Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) ASP-YVV-DXO-40NE FWA-40SSE BJI-40W INL SFC ALG 50NNW ISN-70W FAR-GFK-40NE ODI-40SW DXO 040 ALG ISN-70S BIS-30W ABR-30E ABR-60S FAR-30SW BRD-30NE FWA 080 ALG GLD-SLN-30W BDF-50S JOT-40SE IND-30SW CVG-40SW LOZ
AIRMET (WAUS43) issued by the Meteorological Watch Office (Aviation Weather Center) in Kansas City, Missouri on the 9th day of the month at 1445 UTC. This AIRMET (WA) is the Zulu series bulletin for the Chicago Area Forecast region (CHIZ) issued on the 9th day of the month at 1445 UTC. This is the 4th update to the Zulu series bulletin for icing and freezing levels and is valid until the 9th day of the month at 2100 UTC.
The first (and only) AIRMET noted within the bulletin is for icing affecting Kansas, Iowa, Missouri and Illinois. Within an area bounded from 30 nautical miles west-southwest of Fort Dodge, Iowa (FOD) to Dubuque, Iowa (DBQ) to 50 nautical miles northwest of Decatur, Illinois (DEC) to 50 nautical miles southwest of Farmington, Missouri (FAM) to Oswego, Kansas (OSW) to Kansas City, Missouri (MKC) to 30 nautical miles west-southwest of Fort Dodge, Iowa (FOD). Moderate icing between the freezing level and flight level 200 (approximately 20,000 feet MSL). The freezing level is between 6,000 feet MSL and 10,000 feet MSL. Conditions ending by 2100 UTC.
An outlook for icing between 2100 UTC to 0300 UTC exists over: Iowa, Missouri, Wisconsin, Illinois, Indiana and Kentucky. Within an area bounded by Milwaukee, Wisconsin (BAE) to Lafayette, Indiana (BVT) to Pocket City, Indiana (PXV) to 50 nautical miles southwest of Farmington, Missouri (FAM) to 50 nautical miles northwest of Decatur, Illinois (DEC) to Dubuque, Iowa (DBQ) to Milwaukee, Wisconsin (BAE). Moderate icing between the freezing level and flight level 200 (approximately 20,000 feet MSL). The freezing level is between 8,000 feet MSL and 10,000 feet MSL. Conditions continuing through 0300 UTC.
The freezing level ranges from the surface to 12,000 feet MSL across the Chicago Area Forecast region. Multiple freezing levels exist between 1,500 feet MSL and 8,500 feet MSL within an area bounded by 40 nautical miles west of International Falls, Minnesota (INL) to Thunder Bay, Ontario, Canada to Sault Saint Marie, Michigan (SSM) to 70 nautical miles northnortheast of Oscoda, Michigan (ASP) to Wiarton, Ontario, Canada to Detroit, Michigan (DXO) to 40 nautical miles northeast of Fort Wayne, Indiana (FWA) to 40 nautical miles south-southeast of Bemidji, Minnesota (BJI) to 40 nautical miles west of International Falls, Minnesota (INL).
The freezing level is at the surface along a line from 50 nautical miles north-northwest of Williston, North Dakota (ISN) to 70 nautical miles west of Fargo, North Dakota (FAR) to Grand Forks, North Dakota (GFK) to 40 nautical miles northeast of Nodine, Minnesota (ODI) to 40 nautical miles southwest of Detroit, Michigan (DXO). The freezing level is at 4,000 feet MSL along a line from Williston, North Dakota (ISN) to 70 nautical miles south of Bismarck, North Dakota (BIS) to 30 nautical miles west of Aberdeen, South Dakota (ABR) to 30 nautical miles east of Aberdeen, South Dakota (ABR) to 60 nautical miles south of Fargo, North Dakota (FAR) to 30 nautical miles southwest of Brainerd, Minnesota (BRD) to 30 nautical miles northeast of Fort Wayne, Indiana. The freezing level is 8,000 feet MSL along a line from Goodland, Kansas (GLD) to Salina, Kansas (SLN) to 30 nautical miles west of Bradford, Illinois (BDF) to 50 nautical miles south of Joliet, Illinois to 40 nautical miles southeast of Indianapolis, Indiana (IND) to 30 nautical miles southwest of Covington, Kentucky (CVG) to 40 nautical miles southwest of London, Kentucky (LOZ).
