Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
7.2.3.1 Minimum Observational Requirements for Routine TAF Issuance and Continuation The NWS WFO aviation forecaster must have certain information for the preparation and scheduled issuance of each individual TAF. Although integral to the TAF writing process, a complete surface (METAR/SPECI) observation is not required. Forecasters use the "total observation concept" to write TAFs with data including nearby surface observations, radar, satellite, radiosonde, model data, aircraft, and other sources.
If information sources, such as surface observations, are missing, unreliable, or not complete, forecasters will append AMD NOT SKED to the end of a TAF. The use of AMD NOT SKED indicates the forecaster has enough data, using the total observation concept, to issue a forecast but will not provide updates. This allows airport operations to continue using a valid TAF.
In rare situations where observations have been missing for extended periods of time (i.e., more than one TAF cycle of six hours), and the total observation concept cannot provide sufficient information, the TAF may be suspended by the use of NIL TAF.
7.2.3.2 Sites with Scheduled Part-Time Observations For TAFs with less than 24-hour observational coverage, the TAF will be valid to the end of the routine scheduled forecast period even if observations cease prior to that time. The time observations are scheduled to end and/or resume will be indicated by expanding the AMD NOT SKED statement. Expanded statements will include the observation ending time (AFT Y1Y1HHmm, e.g., AFT 120200), the scheduled observation resumption time (TIL Y1Y1HHmm,
e.g., TIL 171200Z) or the period of observation unavailability (Y1Y1HH/YeYehh, e.g., 2502-2512).
TIL will be used only when the beginning of the scheduled TAF valid period coincides with the time of the last observation or when observations are scheduled to resume prior to the next scheduled issuance time. When used, these remarks will immediately follow the last forecast group. If a routine TAF issuance is scheduled to be made after observations have ceased, but before they resume, the remark AMD NOT SKED will immediately follow the valid period group of the scheduled issuance. After sufficient data using the total observation concept has been received, the AMD NOT SKED remark will be removed.
7.2.3.2.1 Examples of Scheduled Part-Time Observations TAFs
TAF AMD KRWF 150202Z 1502/1524 {TAF text} AMD NOT SKED 1505Z-1518Z= No amendments will be available between the 15th day of the month at 0500 UTC and the 15th day of the month at 1800 UTC due to lack of a complete observational set between those times.
TAF AMD KPSP 190230Z 1903/1924 {TAF text} AMD NOT SKED= Amendments are not scheduled.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-34
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
7.2.3.3 Automated Observing Sites Requiring Part-Time Augmentation TAFs for AWOS-III sites which have part-time augmentation are prepared using the procedures for part-time manual observation sites detailed in the previous section, with one exception. This exception is the remark used when the automated system is unattended. Specifically, the time an augmented automated system is scheduled to go into unattended operation and/or the time augmentation resumes is included in a remark unique to automated observing sites: AMD LTD TO CLD VIS AND WIND (AFT YYHHmm, or TIL YYhhmm, or YYHH-YYhh), where YY is the date, HHmm is the time, in hours and minutes, of last augmented observation and hhmm is the time, in hours and minutes, the second complete observation is expected to be received. This remark, which does not preclude amendments for other forecast elements, is appended to the last scheduled TAF issued prior to the last augmented observation. It will also be appended to all subsequent amendments until augmentation resumes.
The AMD LTD TO (elements specified) remark is a flag for users and differs from the AMD NOT SKED AFT Z remark for part-time manual observation sites. AMD LTD TO (elements specified) means users should expect amendments only for those elements and the times specified.
Example:
TAF AMD KCOE 150202Z 1502/1524 text AMD LTD TO CLD VIS AND WIND 1505-1518=
The amended forecast indicates that amendments will only be issued for wind, visibility and clouds, between the 15th day of the month at 0500Z and the 15th day of the month at 1800Z.
An amendment includes forecasts for all appropriate TAF elements, even those not reported when the automated site is not augmented. If unreported elements are judged crucial to the TAF and cannot be adequately determined (e.g., fog versus moderate snow), the TAF will be suspended (i.e. an amended TAF stating ”AMD NOT SKED”).
