1. FORECASTING COURSE SPECI CODING

2. Presentation Objectives
After this presentation session you will be able to:
Understand the criteria used in the issue of special reports (SPECI)
Apply the criteria in order to issue SPECI

3. SPECIs (special reports) are to be issued under the following weather conditions: -
When a deterioration of one weather element is accompanied by an improvement in another element, a single selected special report shall be issued; it shall then be treated as a deterioration report.
A SPECI representing a deterioration of one weather element and an improvement in another element should be disseminated immediately after the observation.
A SPECI representing a deterioration in conditions should be disseminated immediately after the observation.
A SPECI representing an improvement in conditions should be disseminated, if necessary, to indicate the conditions prevailing at the end of that 10-minute period.  

4. SURFACE WIND CRITERIA
When the mean surface wind direction has changed by ≥ 60° from that given in the latest report,
BUT the mean speed before and/or after the change must be ≥ 20 km/h (10kt).
When the mean surface wind speed has changed by 20 km/h (10kt).
Variation from the mean surface wind speed (gusts) has increased by ≥ 20 km/h (10kt) from that given in the latest report,
BUT the mean speed before and/or after the change being ≥ 30 km/h (15kt)

5. Wind direction and/or speed
Ave wind speed change of ≥ 10kts 1
36 = 360
270 = 27
180 = 18
09 = 090
01 =010
05 = 050
04 = 040
02 = 020
03 = 030
06 = 060
10 = 100
11 = 110
08 = 080
07 = 070
340 = 34
12 = 120
13 = 130
230 = 23
290 = 29
14 = 140
350 = 35
280 = 28
16 = 160
15 = 150
17 = 170
260 = 26
250 = 25
240 = 24
220 = 22
210 = 21
200 = 20
300 = 30
310 = 31
330 = 33
320 = 32
190 = 19
Variation between gusts and ave wind speed is ≥ 10kts The ave wind speed before and or after being ≥ 15 kts 2
Ave wind direction change of ≥ 60° The ave wind speed before and or after being ≥ 10 3

6. HORIZONTAL VISIBILITY CRITERIA
When the visibility changes to or passes 800, or 3 000m
5 000 m, in cases where significant numbers of flights are operated in accordance with the visual flight rules
When the RUNWAY VISUAL RANGE changes to or passes 150, 350, 600 or 800m

7. Horizontal visibility
Horizontal visibility is deteriorating AND passes through the following…
A deterioration
Using RVR
Runway Visual Range
150m
350m
600m
800m
800m
1500m
3000m
5000m
Horizontal visibility
Using eyes & visibility markers
An improvement
Horizontal visibility is improving AND changes to or passes through the following

8. CLOUD AMOUNT CRITERIA
When the amount of cloud below 450 m (1 500 ft) changes from
Less than FEW, FEW or SCT …… to …… BKN or OVC or
BKN or OVC …… to ……SCT or FEW or less than FEW.

9. Cloud amount 7/8 6/8 5/8 8/8 BKN OVC SCT or less BKN or OVC or from
4/8
SCT or less BKN or OVC
or from
OVC or BKN SCT or less
Cloud cover changes from … … …
Cloud base ≤ 1500 ft

10. CLOUD BASE HEIGHT CRITERIA
When the height of the lowest cloud layer of BKN or OVC extent, changes to or passes
30, 60, 150 or 300 m (100, 200, 500 or ft)
AND 450 m (1 500 ft), where significant numbers of flights are operated in accordance with the visual flight rules
VERTICAL VISIBILITY CRITERIA
Where the sky is obscured and the vertical visibility changes to or passes through
30, 60, 150 or 300m (100, 200, 500 or 1 000ft).

11. Cloud height along with Cloud cover of BKN or OVC 1500ft 1500ft
Cloud height lifting or improving AND changes to or passing through
Cloud height lowering or deteriorating AND passing through
1000ft
1000ft
500ft
500ft
200ft
200ft
100ft
100ft
Earth’s surface

12. PRESENT WEATHER CRITERIA
the following significant weather begins or changes or ends in intensity
TS (with or without precipitation), freezing precipitation
Freezing precipitation
FZFG
Mod or heavy precipitation (including showers thereof)
DRDU, DRSA, DRSN
BLDU, BLSA, BLSN
DS, SS and including snowstorm SQ
FC (tornado or waterspout)
…………begins or ends or changes in intensity

13. Present weather – (the start or cessation of)
marked by the advance
of a “wall of dust”
up to 3000m high
including showers
with or without precipitation
Moderate Heavy precipitation FC TS
course sand particles
up to a max of 20–30m
a sudden increase in wind speed
of at least 16 kts
with a new speed of at least 22 kts
and lasting for at least 1 minute
raised by the wind
to more than 2m agl
BLDU
BLSA
BLSN
raised by the wind
to less than 2m agl SQ DS SS
FZRA
FZFG
DRDU
DRSA
DRSN
Surface temperature must be < 0 °C for precipitation or fog to freeze on contact with the surface.

14. SURFACE TEMPERATURE CRITERIA
When an increase in air temperature of ≥ 2°C from that given in its latest report occurs.
TEMP An increase of ≥ 2°C at any given point in time