Report of Solar-Geophysical Activity

Issued: 2006 Apr 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 110 Issued at 2200Z on 20 Apr 2006 IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was at very low levels. Region 871 (S06W79) produced a couple B-class flares during the period. Region 874 (S01W11) continues to exhibit steady growth in spot area and magnetic complexity. No new regions were numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be at very low to low levels. Region 874 has a slight chance of producing an isolated C-class flare.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:

The geomagnetic field was at quiet levels. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels again today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels. A weak recurrent coronal hole may lead to isolated active periods on 23 April.

III. Event Probabilities 21 Apr-23 Apr

Class M 05/05/05

Class X 01/01/01

Proton 01/01/01

PCAF green

IV. Penticton 10.7 cm Flux

Observed 20 Apr 079

Predicted 21 Apr-23 Apr 080/080/085

90 Day Mean 20 Apr 078

V. Geomagnetic A Indices

Observed Afr/Ap 19 Apr 002/004

Estimated Afr/Ap 20 Apr 005/008

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

Active 15/15/20

Minor storm 01/01/05

Major-severe storm 01/01/01

B. High Latitudes

Active 20/20/20

Minor storm 05/05/10

Major-severe storm 01/01/05