Joint USAF/NOAA Report of Solar and Geophysical Activity 25 Oct 2004
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Oct 25 2210 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 299 Issued at 2200Z on 25 Oct 2004
IA. Analysis of Solar Active Regions and Activity from 24/2100Z
to 25/2100Z: Solar activity was low. A C6.8 flare was observed from
Region 687 (N12E03) at 25/1031 UTC. Region 687 also produced
several other low level C-class flares. Region 691 (N15E48)
produced a C4.2 at 25/0252 UTC and maintains a Beta-Gamma-Delta
magnetic configuration.
IB. Solar Activity Forecast: Solar activity is expected to be low
to moderate. Isolated M-class flares from Region 687 are expected.
IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z:
The geomagnetic field was quiet to unsettled with an active period on
25 October between 0900 and 1200 UTC. The active period was most
likely due to a geoeffective coronal hole. ACE data show solar wind
speed has remained around 500 km/s, however the total interplanetary
magnetic field strength has decreased from approximately 10 nT to 4
nT.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled with possible isolated active
conditions on 26 October. On 27 and 28 October, quiet to unsettled
conditions are expected.
III. Event Probabilities 26 Oct-28 Oct
- Class M 55/55/55
- Class X 05/05/05
- Proton 05/05/05
- PCAF Green
IV. Penticton 10.7 cm Flux
- Observed 25 Oct 140
- Predicted 26 Oct-28 Oct 140/135/135
- 90 Day Mean 25 Oct 104
V. Geomagnetic A Indices
- Observed Afr/Ap 24 Oct 006/009
- Estimated Afr/Ap 25 Oct 010/014
- Predicted Afr/Ap 26 Oct-28 Oct 010/012-008/008-005/005
VI. Geomagnetic Activity Probabilities 26 Oct-28 Oct
A. Middle Latitudes
- Active 20/15/15
- Minor storm 10/05/05
- Major-severe storm 05/05/01
B. High Latitudes
- Active 25/25/20
- Minor storm 15/10/10
- Major-severe storm 05/05/05
