Joint USAF/NOAA Report of Solar and Geophysical Activity 25 Dec 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Dec 25 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 360 Issued at 2200Z on 25 Dec 2008

IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: 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 24/2100Z to 25/2100Z: Geomagnetic field activity was at quiet levels. ACE solar wind data indicated Earth remained within a gradually subsiding coronal hole high-speed stream. Solar wind velocities gradually decreased from 519 to 430 km/sec during the period. IMF Bz was variable in the +03 to -04 nT range.

IIB. Geophysical Activity Forecast: Geomagnetic field activity is expected to be at quiet levels during the forecast period (26 – 28 December).

III. Event Probabilities 26 Dec-28 Dec

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

IV. Penticton 10.7 cm Flux

• Observed 25 Dec 069
• Predicted 26 Dec-28 Dec 070/071/071
• 90 Day Mean 25 Dec 069

V. Geomagnetic A Indices

• Observed Afr/Ap 24 Dec 005/005
• Estimated Afr/Ap 25 Dec 003/005
• Predicted Afr/Ap 26 Dec-28 Dec 005/005-005/005-005/005

VI. Geomagnetic Activity Probabilities 26 Dec-28 Dec

A. Middle Latitudes

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

B. High Latitudes

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