6.2.6.2 Hawaii AIRMET Example
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-28
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) WAHW31 PHFO 090945 WA0HI HNLT WA 091000 AIRMET TANGO UPDATE 1 FOR TURB VALID UNTIL 091600 AIRMET TURB...KAUAI OAHU MOLOKAI LANAI MAUI OVR AND IMDT N THRU E OF MTS.
MOD TURB BLW 100. CONDS CONTG BYD 1600Z.
AIRMET (WAHW31) issued by the Meteorological Watch Office (Weather Forecast Office) in Honolulu, Hawaii on the 9th day of the month at 0945 UTC. The National Weather Service AWIPS communication code for this product is WA0HI. This AIRMET (WA) is the Tango series bulletin for the Hawaii Area Forecast region (HNLT) issued on the 9th day of the month at 1000 UTC. This is the 1st update to the Tango series bulletin for turbulence and is valid until the 9th day of the month at 1600 UTC.
The first (and only) AIRMET noted within the bulletin is for turbulence affecting the islands of Kauai, Oahu, Molokai, Lanai and Maui, over and immediately north through east of the mountains. Moderate turbulence below 10,000 feet MSL. Conditions continuing beyond 1600 UTC.
6.2.6.3 Alaska AIRMET Example
WAAK47 PAWU 011740 WA7O JNUS WA 011740 AIRMET SIERRA FOR IFR AND MT OBSC VALID UNTIL 012100 .
LYNN CANAL AND GLACIER BAY JB W OF LYNN CANAL..MTS OCNL OBSC IN CLDS/PCPN.
SPRDG E. INTSF.
.
CNTRL SE AK JC PAOH−PAFE LN W..MTS OCNL OBSC IN CLDS/PCPN. SPRDG E. INTSF.
.
ERN GLF CST JE MTS OCNL OBSC IN CLDS/PCPN. IMPRG.
.
SE AK CSTL WTRS JF OCNL CIG BLW 010 VIS BLW 3SM SN BLSN. NC.
AIRMET (WAAK47) issued by the Meteorological Watch Office (Alaska Aviation Weather Unit) in Anchorage, Alaska on the 1st day of the month at 1740 UTC. The National Weather Service AWIPS communication code for this product is WA7O. This AIRMET (WA) is the Sierra series bulletin for the Juneau forecast area issued on the 1st day of the month at 1740 UTC. This is the AIRMET Sierra series for IFR and mountain obscuration valid until the 1st day of the month at 2100 UTC.
For the Lynn Canal and Glacier Bay forecast regions, Juneau region B...west of Lynn Canal…mountains occasionally obscured in clouds and precipitation. Conditions spreading east and intensifying during the forecast period.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-29
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
For the Central Southeast Alaska forecast region, Juneau region C…from a Hoonan, Alaska (PAOH) to Kake, Alaska (PAFE) line westward, mountains occasionally obscured in clouds and precipitation. Conditions spreading east and intensifying during the forecast period.
For the Eastern Gulf Coast forecast region, Juneau region E…Mountains occasionally obscured in clouds and precipitation. Conditions improving during the forecast period.
For the Southeast Alaska Coastal Waters, Juneau region F…Occasional ceiling below 1,000 feet AGL, visibility below 3 statute miles in snow and blowing snow. No change in conditions is expected during the forecast period.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-30
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
6.3 Center Weather Advisory (CWA) A Center Weather Advisory (CWA) is an aviation weather warning for conditions meeting or approaching national in-flight advisory (AIRMET, SIGMET or Convective SIGMET) criteria. The CWA is primarily used by aircrews to anticipate and avoid adverse weather conditions in the en route and terminal environments. CWAs are available on the Aviation Weather Center (AWC) web site at: http://aviationweather.gov/products/cwsu/.
6.3.1 CWA Issuance CWAs are issued by the NWS Center Weather Service Units (CWSUs). CWSU areas of responsibility in the contiguous U.S. are depicted on Figure 6-12. CWSU Anchorage area of responsibility for Alaska is depicted on Figure 6-13.
Figure 6-12. Center Weather Service Unit (CWSU) Areas of Responsibility, Contiguous U.S.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-31
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 6-13. CWSU Anchorage, AK (PAZA) Area of Responsibility
CWAs are valid for up to two (2) hours and may include forecasts of conditions expected to begin within two (2) hours of issuance. If conditions are expected to persist after the advisory’s valid period, a statement to that effect is included in the last line of the text. Additional CWAs will subsequently be issued as appropriate. Notice of significant changes in the phenomenon described in a CWA is provided by a new CWA issuance for that phenomenon. If the forecaster deems it necessary, CWAs may be issued hourly for convective activity.
