Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Dec 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Dec 20 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 355 Issued at 2200Z on 20 Dec 2008

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was very low. The visible disk remained spotless.

IB. Solar Activity Forecast: Solar activity is expected to remain at very low levels.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was at quiet levels.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on 21 December. Quiet to unsettled conditions are expected for 22 – 23 December. The increase in activity is forecast due to a recurrent coronal hole high speed stream.

III. Event Probabilities 21 Dec-23 Dec

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

IV. Penticton 10.7 cm Flux

• Observed 20 Dec 069
• Predicted 21 Dec-23 Dec 069/069/069
• 90 Day Mean 20 Dec 069

V. Geomagnetic A Indices

• Observed Afr/Ap 19 Dec 002/003
• Estimated Afr/Ap 20 Dec 002/005
• Predicted Afr/Ap 21 Dec-23 Dec 005/005-010/010-008/008

VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec

A. Middle Latitudes

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

B. High Latitudes

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