Joint USAF/NOAA Report of Solar and Geophysical Activity 27 Sep 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Sep 27 2204 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 270 Issued at 2200Z on 27 Sep 2005

IA. Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: Solar activity was very low.

IB. Solar Activity Forecast: Solar activity is expected to be very low with a slight chance for an isolated C-flare from Region 810 (N08W62).

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field was quiet to active. An active period, observed between 0300 and 0600 UTC, was due to a prolonged interval of southward Bz.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be unsettled to active with minor storm periods possible on 28 and 29 September, as a recurrent coronal hole high speed stream moves into geoeffective position. Conditions should decrease to mostly unsettled by 30 September.

III. Event Probabilities 28 Sep-30 Sep

• Class M 05/05/05
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 27 Sep 077
• Predicted 28 Sep-30 Sep 080/080/075
• 90 Day Mean 27 Sep 093

V. Geomagnetic A Indices

• Observed Afr/Ap 26 Sep 009/014
• Estimated Afr/Ap 27 Sep 008/015
• Predicted Afr/Ap 28 Sep-30 Sep 010/020-010/020-008/015

VI. Geomagnetic Activity Probabilities 28 Sep-30 Sep

A. Middle Latitudes

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

B. High Latitudes

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