:Product: Weekly Highlights and Forecasts
:Issued: 2003 Jul 29 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
21 - 27 July 2003

Solar activity was at low levels.  Region 410 (S13, L=195 class/area
Eki/800 on 22 July) produced several C-class flares early on the
21st, but transitioned into a decay phase by 22 July and flare
production ceased.  A 16-degree NE-SW filament erupted from near
disk center at around 21/0900Z.  Faint ejecta were observed on LASCO
imagery, but the event was not expected to be geoeffective.  Region
417 (S21, L=206 class/area Dai/360 on 22 July), which emerged rather
quickly on 20 July, was responsible for several C-class flares
before rotating around the west limb on 24 July.  Active Regions 409
(N15, L=193 class/area Fkc/490 on 15 July) and 412 (N16, L=202
class/area Dac/200 on 20 July) also produced occasional C-class
flares through the 24th.  Low levels persisted through the 25th due
to a single long duration C1 flare that likely originated from the
east limb.  Solar activity decreased to very low levels on the 26th
and 27th.  New Region 421 (S08, L=359 class/area Hax/030 on 27 July)
rotated into view late in the period.  Limb proximity is hindering a
good analysis, but this region appears to be quite active.

A waning high speed solar wind stream was in effect early in the
period.  Speeds near 600 km/s declined to 450 km/s by late on the
21st.  Near nominal solar wind conditions persisted through the
22nd.  A weak transient impact was observed at ACE on the 23rd;
solar wind speed increased to over 500 km/s and periods of sustained
southward Bz occurred.  Solar wind speed gradually declined to very
low levels just above 300 km/s by the 25th.  A strong co-rotating
interaction region (CIR) on 26 July, hailed the onset of a large
recurrent southern coronal hole stream. Total field measurements in
the CIR were over 35 nT, and the Bz component experienced sustained
southward periods near –30 nT.  The solar wind speed associated with
this high speed stream was approximately 800 km/s, and generally
ranged between 550 – 800 km/s for the remainder of the period.

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

The greater than 2 MeV electron flux at geo-synchronous orbit reached
high levels on 21 – 23 July.

A gradual decline in solar wind speed from 600 - 700 km/s late in the
last period to near 450 km/s early this period resulted in quiet to
unsettled levels with isolated active periods on the 21st and 22nd. 
A weak transient passage on the 23rd produced a very weak
disturbance with only isolated active periods.  Mostly quiet to
unsettled conditions persisted through the 25th.  The CIR and
associated high speed coronal hole stream on the 26th produced
predominantly unsettled to minor storm levels through the remainder
of the period.

Forecast of Solar and Geomagnetic Activity
30 July - 25 August 2003

Solar activity is expected to be at low to moderate levels.  Region
421 has the potential for M-class events through the first half of
the period.  The block of active longitudes (L = 190 – 205), which
rotated around the west limb this period, will return by mid August
and may produce moderate solar activity levels.

No greater than 10 MeV proton events at geosynchronous orbit are
expected.

The greater than 2 MeV electron flux is expected to reach high levels
on July 30 – 05 August, 10 - 11 August, and again on 13 –16 August,
due to recurrent coronal hole high speed streams.

The geomagnetic field is expected to range from quiet to major storm
levels during the period.  A large, recurrent coronal hole high
speed stream in expected to become geoeffective on 28 July – 03
August, and produce active to minor storm levels.  Coronal hole
effects are expected again on 7 - 9 August and again on 11 – 17
August.