Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Dec 2006

Product: Report of Solar-Geophysical Activity
Issued: 2006 Dec 21 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment 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 2006

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity continues at very low levels. There are currently no sunspots on the visible disk.

IB. Solar Activity Forecast: Solar activity is expected to continue at very low levels. Old Region 926 (S09, L=138) is due to return to the visible disk tomorrow, and may slightly increase activity levels.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field was at quiet to active levels, with isolated minor storm periods at high latitudes. A high speed coronal hole stream is responsible for the disturbed periods. Solar wind speed is in slow decline and ended the period near 600 km/s. The greater than 2 MeV electrons at geosynchronous orbit were at high levels again today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to active on 22 and 23 December, with isolated minor storm periods at higher latitudes. Quiet to unsettled levels with isolated active periods are expected on 24 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 072
• Predicted 22 Dec-24 Dec 075/080/080
• 90 Day Mean 21 Dec 081

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Dec 016/024
• Estimated Afr/Ap 21 Dec 015/018
• Predicted Afr/Ap 22 Dec-24 Dec 012/015-010/015-008/010

VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec

A. Middle Latitudes

• Active 30/25/20
• Minor storm 15/10/05
• Major-severe storm 05/01/01

B. High Latitudes

• Active 40/35/25
• Minor storm 20/15/05
• Major-severe storm 05/05/01