CHAPTER 9 - SPECIAL OBSERVATIONS

9.1 Introduction

This chapter explains the criteria for taking special observations (SPECI).

9.2 Special Observations

SPECIs are taken whenever mandatory criteria are met, and at the discretion of the observer, to report significant weather changes. Unscheduled, non-hourly observations taken for SAWRS 135 operations will use this classification, but their content will be the same as a METAR. SPECIs are also taken when an aircraft accident or mishap occurs, and for any weather situation that in the opinion of the observer is critical to local operations.

9.2.1 Special Observation Criteria

Take, record, and disseminate a SPECI observation when any of the following is observed to occur:

a. WIND SHIFT. Wind direction changes by 45 degrees or more in less than 15 minutes and the wind speed is 10 knots or more throughout the wind shift.

b. VISIBILITY. Surface visibility as reported in the body of the report decreases to less than or, if below, increases to equal or exceed:

(1) 3 miles.

(2) 2 miles.

(3) 1 mile.

(4) Lowest standard instrument approach procedure minimum as published in the National Oceanic Service (NOS) U. S. Terminal Procedures. If none is published, use 1/2 mile.

c. TORNADO, FUNNEL CLOUD, OR WATERSPOUT.

(1) Is observed.

(2) Disappears from sight or ends.

d. THUNDERSTORM.

(1) Begins (The beginning of a thunderstorm is the earliest time thunder is heard or lightning is observed at the station when the local noise level is sufficient to prevent hearing thunder.) (a SPECI is not required to report the beginning of a new thunderstorm if one is currently being reported).

Ch. 9 Pg. 1 (2) Ends. (The ending of a thunderstorm is considered to be 15 minutes after thunder was last heard).

e. PRECIPITATION. (1) Hail begins or ends.

(2) Freezing precipitation begins, ends, or changes intensity.

(3) Ice pellets begin, end, or change intensity.

f. SQUALLS. When squalls occur.

g. CEILING. The ceiling (rounded off to reportable values) forms or dissipates below, decreases to less than, or, if below, increases to equal or exceed:

(1) 3,000 feet.

(2) 1,500 feet.

(3) 1,000 feet.

(4) 500 feet.

(5) Lowest standard instrument approach procedure minimum as published in the National Oceanic Service (NOS) U. S. Terminal Procedures. If none is published, use 200 feet.

h. SKY CONDITION. A layer of clouds or obscurations aloft is present below 1,000 feet and no layer aloft was reported below 1,000 feet in the preceding METAR or SPECI observation.

i. VOLCANIC ERUPTION. Eruption first noted.

j. AIRCRAFT MISHAP. Upon notification of an aircraft mishap unless there has been an intervening observation.

k. MISCELLANEOUS. Any other meteorological situation which in the observer’s opinion is critical to aviation safety.

9.2.2 SPECI Observations upon Resumption of Observing Function

A SPECI observation shall be taken within 15 minutes after the observer returns to duty following a break in observing coverage at the station unless a record observation is filed during that 15-minute period.

9.2.3 Single-element SPECI Observations

Single-element SPECI observations are authorized to be taken for tornadic activity and volcanic eruptions.

Ch. 9 Pg. 2 Special Observation Criteria for Visibility Reportable Going Down Going Up Visibility Decreases to If Below*, Increases Values Less Than* to Equal or Exceed 4 No SPECI SPECI 3* No SPECI Required SPECI 2 3/4 -- Required 2 1/2 2 1/4 SPECI 2* Required SPECI 1 7/8 Required 1 3/4 1 5/8 1 1/2 1 3/8 1 1/4 1 1/8 SPECI 1* Required SPECI 7/8 Required 3/4 5/8 SPECI 1/2*1 Required SPECI 3/8 No SPECI Required 5/16 No SPECI

1If no lowest SPECI required when first SPECI required when, if below a gray* standard decreasing to less than value in a area, value increases to equal or exceed a minimum gray* area. value in a gray* area.

Ch. 9 Pg. 3 Special Observation Criteria for Ceiling Reportable Going Down Going Up Visibility Decreases to If Below*, Increases Values Less Than* to Equal or Exceed Above 3,000 No SPECI SPECI 3,000* No SPECI Required SPECI 2,900 -- Required

to

1,600 SPECI 1,500* Required SPECI 1,400 Required

to 1,100 SPECI 1,000* Required 900 SPECI Required

to

600 SPECI 500* Required SPECI 400 Required

to

300 SPECI 200*1 Required SPECI Below 200 No SPECI Required

1If no lowest SPECI required when first SPECI required when, if below a gray* standard decreasing to less than value in a area, value increases to equal or exceed a minimum gray* area. value in a gray* area.

