Meteorological Terminal Aviation Routine Weather Report

FAA Aviation Weather Services, Advisory Circular 00-45F

Over the years I have heard many pilots say, “It doesn’t matter what the weather is…we’re going anyway!”  On the general aviation side, there is no one looking over your shoulder to make sure you are legal and safe.  In the airlines, you may have a Dispatcher who is jointly responsible, but that doesn’t mean they will catch everything.  In the end, it’s your license and life on the line.  Being able to read a weather report like a METAR is your first line of defense in preparing for each flight.  Even with all the automation we have today, nothing replaces being able to use your own eyes to read a METAR.  It is a powerful tool that should be mastered.

Each section of the METAR is broken down and discussed below:

1. Type of Report:

METAR…

1. METAR – Hourly Routine Report
2. SPECI – Unscheduled when criteria changes between hourly report

2. Station Identifier:

METAR KOKC… (ICAO format) Refer to ICAO Document 791

1. K-United States
2. OKC – Will Rogers World Airport

3. Date/Time Stamp:

METAR KOKC 011955Z…

1. 01 – Day
2. 19 – Hour 
3.  55 – Minutes
4. Z – Zulu (or Universal Coordinated Time)

4. Report Modifier:

METAR KOKC 011955Z AUTO…

1. AUTO – Automated (No human intervention)
2. COR – Corrected (if significant changes since last automated)

5. Wind:

METAR KOKC 011955Z AUTO 22015G25KT 180V250…

1. 220 degrees
 – Wind direction
2. 15 – Steady speed (KT)
3. G25KT
 – Gust (KT)

Speed code:


1. KT (knots)
2. KPH (kilometers per hour)
3. MPS (meters per second)

 Variable Wind Direction:
 (V) Direction varies by >= 60 degrees and > 6 KTS

Example:

180V250
 – Variable 180 degrees to 250 degrees

6. Visibility:

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM…

1. Surface visibility = prevailing visibility
2. SM – statute miles (US)
3. Space coded between whole number and fraction
4. M – U.S. automated stations use “M” to indicate “less than”

Example: 
1 1/2SM – Visibility = 1½ SM


M3/4SM – Visibility < 3/4 SM 

7. Runway Visual Range (RVR):

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT…

1. Horizontal distance pilot may see down runway
2. Reported when prevailing visibility
3. Touchdown zone’s (TDZ) RVR is reported (U.S. airports only)

Example:

R17L/2600FT – (R) Runway 17L RVR= 2600 RVR

RVR varies on runway – RVR difference shown

Example:

R01L/0600V1000FT – Runway 1L (V) varies between 600 and 1,000 ft.

M = RVR

P = RVR > highest reportable value

Examples:

R27/M0600FT – Runway 27 less than 600 RVR

R27/P6000FT – Runway 27 greater than 6000 RVR

8. Present Weather:

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR…

Present weather includes:

1. Precipitation
2. Obscurations
3. Other weather phenomena

• Codes can be grouped
• When precipitation is forecasted with TS, the intensity (+, -) refers to the precip., not thunderstorm

Examples:

1. -RASN  (Light rain) and (light snow)
2. SHRA  (Moderate rain shower) (absence of – or +)
3. -RASN FG HZ  (Light rain) and (light snow) fog & haze
4. +TSRA  (Thunderstorm, heavy rain)

9. Sky Condition:

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB…

Codes:
1. SKC (Clear skies) – indicates no layers are present
2. CLR automated stations indicate no layers detected at or below 12,000 ft.
3. FEW (Few – 1/8-2/8 coverage)
4. SCT (Scattered – 3/8-4/8 coverage)
5. BKN (Broken – 5/8-7/8 coverage) * ceiling
6. OVC (Overcast – 8/8 coverage) * ceiling

Numeric codes:
1. First three letters – Amount of cloud cover
2. Last three digits – Height of cloud base

* Height of the layer reported in feet Above Ground Level (AGL)

Example:

OVC010CB
• Overcast 1000 feet
• Cloud Base (CB)

Sky condition includes:

1. Cloud cover
2. Vertical visibility
3. Clear skies

Example:

SCT009 SCT024 BKN048

1. Scattered layer at 900 ft.
2. Scattered layer at 2,400 ft.
3. Broken layer (ceiling) at 4,800 ft.

* BKN & OVC are considered ceilings for approach minimums

VV (Vertical visibility) – no particular cloud layer

This limits runway acquisition due to poor slant range visibility because of obscuration (e.g., fog, blowing dust, snow)

* Pilot would see the ground, but not runway.

10. Temperature/Dew Point:

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB 18/16…

Example:
18/16
1. 18 – Temperature ºC
2. 16 – Dew Point ºC

M = Minus temp (M05) – 05ºC

11. Altimeter:

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM
R17L/2600FT +TSRA BR OVC010CB 18/16 A2992…

1. Group always starts “A”
2. Followed by the four-digit group representing the pressure
3. True altitude above a fixed plane of mean sea level (MSL).

Example:
A2992 – Setting of 29.92 inches of Mercury

12. Remarks (RMK):

METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SMR 17L/2600FT +TSRA BR OVC010CB 18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132

Type of Automated Station:

1. AO1 – Automated station without a precipitation discriminator
2. AO2 – automated stations with a precipitation discriminator

Beginning and Ending of Thunderstorms:

1. TS (thunderstorm)
2. B (beginning)
3. E (ending) and the time of occurrence
4. No spaces between elements

Example:

TSB25

TSB – Thunderstorms began

25 – Minutes past hour

Thunderstorm Location:

Example:

TS OHD MOV E

1. TS – Thunderstorm
2. OHD – Overhead of the station
3. MOV – Moving
4. E  – East

Peak Wind:

Example:

PK WND 28045/15

1. PK WND – Peak wind
2. 280 – 280 degrees
3. 45 – 45 KTS
4. 15 – Occurred 15 minutes past the hour

Wind Shift:

Example:

WSHFT 30 FROPA

1. WSHFT – Wind shift
2. FROPA – Accompanied by a frontal passage
3. 30 – Began 30 minutes after hour

Lightning:

When lightning is detected by an automated system:

1. TS – <= 5 NM of Airport Location Point (ALP). Reported in body of METAR report with no remark
2. VCTS – Between 5 and 10 NM of ALP
3. LTG DSNT – > 10, but < 30 NM of ALP

Sea-Level Pressure:

Example:

SLP132

1. SLP – Sea-level pressure
2. 132 – 1,013.2 mb

Hourly Temperature and Dew Point:

1. At designated stations
2. Hourly temperature and dew point group
3. Further coded to tenth of a degree Celsius (ºC)

Example:

T00261015

1. T – Temp Group indicator
2. 0 – First “0” indicates next number is positive (“1” if negative)
3. 026 – Temperature to nearest tenth and read as positive (+02.6ºC)
4. 1 – Indicates the next number is negative (“0” used if number positive)
5. 015 – Dew Point read as negative (-01.5ºC) Reported in Temp section of METAR as 03/M01 (Section #10 above)

Data Not Available

When a data group not available, “/” will be reported instead of group

Example:

//// for visibility, // for weather and ////// for clouds f

Conclusion

There are many more considerations in weather analysis, such as TAFs and Weather Depicton Charts.  We will discuss those later.  For now, being able to read a METAR will get you off to a good start.

We can learn a lot from each other. We hope you find our website and other articles helpful in your career.

Please leave your comments below and share any personal experiences and lessons learned.