:Product: Weekly Highlights and Forecasts
:Issued: 2001 May 29 2112 UT
Highlights of Solar and Geomagnetic Activity
21 - 27 May 2001

Solar activity was predominately low during the period, with a single
day of moderate levels, due to an isolated, M1/1n flare from Region
9468 (N05, l = 093, class/area Dai/150 on 24 May) at 24/1944 UTC.
This flare also had an associated Type II radio sweep and an
Earth-directed coronal mass ejection. Activity levels dropped to
very low on 26 May and then returned to low levels for the remainder
of the period. Isolated C-class subflares comprised most of the
solar activity during the period.

Data were available from the Advanced Composition Explorer (ACE)
spacecraft for most of the period. Periods of elevated solar wind
speeds and proton temperatures, relatively low densities, and
variable IMF Bz occurred during 23-24 May, suggesting high-speed
streams associated with a positive-polarity coronal hole. A weak
shock from the CME that was observed on 24 May, was detected at ACE
on 27/1418 UTC. No disturbances were detected during the rest of the
period.

There were no proton events detected during the period. However,
proton flux enhancements at greater than 100 MeV and greater than 10
MeV occurred on 21 May due to an M6 x-ray flare that occurred on 20
May.

The greater than 2 MeV electron flux at geosynchronous orbit were at
mostly normal levels. Moderate levels occurred on 21 May.

The geomagnetic field was mostly quiet to unsettled with isolated
active conditions occurring on 22, 24, and 26 May. Intermittent
active conditions on 22 May were due to coronal hole effects.
Activity increased to quiet to active levels on 27 May due to a
glancing CME shock passage. A sudden impulse (IS) was detected at
the Boulder USGS magnetometer at 27/1456 UTC.

Forecast of Solar and Geomagnetic Activity
30 May - 25 June 2001

Solar activity is expected to range from low to moderate levels
during the period. Isolated M-class flares will be possible during
the period.

No proton events are expected during 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, high flux levels will be possible around 12 - 15
June.

The geomagnetic field is expected to be at quiet to unsettled levels
during most of the period, barring an Earth-directed CME. However,
active levels will be possible around 11 June.


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