AWOS-III systems with part-time augmentation, which the forecaster suspects are providing unreliable information when not augmented, will be reported for maintenance and treated the same as part-time manual observation sites. In such cases, the AMD NOT SKED AFT YY/aaZ remark will be used.
7.2.3.4 Non-Augmented Automated Observing Sites The TAF issued for a non-augmented ASOS site may be suspended in the event the forecaster is notified of, or strongly suspects, an outage or unrepresentative data. Forecasters may also suspend TAF amendments when an element the forecaster judges to be critical is missing from the observation and cannot be obtained using the total observation concept. The term AMD NOT SKED will be appended, on a separate line and indented five spaces, to the end of an amendment to the existing TAF when appropriate.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-35
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
7.3 International Aviation Route Forecasts (ROFOR) International ROFORs are prepared and issued several hours in advance of regularly scheduled flights. The only NWS office which routinely issues ROFORs is the Weather Forecast Office (WFO) in Honolulu due to its designation as an ICAO Meteorological Watch Office (MWO).
7.3.1 ROFOR Criteria WFO Honolulu will honor all ROFOR requests for flights within the Pacific Region beginning or ending in, or having most of the flight path within its area of responsibility, which is the Oakland Oceanic FIR south of 30N, between 140W and 130E.
7.3.2 Issuance ROFORs are issued for prescribed times, several hours in advance, for regularly scheduled flights. ROFOR requests for unscheduled flights are prepared as soon as time allows.
7.3.2.1 ROFOR Amendments ROFORs are not required to be amended.
7.3.2.2 ROFOR Corrections ROFOR corrections are issued as soon as possible when erroneous data has been transmitted.
7.3.3 ROFOR Content ROFORs contain some or all of the following forecast parameters:
• Winds and temperatures aloft
• Significant en-route weather
• Zone weather
• Weather Synopsis
At a minimum, ROFORs include the first two bullets. They may contain data for multiple altitudes and include TAFs for destination points and/or alternates.
The core of a ROFOR is formatted as follows: 0iQLL 4hhhTT ddFFF
Where i = 1 for zone up to latitude L i = 2 for zone up to longitude LL
Q = 1 east of the dateline in the northern hemisphere Q = 2 west of the dateline in the northern hemisphere Q = 6 east of the dateline in the southern hemisphere Q = 7 west of the dateline in the southern hemisphere
hhh = height to which the temperature and wind refer TT = air temperature in whole degrees Celsius at hhh dd = true direction in tens of degrees from which the wind will blow at hhh AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-36
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) fff = wind speed in know at hhh
01104 4300M31 10010 Decoded as: The 30,000 foot wind (10010) and temperature (M31) are for that zone along the flight path from the equator to 05N east of the dateline.
Note: Refer to Appendix A for definitions of common terms used in ROFORs.
7.3.4 ROFOR Examples
7.3.4.1 Majuro to Kwajalein Route ROFOR Example
FROC32 PHFO 301857 RFRKWA
FOR WSO MAJURO ROFOR VALID 2102 FOR ROUTE PKMJ TO PKWA AND RETURN 01208 4100P09 09010 4180M05 08015 SIGWX...NIL.
