Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 20 May 2004

By SpaceRef Editor

May 20, 2004

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

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2004 May 20 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 141 Issued at 2200Z on 20 May 2004

IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity was low. Newly assigned Region 618
(S10E69) produced all of today’s three C-class flares. The other
sunspot regions on the disk were quiet and stable. A filament in the
northeast quadrant erupted at 0136 UTC and was associated with a CME
off the northeast solar limb. The angular width of the CME was
narrow and the transient does not appear to be directed towards
Earth.

IB. Solar Activity Forecast: Solar activity is expected to be low.
Most of the activity is expected to occur in Region 618.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was mostly quiet to unsettled. However, there
was a period of minor storm levels from 0900-1200 UTC. Solar wind
data at ACE showed a steady increase in solar wind velocity from
initial values around 380 km/s up to about 500 km/s by forecast
issue time. Elevated solar wind temperature and wave patterns in the
magnetic field data suggest that the enhancement may originate from
a coronal hole.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be mostly unsettled but with a fair chance for some
isolated active periods during the next two days (21-22 May). A
decline to quiet to unsettled is expected around mid-day on the
third day (23 May).

III. Event Probabilities 21 May-23 May