Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Apr 2004
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Apr 20 2200 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 111 Issued at 2200Z on 20 Apr 2004
IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity has been very low. Region 596 (S09E31)
remains the largest region on the visible solar disk at 340
millionths of white light coverage. A new region was numbered today
as Region 597 (S06W60).
IB. Solar Activity Forecast: Solar activity is expected to be very
low to low. Region 596 has the potential for continued C-class
activity.
IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was at quiet to unsettled levels.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominately at quiet to unsettled levels. Isolated
periods of active conditions are possible on 23 April due to a
recurrent coronal hole high speed stream.
III. Event Probabilities 21 Apr-23 Apr
- Class M 20/20/20
- Class X 05/05/05
- Proton 01/01/01
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 20 Apr 111
- Predicted 21 Apr-23 Apr 115/120/120
- 90 Day Mean 20 Apr 107
V. Geomagnetic A Indices
- Observed Afr/Ap 19 Apr 004/006
- Estimated Afr/Ap 20 Apr 005/006
- Predicted Afr/Ap 21 Apr-23 Apr 005/010-010/010-010/015
VI. Geomagnetic Activity Probabilities 21 Apr-23 Apr
A. Middle Latitudes
- Active 20/25/25
- Minor storm 05/05/05
- Major-severe storm 01/01/01
B. High Latitudes
- Active 25/25/30
- Minor storm 10/10/10
- Major-severe storm 01/01/01
