Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-29 241310Z The 24th of the month, Special report taken at 1310 UTC 09014G35KT Wind 90 degrees at 14 knots, gusts to 35 knots 1/4SM Visibility one-quarter statute mile +SN FG Heavy snow, fog VV002 Indefinite ceiling, vertical visibility 200 feet AGL 01/01 Temperature 1 C, dew point 1 C A2975 Altimeter 29.75 inches of mercury RMK Remarks AO2 Automated observation with precipitation discriminator TWR VIS 1/2 Tower visibility one-half statute mile RAE08SNB08 Rain ended at 08 past the hour and snow began at 08 minutes past the hour
Denver International Airport, wind zero niner zero at one four, gusts three five, visibility onequarter, heavy snow, fog, indefinite ceiling two hundred, temperature one, dew point one, altimeter two niner seven five, remarks tower visibility one half, ran ended and snow began at zero eight.
METAR KSPS 301656Z 06014KT 020V090 3SM -TSRA FEW040 BKN060CB 12/ A2982 RMK OCNL LTGICCG NE TSB17 TS E MOV NE PRESRR SLP093
METAR Aviation Routine Weather Report KSPS United States Sheppard Air Force Base/Wichita Falls Municipal Airport, Texas 301656Z The 30th day of the month, the 1700 scheduled report taken at 1656 UTC 06014KT 020V090 Wind 60 degrees at 14 knots, wind variable between 020 and 090 degrees 3SM Visibility 3 statute miles -TSRA Thunderstorm, light rain FEW040 BKN060CB Few 4,000 feet AGL, ceiling broken 6,000 feet AGL cumulonimbus 12/ Temperature 12 C, dew point missing A2982 Altimeter 29.82 inches of mercury RMK Remarks OCNL LTGICCG NE Occasional lightning in cloud, cloud-to-ground northeast TSB17 Thunderstorm began at 17 minutes past the hour TS E MOV NE Thunderstorm east moving northeast PRESRR Pressure rising rapidly SLP093 Sea-level pressure 1009.3 hectopascals
Sheppard Air Force Base/Wichita Falls Municipal Airport, automated, wind zero six zero at one four, wind variable between zero two zero and zero niner zero, visibility three, thunderstorm, light rain, few clouds at four thousand, ceiling six thousand broken cumulonimbus, temperature one two, dew point missing, remarks occasional lightning in-cloud, cloud-to-ground northeast, thunderstorm began at one seven, thunderstorm east moving northeast, pressure rising rapidly.
SPECI KBOS 051237Z VRB02KT 3/4SM R15R/4000FT BR OVC004 05/05 A2998 RMK AO2 CIG 002V006 T00520048
SPECI Aviation Selected Special Weather Report
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-30 KBOS United States Boston, Massachusetts 051237Z The 5th of the month, Special report taken at 1237 UTC VRB02KT Wind variable at 2 knots 3/4SM Visibility three-quarters statute mile R15R/4000FT Runway 15R, visual range on runway 4,000 feet BR Mist OVC004 Ceiling overcast 400 feet AGL 05/05 Temperature 5 C, dew point 5 C A2998 Altimeter 29.98 inches of mercury RMK Remarks AO2 Automated observation with precipitation discriminator CIG 002V006 Ceiling variable between 200 to 600 feet T00520048 Temperature 5.2oC, dew point 4.8oC
Boston General Edward Lawrence Logan International Airport, special report, three seven observation, wind variable at two, visibility three-quarters, runway one five right R-V-R four thousand, mist, ceiling four hundred overcast, temperature five, dew point five, altimeter two niner niner eight, remarks, ceiling variable between two hundred and six hundred.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-31
3.2 Pilot Weather Reports (PIREP) No report is timelier than the one made from the flight deck of aircraft in flight. In fact, aircraft in flight are the only means of observing actual icing and turbulence conditions. Pilots welcome pilot weather reports (PIREPs) as well as pilot weather briefers and forecasters. Pilots should report any observation, good or bad, to assist other pilots with flight planning and preparation. If conditions were forecasted to occur but not encountered, a pilot should also report this inaccuracy. This will help the NWS verify forecast products and create more accurate products for the aviation community. Pilots should help themselves, the aviation public, and the aviation weather forecasters by providing PIREPs.
