SPECI Criteria

GENERAL

SPECI is an unscheduled report taken when any of the following criteria have been observed. SPECI shall contain all data elements found in a METAR plus additional plain language information which elaborates on data in the body of the report. All SPECIs shall be made as soon as possible after the relevant criteria are observed.

a. Criteria for SPECI

(1) 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.
(2)VISIBILITY.	Surface visibility as reported in the body of the report decreases to less than, or if below, increases to equal or exceed: (a) 3 miles. (b) 2 miles. (c) 1 mile. (d) The lowest standard instrument approach procedure minimum as published in the National Ocean Service (NOS) U.S. Terminal Procedures. If none published, use 1/2 mile.
(3) RUNWAY VISUAL RANGE (RVR).	The highest value from the designated RVR runway decreases to less than, or if below, increases to equal or exceed 2,400 feet during the preceding 10 minutes. U.S. military stations may not report a SPECI based on RVR.
(4) TORNADO, FUNNEL CLOUD, OR WATERSPOUT.	(a) is observed. (b) disappears from sight, or ends.
(5) THUNDERSTORM.	(a) begins (a SPECI is not required to report the beginning of a new thunderstorm if one is currently reported.) (b) ends.
(6) PRECIPITATION.	(a) hail begins or ends. (b) freezing precipitation begins, ends, or changes intensity. (c) ice pellets begin, end, or change intensity.
(7) SQUALLS.	When squalls occur.
(8) CEILING.	The ceiling (rounded off to reportable values) forms or dissipates below, decreases to less than, or if below, increases to equal or exceed: (a) 3,000 feet. (b) 1,500 feet. (c) 1,000 feet. (d) 500 feet. (e) The lowest standard instrument approach procedure minimum as published in the National Ocean Service (NOS) U.S. Terminal Procedures. If none published, use 200 feet.
(9) 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.
(10) VOLCANIC ERUPTION.	When an eruption is first noted.
(11) AIRCRAFT MISHAP.	Upon notification of an Aircraft Mishap unless there has been an intervening observation.
(12) MISCELLANEOUS.	Any other meteorological situation designated by the responsible agency or which, in the opinion of the observer, is critical.

b. The SPECI criteria are only applicable to stations that have the capability of evaluating the event. For example, visually evaluated elements, such as a tornado, are not applicable to non-staffed automated stations.