Report of Solar-Geophysical Activity

Issued: 2005 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 2005 IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was very low. Region 837 (S11W19) remains the largest group on the disk with about 210 millionths sunspot area. 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 ranged from quiet to active levels. Solar wind speed increased to about 680 km/s after 0200Z with an accompanied increase in temperature. At time of issue, solar wind speed was still elevated at approximately 560 km/s. These solar wind signatures are consistent with a small coronal hole high-speed-stream.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be mostly unsettled for the next 24 hours (21 December) with a chance for isolated active periods. Quiet to unsettled levels are expected for 22 and 23 December.

III. Event Probabilities 21 Dec-23 Dec

Class M 05/05/05

Class X 01/01/01

Proton 01/01/01

PCAF green

IV. Penticton 10.7 cm Flux

Observed 20 Dec 088

Predicted 21 Dec-23 Dec 090/085/085

90 Day Mean 20 Dec 083

V. Geomagnetic A Indices

Observed Afr/Ap 19 Dec 006/008

Estimated Afr/Ap 20 Dec 012/015

Predicted Afr/Ap 21 Dec-23 Dec 010/010-005/008-005/008 VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec A. Middle Latitudes

Active 25/15/15

Minor storm 15/05/05

Major-severe storm 01/01/01

B. High Latitudes

Active 30/25/25

Minor storm 15/10/10

Major-severe storm 05/01/01