:Product: Weekly Highlights and Forecasts
:Issued: 2001 Aug 22 2112 UT
Highlights of Solar and Geomagnetic Activity
13 - 19 August 2001

Solar activity was low throughout the period with isolated B- and
C-class flares. There was no remarkable activity noted in any of the
active regions. However, there were two events of note during the
period. The first was a filament disappearance from the
north-central portion of the disk around midday on 14 August
associated with a long-duration C2 X-ray event and an Earth-directed
full-halo CME. The second was a remarkable far side event late on 15
August, possibly from old Region 9557 (S20, L = 288, class/area
Dki/600 on 07 August), that was associated with a (anti-Earthward)
full-halo CME and a solar energetic particle event (see the
discussion below). Old Region 9557 was near far-side center disk at
the time of the event!

Solar Wind data were available from the Advanced Composition Explorer
(ACE) spacecraft for most of the period. A CME passage occurred
during 17-18 August associated with the filament disappearance
mentioned above. The CME front passed the ACE spacecraft at 17/1017
UTC accompanied by abrupt increases in total IMF field intensity,
velocity, density and temperature; along with a southward turn of
IMF Bz until 17/1830 UTC (Bz turned northward after 17/1830 UTC).
Maximum southward deflections to minus 31 nT (GSM) occurred late on
17 August during this southward turn. Peak velocities reached around
620 km/sec early on 18 August with this passage. ACE data indicated
a possible weak high-speed stream during 19 August with elevated
wind velocities that peaked at about 520 km/sec early in the day.

A proton event at greater than 100 MeV began at 16/0105 UTC, reached
a maximum of 29 pfu at 16/0305 UTC, and ended at 17/1410 UTC. A
proton event at greater than 10 MeV began at 16/0135 UTC, reached a
maximum of 493 pfu at 16/0355 UTC, and ended at 18/1845 UTC. This
activity was associated with the far-side event that occurred late
on 15 August.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels through 15 August. Data were unreliable
during the rest of the period due to effects associated with the
solar energetic particle event mentioned above.

The geomagnetic field was disturbed as the period began as a CME
passage continued with unsettled to minor storm conditions early on
13 August. Activity decreased to quiet to unsettled levels after
13/0600 UTC and remained so through 16 August. A CME-related
disturbance began on 17 August with a sudden impulse at 17/1103 UTC
(36 nT, as measured by the Boulder USGS magnetometer). Activity
increased to active to major storm levels during this disturbance
with brief severe storm periods detected at high latitudes. This
disturbance subsided to quiet to active levels early on 18 August.
Quiet to unsettled levels occurred on the final day of the period.

Forecast of Solar and Geomagnetic Activity
22 August - 17 September 2001

Solar activity is expected to be at low to moderate levels. Isolated
M-class flares are possible. There will be a chance for a major
flare during the first half of the period as old Region 9557 returns
to the visible disk.

There will be a chance for a solar proton event during the first half
of the period.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels during most of the
period. However, there will be slight chance for high flux levels
around 23 - 24 August and 03 - 04 September.

Active geomagnetic field conditions will be possible around 22 - 24
and 27 August, 01 - 02 and 09 - 10 September. Otherwise, quiet to
unsettled levels are expected.


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