Joint USAF/NOAA Report of Solar and Geophysical Activity 25 Dec 2004

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2004 Dec 25 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 360 Issued at 2200Z on 25 Dec 2004

IA. Analysis of Solar Active Regions and Activity from 24/2100Z
to 25/2100Z: Solar activity was very low. Region 713 (S09W36) has
decreased in both area and spot number.

IB. Solar Activity Forecast: Solar activity is expected to be very
low with a chance for C-class activity from Region 713.

IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z:
The geomagnetic field was quiet to active with an isolated period of
minor storming from 0300Z to 0600Z on 25 December. Active
conditions due to the onset of a geoeffective coronal hole high
speed stream.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to active with isolated minor storm periods
possible at high latitudes.

III. Event Probabilities 26 Dec-28 Dec

• Class M 05/05/05
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 25 Dec 093
• Predicted 26 Dec-28 Dec 095/095/095
• 90 Day Mean 25 Dec 104

V. Geomagnetic A Indices

• Observed Afr/Ap 24 Dec 002/004
• Estimated Afr/Ap 25 Dec 010/015
• Predicted Afr/Ap 26 Dec-28 Dec 015/018-015/012-010/010

VI. Geomagnetic Activity Probabilities 26 Dec-28 Dec

A. Middle Latitudes

• Active 25/25/20
• Minor storm 15/15/10
• Major-severe storm 05/05/01

B. High Latitudes

• Active 30/30/25
• Minor storm 15/15/15
• Major-severe storm 10/10/05