Joint USAF/NOAA Report of Solar and Geophysical Activity 23 Dec 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Dec 23 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 358 Issued at 2200Z on 23 Dec 2008

IA. Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: 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 22/2100Z to 23/2100Z: Geomagnetic field activity was at quiet to unsettled levels. ACE solar wind measurements indicated a recurrent coronal hole high-speed stream began early in the summary period. Solar wind velocities increased to a high of 579 km/sec at 23/1419Z and remained elevated during the rest of the period. IMF Bz was variable in the +07 to -07 nT range with a sustained southward period during approximately 22/2300Z to 23/0400Z.

IIB. Geophysical Activity Forecast: Geomagnetic field activity is expected to be at mostly quiet levels throughout the forecast period (24 – 26 December).

III. Event Probabilities 24 Dec-26 Dec

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

IV. Penticton 10.7 cm Flux

• Observed 23 Dec 069
• Predicted 24 Dec-26 Dec 069/069/069
• 90 Day Mean 23 Dec 069

V. Geomagnetic A Indices

• Observed Afr/Ap 22 Dec 003/004
• Estimated Afr/Ap 23 Dec 007/010
• Predicted Afr/Ap 24 Dec-26 Dec 005/005-005/005-005/005

VI. Geomagnetic Activity Probabilities 24 Dec-26 Dec

A. Middle Latitudes

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

B. High Latitudes

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