Joint USAF/NOAA Report of Solar and Geophysical Activity 22 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 22 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 113 Issued at 2200Z on 22 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 21/2100Z
to 22/2100Z: Solar activity was low. Occasional low-level C-class
flares occurred. Region 1459 (S15W25 – Dki/beta) produced a single
C-class flare and showed signs of gradual decay in its intermediate
portion. Region 1465 (S18E14 – Dai/beta) produced two C-class flares
and showed spot and penumbral development as well as some polarity
mixing in its intermediate portion. New Region 1466 (N12E29 –
Cso/beta) emerged early in the period and gradually grew. No
Earth-directed CMEs were observed during the period.

IB. Solar Activity Forecast: Solar activity is expected to be low
through the period (23 – 25 April) with a chance for an isolated
M-class flare.

IIA. Geophysical Activity Summary 21/2100Z to 22/2100Z:
Geomagnetic field activity was at quiet to unsettled levels with a
brief interval of active levels at high latitudes.

IIB. Geophysical Activity Forecast: Geomagnetic field activity is
expected to be at quiet to unsettled levels during days 1 – 2 (23 –
24 April) with a chance for active levels due mainly to a recurrent
coronal hole high-speed stream. Weak CME-passage effects are also
possible on day 1 from the partial-halo CME observed on 19 April.
Field activity is expected to decrease to mostly quiet levels on day
3 (25 April).

III. Event Probabilities 23 Apr-25 Apr
Class M 30/30/30
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 22 Apr 148
Predicted 23 Apr-25 Apr 145/145/140
90 Day Mean 22 Apr 112

V. Geomagnetic A Indices
Observed Afr/Ap 21 Apr 006/008
Estimated Afr/Ap 22 Apr 008/012
Predicted Afr/Ap 23 Apr-25 Apr 010/010-008/010-007/008

VI. Geomagnetic Activity Probabilities 23 Apr-25 Apr
A. Middle Latitudes
Active 25/25/15
Minor storm 05/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 30/30/20
Minor storm 10/10/01
Major-severe storm 01/01/01