Met 14 - Weather Forecasts for Flight Planning

What is the purpose of pre-flight weather information?

To help pilots plan safely and avoid hazardous weather

What do national meteorological services use to make forecasts?

Reports from global stations and computer models

What types of forecasts are available to pilots?

Synoptic charts, AIRMET, GAMET, F215, TAFs, SIGMETs, SPECIs

What are synoptic charts also called?

Surface pressure or MSL pressure charts

What do synoptic charts show?

Pressure systems and fronts at a specific time

When are UK synoptic charts typically valid?

At 00:00 and 12:00 UTC

What does 'H' indicate on a synoptic chart?

Centre of a high-pressure system

What does 'L' indicate on a synoptic chart?

Centre of a low-pressure system

What does a cold front symbol represent?

Leading edge of advancing cold air

What does a warm front symbol represent?

Leading edge of advancing warm air

What is an AIRMET?

A low-level regional forecast (replaced by GAMET in the UK)

When is a strong wind warning issued in AIRMET?

When winds ≥ 15 KT or gusts ≥ 28 KT

What does a GAMET forecast provide?

Detailed weather forecast for general aviation

What is included in a GAMET?

Wind, visibility, cloud, weather, icing, turbulence, outlook

What is the F215 chart?

A UK low-level forecast from surface to 10,000 ft

How often is the F215 issued?

Every 6 hours

What does the F215 outlook cover?

The following 7 hours beyond the chart validity

What do scalloped edges on F215 indicate?

Different forecast areas

What does the F415 chart cover?

Forecast from UK to central Europe up to 10,000 ft

What are SIGWX charts used for?

Showing significant weather phenomena affecting aircraft

What do high-level SIGWX charts show?

CB clouds, icing, turbulence, jet streams, CAT, tropopause level

What does a triangle on a jet stream symbol represent?

50 knots of wind speed

What does each feather on a jet stream symbol represent?

10 knots of wind speed

What cloud types are commonly shown on forecast charts?

CB, TCU, CU, SC, ST, AS, AC

What is the typical base of altostratus or altocumulus?

Around 7000 ft AMSL

What visibility is considered good in F215?

25 km with no weather

What does 'ISOL' mean in F215?

Isolated, affecting less than 25% of the area

What does 'OCNL' mean in F215?

Occasional, affecting 25–50% of the area

What does 'FRQ' mean in F215?

Frequent, affecting more than 50% of the area

What does 'WDSPR' mean in F215?

Widespread

What does 'NSC' mean in aviation forecasts?

No significant cloud

What is the 0° isotherm used for?

To determine the freezing level

What is the freezing level in the southwest in the F215 example?

Above 10,000 ft AMSL

What cloud base is associated with stratus?

300–1000 ft AMSL, 0 ft in fog

What does 'TS or CB' imply in a forecast?

Hail, severe turbulence, and icing

What is considered fog in aviation terms?

Visibility less than 1 km

What does 'Hill Fog' mean?

Cloud base at or below highest terrain, typically under 180 m

What does '+TSRA' mean?

Thunderstorm with heavy rain

What does 'GR' mean in weather codes?

Hail

What does 'DZ' mean?

Drizzle

What does 'BR' mean?

Mist

What does 'FZ' mean in forecasts?

Freezing

What does 'MTW' mean?

Mountain waves

What does 'TS' mean?

Thunderstorm

What does 'SH' mean?

Showers

What does 'RA' mean?

Rain

What is 'CAVOK'?

Visibility ≥10 km, no significant weather, and no cloud below 5000 ft

What does 'SCT' indicate?

Scattered clouds covering 3–4 oktas

What does 'BKN' indicate?

Broken cloud covering 5–7 oktas

What does 'OVC' indicate?

Overcast cloud covering 8 oktas

What does 'FEW' indicate?

1–2 oktas of cloud coverage

What is the symbol 'XXX' used for?

Cloud tops above 10,000 ft AMSL

What does 'FPM' stand for?

Feet per minute

What does 'VSP' mean?

Vertical speed

What does 'N, NE, E, ENE' indicate?

Compass points for directions or areas

What does 'FM 13 Z' mean?

From 1300 Zulu time

Why is it important to consider actual reports along with forecasts?

Because weather may change and actuals confirm current conditions