Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) and disseminated, when possible, in conformance with the U.S. Standard Turbulence Criteria Table 3-8.
Table 3-8. PIREP Turbulence Reporting Criteria Intensity Aircraft Reaction Reaction Inside Aircraft Reporting Term-Definition Light Turbulence that momentarily causes slight, erratic changes in altitude and/or attitude (pitch, roll, yaw). Report as Light Turbulence;1 or Turbulence that causes slight, rapid and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude. Report as Light Chop.
Occupants may feel a slight strain against belts or shoulder straps.
Unsecured objects may be displaced slightly.
Food service may be conducted and little or no difficulty is encountered in walking.
Occasional – Less than 1/3 of the time.
Intermittent-1/3 to 2/3
Continuous-More than 2/3 Moderate Turbulence that is similar to Light Turbulence but of greater intensity.
Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed. Report as Moderate Turbulence;1 or Turbulence that is similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft or attitude. Report as Moderate Chop.1 Occupants feel definite strains against seat belts or shoulder straps.
Unsecured objects are dislodged. Food service and walking are difficult.
NOTE
1. Pilots should report location(s), time (UTC), intensity, weather in or near clouds, altitude, type of aircraft and, when applicable, duration of turbulence.
2. Duration may be based on time between two locations or over a single location. All locations should be readily identifiable.
EXAMPLES:
Over Omaha. 1232Z, Moderate Turbulence, in cloud, flight Level 310, B737.
b. From 50 miles south of Albuquerque to 30 miles north of Phoenix, 1210Z to 1250Z, occasional Moderate Chop, Flight Level 330, DC8.
Severe Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control. Report as Severe Turbulence.1 Occupants are forced violently against seat belts or shoulder straps.
Unsecured objects are tossed about. Food service and walking are impossible.
Extreme Turbulence in which the aircraft is violently tossed about and is practically impossible to control. It may cause structural damage. Report as Extreme Turbulence.1
1 High level turbulence (normally above 15,000 feet ASL) not associated with clouds, including thunderstorms, should be reported as CAT (clear air turbulence) preceded by the appropriate intensity, or light or moderate chop.
3.2.1.11 Icing (/IC) Icing intensity, type and altitude is reported after turbulence.
Intensity is coded first using contractions TRACE, LGT (light), MOD (moderate), or SEV severe). Reports of a range or variation of intensity is separated with a hyphen. If icing was forecast but not encountered, NEG (negative) is coded.
The following table classifies icing intensity according to its operational effects on aircraft.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-39
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Table 3-9. Icing Intensities, Contractions, and Airframe Ice Accumulation Intensity Contraction Airframe Ice Accumulation Trace TRACE Ice becomes perceptible. Rate of accumulation slightly greater than rate of sublimation. It is not hazardous even without the use of deicing/anti-icing equipment unless encountered for an extended period of time (over 1 hour).
Light LGT The rate of accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/anti-icing equipment removes/prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used.
Moderate MOD The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing/anti-icing equipment or diversion is necessary.
Severe SEV The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard. Immediate diversion is necessary.
Icing type is reported second. Reportable types are RIME, CLR (clear), or MX (mixed).
The following table classifies icing type according to it description.
Table 3-10. Icing Types, Contractions, and Descriptions Icing Type Contraction Description Rime RM Rough, milky, opaque ice formed by the instantaneous freezing of small super-cooled water droplets.
Clear CLR A glossy, clear or translucent ice formed by the relatively slow freezing of large super-cooled water droplets.
Mixed MX A combination of both rime and clear.
The reported icing/altitude is coded (last) only if different from the value reported in the altitude/flight level (/FL) group. A hyphen is used to separate reported layers of icing. ABV (above) or BLO (below) is coded when a layer is not defined.
Pilot reports of icing should also include location (/OV), type aircraft (/TP), and air temperature (/TA).
Examples:
/IC LGT-MOD MX 085 Light to moderate mixed icing, 8,500 feet MSL /IC LGT RIME Light rime icing /IC MOD RIME BLO 095 Moderate rime icing below 9,500 feet MSL /IC SEV CLR 035-062 Severe clear icing 3,500 to 6,200 feet MSL
3.2.1.12 Remarks (/RM) The remarks (/RM) group is used to report a phenomenon which is considered important but does not fit in any of the other groups. This includes, but is not limited to, low-level wind shear AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-40
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) (LLWS) reports, thunderstorm lines, coverage and movement, size of hail (1/4-inch increments), lightning, clouds observed but not encountered, geographical or local description of where the phenomenon occurred, and contrails. Hazardous weather is reported first. LLWS is described to the extent possible.
3.2.1.12.1 Wind Shear Ten knots or more fluctuations in wind speed (+/- 10KTS), within 2,000 feet of the surface, require an Urgent (UUA) pilot report. When Low Level Wind Shear is entered in a pilot report, LLWS is entered as the first remark in the remarks (/RM) group.
Example:
/RM LLWS +/-15 KT SFC-008 DURC RY22 JFK Remarks, Low Level Wind Shear, air speed fluctuations of plus or minus 15 knots, surface to 800 feet during climb, runway 22, John F. Kennedy International Airport, New York.
3.2.1.12.2 FUNNEL CLOUD, TORNADO, and WATERSPOUT Funnel cloud, tornado, and waterspout are entered with the direction of movement when reported.
Example:
/RM TORNADO W MOV E Remarks, tornado west moving east
3.2.1.12.3 Thunderstorm Thunderstorm coverage is coded as ISOL (isolated), FEW (few), SCT (scattered), NMRS (numerous) followed by description as LN (line), BKN LN (broken line), SLD LN (solid line) when reported. This is followed with TS, the location and movement, and the type of lightning when reported.
Example:
/RM NMRS TS S MOV E GR1/2 Remarks, numerous thunderstorms south moving east, hail 1/2–inch in diameter
3.2.1.12.4 Lightning Lightning frequency is coded as OCNL (occasional) or FRQ (frequent), followed by type as LTGIC (lightning in cloud), LTGCC (lightning cloud to cloud), LTGCG (lightning cloud to ground), LTGCA (lightning cloud to air), or combinations, when reported.
Example:
/RM OCNL LTGICCG Remarks, occasional lighting in cloud, cloud to ground
3.2.1.12.5 Electrical Discharge For an electrical discharge, DISCHARGE is coded followed by the altitude.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-41
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) Example:
/RM DISCHARGE 120 Remarks, discharge, 12,000 feet MSL
3.2.1.12.6 Clouds Remarks are used when clouds can be seen but were not encountered and reported in the sky condition group (/SK)
Examples:
/RM CB E MOV N Remarks, cumulonimbus east moving north /RM OVC BLO Remarks, overcast below
3.2.1.12.7 Plain Language If specific phraseology is not adequate, plain language is used to describe the phenomena or local geographic locations. Remarks that do not fit in other groups like DURC (during climb), DURD (during descent), RCA (reach cruising altitude), TOP, TOC (top of climb), or CONTRAILS are included.
Examples:
/RM BUMPY VERY ROUGH RIDE /RM CONTRAILS /UA/OV BIS270030/TM 1445/FL060/TP CVLT/TB LGT /RM DONNER SUMMIT PASS
3.2.1.12.8 Volcanic Eruptions Volcanic ash alone is an Urgent PIREP. A report of volcanic activity includes as much information as possible including the name of the mountain, ash cloud and movement, height of the top and bottom of the ash, etc., is included. If the report is received from a source other than a pilot, Aircraft UNKN, Flight Level UNKN, and /RM UNOFFICIAL is entered.
Example:
/UUA/OV ANC240075/TM 2110/FL370/TP DC10/WX VA/RM VOLCANIC ERUPTION 2008Z MT AUGUSTINE ASH 40S MOV SSE
Urgent Pilot Weather Report, 240 degrees at 75 nautical miles from Anchorage International Airport, Alaska, 2110 UTC, flight level 310, a DC10 reported volcanic ash, remarks, volcanic eruption occurred at 2008 UTC Mount Augustine, ash 40 nautical miles south moving southsoutheast.