Pipe Up with a PIREP and help the aviation community operate more safely and effectively.
PIREPs are available in the internet at the Aviation Digital Data Service (ADDS) web page at:
http://adds.aviationweather.gov/pireps/
3.2.1 Format A PIREP is transmitted in a prescribed format (Figure 3-7). Required elements for all PIREPs are: message type, location, time, altitude/flight level, type aircraft, and at least one other element to describe the reported phenomena. The other elements will be omitted when no data is reported with them. All altitude references are mean sea level (MSL) unless otherwise noted.
Distance for visibility is in statute miles and all other distances are in nautical miles. Time is reported in Universal Time Coordinated (UTC).
Figure 3-10. Pilot Weather Report (PIREP) Coding Format
3.2.1.1 Message Type (UUA/UA) The two types of PIREPs are Urgent (UUA) and Routine (UA).
3.2.1.1.1 Urgent PIREPs Urgent (UUA) PIREPs contain information about:
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-32 Tornadoes, funnel clouds, or waterspouts
Severe or extreme turbulence (including Clear Air Turbulence)
Severe icing
Hail
Low Level Wind Shear (LLWS) within 2,000 feet of the surface. LLWS PIREPS are classified as UUA if the pilot reports air speed fluctuations of 10 knots or more or if air speed fluctuations are not reported but LLWS is reported, the PIREP is classified as UUA.
Volcanic ash clouds
Any other weather phenomena reported which are considered by the briefer as being hazardous, or potentially hazardous, to flight operations.
3.2.1.1.2 Routine PIREPs Routine PIREPs are issued after receiving a report from a pilot that does not contain any urgent information as listed in Section 3.2.1.1.1.
3.2.1.2 Location (/OV) The Location (/OV) can be referenced either by geographical position or by route segment.
3.2.1.2.1 Location Location can be referenced to a VHF NAVAID or an airport, using either the three-letter International Air Transport Association (IATA) or four letter International Civil Aviation Organization (ICAO) identifier. If appropriate, the PIREP is encoded using the identifier, then three digits to define a radial and three digits to define the distance in nautical miles.
Examples:
/OV APE Over Appleton VOR /OV KJFK Over John F. Kennedy International Airport, New York City, NY /OV APE230010 230 degrees at 10 nautical miles from the Appleton VOR /OV KJFK107080 107 degrees at 80 nautical miles from John F. Kennedy International Airport, New York City, New York
3.2.1.2.1.1 3.2.1.3.1.1 Route Segment A PIREP can also be referenced using two or more fixes to describe a route.
Examples:
/OV KSTL-KMKC From Lambert-Saint Louis International Airport, Missouri to Charles B. Wheeler Downtown Airport, Kansas City, Missouri /OV KSTL090030-KMKC045015 From 90 degrees at 30 nautical miles from Lambert- Saint Louis International Airport, Missouri to 45 degrees at 15 nautical miles from Charles B. Wheeler Downtown Airport, Kansas City, Missouri
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-33
3.2.1.3 Time (/TM) Time (/TM) is the time that the reported phenomenon occurred or was encountered. It is coded in four digits UTC.
Example:
/TM 1315 1315 UTC
3.2.1.4 Altitude/Flight Level (/FL) The Altitude/Flight Level (/FL) is the altitude in hundreds of feet MSL where the phenomenon was first encountered. If not known, UNKN is entered. If the aircraft was climbing or descending, the appropriate contraction (DURC or DURD) is entered in the remarks (/RM). If the condition was encountered within a layer, the altitude range is entered within the appropriate element that describes the condition.
Examples:
/FL085 8,500 feet MSL /FL310 Flight Level 310 /FLUNKN /RM DURC Flight Level unknown, remarks, during climb
3.2.1.5 Aircraft Type (/TP) Aircraft Type (/TP) is entered. If not known, UNKN is entered. Icing and turbulence reports always include aircraft type.
