NOAA SEC Space Weather Outlook #01- 17 — 1 May 2001

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

SPACE WEATHER OUTLOOK #01- 17

2001 May 01 at 03:18 p.m. MDT (2001 May 01 2118 UT)

**** SPACE WEATHER OUTLOOK ****

Summary For April 23-29

Space weather reached category 2 (moderate) levels on the NOAA Space
Weather Scale (SWS). A category R2 (moderate) radio blackout reached
its peak at 7:12 a.m. MDT on April 26 (2001 April 26 1312 UTC). The
blackout was the result of a major solar flare from NOAA sunspot Region
9433, which is currently crossing to the far side of the Sun. Category
R2 radio blackouts normally result in adverse effects on high-frequency
(HF) radio communications and low-frequency navigation signals on the
sunlit side of Earth (for a more complete list of system effects,
please refer to the NOAA SWS). Region 9433 also caused a number of
category R1 (minor) radio blackouts during April 23 – 27. The major
flare of April 26 spawned an Earth-directed coronal mass ejection (CME)
which reached Earth early on April 28. The CME caused intermittent
category G1 (minor) geomagnetic storm conditions on April 28. Category
G1 storms typically cause minor effects on power systems and spacecraft
operations. A brief category S1 (minor) solar radiation storm occurred
on April 28, also related to the CME passage. This brief, weak storm
may have caused minor impacts on HF radio communication in the polar
regions.

Outlook For May 2-8

Space weather is expected to decrease to minor levels. Isolated category
R1 (minor) radio blackouts will be possible during the period. There
will be a slight chance for a category G1 (minor) geomagnetic storm on
May 4 due to an expected increase in solar wind velocities related to a
coronal hole.

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. More
information is available at SEC’s Web site http://sec.noaa.gov or
(303) 497-5127. The NOAA Public Affairs contact is Barbara McGehan
at bmcgehan@boulder.noaa.gov or (303) 497-6288.