Berlin Heights, Ohio

To:family of services /fos/ subscribers...
NOAA weather wire service /nwws/ subscribers...
emergency managers weather information network /emwin/
subscribers... noaaport subscribers
other National Weather Service /NWS/
customers and partners and NWS employees

From: mike Campbell
    chief... ocwws observing services division

Subject: automated surface observing system wind sensor
          replacement

The following changes have no direct impact on NOAA weather wire
service subscribers

The automated surface observing system /ASOS/ product
improvement program has deployed a replacement wind sensor.
The new sensor will report wind information using the 3-second
world meteorological organization /WMO/ gust Standard.

The current ASOS wind sensor /Belfort 2000 / uses rotating cups
to measure wind speed and a vane to measure wind direction. Over
a two-minute period... ASOS uses 24 five-second averages to
determine the two-minute average wind speed and direction. Every
minute ASOS stores the highest five-second average speed for the
past minute... along with its direction... in the 12-hour archive
for additional processing. This highest speed value is used to
determine if a gust and/or a peak wind remark will be reported.

The new ASOS wind sensor /vaisala 425nws / is a sonic anemometer.
It has no moving parts and will operate better in winter weather
conditions. As with the Belfort sensor... over a two-minute
period... ASOS uses 24 five-second averages to determine the
two-minute average wind speed and direction. But the highest
three-second running average speed is stored for gust and peak
wind processing.

While there will be little difference in two-minute average wind
speed and direction reporting... the changes in gust and peak wind
reporting may be significant. We can expect to see more gusts
and peak winds reported with the new sensor. The mass of the
moving parts in existing sensors limits responsiveness. The new
sensor will be more responsive to short term gusts.

The new wind sensor will be deployed in Northern Ohio at the
following site on or about following date:

Site date of deployment
Akron-Canton Regional Airport /kcak/ July 7, 2009

Further information on ifw implementation plans and status can be
found on the surface observation program web Page at
www.NWS.NOAA.Gov/ops2/surface/index.Htm please note the S in
surface is in upper case.

If you have any questions about this change... please contact one of
the following individuals at NWS headquarters:

     David mannarano
ASOS implementation manager
phone: 301-713-2093 x103
E-mail: David.Mannarano@noaa.Gov

                or

        Richard ahlberg
        ASOS planned product improvement program manager
        phone: 301-713-1975 x160
        E-mail: Richard.Ahlberg@noaa.Gov.

                Local contact

        Brian Mitchell
        observing program Leader
        NWS Cleveland Ohio
        phone: 216-265-2370 x436
        E-mail: Brian.Mitchell@noaa.Gov

Related NWS technical implementation notices are available on the
internet at /use lower case/:

     http://www.NWS.NOAA.Gov/om/notif.Htm

End