Report of Solar-Geophysical Activity

Issued: 2011 Dec 26 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 360 Issued at 2200Z on 26 Dec 2011

IA.  Analysis of Solar Active Regions and Activity from  25/2100Z
to 26/2100Z:  Solar activity has been at moderate levels for the past
24 hour. Region 1387 (S22W42) has produced two M-class flares, the
largest being an M2/Sf event at 26/2030Z. Region 1387 continues to
grow, in areal coverage and magnetic complexity as it rotates into a
more geoeffective location. Region 1386 (S17E37) also continues to
grow and evolve. A proton enhancement at geosynchronous orbit was
observed by the GOES 13 spacecraft, with a max flux of 3 pfu at
26/0135. This enhancement appears to be correlated to the M4/1n
flare from Region 1387 on 25 December. Protons were again at
background level at the time of this report. Over the past 36 hours,
5 CME's have been observed in STEREO and LASCO C2 and C3 imagery.
Three CME's were associated with eruptive filaments and two were
associated with flares from Region 1387. Of these five CME's two are
forecast to become geoeffective.
IB.  Solar Activity Forecast:  Solar activity is expected to be at
moderate levels with a slight chance for X-class events for the next
three days (27 - 29 December).
IIA.  Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field has been at quiet levels for the past 24 hours.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to remain at predominantly quiet levels on day one (27
December). An increase to quiet to active levels with a chance for
an isolated minor storm period on days two and three (28 -29
December) is expected as two CME's, from filament eruptions on 25
December and 26 December, are expected to arrive on 28 December and
early on 29 December,  respectfully.
III.  Event Probabilities 27 Dec-29 Dec
Class M    70/70/70
Class X    10/10/10
Proton     10/10/10
PCAF       Green
IV.  Penticton 10.7 cm Flux
Observed           26 Dec 146
Predicted   27 Dec-29 Dec  150/150/145
90 Day Mean        26 Dec 144
V.  Geomagnetic A Indices
Observed Afr/Ap 25 Dec  003/002
Estimated Afr/Ap 26 Dec  001/001
Predicted Afr/Ap 27 Dec-29 Dec  004/005-013/018-015/018
VI.  Geomagnetic Activity Probabilities 27 Dec-29 Dec
A.  Middle Latitudes
Active                01/40/40
Minor storm           01/25/25
Major-severe storm    01/05/05
B.  High Latitudes
Active                15/40/40
Minor storm           05/30/30
Major-severe storm    01/15/20