NOUS41 KWBC 221825 



Technical Implementation Notice 12-31

National Weather Service Headquarters Washington DC

350 PM EDT Fri Jun 22 2012


To:      National Weather Service (NWS) Offices

         Federal Aviation Administration (FAA) Customers

         Family of Services (FOS) Subscribers

         Other Customers of NWS Aviation Forecasts


From:    Cynthia Abelman

         Chief, Aviation Services Branch


Subject: Ceiling and Visibility Analysis Product to Become

         Operational Effective July 24, 2012 


Note:    The following changes have no impact on NOAA               

         Weather Wire Service subscribers


Effective July 24, 2012, at 1800 Coordinated Universal Time

(UTC), the NWS Aviation Weather Center in Kansas City, MO, will

make the Ceiling and Visibility Analysis (CVA) operationally

available on the Aviation Digital Data Service (ADDS) Website.


CVA presents simplified area maps of ceiling, visibility and

flight category outlined as: 


     Ceiling estimates are displayed as


             (i)   Possible Terrain Obscuration (pale

                   orange) for ceilings less than 200 ft agl,

             (ii)  less than or equal to 1000 ft agl (pale

                   yellow) from 200 to 999 ft, agl, and

             (iii) 1000 ft agl or greater (pale blue). 


     Visibility estimates are displayed as


             (i)  less than 3 miles (pale yellow), and

             (ii) 3 miles or greater (pale blue). 


CVA is intended to accompany other aviation weather products such

as METARS, AIRMETS, TAFs and Area Forecasts to help the general

aviation pilot (particularly the VFR-only pilot) avoid IFR

conditions.  To remain current in rapidly changing conditions,

CVA is updated every 5 minutes using the latest observations. The

use of CVA should be followed by further examination of METARs,

TAFs, AIRMETs, Area Forecasts and other weather information.


CVA primarily is intended to help the general aviation pilot;

however, CVA's quick-glance overview of ceiling and visibility

conditions can be useful to others involved in flight planning or

weather briefing.


CVA initially will be available only via the ADDS website at:


For questions regarding the new CVA product, contact:


     Robert Sallee

     Senior Software Engineer - Aviation Weather Center

     Kansas City, MO 64153

     Phone:  816-584-7256



NWS Technical Implementation Notices are online at: