Joint USAF/NOAA Report of Solar and Geophysical Activity 10 May 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 May 10 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 130 Issued at 2200Z on 10 May 2011
IA. Analysis of Solar Active Regions and Activity from 09/2100Z
to 10/2100Z: Solar activity remained low. A C5 x-ray flare occurred
at 09/2059Z from a region rounding the northeast limb at the time of
this report. This region appeared to be the return of old Region
1193 (N17, L=266), which produced C-class flares during its previous
rotation. The C5 flare was associated with a partial-halo coronal
mass ejection (CME). The CME had an estimated plane-of-sky velocity
of 1225 km/s, based on SOHO/LASCO images, and appeared to have an
Earthward component. No new regions were numbered.
IB. Solar Activity Forecast: Solar activity is expected to be low
through the period (11 – 13 May) with a chance for an M-class flare
from the region now crossing the northeast limb.
IIA. Geophysical Activity Summary 09/2100Z to 10/2100Z:
Geomagnetic field activity was at quiet to active levels. ACE solar
wind measurements indicated a co-rotating interaction region (CIR),
in advance of a coronal hole high-speed stream, commenced around
10/0400Z. Solar wind speeds gradually increased from 302 to 398 km/s
during the period. Interplanetary magnetic field (IMF) changes
associated with the CIR included increased Bt (peak 10 nT at
05/1338Z) and intermittent periods of southward Bz (maximum
deflection -10 nT at 05/1338Z). The greater than 2 MeV electron flux
at geosynchronous orbit briefly reached high levels during the period.
IIB. Geophysical Activity Forecast: Geomagnetic activity is
expected to be at quiet to active levels on day 1 (11 May), then
increase to unsettled to active levels with a chance for minor storm
levels on day 2 (12 May) as the CH HSS persists. The CME observed
today may also disturb the field on 12 May. Activity is expected to
decrease to quiet to unsettled levels on day 3 (13 May) as the CH
HSS subsides.
III. Event Probabilities 11 May-13 May
Class M 20/20/20
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 10 May 098
Predicted 11 May-13 May 100/100/100
90 Day Mean 10 May 110
V. Geomagnetic A Indices
Observed Afr/Ap 09 May 002/003
Estimated Afr/Ap 10 May 008/008
Predicted Afr/Ap 11 May-13 May 012/012-015/015-008/010
VI. Geomagnetic Activity Probabilities 11 May-13 May
A. Middle Latitudes
Active 30/35/10
Minor storm 10/15/05
Major-severe storm 01/05/01
B. High Latitudes
Active 35/40/15
Minor storm 15/20/10
Major-severe storm 05/10/01