Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Sep 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Sep 17 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 261 Issued at 2200Z on 17 Sep 2008

IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: Solar activity was very low. No flares were observed during the past 24 hours. The visible disk remained spotless.

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

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field was predominately quiet. An isolated unsettled period was observed between 17/0300-0600Z. Solar wind speed measured at the ACE spacecraft showed a gradual decrease from approximately 530 km/s to 410 km/s during the forecast period. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels again today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be predominately quiet with isolated unsettled conditions for the next three days (18-20 September).

III. Event Probabilities 18 Sep-20 Sep

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

IV. Penticton 10.7 cm Flux

• Observed 17 Sep 067
• Predicted 18 Sep-20 Sep 066/066/066
• 90 Day Mean 17 Sep 066

V. Geomagnetic A Indices

• Observed Afr/Ap 16 Sep 007/009
• Estimated Afr/Ap 17 Sep 005/005
• Predicted Afr/Ap 18 Sep-20 Sep 005/005-005/005-005/005

VI. Geomagnetic Activity Probabilities 18 Sep-20 Sep

A. Middle Latitudes

• Active 10/10/10
• Minor storm 01/01/01
• Major-severe storm 01/01/01

B. High Latitudes

• Active 10/10/10
• Minor storm 01/01/01
• Major-severe storm 01/01/01