Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Apr 2004
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Apr 17 2200 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 108 Issued at 2200Z on 17 Apr 2004
IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity increased to low levels. A C1 x-ray
flare occurred on the solar southeast limb at 17/1142Z. The source
region for this flare is yet to be numbered due to its location on
the limb. Region 591 (S16W65) continues to decay and was quiescent
throughout the period. Region 595 (S09E55) produced low level
B-class flares early in the period and has since shown decay to the
sunspot area. No new regions were numbered today.
IB. Solar Activity Forecast: Solar activity is expected to be at
very low to low levels.
IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field was at predominantly quiet to unsettled levels.
A period of active conditions occurred between 17/0300 and 0600Z at
the middle latitudes.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels.
III. Event Probabilities 18 Apr-20 Apr
- Class M 05/05/05
- Class X 01/01/01
- Proton 01/01/01
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 17 Apr 098
- Predicted 18 Apr-20 Apr 100/105/105
- 90 Day Mean 17 Apr 107
V. Geomagnetic A Indices
- Observed Afr/Ap 16 Apr 010/012
- Estimated Afr/Ap 17 Apr 008/012
- Predicted Afr/Ap 18 Apr-20 Apr 006/010-003/008-003/008
VI. Geomagnetic Activity Probabilities 18 Apr-20 Apr
A. Middle Latitudes
- Active 15/10/10
- Minor storm 05/05/05
- Major-severe storm 01/01/01
B. High Latitudes
- Active 25/20/20
- Minor storm 10/05/05
- Major-severe storm 01/01/01
