Joint USAF/NOAA Report of Solar and Geophysical Activity 25 Sep 2006

Product: Report of Solar-Geophysical Activity
Issued: 2006 Sep 25 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 268 Issued at 2200Z on 25 Sep 2006

IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: Solar activity was very low. Region 910 (S08W46) has decayed to a plage region with no spots visible in white light imagery. Updated LASCO imagery shows a CME originating from behind the NE limb on 23 Sep. A slow CME was also observed from Region 910 on 24 Sep. Neither event is expected to be geoeffective.

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

IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: The geomagnetic field has been quiet to unsettled. Solar wind speed remains elevated (currently 525 km/s) due to a coronal hole high speed stream. The speed has, however, been steadily decreasing the past 24 hours as the coronal hole rotates into a less geoeffective position. The greater than 2 MeV electron flux reached high levels today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled for the forecast period (26 – 28 Sep).

III. Event Probabilities 26 Sep-28 Sep

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

IV. Penticton 10.7 cm Flux

• Observed 25 Sep 070
• Predicted 26 Sep-28 Sep 070/080/075
• 90 Day Mean 25 Sep 077

V. Geomagnetic A Indices

• Observed Afr/Ap 24 Sep 015/023
• Estimated Afr/Ap 25 Sep 006/008
• Predicted Afr/Ap 26 Sep-28 Sep 005/008-006/008-008/012

VI. Geomagnetic Activity Probabilities 26 Sep-28 Sep A. Middle Latitudes

• Active 15/15/15
• Minor storm 10/10/10
• Major-severe storm 05/05/05

B. High Latitudes

• Active 20/20/20
• Minor storm 15/15/15
• Major-severe storm 05/05/05