Report of Solar-Geophysical Activity

Issued: 2005 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 2005 IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been very low. The largest event was a B4.4 flare from Region 835 (N19W81) at 21/1315Z. Region 837

(S11W32) remains the largest group on the disk with an area of 140 millionths. No new regions were numbered today.

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

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:

The geomagnetic field has been quiet to unsettled. Solar wind speed has declined steadily throughout the day from about 550 km/s to 450 km/s.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled for the next three days (22 - 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 087

Predicted 22 Dec-24 Dec 085/085/085

90 Day Mean 21 Dec 083

V. Geomagnetic A Indices

Observed Afr/Ap 20 Dec 011/016

Estimated Afr/Ap 21 Dec 007/010

Predicted Afr/Ap 22 Dec-24 Dec 008/012-005/007-005/007 VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec A. Middle Latitudes

Active 20/15/15

Minor storm 05/05/05

Major-severe storm 01/01/01

B. High Latitudes

Active 25/25/25

Minor storm 15/10/10

Major-severe storm 05/05/05