Joint USAF/NOAA Report of Solar and Geophysical Activity 30 September 2012

:Product: Report of Solar-Geophysical Activity
:Issued: 2012 Sep 30 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 274 Issued at 2200Z on 30 Sep 2012
IA. Analysis of Solar Active Regions and Activity from 29/2100Z
to 30/2100Z: Solar activity has been at moderate levels for the past
24 hours with Region 1583 (N12W88) producing an isolated M1 solar
x-ray event at 0433Z. Region 1583 had grown rapidly in the past 24
hours, however it is only hours away from rotating off the solar
disk and out of view. The remaining active regions on the disk
remained stable, producing a few low level C-class events. New
Region 1584 (S23E28) was numbered early in the period, and at the
time of this report, had only produced one low level C-class event.
No Earth directed CMEs were observed in the past 24 hours.
IB. Solar Activity Forecast: Solar activity is expected to be at
low levels with a slight chance for continued M-class activity for
the next two days (01 – 02 October). A return to low levels is
expected on day three (03 October), as the active region cluster,
located in the northwest quadrant, rotates around the west limb.
IIA. Geophysical Activity Summary 29/2100Z to 30/2100Z:
The geomagnetic field has been at quiet to active levels for the past
24 hours. The enhanced activity was due to the arrival of a CME from
27 September. At around 1100Z, measurements from the ACE spacecraft,
indicated the arrival of this CME. At 1138Z, a sudden impulse of 15
nT was measured by the Boulder magnetometer, as the CME reached
Earth. Solar wind velocities increased very little with this
initial phase of the CME, increasing from around 280 – 320 km/s. The
total IMF increased as the CME arrived, with sustained periods of
negative Bz. However, with the lower than expected solar wind
speeds, very little geomagnetic effects have been observed.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to active levels with minor storm periods
possible on day one (01 October), as effects of today’s CME
continue. Quiet to unsettled levels are expected on day two (02
October) as CME effects wane. A return to predominantly quiet levels
is expected on day three (03 October).
III. Event Probabilities 01 Oct-03 Oct
Class M 10/10/01
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 30 Sep 136
Predicted 01 Oct-03 Oct 130/130/125
90 Day Mean 30 Sep 124
V. Geomagnetic A Indices
Observed Afr/Ap 29 Sep 004/004
Estimated Afr/Ap 30 Sep 009/011
Predicted Afr/Ap 01 Oct-03 Oct 011/015-007/008-004/005
VI. Geomagnetic Activity Probabilities 01 Oct-03 Oct
A. Middle Latitudes
Active 35/10/05
Minor storm 15/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 10/15/15
Minor storm 25/20/15
Major-severe storm 50/20/10