Chapter 3
3.1 METAR
METAR
- Roughly translated from the French as Aviation Routine Weather Report
- On July 1 1996 the METAR format was adopted for global standardization
- Provides common frame of reference for international flights
METAR
- 2 Types:
- METAR comes out hourly from H+45 to the top of the hour
- SPECI which is non routine and comes out when special conditions exist… see table 3-1
Types of Observations
- Manual Observation
- Done by a human
- Automated Observation
- Automated surface observing system (ASOS)
- Automated Weather Observing System (AWOS)
- Augmented Observation
- Human oversight, including tower personnel
- AUTO is not used when the wx dude gets involved
METAR
- Type of Report
- Station ID
- Date/Time
- Modifier
- Wind
- Visibility
-
- Weather
- Sky condition
- Temp/Dew point
- Altimeter
- Remarks
METAR DECODED
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
TYPE OF REPORT
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
-
- SPECI KMWH 282021Z 00000KT 2SM BR OVC009 01/M01 A3076 RMK AO2 CIG 003V011 T00111011
- Designates if it is a METAR or SPECI
ICAO IDENTIFIER
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- ICAO identifier, K = continental U.S.
DATE AND TIME
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- 30 = day of the month, 1456Z indicates time the report was issued in Zulu
MODIFIER
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- AUTO will be absent if the report is taken by or augmented by a human.
MODIFIER
- METAR KSMP 301456Z COR VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- COR will be present if a corrected report has been sent out.
WIND
- METAR KSMP 301456Z AUTO 09026KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- The first three digits are direction, last two or three digits are velocity in knots. Direction is True and which way it is FROM
WIND
- METAR KSMP 301456Z AUTO 08012G25KT 040V120 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Wind gust is a rapid speed change of 10kts or more.
- To be reported as variable, direction must vary 60˚ or more and speed greater than 6kts. If speed is less than 6, then VRB will be reported.
WIND
- METAR KSMP 301456Z AUTO 00000KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- If calm, then it will be reported as 00000KT
VISIBILITY
- METAR KSMP 301456Z AUTO VRB06KT M1/4SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Automated stations use an M to indicate “less than”
VISIBILITY
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Visibility is reported in Statue Miles.
- P6SM means visibility greater than 6 statue miles.
RVR
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM R32R/3000V4500FT SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- R denotes the group, 32R the runway, 3000V4500FT the visual range 3000 variable to 4500.
RVR
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM R32R/M0600FT SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- RVR is coded from 600’ to 6000’. P or M indicates Above or Below those limits (R32R/M0600FT)
PRESENT WX GROUP
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Intensity qualifiers: (-) = light, none = ( )
- moderate, (+) = heavy.
- Weather is inside a 5 mile radius.
- VC for 5-10 mile radius.
- See table 3-2 for descriptors.
- BR is vis 5/8 to 6 miles, FG is less than 5/8.
PRESENT WX GROUP
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Descriptor qualifiers MI=shallow, PR=partial, BC=patches, DR=low drifting, BL=blowing, SH=showers, TS=t-storm, FZ=freezing.
PRESENT WX GROUP
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM TSB05E45 VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Thunderstorm began 5 min after the hour and ended 45 min after the hour.
SKY CONDITION
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- OVC = overcast, BKN = broken, SCT = scattered, FEW = few, SKC = from a human, CLR = from a machine at or below 12,000. OVC020 clouds are 2000 AGL. See table 3-3.
SKY CONDITION
- Height is reported in AGL
- Cloud type may be reported TCU, CB, ACC
- VV = Vertical Visibility, VV001
- Ceiling is broken or overcast
- If the sky is obscured VV is the ceiling
- Sky is broken into 8ths Table 3-3
Sky Cover
- The abbreviation CLR will be used at automated stations when no layers at or below 12,000 feet are reported
- The abbreviation SKC will be used at manual stations when no layers are reported.
- Any layer amount less than 1/8 is reported as FEW.
