EXPERIMENTAL ULTRAVIOLET INDEX (UVI) FORECASTS

• To: nws-changes@xxxxxxxxxxxxxxxx
• Subject: EXPERIMENTAL ULTRAVIOLET INDEX (UVI) FORECASTS
• From: "Unidata User Support" <support@xxxxxxxxxxxxxxxx>
• Date: Fri, 24 Jun 1994 16:19:50 -0600

NATIONAL TECHNICAL INFORMATION MESSAGE 94-17
NATIONAL WEATHER SERVICE HEADQUARTERS
400 PM EDT TUE JUNE 24 1994

TO:         ALL NWS PRODUCT USERS

FROM:       MARY C. NEWTON
            ACTING CHIEF, SERVICES DEVELOPMENT BRANCH

SUBJECT:    EXPERIMENTAL ULTRAVIOLET INDEX (UVI) FORECASTS

On June 28, 1994, at approximately 1800 UTC, the National Weather
Service's (NWS) Climate Analysis Center, at the request of the
U.S. Environmental Protection Agency (EPA) and in coordination
with the Centers for Disease Control and Prevention (CDC), will
begin the issuance of experimental UVI forecasts.  The forecasts
will be issued once a day and will predict, up to 30 hours in
advance, the maximum exposure to ultraviolet radiation from the
sun's rays during the peak hour of sunlight.  The  forecasts will
be provided for a limited number of cities during the
experimental/evaluation period which will end during Spring 1995.

The experimental UVI is a forecast of ultraviolet irradiance at
the surface integrated over the one-hour period around noon.  The
forecasts consists of an Index number that is categorized by the
EPA into one of 5 exposure levels:  0 - 2 (Minimal); 3 to 4
(Low); 5 to 6 (Moderate); 7 to 9 (High); 10+ (Very High).

The forecasts include consideration for stratospheric ozone
changes and clouds, but do not explicitly include haze or local
pollution effects.  The effects of cloudiness are accounted for
by using the Model Output Statistics (MOS) cloud probability
forecasts from the Nested Grid Model.  The UVI experimental
forecasts produced for Honolulu, Hawaii and San Juan, Puerto Rico
will NOT contain the effects of clouds, initially.  Plans are to
include them before the completion of the experiment.

The UVI forecasts will have an AFOS identifier of NMCUVICAC.  It
is a national bit product, so, for AFOS users, the "CCC" will  be
your local node identifier (rather than NMC).  The World
Meteorological Organization (WMO) identifier for the UVI will be
AEUS41 KWBC.

Three educational information messages on UVI forecasts were
disseminated today under the AFOS identifier WSHPNSWSH (WMO
header ADMN81 KWBC.  Additional materials that contain charts and
graphics which cannot be dispatched electronically will be sent
by U.S. mail.

All questions concerning the UVI may be directed to the NWS
Office of Public Affairs at (301) 713-0622.