Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Apr 2003

By SpaceRef Editor

April 21, 2003

Filed under Space Weather Prediction Center (NOAA), Space Weather Solar-Geophysical Activity, US

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 significant 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