:Product: 1221RSGA.txt :Issued: 2007 Dec 21 2203 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 21 Dec 2007 IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity was very low. The visible disk remains spotless. IB. Solar Activity Forecast: Solar activity is expected to be very low. IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field was quiet to unsettled. Solar wind observations at ACE gradually decreased in velocity from a high of 745 km/s at 20/2128Z to 600 km/s at forecast issue time. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels today. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled for the next three days (22-24 December). Isolated active conditions are possible at high latitudes for days 1 and 2 (22-23 December). III. Event Probabilities 22 Dec-24 Dec Class M 01/01/01 Class X 01/01/01 Proton 01/01/01 PCAF Green IV. Penticton 10.7 cm Flux Observed 21 Dec 071 Predicted 22 Dec-24 Dec 070/069/069 90 Day Mean 21 Dec 071 V. Geomagnetic A Indices Observed Afr/Ap 20 Dec 010/012 Estimated Afr/Ap 21 Dec 008/012 Predicted Afr/Ap 22 Dec-24 Dec 008/010-006/008-005/005 VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec A. Middle Latitudes Active 15/15/15 Minor storm 05/01/01 Major-severe storm 01/01/01 B. High Latitudes Active 30/20/15 Minor storm 10/05/05 Major-severe storm 05/01/01