Joint USAF/NOAA Report of Solar and Geophysical Activity 12 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 12 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 103 Issued at 2200Z on 12 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 11/2100Z
to 12/2100Z: Solar activity has been at very low levels for the past
24 hours. Region 1455 (N06W05) has been the most active region
producing multiple B-class x-ray events. Region 1455 has shown rapid
growth in area and magnetic complexity, now a D-type beta group. New
Region 1456 (S20W19) was numbered today. Multiple CMEs were observed
during the period but none appear to be Earth directed.

IB. Solar Activity Forecast: Solar activity is expected to be at
very low levels with a chance for C-class activity for the next
three days (13 – 15 April) as Regions 1455 and 1456 continue to grow
and evolve.

IIA. Geophysical Activity Summary 11/2100Z to 12/2100Z:
The geomagnetic field has been at quiet to active levels over the
past 24 hours. Characteristics of an anticipated high speed solar
wind stream from a coronal hole were observed by the ACE spacecraft,
with subsequent elevated geomagnetic levels here at Earth.
Measurements from the ACE spacecraft showed an increase in solar
wind speeds from around 370 km/s to around 600 km/s with the total
IMF hovering around 12 nT.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at unsettled to active levels with the chance for
minor storm periods on day one (13 April) as the effects of a
coronal hole high speed stream (CH HSS) continue. Quiet to unsettled
levels with a chance for active periods are expected on day two (14
April) as the effects of the CH HSS wane. Predominantly quiet levels
are expected on day three (15 April) as the geomagnetic field
returns to nominal levels.

III. Event Probabilities 13 Apr-15 Apr
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 12 Apr 095
Predicted 13 Apr-15 Apr 095/095/095
90 Day Mean 12 Apr 114

V. Geomagnetic A Indices
Observed Afr/Ap 11 Apr 005/004
Estimated Afr/Ap 12 Apr 009/010
Predicted Afr/Ap 13 Apr-15 Apr 013/018-010/010-009/008

VI. Geomagnetic Activity Probabilities 13 Apr-15 Apr
A. Middle Latitudes
Active 35/30/25
Minor storm 10/10/10
Major-severe storm 01/01/01
B. High Latitudes
Active 40/35/30
Minor storm 30/20/15
Major-severe storm 15/10/10