Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Apr 2004
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Apr 18 2200 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 109 Issued at 2200Z on 18 Apr 2004
IA. Analysis of Solar Active Regions and Activity from 17/2100Z
to 18/2100Z: Solar activity was very low. Occasional B-class flares
were observed in newly numbered Region 596 (S08E60). This developing
D-type group exhibited frequent brightness fluctuations throughout
the period. New spots have reemerged in Region 593 (S18W11). No
significant changes were observed in the remaining small active
regions.
IB. Solar Activity Forecast: Solar activity is expected to be low.
Isolated C-class events are likely from Region 596.
IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field was quiet to unsettled with an isolated active
period between 18/0600 – 0900Z. Solar wind speed ranged from 350 to
400 km/s.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled.
III. Event Probabilities 19 Apr-21 Apr
- Class M 10/10/10
- Class X 01/01/01
- Proton 01/01/01
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 18 Apr 109
- Predicted 19 Apr-21 Apr 115/115/120
- 90 Day Mean 18 Apr 107
V. Geomagnetic A Indices
- Observed Afr/Ap 17 Apr 006/009
- Estimated Afr/Ap 18 Apr 008/008
- Predicted Afr/Ap 19 Apr-21 Apr 005/008-005/008-005/008
VI. Geomagnetic Activity Probabilities 19 Apr-21 Apr
A. Middle Latitudes
- Active 10/10/10
- Minor storm 01/01/01
- Major-severe storm 01/01/01
B. High Latitudes
- Active 15/15/15
- Minor storm 05/05/05
- Major-severe storm 01/01/01