SKY CONDITION CODING
TEMPERATURE/DEW POINT
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Temperature/Dew Point in Celsius
- M = Minus
ALTIMETER
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Altimeter setting measured in inches of Hg 30.19
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Remarks are used to clarify the conditions specified in the body of the report. Checkout pg 3-18
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- AO2 = Precip discriminator, A01=No Precip discriminator
- PK WND = Highest wind speed since the last METAR in direction, speed and time (PK WND 20032/15)
- WSHFT = Wind shift and the time. If due to frontal passage then FROPA is entered (WSHFT 30 FROPA)
- TWR VIS = Vis given by the tower (TWR VIS 1 1/2)
- VIS 1/2V2 = Variable visibility
- VIS NE 2 1/2 = Sector visibility
- VIS 2 1/2 RWY 14L = Vis at a second location
- OCNL LTGICCG NW, FRQ LTG VC, or LTG DSNT W
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Sea Level Pressure 1025.8 Add a 10 or a 9 whichever will bring the number closest to 1000
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Pecip amount 8/100ths of an inch, 6 hour precip amount .20 inches
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- 6 hour precip amount. 6 is the group indicator, the following 4 digits the amount
- .20 inches of precip
- 2.17 inches would code out to 60217
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T00221028 58004 TSNO $
- Temperature Plus 2.2°C Dew Point Minus 2.8°C 1=minus, 0=plus
- $ means maintenance is needed
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 TSNO
- Pressure tendency 8=steady or increasing then decreasing by 0.04 hectopascals
REMARKS
- METAR KSMP 301456Z AUTO VRB06KT 1/2SM SN FZFG VV001 M02/M03 A3019 RMK AO2 SLP258 P0008 60020 T10221028 58004 SHRAB05E15SHSNB20E55 TSNO
- Rain showers began 0005 and ended 0015 then snow showers began 0020 and ended 0055
AWOS, ASOS, AMOS
- Automated wx
- Provides minute by minute wx data
- Stations are strategically located in the runway complex
- Uses same technique as humans do for pressure, temp, dew point, wind, and precip accumulation
- For sky condition uses fixed location time averaging technique
- Humans use fixed time spatial averaging technique
AWOS, ASOS, AMOS
- 4 MODES
- 1. Full time operation
- 2. Full time operation with local notams
- 3. Full time operation with manual augmentation and local notams
- 4. Manual operation
- Broadcasts ground to air and telephone
AWOS, ASOS, AMOS
- Ceiling and sky cover
- Visibility
- Temp dew point
- Wind direction, speed and gusts
- Altimeter setting
- Remarks, density altitude, variable vis, variable wind direction
- AMOS only gives info when asked by net.
Chapter 3
3.2 PIREPS/AIREPS
Aircraft Obs and Reports
- There are 2 kinds
- –Pilot weather reports
- Routine and urgent
- –Aircraft reports
- Routine and urgent
AIREP
- These can be reported by the pilot or by sensors onboard the aircraft
- The AIREP format is used world wide
- The PIREP format is a U.S. thing
PIREPS
- The only means of getting:
- 1. Cloud tops
- 2. Icing
- 3. Turbulence
- 4. Layers
- 5. In-flight vis
- They are available on the ADDS site
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- ICAO location Identifier
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Type of Report UA = Routine report, UUA = Urgent report (pg 3-32 for details)
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Location = MWH 070º radial, 15 NM out. OV YKM = directly over nav aid
PIREP
- MWH UA /OV MWH070015-EAT250010 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Route description = from the MWH 070 rad at 15 NM to the EAT 250 rad at 10 NM
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Time report was taken in Zulu.
