Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Apr 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 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 2007

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was very low. The visible disk remains spotless.

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

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was quiet.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to range from quiet to active for the next three days due to a recurrent coronal hole high speed stream. Isolated active periods are possible at high latitudes on 21 April.

III. Event Probabilities 21 Apr-23 Apr

• Class M 01/01/01
• Class X 01/01/01
• Proton 01/01/01
• PCAF Green

IV. Penticton 10.7 cm Flux

• Observed 20 Apr 069
• Predicted 21 Apr-23 Apr 070/070/070
• 90 Day Mean 20 Apr 075

V. Geomagnetic A Indices

• Observed Afr/Ap 19 Apr 004/006
• Estimated Afr/Ap 20 Apr 005/008
• Predicted Afr/Ap 21 Apr-23 Apr 012/015-008/008-008/008

VI. Geomagnetic Activity Probabilities 21 Apr-23 Apr

A. Middle Latitudes

• Active 35/25/25
• Minor storm 15/10/10
• Major-severe storm 05/01/01

B. High Latitudes

• Active 40/30/30
• Minor storm 25/15/15
• Major-severe storm 10/05/05