NWS CWSU Seattle

CURRENT SEATTLE ARTCC FLIGHT CATEGORIES (Mouseover to display current TAF and METAR, click station id to display recent METARs)

FLIGHT CATEGORY RULES
SYMBOL	CAT	CIG (ft agl)	Boolean	VIS (miles)
	LIFR	<500	and/or	<1
	IFR	500 to <1000	and/or	1 to <3
	MVFR	1000 to 3000	and/or	3 to 5
	VFR	>3000	and	>5
	MISSING OR INCOMPLETE OBSERVATION

Center Weather Service Unit (CWSU) Seattle

Mission:
Seattle Center Weather Service meteorologists provide weather support and consultation to FAA air traffic managers and controllers. Rerouting of aircraft around hazardous weather is based largely on forecasts provided by the CWSU meteorologist. National products issued by the CWSU meteorologist include Center Weather Advisories (CWA) and Meteorological Impact Statements (MIS). The CWA is a short term advisory valid for two hours or less describing areas of hazardous weather in progress or forecast to develop. The MIS is a forecast product valid up to 12 hours describing areas of weather that may impact air traffic operations.


Operations:
ZSE CWSU meteorologists provide formal weather briefings to FAA supervisors within the Seattle Air Route Traffic Control Center (ARTCC) for the day and evening shifts. Verbal briefings are given to individual controllers at the ARTCC and tower control facilities around the ZSE airspace, as well as to equipment technicians when weather conditions dictate. Two types of written products are also provided by the CWSU meteorologists. The Meteorological Impact Statement (MIS) is a 4 to 12 hour planning forecast of weather conditions expected to impact the ZSE air traffic. The Center Weather Advisory (CWA) is a short-term warning of hazardous weather conditions provided to all aviation interests, including private pilots, towers, flight service stations, and commercial airlines. Thus, a CWA is similar to but more localized than Airmets and Sigmets issued by the Aviation Weather Center (AWC) in Kansas City, Missouri.

Additional Links:
Upper Air Pattern | Jetstream | Seattle TRACON (S46) | Portland TRACON (P80)