:Product: Weekly Highlights and Forecasts
:Issued: 2001 Mar 27 2112 UT
Highlights of Solar and Geomagnetic Activity
19 - 25 March 2001

Solar activity ranged from low to high. The period began with
activity at low levels due to isolated C-class subflares, mostly
from Region 9373 (S07, L = 329, class/area Fai/270 on 19 March),
which was in a growth phase at the time. A faint full-halo CME was
observed early on 19 March, associated with a filament disappearance
near center disk. Activity increased to high levels on 20 March due
to five low-level M-class flares from a few developing regions
including 9373, 9384 (N11, L = 334, class/area Dao/120 on 16 March),
and 9390 (N15, L = 185, class/area Fao/300 on 22 March)(please refer
to the Energetic Events list for flare times). Activity decreased to
moderate levels on 21 March with an isolated M1/Sn from Region 9373
as it approached the west limb. An increasing trend commenced on 22
March as Region 9393 (N20, L = 152, class/area Ekc/1100 on 26 March)
began rotating into view. This very large (its dominant spot mass
spans about five degrees), magnetically complex region may have been
the source for an M1 X-ray flare at 22/0821 UTC associated with
Types II and IV radio sweeps. This region showed significant growth
during the last few days of the period and displayed increased
potential for major flare activity. Region 9390 also produced an
isolated M-class flare on 22 March while in a slow growth phase.
Activity decreased to low levels on 23 March with occasional C-class
subflares. Activity returned to moderate levels during 24 - 25 March
with isolated, low-level M-class flares from developing Regions
9393, 9390, 9376 (S13, L = 301, class/area Cro/020 on 16 March), and
9401 (N22, L = 136, class/area Dao/150 on 25 March). A faint
full-halo CME occurred late on 25 March, associated with a
long-duration C9/1f parallel-ribbon flare from Region 9402 (N17, L =
175, class/area Bxo/010 on 25 March).

Data were available from the Advanced Composition Explorer (ACE)
spacecraft for most of the period. A CME signature was observed
during 19 - 20 March beginning with a shock front passage at ACE at
19/1020 UTC. This CME's most notable characteristic was a strong,
sustained southward turning of IMF Bz late on 19 March continuing
through 20 March with maximum southerly deflections to minus 20 nT
(GSM) detected at approximately 20/1400 UTC. A second CME shock
front passed ACE at 22/1240 UTC. No significant disturbances were
observed in the solar wind flow during the rest of the period.

No proton events were observed. However, a greater than 10 MeV proton
flux enhancement at geosynchronous orbit began late on 25 March.

The greater than 2 MeV electron flux at geosynchronous orbit briefly
reached high levels on 22 March, but was otherwise at normal to
moderate levels.

A major geomagnetic storm occurred during 19 - 20 March due to a CME
passage at Earth. Active to major storm levels occurred during this
storm with isolated severe storm levels detected at high latitudes.
Activity decreased to mostly quiet to unsettled levels on 21 March
as storm effects subsided. Field activity was at mostly quiet levels
on 22 March until a sudden commencement occurred at 22/1340 UTC (12
nT, Boulder USGS magnetometer) due to another CME passage. Unsettled
to minor storm levels occurred during 22 - 23 March as a result of
this passage. Quiet to unsettled conditions prevailed during 24 - 25
March.

Forecast of Solar and Geomagnetic Activity
28 March - 23 April 2001

Activity is expected to be at low to moderate levels during the
period with isolated M-class flares likely. Region 9393 may produce
major flare activity before it crosses the  west limb on 05 April.

There will be an increased chance for a proton event until Region
9393 crosses the west limb on 05 April.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels during most of the
period.

The Geomagnetic field is likely to be disturbed during 28 March due
to an expected CME passage. Active to major storm periods will be
possible during this disturbance. Quiet to unsettled conditions are
expected during the rest of the period, barring another
Earth-directed CME.


.