SigMet Victor and X-Ray?

[carqwik]

I know that there are Sigmets Tango = Turbulence, Sierra = Mtn Obscuration, and Zulu = Icing but what are Victor and X-Ray sigmets?

 

From today on the West Coast:

WSUS06 KKCI 221314
SFOV WS 221314
SIGMET VICTOR 4 VALID UNTIL 221714
SIGMET 
CA NV
FROM 40S OED TO 50ENE FMG TO CZQ TO ENI TO 40S OED
OCNL SEV TURB BTN 080 AND 150. DUE TO STG LOW LVL WNDS. RPTD BY
ACFT. CONDS CONTG BYD 1714Z.

WSUS06 KKCI 221424
SFOX WS 221424
SIGMET XRAY 1 VALID UNTIL 221824
SIGMET 
CA AND CSTL WTRS
FROM 40E EHF TO BZA TO 20S MZB TO 40W RZS TO 40E EHF
OCNL SEV TURB BLW 120. RPTD BY ACFT. CONDS CONTG BYD 1824Z.

Victor seems to be about winds?  and Xray about severe turbulence?  First time I've ever heard of Victor and XRay sigmets....any insight?

[mooniac15u]

Sierra, Tango, and Zulu are reserved for scheduled SIGMETS.  Other non-convective SIGMETS are just assigned a phonetic alphabet designator from a limited list (November, Oscar, Papa, Quebec, Romeo, Uniform, Victor, Whiskey, X-ray, and Yankee).