:Product: Weekly Highlights and Forecasts
:Issued: 2003 Apr 15 2212 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Environment Center
# Product description and SEC contact on the Web
# http://www.sec.noaa.gov/weekly.html
#
#                Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
07 - 13 April 2003

Solar activity ranged from very low to moderate levels.  The period
began on 07-08 April with low and very low activity, respectively. 
On 09 April, Region 326 (S12, L=156, class/area Dao/90 on 09 April)
exhibited rapid growth as it approached the west limb and produced
an M2.5/1f flare at 2329 UTC with an associated Type II radio sweep
and a ten-flare radio burst.   A narrow CME was also associated with
the M2 but did not appear to be Earth directed.  Region 326 also
produced numerous B and C-class flares on 09 April as it rotated
beyond the west limb.  Activity on 10 April was at very low levels. 
Low level activity was observed on 11 April due to a C7 flare from
Region 326 beyond the west limb.  Region 330 (N08, L=80, class/area
Dko/420 on 09 April) was the largest region on the disk during the
period and developed a beta-gamma magnetic configuration on 08
April.  Region 330 was the source of most of the activity for the
last two days of the period resulting in very low and low level
activity on 12 and 13 April, respectively.

Solar wind data were available from the NASA Advanced Composition
Explorer (ACE) spacecraft for most of the summary period.  Solar
wind was near 400 km/s early in the period.  Late on 09 April, a
large equatorial coronal hole rotated into a geo-effective position
marked by a significant rise in solar wind speed.  Solar wind speed
rose through 10 April and peaked near 800 km/s.  The Bz component of
the interplanetary magnetic field due to the coronal hole exhibited
minor oscillations between +/- 5 nT.  Solar wind speed was in
gradual decline from 11 ? 13 April and ended the period near 450
km/s

There were no greater than 10 MeV proton events at geo-synchronous
orbit during the summary period.

The greater than 2 MeV electron flux at geo-synchronous orbit reached
high levels on 07 April and again on 11 ? 13 April.

The geomagnetic field ranged from quiet to minor storm levels.  A
weak CME shock on 08 April produced a 33 nT sudden impulse at 0115
UTC as measured on the Boulder magnetometer.  The CME shock resulted
in unsettled to minor storm levels of activity.  The arrival of the
large equatorial coronal hole on 09 ?10 April produced unsettled to
minor storm levels.

Forecast of Solar and Geomagnetic Activity
16 April - 12 May 2003

Solar activity is expected to be very low to low with a chance of
isolated M-class activity.  Activity is expected to be very low
until the return of Region 321 and 324 on 19 and 21 April
respectively.  These regions are expected to produce low level
activity with a slight chance of an isolated M-class event.   At the
end of the period Region 326 is due to return to the visible disk
and is expected to have low level activity with isolated M-class
potential.

No greater than 10 MeV proton events are expected during the forecast
period.

The greater than 2 MeV electron flux may reach high levels on 19 - 21
April, 27 ? 28 April, 02 ? 03 May and again on 08 ? 10 May.  These
high flux levels are all due to returning coronal holes.

The geomagnetic field is expected to range from quiet to minor storm
levels.  Quiet to isolated active levels are possible early in the
period until the return of a large coronal hole on 23 April.  This
coronal hole may produce unsettled to minor storm levels through 27
April.  Two weaker coronal holes are due to return to a
geo-effective position on 29 April ? 02 May and 06 ? 08 May with
unsettled to active conditions expected.

.