Joint USAF/NOAA Report of Solar and Geophysical Activity 31 Dec 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Dec 31 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 366 Issued at 2200Z on 31 Dec 2008

IA. Analysis of Solar Active Regions and Activity from 30/2100Z to 31/2100Z: 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 30/2100Z to 31/2100Z: Geomagnetic field activity ranged from quiet to active levels. ACE solar wind measurements indicated a recurrent coronal hole high-speed stream began early in the summary period. Velocities gradually increased from 305 to 559 km/sec during the period. IMF changes associated with the transition to the high-speed stream included increased Bt (peak 17 nT at 31/0000Z) and intermittent periods of southward Bz (minimum -16 nT at 31/0131Z).

IIB. Geophysical Activity Forecast: Geomagnetic field activity is expected to range from quiet to active levels during days 1 – 2 (January 1 – 2) as the coronal hole high-speed stream continues. Activity is expected to decrease to quiet to unsettled levels on day 3 (3 January) as the high-speed stream subsides.

III. Event Probabilities 01 Jan-03 Jan

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

IV. Penticton 10.7 cm Flux

• Observed 31 Dec 069
• Predicted 01 Jan-03 Jan 069/069/069
• 90 Day Mean 31 Dec 069

V. Geomagnetic A Indices

• Observed Afr/Ap 30 Dec 001/001
• Estimated Afr/Ap 31 Dec 012/008
• Predicted Afr/Ap 01 Jan-03 Jan 008/008-012/012-008/008

VI. Geomagnetic Activity Probabilities 01 Jan-03 Jan

A. Middle Latitudes

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

B. High Latitudes

• Active 25/30/20
• Minor storm 10/15/10
• Major-severe storm 01/01/01