of an Aviation Watch Notification Message
SPC AWW ddhhmm WWnnnn SEVERE TSTM ST LO DDHHMMZ - DDHHMMZ AXIS...XX STATUTE MILES EITHER SIDE OF A LINE
XXDIR CCC/LOCATION ST/ - XXDIR CCC/LOCATION ST ..AVIATION COORD.. XX NM EITHER SIDE /XXDIR CCC - XXDIR CCC HAIL SURFACE AND ALOFT..X X/X INCHES. WIND GUSTS..XX KNOTS.
MAX TOPS TO XXX. MEAN STORM MOTION VECTOR DIR/SPEED
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-39
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-16. Aviation Watch Notification Message Decoding Example
Table 6-9. Decoding a Severe Weather Watch Bulletin Line Content Description 1 SPC AWW 132101 Issuing office Product Type Issuance date/time 2 WW568
TORNADO OK 132130Z – 140300Z Watch number Watch Type States affected Valid date/time period 3 AXIS..80 STATUTE MILES EAST AND WEST OF A LINE...
Watch axis 4 50SSE FSI/FORT SILL OK/ - 20NW
PNC/PONCA CITY OK/ Anchor points 5 …AVIATION COORDS.. 70NM E/W/ 21E SPS – 43S ICT/ Aviation coordinates 6 HAIL SURFACE AND ALOFT…3 INCHES.
WIND GUSTS..70 KNOTS. MAX TOPS TO
550. MEAN STORM MOTION VECTOR 26030.
Type, intensity, max tops, and mean storm motion using standard contractions.
The Severe Weather Watch Bulletin in Figure 6-16 is decoded as follows:
(Line 1) Alert Severe Weather Watch Bulletin (AWW), issued by the Storm Prediction Center on the 13th at 2101Z,
(Line 2) for Tornado Watch number 568 (WW568) for Oklahoma, valid from the 13th at 2130Z until the 14th at 0300Z.
(Line 3) The Tornado Watch area is along and 80 statute miles east and west of a line from
(Line 4) 50 statute miles south southeast of Fort Sill (Lawton), OK to 20 statute miles northwest of Ponca City, OK.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-40
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
(Line 5) Aviation coordinates for this Tornado Watch are 70 nautical miles east and west of a line from 21 nautical miles east of Sheppard AFB (Wichita Falls), TX to 43 nautical miles south of Wichita, KS.
(Line 6) Hail surface and aloft to 3 inches in diameter, wind gusts to 70 knots, max tops to Flight Level 550, mean storm motion from 260 degrees at 30 knots
6.4.2.1.2 Issuance Watch Notification Messages are non-scheduled, event driven products valid from the time of issuance to expiration or cancellation time. Valid times are in UTC. SPC will correct watches for format and grammatical errors.
When tornadoes or severe thunderstorms have developed, the local NWS Weather Forecast Offices (WFOs) will issue the warnings for the storms.
SPC forecasters may define the watch area as a rectangle (some number of miles either side of line from point A to point B) or as a parallelogram (some number of miles north and south or east and west of line from point A to point B). The axis coordinates are measured in statute miles. The aviation coordinates are measured in nautical miles and referenced to VHF Omni- Directional Range (VOR) navigational aid locations. The watch half-width is in statute miles.
The Aviation Watch Notification Message contains hail size in inches or half inches at the surface and aloft, surface convective wind gusts in knots, maximum tops, and the Mean Storm Motion Vector. Forecasters have discretion in including hail size for tornado watches associated with hurricanes.
6.4.3 Public Severe Thunderstorm Watch Notification Message SPC issues a Public Severe Thunderstorm Watch Notification Message when forecasting six or more hail events of 3/4 inch (penny) diameter or greater or damaging winds of 50 knots (58 mph) or greater. The forecast event minimum threshold is at least 2 hours over an area at least 8,000 square miles. Below these thresholds, SPC, in collaboration with affected NWS offices may issue convective watches along coastlines, near the Canadian and Mexican borders, and for any ongoing organized severe convection.
A Public Severe Thunderstorm Watch Notification Message contains the area description and axis, watch expiration time, a description of hail size and thunderstorm wind gusts expected, the definition of the watch, a call to action statement, a list of other valid watches, a brief discussion of meteorological reasoning, and technical information for the aviation community.
