3.5 Reading TAF Reports

3.5 Reading TAF Reports

A Terminal Aerodrome Forecast (TAF) predicts weather conditions at an airport for a period of 24 to 30 hours. TAFs are issued 4 times daily (0000Z, 0600Z, 1200Z, 1800Z) and use a similar format to METARs but include change groups to show expected weather transitions.

TAF Format

A sample TAF:

TAF KORD 121720Z 1218/1318 27012KT P6SM SCT030 BKN050
  FM130200 33008KT P6SM FEW040 SCT250
  TEMPO 1304/1308 2SM BR OVC010
  BECMG 1310/1312 18015G25KT 3SM -RA OVC020

Header Line

Initial Forecast Line

The first line after the header gives the initial conditions expected during the first portion of the valid period:

• 27012KT — Wind from 270° at 12 knots
• P6SM — Visibility greater than 6 statute miles (P = plus/exceeding)
• SCT030 BKN050 — Scattered at 3,000 ft, broken at 5,000 ft (ceiling: 5,000 ft)

Change Groups

TAFs use specific keywords to indicate how conditions will change:

FM (From)

FM indicates an abrupt change at a specific time:

FM130200 33008KT P6SM FEW040 SCT250

• Starting at 13th day, 0200Z, conditions will shift to:
• Wind from 330° at 8 knots, visibility >6 SM, few at 4,000 ft, scattered at 25,000 ft

Key: FM replaces all previous conditions — everything after FM is the new forecast.

TEMPO (Temporary)

TEMPO indicates temporary fluctuations expected during a specific period:

TEMPO 1304/1308 2SM BR OVC010

• Between 13th 0400Z and 13th 0800Z
• Conditions may temporarily drop to: 2 SM visibility, mist, overcast at 1,000 ft
• Conditions fluctuate — these are temporary variations, not sustained changes
• Each occurrence lasts less than 1 hour and covers less than half the TEMPO period

BECMG (Becoming)

BECMG indicates a gradual change over a specified period:

BECMG 1310/1312 18015G25KT 3SM -RA OVC020

• Between 13th 1000Z and 13th 1200Z, conditions will gradually change to:
• Wind from 180° at 15 knots gusting 25, visibility 3 SM, light rain, overcast at 2,000 ft
• The change is complete by the end time (1312 = 1200Z on the 13th)

PROB (Probability)

PROB indicates the probability of conditions occurring:

PROB40 1302/1306 1SM +TSRA BKN015CB

• 40% probability between 0200Z and 0600Z on the 13th
• Conditions: 1 SM visibility, heavy thunderstorms and rain, broken cumulonimbus at 1,500 ft
• Only PROB30 and PROB40 are used in TAFs

TAF vs. METAR Comparison

Using TAFs for Flight Planning

For Part 107 operations:

1. Check the METAR for current conditions before flying
2. Check the TAF for expected changes during your planned flight window
3. Focus on visibility (must remain ≥3 SM), ceiling (500 ft clearance below BKN/OVC), and wind
4. Pay attention to TEMPO groups — temporary drops to below Part 107 minimums mean you should have a plan to land quickly
5. If a PROB40 +TSRA (40% chance of thunderstorms) appears during your flight window, consider postponing

Exam Tip: TAF questions on the exam will ask you to determine weather conditions at a specific time within the TAF valid period. Work through the change groups chronologically to find which conditions apply at the given time.