3.2.1.12.9 SKYSPOTTER The SKYSPOTTER program is a result of a recommendation from the Safer Skies FAA/INDUSTRY Joint Safety Analysis and Implementation Teams. The term SKYSPOTTER indicates a pilot has received specialized training in observing and reporting in-flight weather phenomenon, pilot weather reports, or PIREPs.
When a PIREP is received from a pilot identifying themselves as a SKYSPOTTER aircraft, the additional comment “/AWC” is added at the end of the remarks section of the PIREP.
Example:
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-42
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
PIREP TEXT/RM REMARKS/AWC
3.2.2 PIREP Examples
UUA /OV ORD/TM 1235/FLUNKN/TP B727/TB MOD/RM LLWS +/- 20KT BLW 003 DURD RWY27L
Urgent Pilot Weather Report, over Chicago O’Hare Airport, Illinois, 1235 UTC, flight level unknown, from a Boeing 727, moderate turbulence, remarks, Low Level Wind Shear, airspeed fluctuations of plus or minus 20 knots below 300 feet AGL during descent, runway 27 left.
UUA /OV BAM260045/TM 2225/FL180/TP BE20/TB SEV/RM BROKE ALL THE
BOTTLES IN THE BAR
Urgent Pilot Weather Report, 260 degrees at 45 nautical miles from Hazen VOR, Nevada, 2225 UTC, 18,000 feet MSL, Beech Super King Air 200, severe turbulence, remarks, broke all the bottles in the bar.
UA /OV KMRB-KPIT/TM 1600/FL100/TP BE55/SK BKN024-TOP032/BKN-OVC043- TOPUNKN /TA M12/IC LGT-MOD RIME 055-080
Pilot Weather Report, Martinsburg, West Virginia to Pittsburgh International Airport, Pennsylvania, 1600 UTC, 10,000 feet MSL, Beechcraft Baron, base of a broken layer 2,400 feet MSL, top 3,200 feet MSL, base of a broken to overcast layer 4,300 feet MSL, top unknown, temperature minus 12, light to moderate rime ice between 5,500 to 8,000 feet MSL.
UA /OV IRW090064/TM 1522/FL080/TP C172/SK SCT090-TOPUNKN/WX FV05SM HZ/TA M04/WV 24040KT/TB LGT/RM IN CLR
Pilot Weather Report, 90 degrees and 64 nautical miles from Will Rogers VORTAC, Oklahoma City, Oklahoma, 1522 UTC, 8,000 feet MSL, Cessna 172, base of a scattered layer 9,000 feet MSL, top unknown, flight visibility 5 statute miles, haze, temperature minus 4, wind 240 degrees at 40 knots, light turbulence, remarks, in clear.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-43
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) UA /OV KLIT-KFSM/TM 0310/FL100/TP BE36/SK SCT070-TOP110/TA M03/WV 25015KT Pilot Weather Report, between Little Rock and Fort Smith, Arkansas, 0310 UTC at 10,000 feet MSL. Beech 36, base of a scattered layer at 7,000 feet MSL, top 11,000 feet MSL, temperature minus 3, wind 250 degrees at 15 knots.
UA /OV KAEG/TM 1845/FL UNKN/TP UNKN /RM TIJERAS PASS CLSD DUE TO FG AND LOW CLDS UNA VFR RTN KAEG.
Pilot Weather Report, over Double Eagle II Airport, Albuquerque, New Mexico, 1845 UTC, remarks, Tijeras Pass closed due to fog and low clouds, unable to fly VFR, returned to Double Eagle II Airport.
UA /OV ENA14520/TM 2200/FL310/TP B737/TB MOD CAT 350-390.
Pilot Weather Report, 145 degrees at 20 nautical miles from Kenai, Alaska, at 2200 UTC, at flight level 310, Boeing 737, moderate clear air turbulence between 35,000 and 39,000 feet MSL.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-44
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
3.3 Radar Weather Report (SD/ROB) A Radar Weather Report (SD/ROB) contains information about precipitation observed by weather radar. This is a textual product derived from the WSR-88D NEXRAD radar without human intervention. The resolution of this textual product is very coarse, up to 80 minutes old, and should only be used if no other radar information is available.
