Biloxi, Mississippi

To: subscribers: NWS partners... users and employees

Subject: National change in minimum hail size criterion
   for issuing Severe Thunderstorm Warning and severe weather
          statement products effective January 5 2010

Effective Tuesday January 5 2010 at 0001 coordinated Universal time
/UTC/... all NWS weather forecast offices will operationally
change the minimum hail size criterion used to issue Severe
Thunderstorm Warning /svr/ and severe weather statement /svs/
products from 3/4 inch /penny/ diameter or larger hail to 1 inch
/quarter/ diameter or larger hail.

No change is being made to the svr and svs product wind criterion
of wind gusts equal to or in excess of 50 knots /58 mph/.

A public information statement /pns/ soliciting comments regarding
this change was issued September 23 2009:

http://www.Weather.Gov/os/notification/pns09_1_inch_hail.Txt

NWS received 63 comments in response to the pns... 54 of which /86
percent/ supported this change. A web Page will be created to
address all comments since some comments indicated a need for
additional outreach. This web Page will be available by December 15
2009 and will be publicized via another pns.

NWS reviewed all comments before deciding to change minimum hail
size criterion for svr and svs products.

Central and western region wfos currently issue svr and svs
products experimentally using the 1 inch /quarter/ diameter or
larger hail size criterion:

http://www.NWS.NOAA.Gov/om/notification/scn09-19hail_change.Txt
and
http://www.NWS.NOAA.Gov/om/notification/scn09-36wr_hail_exp.Txt

These wfos will continue to issue 1 inch /quarter/ hail size
criterion products experimentally through January 4 2010. All NWS
wfos will adopt the new criterion operationally on January 5 2010.

For further information regarding this change please contact:

John T ferree
fire and public weather services branch
Norman OK 73072
John.T.Ferree@noaa.Gov

Or

Frank revitte
warning coordination meteorologist
National Weather Service
62300 Airport Rd
Slidel la 70471
985-649-0357


National service change notices are online at:

http://www.Weather.Gov/os/notif.Htm