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

Product: 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