:Product: 0424RSGA.txt
:Issued: 2012 Apr 24 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 115 Issued at 2200Z on 24 Apr 2012
IA.  Analysis of Solar Active Regions and Activity from  23/2100Z
to 24/2100Z:  Solar activity has been at low levels for the past 24
hours with multiple C-class x-ray events. A C3 flare was observed at
24/0745Z off the east limb from new Region 1467 (N14E72). Associated
with this event, were both a type II radio sweep (estimated shock
velocity of 1029 km/s) and a non-Earth directed CME. Two other new
regions were numbered today, Region 1468 (N09E12) which rapidly
emerged on the disk and Region 1469 (S21E68), which rotated onto the
disk. The remaining active regions were stable and quiet today,
except for Region 1465 (S19W12). Region 1465 showed a consolidation
of both leader and follower spot groups into one cluster and is now
classified as a beta-gamma-delta.
IB.  Solar Activity Forecast:  Solar activity is expected to be at
low levels with a slight chance for M-class activity for the next
three days (25 - 27 April).
IIA.  Geophysical Activity Summary 23/2100Z to 24/2100Z:
The geomagnetic field ranged from quiet to major storm levels during
the past 24 hours due to continued CME effects and the arrival of a
coronal hole high speed stream (CH HSS). Early in the period, 
measurements from the ACE spacecraft showed extensive southward
(negative) periods of the Bz component of the IMF. Even though solar
wind speeds remained well below nominal levels, these periods drove
the majority of the geomagnetic activity. Around 24/0200Z, CH HSS
characteristics were observed by the ACE spacecraft with solar wind
density dropping off as the solar wind speed increased. At the time
of this report, solar wind speeds had increased from around 350 km/s
to around 630 km/s.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at quiet to active levels on day one (25 April) as
the effects of a CH HSS continue. An increase to active with a
chance for isolated minor storm periods is expected on day two (26
April) as the CME from 23 April is expected to become geoeffective.
Quiet to unsettled levels are expected on day three (27 April) as
effects of the CME wane.
III.  Event Probabilities 25 Apr-27 Apr
Class M    20/20/20
Class X    01/01/01
Proton     01/01/01
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           24 Apr 134
Predicted   25 Apr-27 Apr  130/130/125
90 Day Mean        24 Apr 112
V.  Geomagnetic A Indices
Observed Afr/Ap 23 Apr  021/030
Estimated Afr/Ap 24 Apr  021/031
Predicted Afr/Ap 25 Apr-27 Apr  012/018-017/022-011/015
VI.  Geomagnetic Activity Probabilities 25 Apr-27 Apr
A.  Middle Latitudes
Active                25/40/25
Minor storm           10/20/10
Major-severe storm    01/05/01
B.  High Latitudes
Active                45/50/40
Minor storm           25/30/25
Major-severe storm    15/15/10