7.3.4.2 Tarawa to Majuro Route ROFOR Example
FROC33 PHFO 291510 RFRFFN
FOR PKMJYMYX ROFOR VALID 2008 FOR ROUTE NGTA TO PKMJ 01205 4100P08 06010 4140P00 06015 4180M03 07020 01201 4100P08 09015 4140P00 09020 4180M04 10025 SIGWX...ISOL TCU/VIS 5SM SHRA PKMJ 221120Z 221212 NIL=
7.3.4.3 Santa Barbara and San Francisco to Honolulu Route ROFOR Example
FRPN31 PHFO 301857 RFRKSF
WINDS/TEMPERATURES AND WEATHER BY ZONE FOR ROUTE SFO/HNL VIA 31.3N/140W VALID AT 311200Z
FLIGHT LEVELS ZONE FL050 FL100 FL180 FL240 ZONE WEATHER 25 3315 P16 3208 P11 3109 M07 3216 M19 6-8 STSC 010/030 26 3316 P13 3211 P09 3117 M06 3023 M18 4-6 STSC 015/045 27 3013 P12 3212 P09 3020 M06 3024 M18 6-8 MERGING LYR TO 200 ISOL VIS 3-5SM RA ISOL TCU TOPS FL220 28 3008 P14 3008 P08 2815 M06 2918 M18 DO 29 9905 P14 9905 P08 2609 M06 2612 M18 4-6 CUSC 020/050 30 0506 P14 9905 P08 9905 M06 2406 M18 DO 31 0818 P15 0613 P09 0307 M06 9905 M18 4-6 CUSC 020/080
ISOL -SHRA 32 0822 P15 0719 P09 0711 M05 9905 M17 DO
OVERALL COMPONENTS AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-37
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) P4 P2 M4 M10 ROUTE SBA/HNL VIA 29.5N/140W VALID AT 311200Z
FLIGHT LEVELS ZONE FL050 FL100 FL180 FL240 ZONE WEATHER 25 3509 P17 3108 P11 3011 M07 3015 M19 6-8 STSC 010/030 26 3416 P14 3312 P09 3218 M05 3123 M18 4-6 STSC 015/045 27 0111 P13 3510 P10 3017 M05 3021 M18 2-4 CUSC 020/045 28 0307 P14 3606 P09 2713 M05 2717 M18 DO 29 0406 P14 9905 P08 2507 M05 2610 M18 4-6 CUSC 020/050 30 0815 P15 0610 P09 9905 M05 9905 M17 DO 31 0821 P15 0616 P09 0408 M05 9905 M18 4-6 CUSC 020/080
ISOL -SHRA 32 0822 P15 0719 P09 0812 M06 9905 M18 DO
OVERALL COMPONENTS P10 P5 M4 M7 SYNOPSIS...1024MB HIGH CENTERED NEAR N3000 W15600.
AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-38
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
7.4 Wind and Temperature Aloft Forecast (FB) Wind and Temperature Aloft Forecasts (FB) are computer prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations. Forecasts are based on the North American Mesoscale (NAM) forecast model run. FBs are available on the Aviation Weather Center (AWC) web site at: http://aviationweather.gov/products/nws/winds/
7.4.1 Forecast Altitudes The following table contains the altitudes for which winds are forecast. Altitudes up to 15,000 feet are referenced to Mean Sea Level (MSL). Altitudes at or above 18,000 feet are references to flight levels (FL).
Table 7-9. Wind and Temperature Aloft Forecast Levels Actual Altitudes (MSL) 1,000 feet* 1,500 feet* 2,000 feet* 3,000 feet 6,000 feet 9,000 feet 12,000 feet 15,000 feet* Pressure Altitudes (Hectopascals) 18,000 feet (500 Hectopascals) 24,000 feet (400 Hectopascals) 30,000 feet (300 Hectopascals) 34,000 feet (250 Hectopascals) 39,000 feet (200 Hectopascals) 45,000 feet (150 Hectopascals)# 53,000 feet (100 Hectopascals)# * Hawaii and Western Pacific only.
# Not available for selected locations in the Contiguous US.
Wind forecasts are not issued for altitudes within 1,500 feet of a location's elevation.
Temperature forecasts are not issued for altitudes within 2,500 feet of a location's elevation.
Forecasts for intermediate levels are determined by interpolation.
7.4.2 Format The symbolic form of the forecasts is DDff+TT in which DD is the wind direction, ff the wind speed, and TT the temperature.
Wind direction is indicated in tens of degrees (two digits) with reference to true north and wind speed is given in knots (two digits). Light and variable wind or wind speeds of less than 5 knots are expressed by 9900. Forecast wind speeds of 100 through 199 knots are indicated by subtracting 100 from the speed and adding 50 to the coded direction. For example, a forecast AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-39
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) of 250 degrees, 145 knots, is encoded as 7545. Forecast wind speeds of 200 knots or greater are indicated as a forecast speed of 199 knots. For example, 7799 is decoded as 270 degrees at 199 knots or greater.
Temperature is indicated in degrees Celsius (two digits) and is preceded by the appropriate algebraic sign for the levels from 6,000 through 24,000 feet. Above 24,000 feet, the sign is omitted since temperatures are always negative at those altitudes.
The product header includes the date and time observations were collected, the forecast valid date and time, and the time period during which the forecast is to be used.