Figure 3-11. Radar Weather Report (SD/ROB) Coding Format
3.3.1 Format Reports are transmitted hourly from WSR-88D Weather Radar sites (see figure 3-12). The SD/ROB format is presented in Figure 3-8.
3.3.1.1 Location Identifier The location identifier is reported as the three-letter International Air Transport Association (IATA) code.
Example:
TLX Oklahoma City Twin Lakes, Oklahoma
3.3.1.2 Time The time of the observation is reported in four-digits Universal Time Coordinated (UTC).
Example:
1935 1935 UTC
3.3.1.3 Configuration Three types of configurations can be reported: CELL, LN (line), and AREA. Multiple configurations can be reported within one Weather Radar Report.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-45
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) A CELL is a single, isolated convective echo.
A LN (line) is a convective echo that meets the following criteria:
• Contains heavy or greater intensity precipitation
• Is at least 30 miles long
• Length is at least four times greater than width
• Contains at least 25 percent coverage
An AREA is a group of echoes of similar type, not classified as a line.
Figure 3-9 illustrates the three configurations that can be reported in a Weather Radar Report.
Figure 3-12. Radar Weather Report (SD/ROB) Configurations
3.3.1.4 Coverage Coverage of precipitation is coded in single digits representing tenths of coverage.
For echo configurations containing multiple precipitation types, coverage is coded for each type.
Total coverage is obtained by adding the individual values.
Examples:
2TRW+4R 2/10 coverage TRW+, 4/10 coverage R, 6/10 total coverage 3R6S- 3/10 coverage R, 6/10 coverage S-, 9/10 total coverage
3.3.1.5 Precipitation Type Precipitation type is determined by computer model.
Reportable types are:
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-46
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
• Rain (R )
• Rain shower (RW )
• Snow (S)
• Snow shower (SW )
• Thunderstorm ( T)
Multiple precipitation types can be reported within a configuration.
3.3.1.6 Precipitation Intensity Four precipitation intensities can be reported as shown in table 3-11.
Table 3-11. SD/ROB Reportable Intensities Symbol Intensity dBZ
- Light 0-29 (no entry) Moderate 30-40 + Heavy 41-45 ++ Heavy 46-49 X Extreme 50-56 XX Extreme 57 or more
Examples:
7R- 7/10 coverage of light rain 3R-6S 3/10 coverage light rain, 6/10 coverage moderate snow, 9/10 total coverage 2TRWX4R- 2/10 coverage thunderstorms, extreme rain showers , 4/10 coverage light rain, 6/10 total coverage
3.3.1.7 Location An area is coded with two end points and a width that defines a rectangle. Each end point is defined by an azimuth and range (AZRAN).
A line is also coded with two end points and a width that defines a rectangle. Each end point is defined by an AZRAN.
A cell is coded as a single point with a diameter (D). This point is defined by an AZRAN.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-47
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Figure 3-13. SD/ROB AREA, Line (LN), and CELL Location Examples The “+” denotes the radar location.
3.3.1.8 Maximum Top Maximum top (MT or MTS) denotes the altitude and location of the top of the highest precipitation echo.
All radar heights are estimates and assume standard atmosphere conditions and, thus, standard radar wave propagation. MT denotes radar data alone was used to determine the maximum top. MTS denotes both satellite and radar data were used to estimate the maximum top.
The maximum top is coded as a three-digit number in hundreds of feet MSL. Location is coded as an azimuth and range (AZRAN) relative to the radar site. If echo tops are uniform in altitude, the letter “U” precedes the altitude with no AZRAN provided.
Examples:
MT 150 19/32 Maximum top 15,000 feet MSL at 19 degrees, 32 nautical miles MT 340 182/98 Maximum top 34,000 feet MSL at 182 degrees, 98 nautical miles MTS 520 5/121 Maximum top with satellite data 52,000 feet MSL at 5 degrees, 121 nautical miles
3.3.1.9 Cell Movement Cell movement is the average motion of all the cells within a configuration. It is coded in the following format: the cell movement group is indicated by the letter C followed by four digits.
The first two digits represent the direction the cell(s) is (are) moving from in tens of degrees referenced to true north. The last two digits represent the speed of the configuration in knots.