Ch. 9 Pg. 4 REVIEW QUESTIONS

1. Which of the following precipitation events does not require a SPECI report?

a. Ice pellets begin. b. Hail begins. c. –FZRA changes to FZRA. d. –SN changes to +SN.

2. A SPECI is required when visibility of

a. 1¼ miles becomes 2½ miles b. 4 miles becomes 3 miles c. 2 miles becomes 2 3/4 miles d. 3 miles becomes 4 miles

3. Which change in sky condition would require a SPECI observation?

a. SKC to SCT015 b. VV002 to VV005 c. BKN045 to OVC030 d. OVC030 to SKC

4. Which of the following requires a special observation?

a. TS ends b. –SN begins c. SHRA ends d. SG begins

5. Which change in sky condition does not require a special observation?

a. SCT008 to SKC b. BKN013 to BKN006 c. OVC009 to OVC010 d. SKC to FEW008

6. The prevailing visibility was 1 1/4 statute miles during the last observation. A SPECI is required if it increases to:

a. 1 5/8 b. 1 3/4 c. 1 7/8 d. 2 3/4

Ch. 9 Pg. 5 REVIEW QUESTIONS

7. Which of the following requires a special observation?

a. A tornado is reported by the police to have occurred 5 hours ago b. visibility decreases to 3 miles c. volcanic eruptions d. sky condition changes from BKN050 to BKN030

8. The last observation reported a sky condition of SCT250. Which one of the following would require a SPECI observation?

a. BKN030 BKN250 b. SCT015 BKN250 c. FEW005 SCT250 d. SCT010 OVC250

9. The prevailing visibility was 7 statute miles during the last observation. A SPECI is required if it decreases to:

a. 2 3/4 b. 6 c. 3 d. 4

10. Which element may be reported alone as Special observation?

a. Sky condition b. Tornadic activity c. Thunderstorm d. Temperature

11. The last observation reported a sky condition of FEW025. Which one of the following would not require a SPECI observation?

a. SCT025CB b. BKN025TCU c. OVC010 d. OVC028CB

Ch. 9 Pg. 6 REVIEW QUESTIONS

12. A SPECI is required for which of the following changes in Prevailing Visibility?

a. 3 miles becomes 2 ½ miles b. 3 miles becomes 15 miles c. 7/8 miles becomes 1/2 miles d. 40 miles becomes 3 miles

13. Which of the following precipitation events does not require a SPECI report?

a. +PL changes to –PL b. –TSRA changes to +TSRA c. –FZRA changes to FZRA d. Hail begins

14. A SPECI is not required when visibility changes from:

a. 1 mile to 2 miles b. 1 1/4 miles to 2 ½ miles c. 2 miles to 3 miles d. 10 miles to 3 miles

15. In the last observation SKC was reported as the sky condition. Which of the following sky conditions would require A SPECI?

a. SCT010 b. BKN030 c. FEW008 d. OVC250

16. Which of the following changes require a SPECI?

a. –SN begins b. +SHRA begins c. –FZRA begins d. +TSRA to –TSRA

17. The ceiling height of the last observation was 1000 feet. A SPECI observation is required if the ceiling increases to feet.

a. 1,100 b. 1,300 c. 1,400 d. 1,600

Ch. 9 Pg. 7 REVIEW QUESTIONS

18. A SPECI is required when:

a. –TSRA changes to +TSRA b. Snow depth increases 1 inch during the past hour c. FZRA changes to –FZRA d. SHRA changes to SHSN

19. The last observation reported a sky condition of FEW015TCU. Which one of the following would require a SPECI observation?

a. FEW015CB b. SCT015TCU c. SCT010CB d. FEW015CB (with thunder heard)

20. The ceiling height of the last observation was 4,500 feet. A SPECI observation is required if the ceiling decreases to feet.

a. 3,500 b. 3,000 c. 2,900 d. 3,100

21. The ceiling height of the last observation was 500 feet. A SPECI observation is required if the ceiling increases to feet.

a. 600 b. 1,300 c. 800 d. 900

Ch. 9 Pg. 8