Meteorology
To allow you to interpret weather information and assess the actual weather occurring and make decisions based on what you see.
The Met Office
Learning Centre
The Met Office
Interpreting weather maps
The Met Office
Weather charts
The Met Office
Guide to Weather Chart Symbols
The Met Office
Weather abbreviations
The Met Office have information on
Air masses and fronts
Metar - Explanation
The Metar report for Southend will look something like the list below.
| SOUTHEND |
EGMC |
032250Z |
01008KT |
5000 |
-DZ BR |
BKN005 |
08/06 |
Q1028 |
|
| Name of Airport |
Location Indicator |
Date & Time |
Wind |
Visibility |
Present Weather |
Cloud |
Temperature & Dew Point |
QNH |
| Self explanatory |
EGMC is the ICAO indicator
for Southend |
Date & Time
03 - Date
2250Z
10.50pm zulu or UTC time |
Wind Direction & Speed
010degrees/08 Knots |
Visibilty
0000 = 'less than 50 metres'
9999 = 'ten kilometres or more'.
No direction is required. |
DZ=Drizzle
BR=Mist
See list below |
BKN=Broken
005 = 500feet
See list below |
Temperature & Dew Point
M indicates a negative value
M003/M002 |
QNH
Q indicates the sea level pressure millibars.
If the letter A is used QNH is in inches and hundredths. |
|
Present Weather
|
|
+ = Heavy (well developed in the case of +FC and +PO); - = Light;
no qualifier = Moderate.
|
| BC=Patches |
BL=Blowing |
BR=Mist |
DR=Drifting |
| DS=Duststorm |
DU=Dust |
DZ=Drizzle |
FC=Funnel cloud |
| FG=Fog |
FU=Smoke |
FZ=Freezing |
GR=Hail (>5mm) |
| GS=Small hail or snow pellets |
HZ=Haze |
IC=Ice crystals |
MI=Shallow |
| PL=Ice pellets |
PO=Dust devils |
PR=Banks |
RA=Rain |
| SA=Sand |
SH=Showers |
SG=Snow grains |
SN=Snow |
| SQ=Squalls |
SS=Sandstorm |
TS=Thunderstorm |
VA=Volcanic ash |
| VC=In vicinity |
|
|
|
| Up to three groups may be present, constructed
by selecting and combining from the above. Group omitted
if no weather to report. |
| Cloud |
| SKC=Sky clear (0 oktas) |
FEW='few' (1-2 oktas) |
SCT='Scattered' (3-4 oktas) |
BKN='Broken' (5-7 oktas) |
OVC='Overcast'. |
|
There are only two cloud types reported; TCU=towering cumulus and
CB=cumulonimbus. VV///='state of sky obscured' (cloud base
not discernable): Figures in lieu of '///' give vertical visibility
in hundreds of feet. Up to three, but occasionally more, cloud
groups may be reported.
Cloud heights are given in feet above airfield height
|
CAVOK
Visibility greater or equal to 10 km, no cumulonimbus, no cloud below 5000 ft or highest MSA (greater) and no weather significant to aviation.
|
Trends |
| Example | Explanation | Further info |
| BECMG
FM1100 23035G50KT TEMPO FM0630 TL 0830 3000 SHRA |
'becoming
from 1100, 230 degrees 35 KT , max 50 KT, temporarily from 0630
until 0830, 3000 metres, Moderate rain shower's |
| BECMG=Becoming |
TEMPO=Temporarily |
NOSIG=No sig change |
| NSW=No sig weather |
AT=At |
FM=From |
| TL=Until |
NSC=No sig cloud |
|
| Any of the wind forecast, visibility, weather
or cloud groups may be used, and CAVOK. Multiple groups
may be present. |
*CAVOK will replace visibility and cloud groups
|
Dew point - The temperature at which the air, when cooled, will just become saturated.
Hoar frost is composed of tiny ice crystals and is formed by the same process as dew, but when the temperature of the surface falls below freezing point.
Water drops larger than 0.5 mm in diameter are classed as rain.
Precipitation will fall as snow when the air temperature is below 2 °C.
The official definition of fog is a visibility of less than 1,000 metres.
Military Aerodrome colour codes
In addition to a normal TAF or METAR, military aerodromes may use a colour code, which is a form of shorthand for their crews to reinforce the information in the main message. The meaning of each colour is listed below. PPL holders without instrument qualifications are advised that any code except "blue" or "white" may indicate serious problems, and even "white" is no guarantee that the weather is good, even at the time of the report.
Colour Code |
Minimum base of lowest cloud
(SCT or more)above aerodrome level
|
Minimum reported visibility |
Blue |
2500 feet |
8km |
White |
1500 feet |
5km |
Green |
700 feet |
3700 m |
Amber |
200 feet |
800 m |
Red |
Below 200 feet (or sky obscured) |
below 800 m |
| Black |
Aerodrome unavailable for reasons other than cloud or visibilty |
|