:Product: 20030421RSGA.txt
:Issued: 2003 Apr 21 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Environment Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 111 Issued at 2200Z on 21 Apr 2003
IA.  Analysis of Solar Active Regions and Activity from  20/2100Z
to 21/2100Z:  Solar activity increased to moderate levels. Region 338
(N18W05) produced an M2/1n flare at 21/1307Z. Considerable radio
emissions were associated with this flare, including a Type II (1200
km/s) and Type IV sweep, and a 300 sfu tenflare. A partial halo CME
was also noted from LASCO imagery. This beta-gamma region is in a
slow growth phase with a moderate increase in the number of
sunspots visible over the past 24 hours. Region 337 (S13E43) is the
largest and most complex region on the visible disk, and now
contains a weak delta configuration in the 350 millionths of white
light areal coverage. Only minor C-class flares have been observed
so far from this region. Minor C-class activity was also observed in
Region 339 (N16W58). New Regions 340 (S04E55), and 341 (S10E74),
were numbered today.
IB.  Solar Activity Forecast:  Solar activity is expected to be low
to moderate. An isolated M-class flare is possible from Regions 337
or 338.
IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field was at predominantly unsettled to active levels
with isolated high latitude minor storm periods. A high speed solar
wind stream, with winds ranging from 520 - 600 km/s, continues to
buffet the geomagnetic field. The greater than 2 MeV electrons at
geosynchronous orbit reached high levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at unsettled to active levels through day one. Minor
storm periods are possible on days two and three with the
anticipated arrival of the CME from today's M2 flare.
III.  Event Probabilities 22 Apr-24 Apr
Class M    25/25/25
Class X    05/05/05
Proton     05/05/05
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           21 Apr 126
Predicted   22 Apr-24 Apr  135/140/145
90 Day Mean        21 Apr 126
V.  Geomagnetic A Indices
Observed Afr/Ap 20 Apr  012/016
Estimated Afr/Ap 21 Apr  015/020
Predicted Afr/Ap 22 Apr-24 Apr  012/015-020/030-020/030
VI.  Geomagnetic Activity Probabilities 22 Apr-24 Apr
A.  Middle Latitudes
Active                30/40/40
Minor storm           10/20/20
Major-severe storm    01/05/05
B.  High Latitudes
Active                40/50/50
Minor storm           15/30/30
Major-severe storm    05/15/15