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Flight level = 37,000 feet. FL040 = 4,000 feet MSL
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Aircraft Type TP UNKN means type is unknown
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Sky cover = Overcast with bases at 4,000 tops at 8,000
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Flight Visibility in statute miles. FV99SM = visibility unrestricted See table 3-7 for restrictions to vis
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Temperature in ºC, M = minus
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Wind direction in mag velocity in knots = 320º at 52 kts
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Turbulence can be classified as Light, Moderate, Severe, and Extreme (Table 3-8)
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /IC LGT RIME /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Icing intensities trace, light, moderate, severe and type rime, clear, mixed. (Table 3-9)
PIREP
- MWH UA /OV MWH070015 /TM 1448 /FL370 /TP B757 /SK OVC040-TOP080 /WX FV50SM /TA M58 /WV 32052KT /TB SMOOTH WITH OCSNL MOD CHOP /RM MOUNTAIN WAVE +/- 20K…LAST 30 MILES
- Remarks clarify items in the body of the report. LLWS, TORNADO, TS, LTGIC (in cloud), LTGCC, LTGCG, LTGCA (cloud to air)
PIREP
PIREPS
- All altitudes are MSL unless otherwise noted
- Distance for visibility is in statute miles
- Distance for everything else is in nautical miles
- Time is in Zulu
Chapter 3
Section 3.3 Radar
Weather Surveillance Radar
- WSR-88D
- Weather Surveillance Radar – 1988 Doppler
- AKA NEXRAD
- Consists of 159 (2/17) radar installations
- Observation times are not standard
- Nor are they linked to other radar sites
- So good for the time listed
Modes of Operation
- Clear Air Mode
- Most sensitive
- Slowest rotation rate
- Images update every 10 minutes
- Precipitation Mode
- Less sensitive
- Faster rotation rate
- Images update every 4 to 6 minutes
Echo Intensities
- Colors represent echo intensities in dBZ
- Scale goes from -30 (least) to 75 (most)
- Check table 4-1 for ATC terminology based on echoes
- Values below 15 dBZ are usually just clouds but may be dust, insects, pollen ect.
- This means values above 15dBZ are probably precip, although may be virga
- Snowfall intensity is not show by the table
- Usually the higher the return the heavier the snowfall rate
Radar Mosaics
- Multiple radar images combined
- These may be base or composite
- Intellicast has my favorite
Base Reflectivity
- Radar is aimed about half a degree above the horizon (0.5°)
- Short range to 124 NM
- Long range out to 248 NM
Base Reflectivity
- Useful for:
- Finding precip probably reaching the ground
- The intensity of precip
- Coverage of precip
- When looped, movement of precip
Base Reflectivity
- For stratiform precip look for:
- Widespread coverage
- Weak reflectivity
- 39 dBZs or less
- Slow change when looped
- For cumulus precip look for:
- Small cells
- Strong reflectivity
- High dBZs
- Can be fast moving and or dissipating
Base Reflectivity Limitations
- Beam Overshoot
- Curvature of the earth contributes
- Use a mosaic or a closer site
Base Reflectivity Limitations
- Beam Undershoot
- Happens at elevations above the base scan close to the station
Base Reflectivity Limitations
- Beam Blockage
- May be minimized by looking at the mosaics
Base Reflectivity Limitations
- Ground Clutter
- Trees, buildings and stuff
- Computer is supposed to eliminate most of this
Base Reflectivity Limitations
- Ghost
- Caused by
- insects
- superrefraction
- certain settings used on the radar equipment when the real echo is farther out
Base Reflectivity Limitations
- Angels
- Bats, Birds, Insects
- Usually only happens in clear air mode
- Base Reflectivity Limitations
- Anomalous Propagation
- One of the biggest enemies of radar
- Changes in air density can bend the radar
- Computer enhancement and use of multiple sites to defeat AP
Base Reflectivity Limitations
- Wind farms
- If within 10 NM they cause
- Beam blockage
- False echoes
- High reflectivity values
Composite Reflectivity
- Radar scans through multiple elevations
- Gives a more complete vertical picture
- When compared to the base reflectivity you can get an idea of the structure of the precip
- Has the same limitations as discussed for the base
Base vs Composite Reflectivity
- Especially useful for cumuliform cloud structures.
