Extreme Solar Flare Alert

Official Space Weather Advisory issued by NOAA Space Environment Center
Boulder, Colorado, USA

SPACE WEATHER ADVISORY BULLETIN #03- 5

2003 November 04 at 05:25 p.m. MST (2003 November 05 0025 UTC)

**** EXTREME SOLAR FLARE ****

Powerful Active Region 486 has produced one of the most intense solar
flares ever measured. The event began at 12:29 P.M. MST (1929 UTC) on
November 4th and rose quickly to exceed X17 on the GOES-12 X-ray
sensor. By 12:44 P.M. MST (1944 UTC), the GOES sensor was saturated and
remained that way until 12:56 P.M. (1956 UTC), suggesting this event
extended well in to the very highest flare category, the X20 plus
range. This massive flare produced a category R5 (extreme) radio
blackout. All short-wave communications through the sunlit hemisphere
of the Earth experienced complete blackout conditions.

An associated solar radiation storm is underway. The current storm is at
category S1 (minor) levels, and rising. The radiation storm is expected
to reach category S2 (moderate) levels, and there is a small chance for
a category S3 (strong) radiation storm. High latitude aviation
interests are advised to closely monitor radiation levels over the next
24 hours. High latitude short-wave communications will likely
experience considerable degradation for the next 24 to 48 hours. All
agencies with space interests should also carefully monitor radiation
levels.

A powerful, and extremely fast (over 5 million miles per hour) mass
ejection occurred from this flare site, but is mostly directed away
from Earth. As a result, only category G1 (minor) to G2 (moderate)
geomagnetic storm levels are likely on November 6th.

This solar flare was the largest in a series of very large flares that
have occurred in Active Region 486 over the past two weeks. At its
peak, this sunspot cluster was approximately 15 times larger than
Earth. This active region will rotate to the backside of the sun over
the next 24 hours. Another large flare is still possible from this
region, but large flare activity will become much less likely after the
next 24 to 48 hours.

Data used to provide space weather services are contributed by NOAA,
USAF, NASA, NSF, USGS, the International Space Environment Services
and other observatories, universities, and institutions. For more
information, including email services, see SEC’s Space Weather
Advisories Web site http://sec.noaa.gov/advisories or (303) 497-5127.
The NOAA Public Affairs contact is Barbara McGehan at
Barbara.McGehan@noaa.gov or (303) 497-6288.