:Product: Weekly Highlights and Forecasts
:Issued: 2001 Oct 30 2112 UT
Highlights of Solar and Geomagnetic Activity
22 - 28 October 2001

Solar activity ranged from low to high levels. Region 9672 (S18,
L=268, class/area Dki/590 on 26 October) produced four major flares
during 22 - 23 and 25 October: an M6/2n at 22/1508 UTC, an X1/2b at
22/1759 UTC, an M6/1b at 23/0223 UTC, and an X1/2b at 25/1502 UTC.
All but the M6 at 23/0223 UTC were associated with Earth-directed
coronal mass ejections (CME). Region 9672 was large and magnetically
complex. It showed gradual development through 24 October to include
the formation of a strong magnetic delta configuration in its leader
spot. It ceased to grow on 25 October, but remained large and
magnetically complex and produced isolated C-class and low-level
M-class flares until it began to cross the west limb as the period
ended. Region 9678 (N08, L = 221, class/area Ekc/680 on 26 October)
produced isolated C-class flares and a low-level M-class flare
during 24 - 26 October as it underwent a rapid growth phase (for
flare times and magnitudes, please refer to the Energetic Events and
Optical Flares lists). This large, moderately complex region began
to gradually decay on 27 October. Region 9682 (N11, l = 170,
class/area Eki/990 on 27 October) produced occasional C-class and
isolated M-class flares during the latter half of the period as it
grew in spot count, area, and magnetic complexity. At the close of
the period it was large and magnetically complex with a magnetic
delta configuration within its large leading spot mass. Other
regions of interest included 9658 (S14, L = 024, class/area Fao/230
on 19 October) and 9661 (N15, L = 357, class/area Ekc/800 on 16
October). Each region had a history of isolated major flare
production. Both were gradually decaying as they rotated out of view
early in the period.

Solar Wind data were available from the NASA Advanced Composition
Explorer (ACE) spacecraft for most of the period. A CME passage was
in progress as the period began. The likely source for this CME was
an X1/2b flare at 19/0105 UTC from Region 9661. Peak velocities
during the passage were in the 700 to 730 km/sec range. IMF Bz
turned southward around 22/1900 UTC and remained so until early on
23 October with peak deflections to minus 15 nT (GSM). CME effects
subsided by midday on 23 October. Another CME passage occurred
during 25 - 26 October associated with major flare activity from
Region 9672 on 22 October. The CME shock front passed the spacecraft
at around 25/0802 UTC and was the source of the sudden impulse
mentioned above. There were moderate increases in velocity and
density associated with this passage. Its most interesting
characteristic was its lack of southward IMF Bz component. IMF Bz
turned northward (peaks to plus 10 nT) shortly after passage began
and remained so for the rest of the passage. A third CME passage
began around 28/0242 UTC. The likely source for the CME was an X1/2b
flare at 25/1502 UTC from Region 9672. Abrupt increases in velocity
(peaks to 530 km/sec), total IMF field intensity, and temperature
accompanied the passage. IMF Bz, which was southward prior to
passage, turned more strongly southward following the passage, with
peak deflections to minus 20 nT.

A greater than 10 MeV proton flux event occurred at geosynchronous
orbit on 22 October in the wake of major flare activity from Region
9672. The event began at 22/1910 UTC, reached a maximum flux of 24.2
PFU at 22/2130 UTC, and ended at 23/0115 UTC.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal levels through the period.

A major geomagnetic storm was in progress as the period began. Active
to severe storm levels occurred during this disturbance (which began
late on 21 October), but the severe storm levels were limited to
high latitudes. Quiet to unsettled levels prevailed during 24 - 27
October, despite a sudden impulse at 25/0850 UTC (22 nT, as measured
by the Boulder USGS magnetometer). Another geomagnetic storm began
early on 28 October due to a CME passage. Active to major storm
levels occurred during this disturbance.

Forecast of Solar and Geomagnetic Activity
31 October - 26 November 2001

Solar activity is expected to range from low to moderate levels
throughout the period. Isolated, low-level M-class flares are
expected throughout the period. There will be a chance for isolated
major flare activity during the period as well as Region 9682 could
produce an isolated major flare until it rotates out of view around
07 November.

There will be a slight chance for a proton event during the period.
Region 9682 provides a slight chance for a proton flare until is
rotates out of view around 07 November.

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

Active geomagnetic field conditions may occur on 01 November due to a
possible CME passage. Otherwise, quiet to unsettled conditions are
expected throughout the period.

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