Joint USAF/NOAA Report of Solar and Geophysical Activity 24 September 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Sep 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 267 Issued at 2200Z on 24 Sep 2011
IA. Analysis of Solar Active Regions and Activity from 23/2100Z
to 24/2100Z: Solar activity was high. Region 1302 (N12E47) produced
a X1/2b flare at 24/0940Z, a M7 long duration x-ray flare at
24/1320Z, and a M5 x-ray flare at 24/2036Z. Coronal mass ejections
(CMEs) were observed in association with the first two of these
events. The second CME, which was must faster, appears to overtake
the first, and has a partial halo signature from the LASCO/Earth
perspective. Estimate speeds of the CME range between 1900 – 2600
km/s. Region 1302 produced three other flares greater than M1 during
the period. Region 1295 (N26W84) produced a M3 x-ray flare at
24/1725Z. Another large sunspot is beginning to emerge around the
East limb of the disk near N15.
IB. Solar Activity Forecast: Solar activity is expected to be high
to very high for the next 3 days (25-27 September) due to the
activity produced by Region 1302.
IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z:
The geomagnetic field was quiet. The greater than 10MeV proton flux
at geosynchronous orbit exceeded the 10 pfu threshold at 23/2255Z,
peaked at 12 pfu during the day, and remains above threshold at the
time of this report. The noon F10 solar flux was observed at 190,
but is believed to be enhanced by the flares which occurred today.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be mostly quiet to unsettled on day 1 (25 September) due
to recurrent coronal hole effects. Conditions are forecast to
increase to unsettled to minor storm levels with the chance for a
major storm starting late on day 1 through midday on day 2 (26
September) due to the anticipated partial impact from the CME from
earlier today. Conditions are forecast to carry over to day 3 (27
September) with mostly unsettled to active periods expected. The
greater than 10 MeV proton flux is expected to remain above the 10
pfu threshold for days 1 and 2, before decreasing on day 3.
III. Event Probabilities 25 Sep-27 Sep
Class M 80/80/80
Class X 40/40/40
Proton 99/99/80
PCAF yellow
IV. Penticton 10.7 cm Flux
Observed 24 Sep 190
Predicted 25 Sep-27 Sep 160/160/160
90 Day Mean 24 Sep 107
V. Geomagnetic A Indices
Observed Afr/Ap 23 Sep 002/003
Estimated Afr/Ap 24 Sep 005/005
Predicted Afr/Ap 25 Sep-27 Sep 010/010-025/030-012/012
VI. Geomagnetic Activity Probabilities 25 Sep-27 Sep
A. Middle Latitudes
Active 40/10/10
Minor storm 30/50/40
Major-severe storm 01/30/20
B. High Latitudes
Active 40/10/10
Minor storm 30/60/60
Major-severe storm 01/30/30