SPC includes the term “adjacent coastal waters” when the watch affects coastal waters adjacent to the Pacific/Atlantic coast, Gulf of Mexico, or Great Lakes. Adjacent coastal waters refers to a WFO’s near-shore responsibility (out to 20 miles for oceans), except for convective watches which include portions of the Great Lakes.
SPC issues a watch cancellation message when no counties, parishes, independent cities and/or marine zones remaining are in the watch area prior to the expiration time. The text of the message will specify the number and area of the cancelled watch.
6.4.3.1 Format of Public Severe Thunderstorm Watch Notification Message WWUS20 KWNS ddhhmm (ICAO communication header)
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-41
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER nnnn
NWS STORM PREDICTION CENTER NORMAN OK time am/pm time zone day mon dd yyyy
THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
PORTION OF STATE
PORTION OF STATE
AND ADJACENT COASTAL WATERS (IF REQUIRED)
EFFECTIVE (TIME PERIOD) UNTIL hhmm am/pm time zone.
...THIS IS A PARTICULARLY DANGEROUS SITUATION (IF FORECAST)...
HAIL TO X INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO XX MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
NARRATIVE DESCRIPTION OF WATCH AREA USING A LINE AND ANCHOR POINTS. DISTANCES TO EITHER SIDE OF THE LINE WILL BE IN STATUTE MILES.
CALL TO ACTION STATEMENTS
OTHER WATCH INFORMATION...OTHER WATCHES IN EFFECT AND IF THIS WATCH REPLACES A PREVIOUS WATCH.
NARRATIVE DISCUSSION OF REASON FOR THE WATCH.
AVIATION...BRIEF DESCRIPTION OF SEVERE WEATHER THREAT TO AVIATORS.
HAIL SIZE WILL BE GIVEN IN INCHES AND WIND GUSTS IN KNOTS. MAXIMUM STORM TOPS AND A MEAN STORM VECTOR WILL ALSO BE GIVEN.
$$
..FORECASTER NAME.. MM/DD/YY
6.4.3.2 Example of a Public Severe Thunderstorm Watch Notification Message WWUS20 KWNS 161711 (ICAO communication header) SPC WW 161710
URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 647
NWS STORM PREDICTION CENTER NORMAN OK 1210 PM CDT FRI JUL 16 2004
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
EASTERN IOWA
NORTHERN ILLINOIS AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-42
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
NORTHWEST INDIANA
LAKE MICHIGAN
EFFECTIVE THIS FRIDAY AFTERNOON FROM 1210 PM UNTIL 500 PM CDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 75 STATUTE MILES EITHER SIDE OF A LINE FROM 40 MILES SOUTHEAST OF SOUTH BEND INDIANA TO 35 MILES SOUTHWEST OF CEDAR RAPIDS IOWA.
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 646...
DISCUSSION...THUNDERSTORMS WILL CONTINUE TO INCREASE ACROSS WATCH AREA WHERE AIR MASS HAS BECOME STRONGLY UNSTABLE AND UNCAPPED.
VEERING SHEAR PROFILE SUPPORT STORMS EVOLVING INTO SHORT LINE
SEGMENTS ENHANCING WIND DAMAGE POTENTIAL
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 33025.
...HALES
6.4.4 Public Tornado Watch Notification Message SPC issues a Public Tornado Watch Notification Message when forecasting three or more tornadoes or any tornado which could produce F2 or greater damage. The forecast event minimum thresholds are at least 2 hours over an area at least 8,000 square miles. Below these thresholds, SPC, in collaboration with affected NWS offices, may issue convective watches along coastlines, near the Canadian and Mexican borders and for any ongoing organized severe convection.
A Public Tornado Watch Notification Message contains the area description and axis, watch expiration time, the term “damaging tornadoes”, a description of the largest hail size and strongest thunderstorm wind gusts expected, the definition of the watch, a call to action statement, a list of other valid watches, a brief discussion of meteorological reasoning, and technical information for the aviation community.
SPC includes the term “adjacent coastal waters” when the watch affects coastal waters adjacent to the Pacific/Atlantic coast, Gulf of Mexico, or Great Lakes. Adjacent coastal waters refers to a WFO’s near shore responsibility (out to 20 nautical miles for oceans), except for convective watches which include portions of the Great Lakes.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-43
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
SPC issues a watch cancellation message whenever it cancels a watch prior to the expiration time. The text of the message will specify the number and area of the cancelled watch.
