Joint USAF/NOAA Report of Solar and Geophysical Activity 19 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 19 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 110 Issued at 2200Z on 19 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 18/2100Z
to 19/2100Z: Solar activity was low. The largest event of the period
was a C7 x-ray flare at 19/1126Z associated with Types II and IV
radio sweeps and a non-Earth-directed CME. This event may have
originated in old Region 1455 (N05, L=206), now about two days
beyond the west limb. Regions 1460 (N16W01) and 1463 (S26W49) each
produced a low-level C-class flare. Region 1460 showed spot growth
in its intermediate portion. Region 1462 (S24W31) produced a C1
flare at 19/1515Z associated with a CME that may have had an
Earthward component. Further analysis is required to determine if
the CME is likely to be geoeffective. New Region 1464 (N23E01,
Bxo-Beta) was numbered.

IB. Solar Activity Forecast: Solar activity is expected to be low
during days 1 – 3 (20 – 22 April) with a chance for an isolated
M-class flare.

IIA. Geophysical Activity Summary 18/2100Z to 19/2100Z:
The geomagnetic field was quiet.

IIB. Geophysical Activity Forecast: Geomagnetic field activity is
expected to be at quiet to unsettled levels on day 1 (20 April) with
a chance for brief active levels due to a recurrent solar sector
boundary crossing. Quiet levels are expected during days 2- 3 (21 –
22 April).

III. Event Probabilities 20 Apr-22 Apr
Class M 30/30/30
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 19 Apr 138
Predicted 20 Apr-22 Apr 135/135/135
90 Day Mean 19 Apr 112

V. Geomagnetic A Indices
Observed Afr/Ap 18 Apr 007/008
Estimated Afr/Ap 19 Apr 004/005
Predicted Afr/Ap 20 Apr-22 Apr 007/008-004/005-003/005

VI. Geomagnetic Activity Probabilities 20 Apr-22 Apr
A. Middle Latitudes
Active 25/10/10
Minor storm 05/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 35/15/15
Minor storm 15/01/01
Major-severe storm 01/01/01