Examples
1312+05 The wind direction is from 130 degree (i.e. - southeast), the wind speed is 12 knots and the temperature is 5 degrees Celsius.
9900+10 Wind light and variable, temperature +10 degrees.
7735-07 The wind direction is from 270 degrees (i.e. west), the wind speed is 135 knots and the temperature is minus 7 degrees Celsius.
7.4.2.1 Coding Example Sample winds aloft text message:
DATA BASED ON 010000Z VALID 010600Z FOR USE 0500-0900Z. TEMPS NEG ABV 24000 FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252
Sample message decoded:
(Line 1) DATA BASED ON 010000Z
Forecast data is based on computer forecasts generated the first day of the month at 0000 UTC.
(Line 2) VALID 010600Z FOR USE 0500-0900Z. TEMPS NEG ABV 24000
The valid time of the forecast is the 1st day of the month at 0600 UTC. The forecast winds and temperature are to be used between 0500 and 0900 UTC. Temperatures are negative above 24,000 feet.
(Line 3) FT 3000 6000 9000 12000 18000 24000 30000 34000 39000
FT indicates the altitude of the forecast.
(Line4) MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252 AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-40
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
MKC indicates the location of the forecast. The rest of the data is the winds and temperature aloft forecast for the respective altitudes.
The following table shows data for MKC (Kansas City, MO).
Table 7-10. Wind and Temperature Aloft Forecast Decoding Examples FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252 Altitude (feet) Coded Wind Temperature (oC) 3,000 FT 9900 Light and variable Not forecast 6,000 FT 1709+06 170 degrees at 9 knots +06 degrees Celsius 9,000 FT 2018+00 200 degrees at 18 knots Zero degrees Celsius 12,000 FT 2130-06 210 degrees at 30 knots -06 degrees Celsius 18,000 FT 2242-18 220 degrees at 42 knots -18 degrees Celsius 24,000 FT 2361-30 230 degrees at 61 knots -30 degrees Celsius 30,000 FT 247242 240 degrees at 72 knots -42 degrees Celsius 34,000 FT 258848 250 degrees at 88 knots -48 degrees Celsius 39,000 FT 750252 250 degrees at 102 knots -52 degrees Celsius
7.4.2.2 Example for the Contiguous US and Alaska DATA BASED ON 091200Z VALID 091800Z FOR USE 1400-2100Z. TEMPS NEG ABV 24000
FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 ABI 1931+10 1929+10 2024+06 2331-10 2448-23 235239 246348 256056 ABQ 2213+03 2327-04 2253-17 2263-27 227242 236946 245749 ABR 2017 2312+14 2308+09 2615+02 2724-13 2527-26 273641 274051 274562 AGC (etc.)
FT 45000 53000 ABI 301049 281149 ABQ 235061 244859 ABR 224559 243756 AGC (etc.)
Note: 45,000- and 53,000-foot winds are not available for selected locations in the conterminous US.
7.4.2.3 Example for Hawaii and the Western Pacific DATA BASED ON 091200Z VALID 091800Z FOR USE 1400-2100Z. TEMPS NEG ABV 24000
FT 1000 1500 2000 3000 6000 9000 12000 15000 18000 24000 LIH 9900 9900 1705 1806 1711+13 2216+10 2520+05 2523+01 2833-07 2937-19 HNL 9900 9900 9900 9900 1407+14 1908+11 2410+05 2612+01 2928-07 2930-18 LNY 9900 9900 9900 9900 1208+14 9900+11 9900+06 2909+01 3024-07 3027-18 OGG (etc.)
FT 30000 34000 39000 45000 53000 LIH 040734 990044 241055 281666 990072 HNL 051234 010543 250654 301066 990072 AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-41
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) INY 041433 010743 230754 260966 990072 OGG (etc) Note: The altitudes forecast in the Hawaii and western Pacific bulletins are different than those forecast in the Contiguous US and Alaska Note: The Hawaii and western Pacific bulletins are separated at the 24,000 foot level instead of 39,000 feet because of the additional, lower levels noted in Table 7-8.