6.4.4.1 Format of a Public Tornado Watch Notification Message WWUS20 KWNS ddhhmm (ICAO communication header)
URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER nnnn
NWS STORM PREDICTION CENTER NORMAN OK time am/pm time zone day mon dd yyyy
THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
PORTION OF STATE
PORTION OF STATE
AND ADJACENT COASTAL WATERS (IF REQUIRED)
EFFECTIVE (TIME PERIOD) UNTIL hhmm am/pm time zone.
...THIS IS A PARTICULARLY DANGEROUS SITUATION (IF FORECAST)...
DESTRUCTIVE TORNADOES...HAIL TO X INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO XX MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
NARRATIVE DESCRIPTION OF WATCH AREA USING A LINE AND ANCHOR POINTS.
DISTANCES TO EITHER SIDE OF THE LINE WILL BE IN STATUTE MILES.
CALL TO ACTION STATEMENTS
OTHER WATCH INFORMATION...OTHER WATCHES IN EFFECT AND IF THIS WATCH REPLACES A PREVIOUS WATCH.
NARRATIVE DISCUSSION OF REASON FOR THE WATCH.
AVIATION...BRIEF DESCRIPTION OF SEVERE WEATHER THREAT TO AVIATORS.
HAIL SIZE WILL BE GIVEN IN INCHES AND WIND GUSTS IN KNOTS. MAXIMUM STORM TOPS AND A MEAN STORM VECTOR WILL ALSO BE GIVEN.
$$
..FORECASTER NAME.. MM/DD/YY
6.4.4.2 Example of a Public Tornado Watch Notification Message WWUS20 KWNS 050550 (ICAO communication header)
URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 243
NWS STORM PREDICTION CENTER NORMAN OK AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-44
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) 1250 AM CDT MON MAY 5 2003
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
WESTERN AND CENTRAL ARKANSAS
SOUTHERN MISSOURI
FAR EASTERN OKLAHOMA
EFFECTIVE THIS MONDAY MORNING FROM 1250 AM UNTIL 600 AM CDT.
...THIS IS A PARTICULARLY DANGEROUS SITUATION...
DESTRUCTIVE TORNADOES...LARGE HAIL TO 2 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS ALONG AND 100 STATUTE MILES EAST AND WEST OF A LINE FROM 15 MILES WEST NORTHWEST OF FORT LEONARD WOOD MISSOURI TO 45 MILES SOUTHWEST OF HOT SPRINGS ARKANSAS.
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO WATCH NUMBER 237. WATCH NUMBER 237 WILL NOT BE IN EFFECT AFTER 1250 AM CDT. CONTINUE...WW 239...WW 240...WW 241...WW 242...
DISCUSSION...SRN MO SQUALL LINE EXPECTED TO CONTINUE EWD...WHERE
LONG/HOOKED HODOGRAPHS SUGGEST THREAT FOR EMBEDDED SUPERCELLS/POSSIBLE TORNADOES. FARTHER S...MORE WIDELY SCATTERED
SUPERCELLS WITH A THREAT FOR TORNADOES WILL PERSIST IN VERY STRONGLY DEEP SHEARED/LCL ENVIRONMENT IN AR.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 26045.
.
..CORFIDI AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-45
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.5 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 and the adverse conditions associated with them. These above listed products are the primary source of information. The NWS also issues other products pertaining to Tropical Cyclones. These additional products are defined in this section.
6.5.1 Aviation Tropical Cyclone Advisory (TCA) The Aviation Tropical Cyclone Advisory (TCA) is intended to provide short-term tropical cyclone forecast guidance for international aviation safety and routing purposes. It is prepared by the National Hurricane Center (NHC) and the Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii, for all on-going tropical cyclone activity in their respective areas of responsibility. This requirement is stated in the World Meteorological Organization Region IV hurricane plan. Any valid TCA in the Atlantic or eastern Pacific is available on the NHC web site at:
http://www.nhc.noaa.gov. Any valid TCA for the central Pacific is available on the CPHC web site at: http://www.prh.noaa.gov/hnl/cphc/
6.5.1.1 Issuance TCAs are issued at 0300, 0900, 1500, and 2100 UTC and are valid from the time of issuance until the next scheduled issuance or update.
