Joint USAF/NOAA Report of Solar and Geophysical Activity 26 May 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 May 26 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 146 Issued at 2200Z on 26 May 2011
IA. Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity was low. A fast emerging flux region
was numbered today as Region 1223 (S15E14). This region produced
two C-class events as it evolved. The first was a C1 at 25/2103Z
then followed by a second C1 at 25/2158Z. It is configured as a Cso
group with a beta magnetic classification.
IB. Solar Activity Forecast: Solar activity is expected to be very
low to low with a chance for a C-class event.
IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field was mainly quiet with an active period reported
at 25/1800Z at mid-latitudes. Observations from the ACE spacecraft
indicated a possible co-rotating interaction region (CIR) at around
25/1330Z. Solar wind speed increased from around 340 to 390 km/s
and density jumped to 6 p/cc. Interplanetary magnetic field changes
included an increase in Bt to +7 nT, while Bz dipped to -6 nT.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be mostly unsettled with isolated active periods, and
isolated minor storms possible at high-latitudes, for the next three
days (27-29 May). Activity is expected due to a recurrent coronal
hole high speed stream. In addition, a disappearing filament
observed at 25/0801Z may possibly disturb the field on day two (28
May).
III. Event Probabilities 27 May-29 May
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 26 May 083
Predicted 27 May-29 May 085/085/085
90 Day Mean 26 May 108
V. Geomagnetic A Indices
Observed Afr/Ap 25 May 002/004
Estimated Afr/Ap 26 May 005/007
Predicted Afr/Ap 27 May-29 May 010/010-015/015-010/012
VI. Geomagnetic Activity Probabilities 27 May-29 May
A. Middle Latitudes
Active 20/25/20
Minor storm 05/10/05
Major-severe storm 01/05/01
B. High Latitudes
Active 30/35/30
Minor storm 10/15/10
Major-severe storm 05/05/05