7.4.3 Issuance The NWS National Centers for Environmental Prediction (NCEP) produces scheduled Wind and Temperature Aloft Forecasts (FB) four (4) times daily for specified locations in the Continental United States (CONUS), the Hawaiian Islands, Alaska and coastal waters, and the western Pacific Ocean (Figures 7-8 through 7-11).
Amendments are not issued to the forecasts.
•CAR SEA
AST PDXYKM GEGFCA FEMLEEGR
•OTH KUM IMB •BOI ELWS •DLN «BIL"MLS DIK •GTF "GGW «MOT GFK INL CABRAXN *OLH NQT SSM NO MKG ECK BUF AVP JFK SYR ALB PACK SPLE PWR BUL ABOS FOT SIY "MSP *RBL •РІН •CZI CRAP PIR • LSE SFO •SACRNO BAM •ELY "SLC RKS, *LND MBW BFF ONL "GRI OMA DSMI BRL JOT FWACMHAGC ENI SCLE PSB CEKN RIC SACY ВІН "SP! "IND _ORF "FAT •ВСЕ TRI "RDU HAT SBA •WJF SAN BLH *PRC • ONT •LAS ZUN ABO fCC AMA •OKC °FSM * FMN ALS *GCK ICT •SGF • GAG +TUL SGRU CGI BNA YS MEM HSV GSP FLOWN •CAE PCHS
•РНХ •LIT •BHMATL TSAV
• TUS HELP INK + ROW LBB • MRF +DRT ABI *DAL *SHV •SAFPSX • T01•TO6 "TO7 "443 PIE SPS *CLL LOLCH NSTMOE PEN SHOU -JAN MGM SCSG ATLH AMLE
• H61 AMIA
ALRD CRP BRO H51 ФH52 . CETW Figure 7-8. Wind and Temperature Aloft Forecast Network - Contiguous US AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-42
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) 70
•BRW LUR QTZ AFM *BTT *FYU
• GAL • FAI LOUNK 60 ÇZF *MCG • TKA GKN ORT
BET ALANC
•SNP JEHM WAKN * HOM *MDO • 5AG
• 5AP FANN * 5AB *SAE
•ADK + 5AD 5AC -180 -170 -160 -150 -140 -130 Figure 7-9. Wind and Temperature Aloft Forecast Network - Alaska 22 LIH AHNL ragG LNY 20
KOA LITO 160 - 158 156 Figure 7-10. Wind and Temperature Aloft Forecast Network - Hawaii AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-43
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) AC 00-45F, CHG 2 Section 7: Forecast Text Products Page 7-44
Figure 7-11. Wind and Temperature Aloft Forecast Network - Western Pacific
Table 7-11. Wind and Temperature Aloft Forecast (FB) Periods Model Run Product Available 6 hour Forecast 12 hour Forecast 24 hour Forecast Valid For Use Valid For Use Valid For Use 0000Z ~0200Z 0600Z 0200-0900Z 1200Z 0900-1800Z 0000Z 1800-0600Z 0600Z ~0800Z 1200Z 0800-1500Z 1800Z 1500-0000Z 0600Z 0000-1200Z 1200Z ~1400Z 1800Z 1400-2100Z 0000Z 2100-0600Z 1200Z 0600-1800Z 1800Z ~2000Z 0000Z 2000-0300Z 0600Z 0300-1200Z 1800Z 1200-0000Z
7.4.4 Delayed Forecasts If the scheduled forecast transmission is delayed, the existing valid forecast based on the earlier 6-hourly data can be used until a new forecast is transmitted.
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) 8 FORECAST CHARTS
8.1 Short-Range Surface Prognostic (Prog) Charts Short-Range Surface Prognostic (Prog) Charts (Figure 8-1) provide a forecast of surface pressure systems, fronts and precipitation for a 2-day period. The forecast area covers the 48- contiguous states, the coastal waters and portions of adjacent countries. The forecasted conditions are divided into four forecast periods, 12-, 24-, 36-, and 48-hours. Each chart depicts a “snapshot” of weather elements expected at the specified valid time.
The Surface Prognostic (Prog) Charts are available at the Aviation Digital Data Services (ADDS) web site at: http://adds.aviationweather.noaa.gov/progs/.
Figure 8-1. Surface Prog Chart Example
AC 00-45F, CHG 2 Section 8: Forecast Charts Page 8-1