6.5.1.2 Content TCAs list the current tropical cyclone position, motion and intensity, and 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 models, and is coordinated with affected NWS offices, the NWS National Centers, and the Department of Defense.
6.5.1.3 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 $$
NOTE: As part of the header, a coded string is appended at the end of the “ISSUING OFFICE CITY STATE” line. (Example: NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
BBCCYYY)
Where: (BB) is the basin AL – North Atlantic, EP – East Pacific, or CP – Central Pacific Where: (CC) is the cyclone number (01, 02, 03,…49) Where: (YYYY) is the 4 digit year.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-46
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.5.1.4 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 FCST PSN + 24 HR: 220600 N3436 W07836 FCST MAX WIND + 24 HR: 040KT NXT MSG: 20071021/1500Z
$$
6.5.2 Tropical Cyclone Public Advisory (TCP) A Tropical Cyclone Public Advisory (TCP) is the primary tropical cyclone information product issued to the public. The TCP provides critical tropical cyclone watch, warning, and forecast information for the protection of life and property.
6.5.2.1 TCP Responsibility The National Hurricane Center (NHC), as a part of the Tropical Prediction Center (TPC); the Central Pacific Hurricane Center (CPHC); and Weather Forecast Office (WFO) Tiyan, Guam, issue TCPs. In the Atlantic and central Pacific, NHC and CPHC issue TCPs for all tropical cyclones respectively. In the eastern Pacific, NHC will issue public advisories when watches or warnings are required, or the tropical cyclone is otherwise expected to impact nearby land areas. In the western Pacific, WFO Guam will issue public advisories generally based on the tropical cyclone bulletins of the Joint Typhoon Warning Center (JTWC) for all tropical cyclones expected to affect land within 48 hours.
Valid TCP in the Atlantic or eastern Pacific is available on the NHC web site at:
http://www.nhc.noaa.gov.
Valid TCP for the central Pacific is available on the CPHC web site at:
http://www.prh.noaa.gov/hnl/cphc/.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-47
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
TCPs issued by WFO Guam for the western Pacific are available at:
http://www.prh.noaa.gov/pr/guam/cyclone.php.
6.5.2.2 TCP Issuance The initial advisory may be issued when data confirm a tropical cyclone has developed. The title of the advisory will depend upon the intensity of the tropical cyclone as listed below.
• A tropical depression advisory refers to a tropical cyclone with 1-minute sustained winds up to 33 knots (38 mph).
• A tropical storm advisory will refer to tropical cyclones with 1-minute sustained surface winds 34 to 63 knots (39 to 73 mph).
• A hurricane/typhoon advisory will refer to tropical cyclones with winds 64 knots (74 mph) or greater.
Public advisories are discontinued when the tropical cyclone:
• Ceases to be a tropical cyclone; that is, it becomes extratropical, a remnant low, or dissipates, or
• Is centered over land, is below tropical storm strength, and is not forecast to move back over water as a tropical cyclone, and no coastal tropical cyclone watches or warnings are in effect.
• For Guam when the tropical cyclone moves out of the WFO area of responsibility.
Tropical Cyclone Public Advisories are issued according to the schedule below and are valid from the time of issuance until the next scheduled issuance or update. Valid position times correspond to the advisory time.
Table 6-10. Tropical Cyclone Public Advisory Issuance Schedule
TPC/CPHC
ISSUANCE TIME (UTC)
WFO GUAM
ISSUANCE TIME (UTC) 0300 0400 0900 1000 1500 1600 2100 2200
Times in advisories are local time of the affected area; however, local time and UTC are used when noting the storm’s location. All advisories use statute miles and statute miles per hour.
The Tropical Cyclone Center (TPC and CPHC) and WFO Guam, at their discretion, may use nautical miles/knots in parentheses immediately following statute miles/mph. Advisories include the metric units of kilometers and kilometers per hour following the equivalent English units except when the United States is the only country threatened.
NHC, CPHC and WFO Guam issue tropical storm/hurricane/typhoon watches if tropical storm/hurricane/typhoon conditions are possible over land areas within 36 hours, except 48 AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-48