Joint USAF/NOAA Report of Solar and Geophysical Activity 29 May 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 May 29 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 149 Issued at 2200Z on 29 May 2011
IA. Analysis of Solar Active Regions and Activity from 28/2100Z
to 29/2100Z: Solar activity was moderate. At 29/1033Z, a
long-duration M1/1F flare occurred from Region 1126 (S21E54). The
flare was accompanied by a Type II (554 km/s shock velocity) radio
emission and a CME was later visible in both SOHO/LASCO and STEREO
COR2 imagery. The CME speed was estimated at 550 km/s using
plane-of-sky measurements. The CME is not expected to be
geoeffective, based on its origin. Region 1126 grew in area and
spot count over the past 24 hours. Two magnetically simple new
regions, 1127 (S19E69) and 1128 (N17E67), were numbered.
IB. Solar Activity Forecast: Solar activity is expected to be low
to moderate. More C-class events are expected and there is a
continued chance of an M-class event.
IIA. Geophysical Activity Summary 28/2100Z to 29/2100Z:
The geomagnetic field ranged from unsettled to minor storm levels.
Solar wind speed rose above 500 km/s early in the period and ranged
between 700-800 km/s for the remainder. The Bz component of the
interplanetary magnetic field fluctuated between +7 and -9 nT. At
the same time the wind speed increased, temperature increased,
density decreased and the Phi angle became negative. These
observations were consistent with a geoeffective coronal hole high
speed stream. The greater than 2 MeV electron flux at geosynchronous
orbit reached high levels during the period.
IIB. Geophysical Activity Forecast: The goemagnetic field is
expected to decline from predominantly unsettled to active levels on
day 1 (30 May), to quiet to unsettled levels on days 2 and 3 (31 May
– 01 Jun) as the coronal hole high speed stream wanes. There
remains a chance for isolated minor storm periods at high latitudes
on day 1.
III. Event Probabilities 30 May-01 Jun
Class M 40/40/40
Class X 05/05/05
Proton 05/05/05
PCAF green
IV. Penticton 10.7 cm Flux
Observed 29 May 111
Predicted 30 May-01 Jun 110/110/110
90 Day Mean 29 May 108
V. Geomagnetic A Indices
Observed Afr/Ap 28 May 032/040
Estimated Afr/Ap 29 May 025/043
Predicted Afr/Ap 30 May-01 Jun 015/020-010/012-005/010
VI. Geomagnetic Activity Probabilities 30 May-01 Jun
A. Middle Latitudes
Active 25/10/05
Minor storm 10/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 35/20/05
Minor storm 20/10/01
Major-severe storm 10/05/01