Joint USAF/NOAA Report of Solar and Geophysical Activity 24 Sep 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 Sep 24 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 267 Issued at 2200Z on 24 Sep 2007

IA. Analysis of Solar Active Regions and Activity from 23/2100Z to 24/2100Z: Solar activity was very low. The visible solar disk remains spotless.

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

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z: The geomagnetic field ranged from quiet to active with a period of minor storming observed at middle latitudes. An elevated solar wind speed due to a coronal hole high speed stream contributed to the activity. Solar wind speed remains elevated at approximately 620 km/s at the time of issue. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled with a chance for active periods on 25 September due to the ongoing coronal hole high speed stream. Expect quiet to unsettled conditions on 26 – 27 September.

III. Event Probabilities 25 Sep-27 Sep

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

IV. Penticton 10.7 cm Flux

• Observed 24 Sep 066
• Predicted 25 Sep-27 Sep 066/066/067
• 90 Day Mean 24 Sep 070

V. Geomagnetic A Indices

• Observed Afr/Ap 23 Sep 011/015
• Estimated Afr/Ap 24 Sep 009/010
• Predicted Afr/Ap 25 Sep-27 Sep 007/008-005/005-005/008

VI. Geomagnetic Activity Probabilities 25 Sep-27 Sep

A. Middle Latitudes

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

B. High Latitudes

• Active 20/10/15
• Minor storm 05/05/05
• Major-severe storm 01/01/01