- Allows you to develop a vertical picture of intensities
Radar Coded Message
- The RCM replaced the RAREP, ROB, SD
- Updated every 30 min
- Based on the composite reflectivity
- Includes the max echo top for each site
- Can show errors when precip is far away
New Stuff
- Product update to 5 min
- Mosaicked Composite Reflectivity
- Dual Polarization Radar
- Better at determining what the precip is
- Including Graupel (snow pellets) and
- Hail
Terminal Doppler Weather Radar
- Used for detection of
- Wind shear (microbursts)
- Precipitation
- Winds aloft
- There are 47 TDWR stations at bigger airports
Terminal Doppler Weather Radar
- TDWR vs WSR-88D
- Resolution is higher
- TDWR 150 meters (500’) within 135 km (72NM) and 300 m (1000’) beyond 135 km
- WSR-88D 250 m (820’)and 1 km (.5NM) for surveillance data
- Beam width
- TDWR .55 degrees
- WSR-88D .95 degrees
Terminal Doppler Weather Radar
- Normally the radar runs in monitor mode (VCP 90) until
- A region of 20 dBZ echoes located within 24.3 NM from the associated airport with a nominal areal extent of 1.3 NM and an altitude of at least 1.3 NM AGL, or
- The radar detects windshear or a microburst.
- At which point the radar shifts into hazardous mode (VCP80) to achieve higher rates of data
Terminal Doppler Weather Radar
- There are 3 categories of products available
- General Products
- Base Reflectivity, Base Velocity, Spectrum Width, Vertically Integrated Liquid, and the Velocity Azimuth Display (VAD) Wind Profile.
- Precipitation Products
- Estimated ground accumulated rainfall
- Overlay Products
- Detailed info for storm cells
- Radar Messages
- Information about the radar status and special product data
Chapter 3
Section 3.4 Satellite
GOES-R Series Satellites
- GOES (Geostationary Environmental Satellite) sit at 22,000 miles out in geostationary orbit
- GOES 16 was Launched in 11/19/2016
- GOES-16 observes Earth from the coast of West Africa, to Hawaii, and everything in between.
- GOES-17 was launched on 03/01/2018
- GOES-17 will cover the west coast of the US and the Pacific to New Zealand
- Is the single most important source of wx data
Spider Lightning
SATELLITE PICTURES
- 1. GOES Geostationary Environmental Satellite
- visible imagery depends on height thickness and ability to reflect
- infrared is heat radiation (high clouds less heat)
- 2. POES Polar Orbiter Environmental Satellite
- They orbit from 124 to 1.240 miles up
- Since they are closer the resolution is better, 5/8 of a mile
- Not stationary so it can be several hours before it passes over an area
Satellite
- 3 different images
- Visible
- Infrared
- Water vapor
Visible Imagery
- The amount of reflected light is referred to as albedo
- The band across the top is the albedo in %
- Visible imagery has the highest resolution of the 3
- It approximates what the eye sees
- High thin clouds are grey
- Thicker more dense and snow appear whiter
Infrared Imagery
- This is a measurement of temperature
- The warmer the more energy
- The colors are used to enhance readability
- Sort of like the colors on the Coors light bottle enhance drinkability
Color IR
https://www.aviationweather.gov/satellite?date=
Infrared Imagery
- Unenhanced decoding
- Shades of grey are equated to temp in C
- Land is warm
- High clouds are cold duh!
Water Vapor
- Displays the quantity of water vapor located from about 700mb (10,000 ft) to 200mb (FL390)
- No direct relationship between temp on the chart and the temp of the clouds
- Most useful for locations and movements of weather systems, jets and thunderstorms
- Shades of red are very dry
- Shades of blue or green are moist
- Available 24 hours a day
Water Vapor Imagery
- Displays the quantity of water vapor
- Good for locating wx systems, jet and TS
- Shades of red indicate very dry conditions
- Shades of pink, blue and orange indicate lots of moisture
- When used with other wx products it may give an idea of what type of clouds to expect
Using Them Together
Chapter 3
3.5 Upper-Air Observations
RADIOSONDE OBSERVATIONS
- A radiosonde is a small instrument package carried aloft by balloon
- Measures pressure, temp, wind speed/direction and moisture
- Ascends at about 1,000 ft/min
- Launched twice daily at 11:00z and 23:00z
- Takes about 90 minutes to reach 100,000 feet
DROPWINDSONDE
- Dropped from weather research aircraft
- Usually dropped over the ocean where meteorological information is highly lacking
- Measures pressure, temperature, moisture, and the vertical distribution of horizontal wind speed and wind direction
- They play an important role in improving the forecast of typhoon/hurricane track and intensity.
Chapter 3
3.7.2 METARS on Aviationweather.gov