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

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Mar 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 085 Issued at 2200Z on 26 Mar 2011
IA. Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity was moderate due to an impulsive M1
X-ray event at 25/2322Z from Region 1176 (S16E16). Associated with
this event were Type II (673 km/s), Type IV and 10.7 cm (170 sfu)
radio signatures. Region 1176 remained mostly unchanged through the
period, though it increased in longitudinal extent, and is
classified as an F-type group. Region 1178 (S15E43) developed
penumbra in its trailer spots to become a D-type group. At about
26/0500Z, GOES-15 SXI BE12A imagery observed a large surge from
Region 1180 (N25E53) that appeared to continue for about six hours.
X-ray data was mostly unavailable during this event due to GOES-13
and GOES-15 eclipse phase. Associated with this event was a
fast-moving (approximately 850 km/s) partial-halo, asymmetric CME
first observed in LASCO C3 imagery at 26/0630Z and STEREO-A and B
COR2 imagery at 26/0709Z. Though this CME does not appear to have an
Earth-directed component, further analysis is required.
IB. Solar Activity Forecast: Solar activity is expected to be low
for the next three days (27 – 29 March). A chance for M-class
activity exists on day one (27 March) becoming likely on days two
and three (28 – 29 March) with a slight chance for X-class activity
on 29 March. This expected increase in activity is due to the
complex nature of Region 1176 and the return of old Region 1166
(N10, L=110) on 27 March. On its last transit across the disk, old
Region 1166 produced four M-class events and one X-class event.
IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field was at quiet levels. ACE solar wind data
indicated a gradual decrease in wind velocities from a high of 460
km/s at 26/0243Z to a low of 360 km/s at 26/1841Z. IMF Bz was
predominately north through the period.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at mostly quiet levels for day one (27 March). By day
two (28 March), quiet to unsettled conditions, with isolated active
periods, are possible due to effects from the 24 March CME. Quiet
levels are expected to return on day three (29 March).
III. Event Probabilities 27 Mar-29 Mar
Class M 50/60/70
Class X 05/05/10
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 26 Mar 115
Predicted 27 Mar-29 Mar 120/125/125
90 Day Mean 26 Mar 096
V. Geomagnetic A Indices
Observed Afr/Ap 25 Mar 002/003
Estimated Afr/Ap 26 Mar 002/003
Predicted Afr/Ap 27 Mar-29 Mar 005/005-010/010-005/005
VI. Geomagnetic Activity Probabilities 27 Mar-29 Mar
A. Middle Latitudes
Active 10/20/10
Minor storm 01/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/25/15
Minor storm 01/10/01
Major-severe storm 01/01/01