Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Dec 2006

Product: Report of Solar-Geophysical Activity
Issued: 2006 Dec 20 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 354 Issued at 2200Z on 20 Dec 2006

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was very low. No new regions were numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be very low.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was quiet to active. Active periods were due to a recurrent coronal hole high speed stream. Solar wind speed at ACE has increased from approximately 600 km/s to 740 km/s. 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 at unsettled to minor storm levels. Isolated major storm periods are possible at higher latitudes on 21 December. By 23 December, conditions are expected to decrease to mostly quiet to unsettled levels.

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 072
• Predicted 21 Dec-23 Dec 075/075/080
• 90 Day Mean 20 Dec 081

V. Geomagnetic A Indices O

• bserved Afr/Ap 19 Dec 009/014
• Estimated Afr/Ap 20 Dec 012/020
• Predicted Afr/Ap 21 Dec-23 Dec 015/030-012/020-010/015

VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec

A. Middle Latitudes

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

B. High Latitudes

• Active 45/40/30
• Minor storm 25/15/15
• Major-severe storm 20/10/05