6.3.2 CWA Communications Headers (UCWA / CWA) The Urgent CWA (UCWA) communications header is intended for those situations where weather conditions have an immediate effect on the safe flow of air traffic within the ARTCC area of responsibility. It is only used when the CWSU meteorologist believes any delay in dissemination to FAA facilities would impact aviation safety. The routine CWA header is used for subsequent issuances of the same phenomenon.
6.3.3 CWA Criteria CWAs are used in the four (4) following situations:
• Precede an Advisory o When the AWC has not yet issued an advisory, but conditions meet or will soon meet advisory criteria.
o In the case of an impending advisory, the CWA can be issued as an Urgent CWA (UCWA) to allow the fastest possible dissemination.
• Refine an existing Advisory o To supplement an existing AWC advisory for the purpose of refining or updating the location, movement, extent, or intensity of the weather event relevant to the ARTCC’s area of responsibility.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-32
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
• Highlight significant conditions not meeting Advisory criteria o When conditions do not meet advisory criteria, but conditions, in the judgment of the CWSU meteorologist, will adversely impact air traffic within the ARTCC area of responsibility.
• To cancel a CWA when the phenomenon described in the CWA is no longer expected.
6.3.4 CWA Format
Figure 6-14. Center Weather Advisory (CWA) Decoding Example
Table 6-7. Decoding a Center Weather Advisory (CWA) Line Content Description 1 ZDV ARTCC Identification 2 Phenomenon Number (single digit, 1-6) CWA Product Type (UCWA/CWA) 032140 Beginning and/or issuance UTC date/time 2 ZDV ARTCC Identification CWA Product Type 2 Phenomenon Number (single digit, 1-6) 02 Issuance Number (issued sequentially for each Phenomenon Number) VALID TIL 032340Z Ending valid UTC date/time 3 FROM FMN TO 10N FMN TO 20NE FMN TO 10E FMN TO FMN Phenomenon Location 4 ISOLD SEV TS NR FMN MOVG NEWD 10KTS. TOP FL410. WND GSTS TO 55KTS. HAIL TO 1 INCH RPRTD AT FMN. SEV TS CONTG BYD 2340Z Phenomenon Description
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-33
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) Time permitting, any CWA overlapping into another center's airspace is coordinated and a statement is included in the text, e.g., SEE ZOB CWA 201 FOR TS CONDS IN ZOB CTA (CTA is control area). If issuance prior to coordination is necessary, a statement regarding the area(s) affected is included in the text, e.g., LINE TS EXTDS NW INTO ZOB CTA.
AIRMETs/SIGMETs being augmented by the CWA will be referenced in a text remark, e.g.
SEE CONVECTIVE SIGMET 8W.
The CWA in Figure 6-14 is decoded as follows:
(Line 1) Center Weather Advisory issued for the Denver ARTCC (ZDV) CWSU. The “2” after ZDV in the first line denotes this is the second meteorological event of the local calendar day.
This CWA was issued/begins on the 3rd day of the month at 2140 UTC.
(Line 2) The Denver ARTCC (ZDV) is identified again. The “202” in the second line denotes the phenomena number again (2) and the issuance number (02) for this phenomenon. This CWA is the valid until the 3rd day of the at 2340 UTC.
(Line 3) From Farmington, New Mexico to 10 nautical miles north of Farmington, New Mexico to 20 nautical miles northeast of Farmington, NM to 10 nautical mile east of Farmington, New Mexico to Farmington, New Mexico.
(Line 4) Isolated severe thunderstorms near Farmington moving northeastward at 10 knots.
Tops to Flight Level 410. Wind gusts to 55 knots. Hail to one inch reported at Farmington.
Severe thunderstorms continuing beyond 2340 UTC.
6.3.5 Examples
ZME1 CWA 081300
ZME CWA 101 VALID TIL 081500
FROM MEM TO JAN TO LIT TO MEM OCNL TS MOV FM 26025KT. TOPS TO FL450.
Center Weather Advisory issued for the Memphis, Tennessee ARTCC on the 8th day of the month at 1300 UTC. The 1 after the ZME in the first line denotes this CWA has been issued for the first weather phenomenon to occur for the local calendar day. The 101 in the second line denotes the phenomenon number again (1) and the issuance number (01) for this phenomenon.
