NOAA/SEC Space Weather Advisory Bulletin #04- 1

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

SPACE WEATHER ADVISORY BULLETIN #04- 1

2004 July 26 at 01:17 p.m. MDT (2004 July 26 1917 UTC)

**** STRONG GEOMAGNETIC STORM EXPECTED ****

A large and moderately complex sunspot cluster known as NOAA Region 652
was responsible for a significant eruption on 25 July, 2004 at 915 a.m.
MDT. A radiation storm, currently at the S2 level, began soon after the
eruption was observed on the Sun. An Earth-directed coronal mass
ejection (CME) was also observed and is expected to impact the
geomagnetic field early on 27 July. This CME will likely produce
periods of strong (G3) geomagnetic storming.

Agencies impacted by geomagnetic storms and radiation storms may
experience disruptions in the next 48 hours. These include spacecraft
operations, electric power systems, HF communications, and navigation
systems.

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.