Joint USAF/NOAA Report of Solar and Geophysical Activity 27 March 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Mar 27 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 086 Issued at 2200Z on 27 Mar 2011
IA. Analysis of Solar Active Regions and Activity from 26/2100Z
to 27/2100Z: Solar activity was low. Region 1176 (S15E02) produced a
C3/Sf at 27/0014Z with discrete radio emissions. Associated with
this event was a CME, first observed in LASCO C2 and C3 imagery at
27/0200Z and 27/0242Z respectively. The CME appeared as a narrow
band extending east, as viewed in LASCO, and had an estimated
plane-of-sky velocity of 630 km/s. SDO/AIA 193 imagery indicated
material movement in a wide band extending north through east with
stronger movement in an easterly direction. Region 1176 showed
little change during the period. At 27/0511Z, Type II (estimated
shock velocity of 651 km/s) and Type IV radio signatures were
observed. GOES13 and 15 were in eclipse phase, so GOES XRS data was
not available. At 27/0512Z, limited GOES-15 SXI data indicated
surging and material movement off the NE limb in the vicinity of new
Region 1183 (N15E62). LASCO C2 (27/0536Z) and C3 (27/0606Z) imagery
detected an asymmetric, partial-halo CME lifting off the NE limb
with an estimated plane-of-sky velocity of 880 km/s. New Region 1183
rotated on as a large, 8-spot E-type group with beta-gamma magnetic
characteristics. New Region 1182 (N13E01) evolved on the disk as a
single spot unipolar group. The remaining groups were quiet and
stable during the period. At this time, neither CMEs observed on 27
March appeared to have an Earth-directed component. The Penticton
10.7 cm flux and 90 day mean are estimated due to non-receipt of 27
March’s flux reading.
IB. Solar Activity Forecast: Solar activity is expected to be
moderate for the next three days (28-30 March). A chance for M-class
activity exists on day one (28 March) becoming likely on days two
and three (29 – 30 March) with a slight chance for X-class activity
on 29 – 30 March. This expected increase in activity is due to the
complex nature of Regions 1176 and 1183 plus the return of old
Regions 1166 (N10, L=110) on 28 March and 1169 (N17, L=078) on 30
March. On their last transit across the disk, these regions produced
a total of six M-class events and one X-class event.
IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:
The geomagnetic field was quiet. ACE solar wind velocities were low,
varying between 300 to 370 Km/s, while the Bz component of the IMF
was generally north through a majority of the period.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels, with isolated active
periods, on day one (28 March) due to possible effects from the 24
March CME. Mostly quiet conditions are expected for day two (29
March). By day three (30 March), quiet to unsettled conditions, with
isolated active periods, are expected due to the arrival of a
recurrent coronal hole high speed stream.
III. Event Probabilities 28 Mar-30 Mar
Class M 50/60/70
Class X 05/10/10
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 27 Mar 117
Predicted 28 Mar-30 Mar 125/125/130
90 Day Mean 27 Mar 097
V. Geomagnetic A Indices
Observed Afr/Ap 26 Mar 001/001
Estimated Afr/Ap 27 Mar 001/001
Predicted Afr/Ap 28 Mar-30 Mar 010/010-005/005-010/010
VI. Geomagnetic Activity Probabilities 28 Mar-30 Mar
A. Middle Latitudes
Active 20/10/20
Minor storm 05/01/05
Major-severe storm 01/01/01
B. High Latitudes
Active 25/15/25
Minor storm 10/01/10
Major-severe storm 01/01/01