Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Dec 2004

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

Updated 2004 Dec 21 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 356 Issued at 2200Z on 21 Dec 2004

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity has been very low. Region 713 (S08E22)
has produced several B-class flares and retains its beta-gamma
magnetic configuration.

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

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field was quiet to unsettled with an isolated period
of active to minor storm conditions observed at 21/1200 UTC. Solar
wind data indicated a possible co-rotating interaction region
signature during this period. Solar wind speed ranged from around
350 to 490 km/s with the IMF Bz fluctuating to -14 nT.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominately quiet to unsettled with isolated
periods of active conditions on 22-23 December due to coronal hole
effects. Quiet to unsettled conditions are expected for 24
December.

III. Event Probabilities 22 Dec-24 Dec

• Class M 20/20/20
• Class X 01/01/01
• Proton 01/01/01
• PCAF Green

IV. Penticton 10.7 cm Flux

• Observed 21 Dec 101
• Predicted 22 Dec-24 Dec 100/105/105
• 90 Day Mean 21 Dec 104

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Dec 002/004
• Estimated Afr/Ap 21 Dec 008/015
• Predicted Afr/Ap 22 Dec-24 Dec 015/020-010/015-010/010

VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec

A. Middle Latitudes

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

B. High Latitudes

• Active 30/30/25
• Minor storm 20/15/15
• Major-severe storm 05/05/01