Joint USAF/NOAA Report of Solar and Geophysical Activity 27 April 2012

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.
Updated 2012 Apr 27 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 118 Issued at 2200Z on 27 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 26/2100Z
to 27/2100Z: Solar activity was at moderate levels due to an M1/1n
flare at 27/0824Z from Region 1466 (N11W38). Other activity
consisted of single, low-level C-class flares from Regions 1459
(S19W88), 1465 (S17W53), 1467 (N11E32), 1469 (S24E28) and 1466.
During the period, Region 1465 developed into a beta-gamma-delta
magnetic configuration while the remaining regions showed little
change. Numerous non-Earth directed CMEs were observed off the SW
limb over the past 24 hours, all originating from old Region 1462
(S25, L=139) which rotated around the west on 24 April.

IB. Solar Activity Forecast: Solar activity is expected to be low
with a slight chance for M-class activity for the next three days
(28 – 30 April).

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:
The geomagnetic field was at quiet to unsettled levels. Through the
period, ACE solar wind velocities steadily decreased from about 560
km/s to near 500km/s while the Bz component of the interplanetary
magnetic field was variable between +/-4 nT. The greater than 2 MeV
electron flux at geosynchronous orbit was at high levels throughout
the period.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominately quiet levels for the next three days
(28 – 30 April).

III. Event Probabilities 28 Apr-30 Apr
Class M 20/20/20
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 27 Apr 118
Predicted 28 Apr-30 Apr 115/110/110
90 Day Mean 27 Apr 112

V. Geomagnetic A Indices
Observed Afr/Ap 26 Apr 017/020
Estimated Afr/Ap 27 Apr 006/008
Predicted Afr/Ap 28 Apr-30 Apr 004/005-004/005-004/005

VI. Geomagnetic Activity Probabilities 28 Apr-30 Apr
A. Middle Latitudes
Active 10/10/10
Minor storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 10/10/10
Minor storm 01/01/01
Major-severe storm 01/10/01