Joint USAF/NOAA Report of Solar and Geophysical Activity 11 August 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Aug 11 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 223 Issued at 2200Z on 11 Aug 2011
IA. Analysis of Solar Active Regions and Activity from 10/2100Z
to 11/2100Z: Solar activity was low. Region 1263 (N17, L=301)
produced a C6 x-ray flare from beyond the west limb. New regions
1269 (S22E17) and 1270 (S23E54) were numbered today; both are small
and magnetically simple. A CME was observed on the west limb,
evident in SOHO/LASCO C2 imagery at 11/1036Z. Material movement and
subsequent darkening was observed in STEREO-A EUV imagery beginning
at approximately 11/1005Z. This CME is not expected to be
geoeffective.
IB. Solar Activity Forecast: Solar activity is expected to be very
low to low. There is a chance for a C class x-ray event throughout
the period.
IIA. Geophysical Activity Summary 10/2100Z to 11/2100Z:
The geomagnetic field was quiet. Solar wind speed at the ACE
spacecraft continued to decline and ended the period near 400 km/s.
The Phi angle briefly switched to negative between 11/10Z and
11/12Z. The Bz component of the interplanetary magnetic field
remained around zero. A shock was observed in the STEREO-A beacon
data at roughly 11/0600Z. This is most likely the arrival of the 09
August CME from Region 1263. The greater than 2 MeV electron flux at
geosynchronous orbit was at high levels throughout the period.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominantly quiet for the next three days (12-14
August).
III. Event Probabilities 12 Aug-14 Aug
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 11 Aug 084
Predicted 12 Aug-14 Aug 085/085/090
90 Day Mean 11 Aug 096
V. Geomagnetic A Indices
Observed Afr/Ap 10 Aug 008/007
Estimated Afr/Ap 11 Aug 005/004
Predicted Afr/Ap 12 Aug-14 Aug 005/005-005/005-005/005
VI. Geomagnetic Activity Probabilities 12 Aug-14 Aug
A. Middle Latitudes
Active 15/05/05
Minor storm 05/05/05
Major-severe storm 01/01/01
B. High Latitudes
Active 20/10/20
Minor storm 10/05/10
Major-severe storm 05/01/05