Joint USAF/NOAA Report of Solar and Geophysical Activity 1 April 2011
:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Apr 01 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 091 Issued at 2200Z on 01 Apr 2011
IA. Analysis of Solar Active Regions and Activity from 31/2100Z
to 01/2100Z: Solar activity remained at low levels. Region 1178
(S17W36) produced a C1/Sf at 31/2221Z associated with a partial-halo
CME that appeared to be directed southward, out of the ecliptic
plane. Region 1178 decayed to a plage area during the period. Region
1176 (S16W65) produced C3 flares at 01/0156Z and 01/0354Z, each of
which were associated with CME activity. This CME activity also
appeared to be directed southward, out of the ecliptic plane. Region
1176 gradually decayed during the period with a loss of spot count
and area. It was classified as an Fso-type with a simple beta
magnetic configuration. Region 1183 (N17E01) showed a gradual
increase in spot count and area and was classified as an Esi-type
with a beta magnetic configuration. New Region 1184, a single-spot
Axx-type, was numbered.
IB. Solar Activity Forecast: Solar activity is expected to be low
during the period (02 – 04 April) with a slight chance for moderate
activity (isolated M-class).
IIA. Geophysical Activity Summary 31/2100Z to 01/2100Z:
Geomagnetic activity increased to quiet to active levels. ACE solar
wind observations indicated the onset of a coronal hole high-speed
stream (CH HSS) at approximately 01/1600Z. Velocities increased to a
peak of 495 km/s at 01/1801Z. IMF changes associated with the CH HSS
included increased Bt (peaks to 12 nT during 01/2000 – 2100Z) and
intervals of southward Bz (maximum deflection -10 nT at 01/1628Z).
IIB. Geophysical Activity Forecast: Geomagnetic activity is
expected to be at quiet to unsettled levels during day 1 (02 April)
with a chance for active levels as CH HSS effects persist. Activity
is expected to decrease to mostly quiet levels during days 2 – 3 (03
– 04 April) as CH HSS effects subside.
III. Event Probabilities 02 Apr-04 Apr
Class M 25/25/25
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 01 Apr 109
Predicted 02 Apr-04 Apr 110/110/110
90 Day Mean 01 Apr 098
V. Geomagnetic A Indices
Observed Afr/Ap 31 Mar 002/003
Estimated Afr/Ap 01 Apr 010/013
Predicted Afr/Ap 02 Apr-04 Apr 007/007-005/005-005/005
VI. Geomagnetic Activity Probabilities 02 Apr-04 Apr
A. Middle Latitudes
Active 20/15/10
Minor storm 05/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 25/20/15
Minor storm 10/10/01
Major-severe storm 01/01/01