The CWA is valid until the 8th of the month at 1500 UTC. From Memphis, Tennessee to Jackson, Mississippi to Little Rock, Arkansas to Memphis, Tennessee. Occasional thunderstorms moving from 260 degrees at 25 knots. Tops to flight level 450.
ZLC3 CWA 271645
ZLC CWA 303 VALID TIL 271745 CNL CWA 302.
SEE CONVECTIVE SIGMET 8W.
Center Weather Advisory issued for the Salt Lake City, Utah ARTCC on the 27th day of the month at 1645 UTC. The 3 after the ZLC in the first line denotes this CWA has been issued for the third weather phenomenon to occur for the local calendar day. The 303 in the second line AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-34
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) denotes the phenomenon number again (3) and the issuance number (03) for this phenomenon.
The CWA is valid until the 27th day of the month at 1745 UTC. CWA number 302 has been cancelled. See Convective SIGMET 8W.
ZME1 CWA 040100
ZME CWA 101 VALID TIL 040300
VCY MEM SEV CLR ICE BLW 020 DUE TO FZRA. NUMEROUS ACFT REP RAPID ACCUMULATION OF ICE DRG DES TO MEM. NO ICE REPS ABV 020. CONDS CONTG AFT 03Z. NO UPDATES AFT 040200Z.
Center Weather Advisory issued for the Memphis, Tennessee ARTCC on the 4th day of the month at 0100 UTC. The 1 after the ZLC in the first line denotes this CWA has been issued for the first weather phenomenon to occur for the local calendar day. The 101 in the second line denotes the phenomenon number again (1) and the issuance number (01) for this phenomenon.
The CWA is valid until the 4th day of the month at 0300 UTC. For the Memphis, Tennessee vicinity. Severe clear icing below 2,000 feet MSL due to freezing rain. Numerous aircraft report rapid accumulation of icing during descent to Memphis. No icing reports above 2,000 feet MSL.
Conditions continuing after 0300 UTC. No updates after 4th day of the month at 0200 UTC.
ZNY5 UCWA 021400
ZNY CWA 502 VALID TIL 021600 FROM BGM TO 18WNW JFK TO HAR TO SLT TO BGM NUMEROUS ACFT REP SEV TURB AND WS BLW 020.
CONDS EXTD NE INTO ZBW CTA. CONDS EXP TO CONT AFT 16Z.
Center Weather Advisory issued for the New York ARTCC on the 2nd day of the month at 1400 UTC. The 5 after the ZNY in the first line denotes this CWA has been issued for the fifth weather phenomenon to occur for the local calendar day. The 502 in the second line denotes the phenomenon number again (5) and the issuance number (02) for this phenomenon. The CWA is valid until the 2nd day of the month at 1600 UTC. From Binghamton, New York; to 18 nautical miles west-northwest of New York (JFK Airport), New York; to Harrisburg, Pennsylvania; to Slate Run, Pennsylvania; to Binghamton, New York. Numerous aircraft report severe turbulence and wind shear below 2,000 feet MSL. Conditions extending northeast into Nashua, New Hampshire control area. Conditions expected to continue after 1600 UTC.
ZNY4 UCWA 041500
ZNY CWA 401 VALID TIL 041700 40N SLT TO 18WNW JFK DEVELOPING LINE TS 25 NM WIDE MOV 24020KT. TOPS ABV FL350.
LINE TS EXTDS NW INTO ZOB CTA.
Urgent Center Weather Advisory issued for the New York ARTCC on the 4th day of the month at 1500 UTC. The 4 after the ZNY in the first line denotes this CWA has been issued for the fourth weather phenomenon to occur for the local calendar day. The 401 in the second line denotes the phenomenon number again (4) and the issuance number (01) for this phenomenon. The AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-35
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) CWA is valid until the 4th day of the month at 1700 UTC. From 40 nautical miles north of Slate Run, Pennsylvania; to 18 nautical miles west-northwest of New York (JFK Airport), New York.
Developing line of thunderstorms 25 nautical miles wide moving from 240 degrees at 20 knots.
Tops above flight level 350. The line of thunderstorms extends northwest into the Oberlin, Ohio control area.
AC 00-45F, CHG 2 Section 6: Products for Aviation Hazards Page 6-36
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
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