Report of Solar-Geophysical Activity

Issued: 2011 Sep 29 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 272 Issued at 2200Z on 29 Sep 2011

IA.  Analysis of Solar Active Regions and Activity from  28/2100Z
to 29/2100Z:  Solar activity has been low for the past 24 hours.
Region 1305 (N13E16) has grown in aerial coverage and is now
considered a Cso-type spot group with a beta-gamma magnetic
configuration. The region produced a C1 event at 29/1023Z. Region
1302 (N13W16) produced a long duration C2/Sf at 29/1247Z. A Type II
Radio Sweep with an estimated speed of 608 km/s was associated with
this event. It is difficult to see in STEREO COR2 imagery but does
appear to be Earth directed with an estimated plane-of-sky speed of
628 km/s. Further analysis will be done as LASCO imagery becomes
available.
IB.  Solar Activity Forecast:  Solar activity is expected to be low
for the next three days (30 September - 02 October) with a chance
for isolated M-class and X-class events mainly from Region 1302.
IIA.  Geophysical Activity Summary 28/2100Z to 29/2100Z:
The geomagnetic field was mostly unsettled with isolated minor to
major storm levels observed between 29/0000-0600Z due to
substorming. Solar wind speeds jumped slightly to 600 km/s, in
conjunction with an increase in temperature and density around
29/0030Z. Bt reached +13 nT and Bz dipped south with a maximum
deviation of -10 nT.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be quiet to unsettled with a chance for isolated active
periods early on day one (30 September) due to residual effects from
the CME. Quiet to unsettled conditions are expected on day two (01
October) due to the arrival of a recurrent coronal hole high speed
stream. Quiet to unsettled conditions are expected on day three (02
October).
III.  Event Probabilities 30 Sep-02 Oct
Class M    60/60/60
Class X    30/30/30
Proton     15/15/15
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           29 Sep 137
Predicted   30 Sep-02 Oct  140/140/140
90 Day Mean        29 Sep 110
V.  Geomagnetic A Indices
Observed Afr/Ap 28 Sep  013/024
Estimated Afr/Ap 29 Sep  015/015
Predicted Afr/Ap 30 Sep-02 Oct  010/012-008/010-005/005
VI.  Geomagnetic Activity Probabilities 30 Sep-02 Oct
A.  Middle Latitudes
Active                20/10/05
Minor storm           05/01/01
Major-severe storm    01/01/01
B.  High Latitudes
Active                25/10/05
Minor storm           05/05/01
Major-severe storm    01/01/01