Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Apr 2005
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Apr 17 2210 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 107 Issued at 2200Z on 17 Apr 2005
IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity has been low. Newly numbered Region 755
(S11E76) generated three C-class events on 17 Apr, two near 1300Z
and one at 2054Z. All other regions remain steady.
IB. Solar Activity Forecast: Solar activity is expected to be low.
Region 755 has the continued potential to produce C-class activity.
IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field has been at quiet to unsettled levels. The
greater than 2 MeV electron flux at geosynchronous orbit reached
high levels today.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels. There’s a chance for
isolated periods of active levels as a high-speed stream from a
small, but well defined coronal hole rotates into potentially
geoeffective range from 19 – 20 Apr.
III. Event Probabilities 18 Apr-20 Apr
- Class M 10/15/15
- Class X 01/01/01
- Proton 01/01/01
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 17 Apr 084
- Predicted 18 Apr-20 Apr 090/090/090
- 90 Day Mean 17 Apr 093
V. Geomagnetic A Indices
- Observed Afr/Ap 16 Apr 004/007
- Estimated Afr/Ap 17 Apr 005/006
- Predicted Afr/Ap 18 Apr-20 Apr 005/008-010/012-008/012
VI. Geomagnetic Activity Probabilities 18 Apr-20 Apr
A. Middle Latitudes
- Active 15/20/20
- Minor storm 01/05/05
- Major-severe storm 01/01/01
B. High Latitudes
- Active 20/25/25
- Minor storm 05/10/10
- Major-severe storm 02/05/05