Examples:
/TP BE20 Super King Air 200 /TP SR22 Cirrus 22 /TP P28R Piper Arrow /TP UNKN Type unknown
3.2.1.6 Sky Condition (/SK) Sky Condition (/SK) group is used to report height of cloud bases, tops, and cloud cover. The height of the base of a layer of clouds is coded in hundreds of feet MSL. The top of a layer is entered in hundreds of feet MSL preceded by the word -TOP. If reported as clear above the highest cloud layer, SKC is coded following the reported level.
Examples:
/BKN040-TOP065 Base of broken layer 4,000 feet MSL, top 6,500 feet MSL /SK OVC100-TOP110/ SKC Base of an overcast layer 10,000 feet MSL, top 11,000 feet MSL, clear above /SK OVC015-TOP035/OVC230 Base of an overcast layer 1,500 feet MSL, top 3,500 feet MSL, base of an overcast layer 23,000 feet MSL /SK OVC-TOP085 Overcast layer, top 8,500 feet MSL
Cloud cover amount ranges are entered with a hyphen separating the amounts; i.e., BKN-OVC.
Examples:
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-34
/SK SCT-BKN050-TOP100 Base of a scattered to broken layer 5,000 feet MSL, top 10,000 feet MSL /SK BKN-OVCUNKN-TOP060/BKN120-TOP150/ SKC Base of a broken to overcast layer unknown, top 6,000 feet MSL, base of a broken layer 12,000 feet MSL, top 15,000 feet MSL, clear above
Unknown heights are indicated by the contraction UNKN.
Example:
/SK OVC065-TOPUNKN Base of an overcast layer 6,500 feet MSL, top unknown
If a pilot indicates he/she is in the clouds, IMC is entered.
Example:
/SK OVC065-TOPUNKN /RM IMC Base of an overcast layer 6,500 feet MSL, top unknown, remark, in the clouds
When more than one layer is reported, layers are separated by a solidus (/).
3.2.1.7 Flight Visibility and Weather (/WX) Weather conditions encountered by the pilot are reported as follows:
Flight visibility, when reported, is entered first in the /WX field. It is coded as FV followed by a two-digit visibility value rounded down, if necessary, to the nearest whole statute mile and appended with SM (FV03SM). If visibility is reported as unrestricted, FV99SM is entered.
Flight weather types are entered using one or more of the standard surface weather reporting symbols contained in Table 3-7.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-35
Table 3-7. PIREP Weather Type and Symbols Type METAR Code Drifting / Blowing Snow DRSN/BLSN Drifting Dust DRDU Drifting Sand DRSA Drizzle/Freezing Drizzle DZ/FZDZ Dust / Blowing Dust DU/BLDU Duststorm DS Fog (visibility less than 5/8SM) FG Freezing Fog FZFG Freezing Rain FZRA Funnel Cloud FC Hail (Approximately ¼-inch diameter or more) GR Hail Shower SHGR Haze HZ Ice Crystals IC Ice Pellets/Showers PL/SHPL Mist (visibility great than or equal to 5/8SM) BR Patchy Fog BCFG Patchy Fog on part of airport PRFG Rain/Showers RA/SHRA Sand/Blowing Sand SA/BLSA Sandstorms SS Shallow Fog MIFG Small Hail/Snow Pellet Showers SHGS Small Hail/Snow Pellets GS Smoke FU Snow Grains SG Snow / Showers SN/SHSN Spray PY Squalls SQ Thunderstorm TS Tornado/Waterspout +FC Unknown Precipitation UP Volcanic Ash VA Well developed Dust/Sand Whirls PO
Intensity modifiers for precipitation (- for light, no qualifier for moderate, and + for heavy) indicates precipitation type, except ice crystals and hail, including those associated with a thunderstorm and those of a showery nature.
Intensity modifiers for obscurations are ascribed as moderate or heavy (+) for dust and sandstorms only. No intensity modifiers are used for blowing dust, blowing sand, or blowing snow.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-36 Example:
/WV FV01SM +DS000-TOP083/SKC /RM DURC Flight visibility 1 statute mile, base heavy duststorm layer at the surface, top 8,300 feet MSL, clear above, remarks, during climb
When more than one form of precipitation is combined in the report, the dominant type is reported first.