Movement of areas and lines is not coded.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-48
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009)
Examples:
C0209 Cell movement from 20 degrees at 9 knots C2043 Cell movement from 200 degrees at 43 knots C3616 Cell movement from 360 degrees at 16 knots
3.3.1.10 Remarks Remarks contain information about the radar’s status and type of report. Currently, all weather radar reports are automated.
Table 3-12. Weather Radar Report Remarks and Meaning
REMARK MEANING PPINE Equipment normal and operating, but no echoes observed PPINA Observation not available PPIOM Radar out for maintenance AUTO Report derived from an automated weather radar
3.3.1.11 Digital Section The information contained in the digital section is used primarily to create the Radar Summary Chart. However, with the proper grid overlay chart for the corresponding radar site, the digital section code can also be used to determine precipitation location and intensity. (See Figure 3- 11 for an example of a digital code plotted from the Oklahoma City, Oklahoma, Weather Radar Report.)
Each digit represents the maximum precipitation intensity found within a grid box as determined by the weather radar. Light intensity is denoted by a 1, 2 is for moderate, 3 and 4 is for heavy, 5 and 6 is used for extreme precipitation. These digits were once commonly referred to as VIP levels because precipitation intensity, and therefore the digit, was derived using a video integrator processor (VIP). Whereas the old WSR-57 and WSR-74 weather radar video integrator processors displayed six data levels, the WSR-88D weather radar displays sixteen data levels. The data levels are still converted back to six levels for use in the Radar Weather Report. To avoid confusion, the term VIP should no longer be used to describe precipitation intensity. For example, if a grid box is coded with the number 2, it would be described as “moderate” precipitation,” not “VIP 2” or “level 2” precipitation.
A grid box is identified by two letters. The first represents the row in which the box is found and the second letter represents the column. For example MO1 identifies the box located in row M and column O as containing light precipitation. A code of MO1234 indicates precipitation in four consecutive boxes in the same row. Working from left to right: box MO = 1, box MP = 2, MQ = 3, and box MR = 4.
A Weather Radar Report contains data about precipitation echoes only. It does not contain information about important non-precipitation echoes such as clouds, fronts, dust, etc., which can be detected by weather radar under certain circumstances.
AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-49
Aviation Weather Services, Advisory Circular 00-45F, Change 2 (March 2009) HQ N HI HJ HM
• HP HQ HR JG IP JK JL
KG JM JN JO JP
KJ KK KL JS KN КР
LK LM I KS
MG LM UN LO LP
MI MJ MK ML ILO LR
AMILX MN MO MP NI INJ NK NL NM 1 MR †MS /Og NN I NO INP au 1 NQ INR >G PI IPJ PK /PL OL OM ON 100 /OP 0Q OR ros ан PN 4 PO PP IPQ ак PS 1 PT ам ON RI OR
RK AL RM
ISH SI SJ RP RO RS RT SM SN
ITH TI TJ TK TL TM S SP SQ SA SS ST
I TO TP Figure 3-14. SD/ROB Digital Section Information Plotted on a PPI Grid Overlay Example (See Table 3-11 for Intensity Level Codes 1 through 6.)
3.3.2 Examples GRB 1135 AREA 4TRW+ 9/101 133/76 54W MT 310 45/47 C2428 AUTO Green Bay, Wisconsin, automated Radar Weather Report at 1135 UTC. An area of echoes, 4/10 coverage, contained thunderstorms and heavy rain showers. Area is defined by points (referenced from GRB radar site) at 9 degrees, 101 nautical miles and 133 degrees, 76 nautical miles. These points, plotted on a map and connected with a straight line, define the center line of the echo pattern. The width of the area was 54 nautical miles; i.e., 27 nautical miles either side of the center line. Maximum top was 31,000 feet MSL located at 45 degrees and 47 nautical miles from Green Bay. Cell movement was from 240 degrees at 28 knots.
ICT 1935 IN 9TRWX 274/84 216/93 22W MTS 440 260/48 C2131 AUTO Wichita, Kansas, automated Radar Weather Report at 1935 UTC. A line of echoes, 9/10 coverage, contained thunderstorm with intense rain showers. The center of the line extended AC 00-45F, CHG 2 Section 3: Observed Text Products Page 3-50