Report of Solar-Geophysical Activity
Issued: 2005 Sep 13 2214 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 256 Issued at 2200Z on 13 Sep 2005 IA. Analysis of Solar Active Regions and Activity from 12/2100Z to 13/2100Z: Solar activity was high. Region 808 (S11E04) produced an M1.3 at 13/1121 UTC and an X1.5/3b at 13/1927 UTC. Strong centimetic radio bursts accompanied this flare including a 4900 sfu Tenflare and a 24,000 sfu burst on the 8800 MHz frequency. The X1.5 flare initially began as an impulsive flare; however, X-ray flux values began rising again resulting in a long duration event with a second peak above X1 levels. LASCO imagery shows a very bright and fast full halo CME with this event with a preliminary speed estimate of 1500 km/s. Region 808 underwent some slow decay over the last 24 hours, but still retains a strong beta-gamma-delta configuration.
IB. Solar Activity Forecast: Solar activity is expected to be moderate to high. Region 808 has potential for M and X-class activity.
IIA. Geophysical Activity Summary 12/2100Z to 13/2100Z:
The geomagnetic field has been at unsettled to major storm levels.
Storm conditions persisted through much of this period due to transient flow from the intense CME activity over the past several days. Conditions returned to predominantly unsettled levels by the end of the period. Solar wind speed at ACE remains elevated, but decreased from a high near 800 km/s to approximately 650 km/s by the end of the period. The greater than 10 MeV proton event that began on 08 September fell below the 10 pfu threshold today. 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 unsettled to minor storm levels on 14 September. On
15 September, major to severe storm periods are possible due to the expected arrival of the CME associated with today's X1 flare.
Conditions should subside to mostly unsettled to active levels by 16 September, with isolated minor storm periods possible.
III. Event Probabilities 14 Sep-16 Sep
Class M 80/75/70
Class X 50/40/30
Proton 40/40/30
PCAF green
IV. Penticton 10.7 cm Flux
Observed 13 Sep 114
Predicted 14 Sep-16 Sep 115/110/110
90 Day Mean 13 Sep 092
V. Geomagnetic A Indices
Observed Afr/Ap 12 Sep 032/066
Estimated Afr/Ap 13 Sep 025/060
Predicted Afr/Ap 14 Sep-16 Sep 018/025-050/100-015/020 VI. Geomagnetic Activity Probabilities 14 Sep-16 Sep A. Middle Latitudes
Active 30/10/30
Minor storm 20/20/15
Major-severe storm 10/70/05
B. High Latitudes
Active 35/10/30
Minor storm 20/20/20
Major-severe storm 15/70/10