:Product: Weekly Highlights and Forecasts
:Issued: 2004 Jan 27 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
19 - 25 January 2004

Solar activity ranged from very low to high levels.  The period began
at moderate levels with Region 540 (S11, L=285, class/area Eao/500
on 13 January) producing two M1 flares and several C-class flares.
This moderate sized region was in gradual decay, but maintained
considerable complexity during the first half of the period.
Activity increased to high levels on 20 January as Region 540
produced an M6/2n flare with moderate radio bursts that included a
4500 sfu burst on 245 MHz and a Type II radio sweep (950 km/s). This
region also produced an impressive long duration C5 flare on the
20th. An associated Earth-directed halo CME was observed on
SOHO/LASCO imagery. Activity levels were very low to low for the
remainder of the period. Occasional C-class activity was observed in
Region 543 (S16, L=269, class/area Dao/100 on 21 January), the
largest being a C6 flare late on the 25th. Two large filament
eruptions occurred on the 21st. The first was a 28-degree filament
eruption and CME that occurred in the southeast quadrant at around
1200 UTC on 21 January. The second event occurred late on the 21st,
when a large prominence erupted off the northwest limb. A CME was
visible on LASCO imagery following the eruption.

Solar wind data were available from the NASA Advanced Composition
Explorer (ACE) spacecraft during most of the summary period.  The
period began with elevated solar wind speeds near 560 to 660 km/s in
the waning stages of a high speed coronal hole stream. Solar wind
speed continued its gradual decline through early on the 22nd. At
0100 UTC on the 22nd, a CME impacted ACE; solar wind speed increased
sharply from 475 km/s to over 700 km/s. Sharp increases in density
and temperature were also noted. IMF Bz was initially northward, but
rotated southward at around 0900 UTC on the 22nd, and stayed
southward through most of the 23rd. A second weaker transient
impacted ACE at approximately 1400 UTC on the 23rd. Solar wind
plasma parameters again rose sharply, but to a much lesser degree
than the previous transient. Weak transient signatures were again
evident late on the 24th through the 25th, but solar wind speed
remained at or below 500 km/s.

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

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels every day this period.

The geomagnetic field ranged from quiet to severe storm levels. 
Quiet to active conditions were observed on 19 – 21 January due to a
high speed coronal hole stream. A 33 nT sudden impulse early on the
22nd, signified the onset of a severe geomagnetic storm. This CME
was likely associated with the long duration C5 flare observed in
Region 540 on 20 January. Severe storm periods were observed at all
latitudes until midday on the 22nd. Unsettled to minor storm
conditions prevailed late on the 22nd through the 23rd. Mostly quiet
to active conditions were observed on the 24th. Unsettled to minor
storm conditions were observed on the 25th due to weak transient
solar wind flow.

Forecast of Solar and Geomagnetic Activity
28 January - 23 February 2004

Solar activity is expected to be at very low to moderate levels. The
period will begin with an almost spotless visible disk, so expect
very low to low conditions to persist through into the first few
days of the period. Old active Region 536 is due to rotate back into
view in the next few days and will likely elevate activity levels
from very low to low with a chance for an M-class flare. Old active
Region 537 will return in early February and further enhance flare
probabilities. The late stages of the forecast period will likely
see a return to low and even very low conditions as the active
longitudes rotate out of view.

There is a slight chance for a greater than 10 MeV proton event
during the period.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to reach high levels on 28 January, 01 – 08 February, and
again on 12 – 18 February, due to recurrent coronal holes.

Geomagnetic activity is expected to range from quiet to minor storm
levels with a chance of isolated major storm levels. The large
transequatorial coronal hole of the last few rotations has broken up
into several smaller coronal holes.  This series of recurrent
coronal holes is due to return on 31 January – 07 February and is
expected to produce minor storm level activity with a chance of
isolated major storm levels. Another coronal hole is expected to
return on 11 – 14 February and produce active to minor storm levels.