Examples:
/WX FV00SM +TSRAGR Flight visibility zero statute miles, thunderstorm, heavy rain, hail /WX FV02SM BRHZ000-TOP083 Flight visibility 2 statute miles, base of a haze and mist layer at the surface, top 8,300 feet MSL
If a funnel cloud is reported, it is coded as FC following /WX group and is spelled out as Funnel Cloud after /RM group. If a tornado or waterspout is reported, it is coded +FC following /WX group and TORNADO or WATERSPOUT is spelled out after the /RM group.
Examples:
/WX FC /RM FUNNEL CLOUD Funnel cloud, remarks, funnel cloud /WX +FC /RM TORNADO Tornado, remark, tornado
When the size of hail is stated, it is coded in 1/4-inch increments in remarks (/RM) group.
The proximity qualifier VC (vicinity) is only used with TS, FG, FC, +FC, SH, PO, BLDU, BLSA, and BLSN.
Example:
/WX FV02SM BLDU000-TOP083 VC W Flight visibility 2 statute miles, base of a blowing dust layer at the surface, top 8,300 feet MSL in the vicinity, west
When more than one type of weather is reported, they are reported in the following order:
TORNADO, WATERSPOUT, or FUNNEL CLOUD Thunderstorm with or without associated precipitation Weather phenomena in order of decreasing predominance.
No more than three groups are used in a single PIREP.
Weather layers are entered with the base and/or top of the layer when reported. The same format as in the sky condition (/SK) group is used.
Example:
/WX FU002-TOP030 Base of a smoke layer, 200 feet MSL, top 3,000 feet MSL
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-37
3.2.1.8 Air Temperature (/TA) Outside air temperature (/TA) is reported using two digits in degrees Celsius. Negative temperatures is prefixed with an M; e.g., /TA 08 or /TA M08.
3.2.1.9 Wind Direction and Speed (/WV) Wind direction and speed is encoded using three digits to indicate wind direction (magnetic) and two or three digits to indicate reported wind speed. When the reported speed is less than 10 knots, a leading zero is used. The wind group will always have KT appended to represent the units in knots.
Examples:
/WV 02009KT Wind 20 degrees (magnetic) at 9 knots /WV 28057KT Wind 280 degrees (magnetic) at 57 knots /WV 350102KT Wind 350 degrees (magnetic) at 102 knots
3.2.1.10 Turbulence (/TB) Turbulence intensity, type, and altitude are reported after wind direction and speed.
Intensity is coded first. Duration is coded next if reported by the pilot (intermittent, occasional, continuous) followed by the intensity using contractions LGT, MOD, SEV, or EXTRM. Range or variation of intensity is separated with a hyphen; e.g., MOD-SEV. If turbulence was forecasted, but not encountered, NEG is entered.
Type is coded second. CAT (Clear Air Turbulence) or CHOP is entered if reported by the pilot.
High-level turbulence (normally above 15,000 feet AGL) not associated with clouds (including thunderstorms) is reported as CAT.
Altitude is reported (last) only if it differs from value reported in the Altitude/Flight Level (/FL) group. When a layer of turbulence is reported, height values are separated with a hyphen. If lower or upper limits are not defined, BLO or ABV is used.
Examples:
/TB LGT Light turbulence /TB LGT 040 Light turbulence at 4,000 feet MSL /TB OCNL MOD-SEV BLO 080 Occasional moderate to severe turbulence below 8,000 feet MSL /TB MOD-SEV CAT 350 Moderate to severe clear air turbulence at 35,000 feet MSL /TB NEG 120-180 Negative turbulence between 12,000 to 18,000 feet MSL /TB CONS MOD CHOP 220/NEG 230-280 Continuous moderate chop at 22,000 feet MSL, negative turbulence between 23,000 to 28,000 feet MSL /TB MOD CAT ABV 290 Moderate clear air turbulence above 29,000 feet MSL
Turbulence reports should include location, altitude, or range of altitudes, and aircraft type, and, when reported, whether in clouds or clear air. The pilot determines the degree of turbulence, intensity, and duration (occasional, intermittent, and continuous). The report should be obtained
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-38 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.
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-39
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
Aviation Weather Services, Advisory Circular 00-45F, Revision 1 AC 00-45F (July 2008) Section 3: Observed Text Products Page 3-40 (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.