Joint USAF/NOAA Report of Solar and Geophysical Activity 28 Sep 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force. Updated 2005 Sep 28 2204 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 271 Issued at 2200Z on 28 Sep 2005

IA. Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity was very low. Regions 810 (N08W74) and 812 (S02E05) produced no flares and exhibited no significant development. No new regions were numbered today.

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

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic field was quiet to active. Solar wind speed remains low, with end-of-day speeds around 370 km/s. Active periods were due to sustained southward Bz between 0100 – 0900 UTC.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be unsettled to active with possible isolated minor storming on 29 September as a recurrent coronal hole high speed stream moves into geoeffective position. Mostly unsettled conditions are expected on 30 September and 01 October.

III. Event Probabilities 29 Sep-01 Oct

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

IV. Penticton 10.7 cm Flux

• Observed 28 Sep 075
• Predicted 29 Sep-01 Oct 075/070/070
• 90 Day Mean 28 Sep 093

V. Geomagnetic A Indices

• Observed Afr/Ap 27 Sep 010/013
• Estimated Afr/Ap 28 Sep 010/020
• Predicted Afr/Ap 29 Sep-01 Oct 010/020-008/015-008/015

VI. Geomagnetic Activity Probabilities 29 Sep-01 Oct

A. Middle Latitudes

• Active 25/20/20
• Minor storm 10/10/10
• Major-severe storm 01/01/01

B. High Latitudes

• Active 35/30/30
• Minor storm 25/20/20
• Major-severe storm 15/10/10