Joint USAF/NOAA Report of Solar and Geophysical Activity 9 August 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Aug 09 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 221 Issued at 2200Z on 09 Aug 2011
IA. Analysis of Solar Active Regions and Activity from 08/2100Z
to 09/2100Z: Solar activity was high. Region 1263 (N17W83) produced
an X6/2b flare at 09/0805Z, the largest x-ray event so far in Cycle
24. This flare was accompanied by multi-frequency radio emissions,
including a Tenflare (710sfu), and Type II (1551 km/s) and IV
signatures. A full halo CME was subsequently observed in LASCO C3
imagery at 09/0906Z. Initial plane-of-sky speed was estimated to be
about 1000 km/s. Earlier in the period, a CME was observed in LASCO
C3 imagery at 0406Z. This event was attributed to an M2/1b flare
from Region 1263 at 09/03435Z. While the area of Region 1263
diminished over the last 24 hours, the longitudinal extent expanded,
and the region ended the period as an Ehc type spot group with a
beta-gamma-delta magnetic configuration.
IB. Solar Activity Forecast: Solar activity is likely to be low to
moderate. A slight chance for an isolated X-class flare, and/or
proton event, remains for Day 1 (10 August). Event probabilities are
expected to gradually decrease as Region 1263 rotates around the
west limb.
IIA. Geophysical Activity Summary 08/2100Z to 09/2100Z:
The geomagnetic field was quiet to unsettled through the period under
the continued influence of a coronal hole high speed stream. Solar
wind speed at the ACE spacecraft was approximately 600 km/s for most
of the period. The Bz component of the interplanetary magnetic
field was predominantly near zero. The greater than 100 MeV protons
crossed the 1 pfu event threshold at 09/0825Z, reached a maximum of
2 pfu at 09/0855Z, and ended at 09/1045Z. The greater than 10 MeV
protons crossed the 10 pfu event threshold at 09/0845Z, reached a
maximum of 26 pfu at 09/1210Z, and ended at 09/1715Z. The greater
than 2 MeV electron flux at geosynchronous orbit reached high levels
during the period.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominantly quiet to unsettled for the next three
days (10-12 August). Unsettled conditions are expected on Day 1 (10
August) as a weak remnant of the 08 August CME arrives. Currently,
a return to mostly quiet conditions is expected on Days 2 and 3
(11-12 August). Analysis of the 09/0906Z CME is presently underway
to determine its potential geoeffectiveness.
III. Event Probabilities 10 Aug-12 Aug
Class M 60/40/20
Class X 10/10/05
Proton 99/60/10
PCAF Yellow
IV. Penticton 10.7 cm Flux
Observed 09 Aug 098
Predicted 10 Aug-12 Aug 095/085/085
90 Day Mean 09 Aug 096
V. Geomagnetic A Indices
Observed Afr/Ap 08 Aug 008/010
Estimated Afr/Ap 09 Aug 008/008
Predicted Afr/Ap 10 Aug-12 Aug 010/010-007/007-005/005
VI. Geomagnetic Activity Probabilities 10 Aug-12 Aug
A. Middle Latitudes
Active 20/15/05
Minor storm 05/05/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/20/10
Minor storm 10/05/05
Major-severe storm 05/05/01