Joint USAF/NOAA Report of Solar and Geophysical Activity 25 March 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Mar 25 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 084 Issued at 2200Z on 25 Mar 2011
IA. Analysis of Solar Active Regions and Activity from 24/2100Z
to 25/2100Z: Solar activity was at low levels. Only isolated B-class
and low-level C-class events were observed during the period, all
from Region 1176 (S16E30). The region grew in area and spot count,
mostly from new development just to the NNE of the large leader
spot. Both Regions 1177 (N21E24) and 1178 (S15E55) developed
penumbra in their leader spots and were classified as bi-polar
C-type groups. Two new regions rotated on the disk during the
period; Region 1180 (N26E66) and Region 1181 (S23E69), both H-type
groups. A partial Halo CME was first observed at 24/1203Z in LASCO
C3 imagery extending through the northern hemisphere of the solar
disk. The likely source was from the M1/1f flare from Region 1176 at
24/1207Z.
IB. Solar Activity Forecast: Solar activity is expected to be low
for the next three days (26 – 28 March) with a chance for M-class
activity, primarily from Region 1176.
IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z:
The geomagnetic field was quiet. ACE solar wind data indicated a
gradual decrease in velocities from a high of near 500 km/s at
24/2304Z to a low of about 400 km/s at 25/1438Z. During the period,
IMF Bz was variable between +5 nT and -4 nT.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominately quiet levels for the days one and
two (26 – 27 March). By day three (28 March), quiet to unsettled
conditions, with isolated active periods, are possible due to
effects from the 24 March CME.
III. Event Probabilities 26 Mar-28 Mar
Class M 40/40/40
Class X 05/05/05
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 25 Mar 113
Predicted 26 Mar-28 Mar 120/125/130
90 Day Mean 25 Mar 096
V. Geomagnetic A Indices
Observed Afr/Ap 24 Mar 003/004
Estimated Afr/Ap 25 Mar 003/004
Predicted Afr/Ap 26 Mar-28 Mar 005/005-005/005-010/005
VI. Geomagnetic Activity Probabilities 26 Mar-28 Mar
A. Middle Latitudes
Active 10/10/20
Minor storm 01/01/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/25
Minor storm 01/01/10
Major-severe storm 01/01/01