Report of Solar-Geophysical Activity

Issued: 2006 Apr 23 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 113 Issued at 2200Z on 23 Apr 2006 IA. Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: Solar activity was very low. New Region 875 (S11E71) was numbered today. This region was responsible for numerous B-class flares.

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

IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z:

The geomagnetic field was mostly quiet to unsettled. An isolated active period was observed at mid-latitudes between 23/0600 UTC and 0900 UTC. Solar wind speed at ACE has decreased from approximately 600 km/s to 500 km/s.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled.

III. Event Probabilities 24 Apr-26 Apr

Class M 05/05/05

Class X 01/01/01

Proton 01/01/01

PCAF green

IV. Penticton 10.7 cm Flux

Observed 23 Apr 087

Predicted 24 Apr-26 Apr 085/085/090

90 Day Mean 23 Apr 078

V. Geomagnetic A Indices

Observed Afr/Ap 22 Apr 010/018

Estimated Afr/Ap 23 Apr 008/008

Predicted Afr/Ap 24 Apr-26 Apr 005/008-005/005-005/005 VI. Geomagnetic Activity Probabilities 24 Apr-26 Apr A. Middle Latitudes

Active 15/15/15

Minor storm 05/05/05

Major-severe storm 01/01/01

B. High Latitudes

Active 20/15/15

Minor storm 10/05/05

Major-severe storm 01/01/01