Section 8. Center Weather Advisory (CWA)
A Center Weather Advisory () is an unscheduled weather advisory for conditions meeting or approaching national in-flight advisory (, , or ) criteria. It is primarily used by aircrews to anticipate and avoid adverse weather conditions in the en route and terminal environments.
- s are valid for up to 2 hours and may include forecasts of conditions expected to begin within 2 hours of issuance. If conditions are expected to persist after the advisory's valid period, a statement to that effect is included in the last line of the text. Additional s will subsequently be issued as appropriate. The CWSU will issue a :
- When necessary to supplement an existing , , or for the purpose of refining or updating the location, movement, extent, or intensity of the weather event relevant to the 's area of responsibility.
- When an inflight advisory has not yet been issued, but the observed or expected weather conditions meet , or criteria based on current pilot reports and reinforced by other sources of information concerning existing meteorological conditions.
- When observed, or developing weather conditions do not meet , or criteria but current pilot reports or other weather information sources indicate that an existing, or anticipated, meteorological phenomena will adversely affect the safe flow of air traffic within the 's area of responsibility.
- The will describe the location of the phenomenon using relevant points of reference, such as VORs, and will include the height, extent, intensity, and movement of the phenomenon. Each will have a phenomenon number.
- The format of the communications header is: ( designator)(phenomenon number) (date/time issued in UTC)/( designator) (issuance number) VALID UNTIL (date/time in UTC)/(FROM) (affected area)/(text).
ZOB CWA 101 VALID UNTIL 032300
FROM 10S DET TO 40N DJB TO 40E SBN TO 80SE MKG
LN SEV TSTMS WITH EXTRM PCPN MOVG FROM 2525 3/4 INCH HAIL RPRTD LAST 5 MINS 20 SW YIP.
TSTMS WITH HVY TO EXTRM PCPN CONTG DTW AREA BYD 2300
ZKC CWA 102 VALID UNTIL 121728
STL DIAM 30 NM. NMRS RPTS OF MOD TO SEV ICG 080/090.. LGT OR NEG ICG RPTD 040/120 RMNDR OF ZKC AREA AND NE OF AREA.
The will be distributed to area supervisors and traffic management coordinators and will be entered through FAA AISR and other communications media to make it available for dissemination to other FAA and NWS facilities.