Joint USAF/NOAA Report of Solar and Geophysical Activity 24 Dec 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Dec 24 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 359 Issued at 2200Z on 24 Dec 2008

IA. Analysis of Solar Active Regions and Activity from 23/2100Z to 24/2100Z: Solar activity was very low. No flares were observed. The visible disk was spotless.

IB. Solar Activity Forecast: Solar activity is expected to be very low.

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z: Geomagnetic field activity was at quiet to unsettled levels. ACE solar wind data indicated Earth remained within a recurrent coronal hole high-speed stream. Solar wind velocities gradually decreased from a high of 552 km/sec to a low of 452 km/sec during the period. IMF Bz was variable in the +05 to -05 nT range.

IIB. Geophysical Activity Forecast: Geomagnetic field activity is expected to be at mostly quiet levels during the forecast period (25 – 27 December).

III. Event Probabilities 25 Dec-27 Dec

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

IV. Penticton 10.7 cm Flux

• Observed 24 Dec 069
• Predicted 25 Dec-27 Dec 069/070/071
• 90 Day Mean 24 Dec 069

V. Geomagnetic A Indices

• Observed Afr/Ap 23 Dec 008/009
• Estimated Afr/Ap 24 Dec 008/008
• Predicted Afr/Ap 25 Dec-27 Dec 005/005-005/005-005/005

VI. Geomagnetic Activity Probabilities 25 Dec-27 Dec

A. Middle Latitudes

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

B. High Latitudes

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